Science.gov

Sample records for acquired cloud cover

  1. Cloud Cover

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

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

  2. Estimating Cloud Cover

    ERIC Educational Resources Information Center

    Moseley, Christine

    2007-01-01

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

  3. Automatic cloud cover mapping.

    NASA Technical Reports Server (NTRS)

    Strong, J. P., III; Rosenfeld, A.

    1971-01-01

    A method of converting a picture into a 'cartoon' or 'map' whose regions correspond to differently textured regions is described. Texture edges in the picture are detected, and solid regions surrounded by these (usually broken) edges are 'colored in' using a propagation process. The resulting map is cleaned by comparing the region colors with the textures of the corresponding regions in the picture, and also by merging some regions with others according to criteria based on topology and size. The method has been applied to the construction of cloud cover maps from cloud cover pictures obtained by satellites.

  4. Methods for Cloud Cover Estimation

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Several methods for cloud cover estimation are described relevant to assessing the performance of a ground-based network of solar observatories. The methods rely on ground and satellite data sources and provide meteorological or climatological information. One means of acquiring long-term observations of solar oscillations is the establishment of a ground-based network of solar observatories. Criteria for station site selection are: gross cloudiness, accurate transparency information, and seeing. Alternative methods for computing this duty cycle are discussed. The cycle, or alternatively a time history of solar visibility from the network, can then be input to a model to determine the effect of duty cycle on derived solar seismology parameters. Cloudiness from space is studied to examine various means by which the duty cycle might be computed. Cloudiness, and to some extent transparency, can potentially be estimated from satellite data.

  5. Seasons on Venus - cloud cover signatures

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay; Markiewicz, Wojciech; Krauss, Robert

    2015-04-01

    With the smallest obliquity and orbital eccentricity of any planet around the Sun, Venus is not generally expected to show any seasonal variations in its atmosphere. Careful analysis of the global images obtained by the Venus Monitoring Camera (VMC) on board European Space Agency's Venus Express orbiter from 12 June 2006 orbit 24) till 15 September 2014 (orbit 3043) reveal short term variations and a detectable periodic variation in the normalized intensity (reflectance) as well as in unit optical depth at a fixed local time at low latitudes as well as at high latitudes. VMC ultraviolet images were brightness normalized using Minnaert Law and the brightness at the sub-solar meridian at different latitudes in the southern hemisphere. The unit optical dept was inferred by precision location of the limb location in images acquired during the apoapsis portion of the orbit at range greater than ~ 30,000 km from Venus center. The temporal changes of the unit optical depth was monitored at fixed solar zenith angles and latitude. The seasonal signature is more pronounced at high latitudes compared to low latitudes. The data suggest that the variations in insolation due to heliocentric range and the small obliquity are responsible for the periodic changes in the Venus cloud cover. Concurrent changes in the cloud changes are also observed at other three wavelengths (550, 950 and 1050 nm) at which VMC obtained images, but the number of images at these wavelengths is much smaller. A secular decrease in the image brightness is observed over the life of the Venus Express mission, most likely due to the degradation of the some of the optical/sensor elements.

  6. Some new worldwide cloud-cover models

    NASA Technical Reports Server (NTRS)

    Bean, S. J.; Somerville, P. N.

    1981-01-01

    Using daily measurements of day and night infrared, and incoming and absorbed solar radiation obtained from a Tiros satellite over a period of approximately 45 months, and integrated over 2.5 deg latitude-longitude grids, the proportion of cloud cover over each grid each day was derived for the entire period. For each of four 3-month periods, for each grid location, estimates a and b of the two parameters of the best-fit beta distribution were obtained. The (a, b) plane was divided into a number of regions. All the geographical locations whose (a, b) estimates were in the same region in the (a, b) plane were said to have the same cloud cover type for that season. For each season, the world is thus divided into separate cloud-cover types.

  7. The beta distribution: A statistical model for world cloud cover

    NASA Technical Reports Server (NTRS)

    Falls, L. W.

    1973-01-01

    Much work has been performed in developing empirical global cloud cover models. This investigation was made to determine an underlying theoretical statistical distribution to represent worldwide cloud cover. The beta distribution with probability density function is given to represent the variability of this random variable. It is shown that the beta distribution possesses the versatile statistical characteristics necessary to assume the wide variety of shapes exhibited by cloud cover. A total of 160 representative empirical cloud cover distributions were investigated and the conclusion was reached that this study provides sufficient statical evidence to accept the beta probability distribution as the underlying model for world cloud cover.

  8. Cloud cover analysis with Arctic AVHRR data: 1. Cloud detection

    NASA Astrophysics Data System (ADS)

    Key, J.; Barry, R. G.

    1989-12-01

    Automated analyses of satellite radiance data have concentrated heavily on low and middle latitude situations. Some of the design objectives for the International Satellite Cloud Climatology Project (ISCCP) cloud detection procedure such as space and time contrasts are used in a basic algorithm from which a polar cloud detection algorithm is developed. This algorithm is applied to Arctic data for January and July conditions. Both advanced very high resolution radiometer (AVHRR) and scanning multichannel microwave radiometer (SMMR) data are utilized. Synthetic AVHRR and SMMR data for a 7-day analysis period are also generated to provide a data set with known characteristics on which to test and validate algorithms. Modifications to the basic algorithm for polar conditions include the use of SMMR and SMMR-derived data sets for the estimation of surface parameters, elimination of the spatial test for the warmest pixel, the use of AVHRR channels 1 (0.7 μm), 3 (3.7 μm), and 4 (11 μm) in the temporal tests and the final multispectral thresholding, and the use of surface class characteristic values when clear-sky values cannot be obtained. Additionally, the difference between channels 3 and 4 is included in the temporal test for the detection of optically thin cloud. Greatest improvement in computed cloud fraction is realized over snow and ice surfaces; over open water or snow-free land, all versions perform similarly. Since the inclusion of SMMR for surface analysis and additional spectral channels increases the computational burden, its use may be justified only over snow and ice-covered regions.

  9. Shuttle landing facility cloud cover study: Climatological analysis and two tenths cloud cover rule evaluation

    NASA Technical Reports Server (NTRS)

    Atchison, Michael K.; Schumann, Robin; Taylor, Greg; Warburton, John; Wheeler, Mark; Yersavich, Ann

    1993-01-01

    The two-tenths cloud cover rule in effect for all End Of Mission (EOM) STS landings at the Kennedy Space Center (KSC) states: 'for scattered cloud layers below 10,000 feet, cloud cover must be observed to be less than or equal to 0.2 at the de-orbit burn go/no-go decision time (approximately 90 minutes before landing time)'. This rule was designed to protect against a ceiling (below 10,000 feet) developing unexpectedly within the next 90 minutes (i.e., after the de-orbit burn decision and before landing). The Applied Meteorological Unit (AMU) developed and analyzed a database of cloud cover amounts and weather conditions at the Shuttle Landing Facility for a five-year (1986-1990) period. The data indicate the best time to land the shuttle at KSC is during the summer while the worst time is during the winter. The analysis also shows the highest frequency of landing opportunities occurs for the 0100-0600 UTC and 1300-1600 UTC time periods. The worst time of the day to land a shuttle is near sunrise and during the afternoon. An evaluation of the two-tenths cloud cover rule for most data categorizations has shown that there is a significant difference in the proportions of weather violations one and two hours subsequent to initial conditions of 0.2 and 0.3 cloud cover. However, for May, Oct., 700 mb northerly wind category, 1500 UTC category, and 1600 UTC category there is some evidence that the 0.2 cloud cover rule may be overly conservative. This possibility requires further investigation. As a result of these analyses, the AMU developed nomograms to help the Spaceflight Meteorological Group (SMG) and the Cape Canaveral Forecast Facility (CCFF) forecast cloud cover for EOM and Return to Launch Site (RTLS) at KSC. Future work will include updating the two tenths database, further analysis of the data for several categorizations, and developing a proof of concept artificial neural network to provide forecast guidance of weather constraint violations for shuttle

  10. Validation of Land Cover Maps Utilizing Astronaut Acquired Imagery

    NASA Technical Reports Server (NTRS)

    Estes, John E.; Gebelein, Jennifer

    1999-01-01

    This report is produced in accordance with the requirements outlined in the NASA Research Grant NAG9-1032 titled "Validation of Land Cover Maps Utilizing Astronaut Acquired Imagery". This grant funds the Remote Sensing Research Unit of the University of California, Santa Barbara. This document summarizes the research progress and accomplishments to date and describes current on-going research activities. Even though this grant has technically expired, in a contractual sense, work continues on this project. Therefore, this summary will include all work done through and 5 May 1999. The principal goal of this effort is to test the accuracy of a sub-regional portion of an AVHRR-based land cover product. Land cover mapped to three different classification systems, in the southwestern United States, have been subjected to two specific accuracy assessments. One assessment utilizing astronaut acquired photography, and a second assessment employing Landsat Thematic Mapper imagery, augmented in some cases, high aerial photography. Validation of these three land cover products has proceeded using a stratified sampling methodology. We believe this research will provide an important initial test of the potential use of imagery acquired from Shuttle and ultimately the International Space Station (ISS) for the operational validation of the Moderate Resolution Imaging Spectrometer (MODIS) land cover products.

  11. A cloud cover model based on satellite data

    NASA Technical Reports Server (NTRS)

    Somerville, P. N.; Bean, S. J.

    1980-01-01

    A model for worldwide cloud cover using a satellite data set containing infrared radiation measurements is proposed. The satellite data set containing day IR, night IR and incoming and absorbed solar radiation measurements on a 2.5 degree latitude-longitude grid covering a 45 month period was converted to estimates of cloud cover. The global area was then classified into homogeneous cloud cover regions for each of the four seasons. It is noted that the developed maps can be of use to the practicing climatologist who can obtain a considerable amount of cloud cover information without recourse to large volumes of data.

  12. Cloud cover models derived from satellite radiation measurements

    NASA Technical Reports Server (NTRS)

    Bean, S. J.; Somerville, P. N.

    1979-01-01

    Using daily measurement of day and night infrared and incoming and absorbed solar radiation obtained from a TIROS satellite over a period of approximately 45 months, and integrated over 2.5 degree latitude-longitude grids, the proportion of cloud cover over each grid each day was derived for the entire period. For each of four three-month periods, estimates a and b of the two parameters of the best-fit beta distribution were obtained for each grid location. The (a,b) plane was divided into a number of regions. All the geographical locations whose (a,b) estimates were in the same region in the (a,b) plane were said to have the same cloud cover type for that season. For each season, the world was thus divided into separate cloud cover types. Using estimates of mean cloud cover for each season, the world was again divided into separate cloud cover types. The process was repeated for standard deviations. Thus for each season, three separate cloud cover models were obtained using the criteria of shape of frequency distribution, mean cloud cover, and variability of cloud cover. The cloud cover statistics were derived from once-a-day, near-local-noon satellite radiation measurements.

  13. Albedo climatology analysis and the determination of fractional cloud cover

    NASA Technical Reports Server (NTRS)

    Curran, R. J.; Wexler, R.; Nack, M. L.

    1978-01-01

    Monthly and zonally averaged surface cover climatology data are presented which are used to construct monthly and zonally averaged surface albedos. The albedo transformations are then applied to the surface albedos, using solar zenith angles characteristic of the Nimbus 6 satellite local sampling times, to obtain albedos at the top of clear and totally cloud covered atmospheres. These albedos are then combined with measured albedo data to solve for the monthly and zonally averaged fractional cloud cover. The measured albedo data were obtained from the wide field of view channels of the Nimbus 6 Earth Radiation Budget experiment, and consequently the fractional cloud cover results are representative of the local sampling times. These fractional cloud cover results are compared with recent studies. The cloud cover results not only show peaks near the intertropical convergence zone, but the monthly migration of the position of these peaks follows general predictions of atmospheric circulation studies.

  14. Smoke and Pollution Aerosol Effect on Cloud Cover

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Koren, Ilan

    2006-01-01

    Pollution and smoke aerosols can increase or decrease the cloud cover. This duality in the effects of aerosols forms one of the largest uncertainties in climate research. Using solar measurements from Aerosol Robotic Network sites around the globe, we show an increase in cloud cover with an increase in the aerosol column concentration and an inverse dependence on the aerosol absorption of sunlight. The emerging rule appears to be independent of geographical location or aerosol type, thus increasing our confidence in the understanding of these aerosol effects on the clouds and climate. Preliminary estimates suggest an increase of 5% in cloud cover.

  15. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Key, J. R.; Maslanik, J. A.

    1988-01-01

    The principal objectives of this project are: (1) to develop suitable validation data sets to evaluate the effectiveness of the International Satellite Cloud Climatology Project (ISCCP) operational algorithm for cloud retrieval in polar regions and to validate model simulations of polar cloud cover; (2) to identify limitations of current procedures for varying atmospheric surface conditions, and to explore potential means to remedy them using textural classifiers; and (3) to compare synoptic cloud data from a control run experiment of the GISS climate model II with typical observed synoptic cloud patterns.

  16. Cloud Cover and Wildfire Variations in Vietnam and Southeast Asia

    NASA Astrophysics Data System (ADS)

    Lasko, K.

    2015-12-01

    Monitoring fires from space is constrained by cloud cover, particularly in tropical regions. Cloud cover-fire variations were assessed using the CERES SSF1Deg and MODIS active fire (MCD14ML) products in Vietnam and Southeast Asia. Twelve years (2003-2014) of data have been analyzed spatially and temporally at four spatial scales: a) country level; b). 1x1 degree scale; c). land cover type; d). regions. Country-level results suggested Vietnam having the highest monthly cloud cover (72.37%) followed by Cambodia (69.69%), Laos (67.64%), Thailand (67.58%), and Myanmar (59.90%). Strong negative correlation between cloud cover and MODIS active fires has been observed during the biomass burning months (Jan-Apr). Of the different countries, Vietnam also had the lowest monthly fire detections. Pixel by pixel spatial correlation at 1x1 degree suggested negative fire-cloud relationships over the Red River Delta of Vietnam, the forests of northern Laos, and agriculture-dominated peninsulas of Thailand and Myanmar. Among the different land cover types, the average monthly cloud cover varied between 64% - 66%. Further, results from daily data showed the Red River Delta to have consistently more cloud cover (20-40% more) than the Mekong River Delta in Vietnam, with fewer fire detections in the former than the latter. The study highlights potential fire under-detection due to clouds. Our results highlight spatial and temporal variations in cloud-fire relationships and the difficulty of using optical data for fire detection and characterization in persistently cloudy regions.

  17. Observational evidence for cloud cover enhancement over western European forests

    NASA Astrophysics Data System (ADS)

    Teuling, Adriaan J.; Taylor, Christopher M.; Meirink, Jan Fokke; Melsen, Lieke A.; Miralles, Diego G.; van Heerwaarden, Chiel C.; Vautard, Robert; Stegehuis, Annemiek I.; Nabuurs, Gert-Jan; de Arellano, Jordi Vilà-Guerau

    2017-01-01

    Forests impact regional hydrology and climate directly by regulating water and heat fluxes. Indirect effects through cloud formation and precipitation can be important in facilitating continental-scale moisture recycling but are poorly understood at regional scales. In particular, the impact of temperate forest on clouds is largely unknown. Here we provide observational evidence for a strong increase in cloud cover over large forest regions in western Europe based on analysis of 10 years of 15 min resolution data from geostationary satellites. In addition, we show that widespread windthrow by cyclone Klaus in the Landes forest led to a significant decrease in local cloud cover in subsequent years. Strong cloud development along the downwind edges of larger forest areas are consistent with a forest-breeze mesoscale circulation. Our results highlight the need to include impacts on cloud formation when evaluating the water and climate services of temperate forests, in particular around densely populated areas.

  18. Observational evidence for cloud cover enhancement over western European forests

    PubMed Central

    Teuling, Adriaan J.; Taylor, Christopher M.; Meirink, Jan Fokke; Melsen, Lieke A.; Miralles, Diego G.; van Heerwaarden, Chiel C.; Vautard, Robert; Stegehuis, Annemiek I.; Nabuurs, Gert-Jan; de Arellano, Jordi Vilà-Guerau

    2017-01-01

    Forests impact regional hydrology and climate directly by regulating water and heat fluxes. Indirect effects through cloud formation and precipitation can be important in facilitating continental-scale moisture recycling but are poorly understood at regional scales. In particular, the impact of temperate forest on clouds is largely unknown. Here we provide observational evidence for a strong increase in cloud cover over large forest regions in western Europe based on analysis of 10 years of 15 min resolution data from geostationary satellites. In addition, we show that widespread windthrow by cyclone Klaus in the Landes forest led to a significant decrease in local cloud cover in subsequent years. Strong cloud development along the downwind edges of larger forest areas are consistent with a forest-breeze mesoscale circulation. Our results highlight the need to include impacts on cloud formation when evaluating the water and climate services of temperate forests, in particular around densely populated areas. PMID:28074840

  19. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Key, J. R.; Maslanik, J. A.

    1988-01-01

    The principal objectives of this project are: to develop suitable validation data sets to evaluate the effectiveness of the ISCCP operational algorithm for cloud retrieval in polar regions and to validate model simulations of polar cloud cover; to identify limitations of current procedures for varying atmospheric surface conditions, and to explore potential means to remedy them using textural classifiers: and to compare synoptic cloud data from a control run experiment of the Goddard Institute for Space Studies (GISS) climate model 2 with typical observed synoptic cloud patterns. Current investigations underway are listed and the progress made to date is summarized.

  20. Cloud cover estimation optical package: New facility, algorithms and techniques

    NASA Astrophysics Data System (ADS)

    Krinitskiy, Mikhail

    2017-02-01

    Short- and long-wave radiation is an important component of surface heat budget over sea and land. For estimating them accurate observations of the cloud cover are needed. While massively observed visually, for building accurate parameterizations cloud cover needs also to be quantified using precise instrumental measurements. Major disadvantages of the most of existing cloud-cameras are associated with their complicated design and inaccuracy of post-processing algorithms which typically result in the uncertainties of 20% to 30% in the camera-based estimates of cloud cover. The accuracy of these types of algorithm in terms of true scoring compared to human-observed values is typically less than 10%. We developed new generation package for cloud cover estimating, which provides much more accurate results and also allows for measuring additional characteristics. New algorithm, namely SAIL GrIx, based on routine approach, also developed for this package. It uses the synthetic controlling index ("grayness rate index") which allows to suppress the background sunburn effect. This makes it possible to increase the reliability of the detection of the optically thin clouds. The accuracy of this algorithm in terms of true scoring became 30%. One more approach, namely SAIL GrIx ML, we have used to increase the cloud cover estimating accuracy is the algorithm that uses machine learning technique along with some other signal processing techniques. Sun disk condition appears to be a strong feature in this kind of models. Artificial Neural Networks type of model demonstrates the best quality. This model accuracy in terms of true scoring increases up to 95,5%. Application of a new algorithm lets us to modify the design of the optical sensing package and to avoid the use of the solar trackers. This made the design of the cloud camera much more compact. New cloud-camera has already been tested in several missions across Atlantic and Indian oceans on board of IORAS research vessels.

  1. Modelling the Global Cloud Cover of HD 189733b

    NASA Astrophysics Data System (ADS)

    Huat Lee, Graham Kim; Helling, Christiane; Dobbs-Dixon, Ian; Juncher, Diana

    2015-12-01

    Context.Each rain droplet on Earth contains a microscopic condensation seed of sand or ash at its center, leading to more efficient water droplet formation than supersaturated vapour alone. Similarly, in hot Jupiter atmospheres, the formation of seed particles from the gas phase allows the condensation of solid mineral compounds such as Iron, Quartz and Enstatites. Recent observations of the atmosphere on HD 189733b suggest that clouds form in its atmosphere. Clouds have a large effect on the local thermodynamic and chemical properties of the atmosphere. The different thermodynamic conditions on the dayside and nightside will result in locally different cloud structures.Aims.Inspired by mineral cloud modelling efforts for Brown Dwarf atmospheres, we present spatially varying kinetic cloud model structures for HD 189733b. We investigate the resulting cloud properties at the dayside, nightside and terminator regions of the planet.Methods.We apply a 2-model approach, using results from a 3D radiative-hydrodynamic (RHD) simulation of the atmosphere of HD 189733b and our kinetic cloud formation model. 1D Tgas-pgas profiles at the equator and +45 latitude covering the dayside, nightside and terminator regions of the simulation were chosen as input for the cloud formation model. Effective medium theory and Mie theory are applied to calculate the wavelength dependent opacity of the cloud materials.Results.We present results of the local cloud properties such as number density, size, composition and opacity at the chosen locations. The mean grain size varies between nm at the cloud deck to mm sizes at the cloud base. Cloud particle sizes in the upper atmosphere were found to be one order of magnitude larger on the dayside compared to the nightside. More efficient nucleation of cloud particles on the nightside leads to larger number densities compared to the dayside. The solid composition of cloud particles throughout the atmosphere is dominated by a combination of Silicate

  2. Cloud cover retrieved from skyviewer: A validation with human observations

    NASA Astrophysics Data System (ADS)

    Kim, Bu-Yo; Jee, Joon-Bum; Zo, Il-Sung; Lee, Kyu-Tae

    2016-02-01

    Cloud cover information is used alongside weather forecasts in various fields of research; however, ground observation of cloud cover is conducted by human observers, a method that is subjective and has low temporal and spatial resolutions. To address these problems, we have developed an improved algorithm to calculate cloud cover using sky image data obtained with Skyviewer equipment. The algorithm uses a variable threshold for the Red Blue Ratio (RBR), determined from the frequency distribution of the Green Blue Ratio (GBR), to calculate cloud cover more accurately than existing algorithms. To verify the accuracy of the algorithm, we conducted daily, monthly, seasonal, and yearly statistical analyses of human observations of cloud cover, obtained every hour from 0800 to 1700 Local Standard Time (LST) for the entirety of 2012 at the Gangwon Regional Meteorological Administration (GRMA), Korea. A case study compared daily images taken at 1200 LST in each season with pixel images of cloud cover calculated by our improved algorithm. The selected cases yielded a high correlation coefficient of 0.93 with the GRMA data. A monthly case study showed low root mean square errors (RMSEs) and high correlation coefficients (Rs) for December (RMSE = 1.64 tenths and R = 0.92) and August (RMSE = 1.43 tenths and R = 0.91). In addition, seasonal cases yielded a high correlation of 0.9 and 87% consistency within ± 2 tenths for winter and a correlation of 0.83 and 82% consistency for summer, when cases of cloud-free or overcast conditions are frequent. Annual analyses showed that the bias of GRMA and Skyviewer cloud cover data for 2012 was -0.36 tenth, and the RMSE was 2.12 tenths, with the GRMA data showing more cloud cover. Considering that the GRMA and Skyviewer data were gathered at different spatial locations, GRMA and Skyviewer data were well correlated (R = 0.87) and showed a consistency of 80% in their cloud cover data (consistent within ± 2 tenths).

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  4. THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA

    SciTech Connect

    Line, Michael R.; Parmentier, Vivien

    2016-03-20

    We model the impact of nonuniform cloud cover on transit transmission spectra. Patchy clouds exist in nearly every solar system atmosphere, brown dwarfs, and transiting exoplanets. Our major findings suggest that fractional cloud coverage can exactly mimic high mean molecular weight atmospheres and vice versa over certain wavelength regions, in particular, over the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) bandpass (1.1–1.7 μm). We also find that patchy cloud coverage exhibits a signature that is different from uniform global clouds. Furthermore, we explain analytically why the “patchy cloud-high mean molecular weight” degeneracy exists. We also explore the degeneracy of nonuniform cloud coverage in atmospheric retrievals on both synthetic and real planets. We find from retrievals on a synthetic solar composition hot Jupiter with patchy clouds and a cloud-free high mean molecular weight warm Neptune that both cloud-free high mean molecular weight atmospheres and partially cloudy atmospheres can explain the data equally well. Another key finding is that the HST WFC3 transit transmission spectra of two well-observed objects, the hot Jupiter HD 189733b and the warm Neptune HAT-P-11b, can be explained well by solar composition atmospheres with patchy clouds without the need to invoke high mean molecular weight or global clouds. The degeneracy between high molecular weight and solar composition partially cloudy atmospheres can be broken by observing the molecular Rayleigh scattering differences between the two. Furthermore, the signature of partially cloudy limbs also appears as a ∼100 ppm residual in the ingress and egress of the transit light curves, provided that the transit timing is known to seconds.

  5. Clouds and relative humidity in climate models; or what really regulates cloud cover?

    SciTech Connect

    Walcek, C.

    1995-09-01

    The response and impact of clouds remains one of the largest outstanding questions in GCMs. Clouds are not homogeneous, though they are treated as such in the models. When averaged over areas typically used as numerical grid elements by GCMs, observations suggest that there are some clouds at all relative humidities. Fractional cloud cover at 100% relative humidity is rarely 100%, and totally clear skies rarely occur, even for low relative humidities. Relative humidity is the best single indicator of cloud coverage. However, if there is a relationship between cloud coverage and relative humidity, our current models and observations are inadequate to reveal exactly what that relationship is. It does appear that cloud coverage decreases exponentially as humidity falls below 100%. 2 refs., 2 figs.

  6. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Key, J.

    1989-01-01

    The objectives are to develop a suitable validation data set for evaluating the effectiveness of the International Satellite Cloud Climatology Project (ISCCP) algorithm for cloud retrieval in polar regions, to identify limitations of current procedures and to explore potential means to remedy them using textural classifiers, and to compare synoptic cloud data from model runs with observations. Toward the first goal, a polar data set consisting of visible, thermal, and passive microwave data was developed. The AVHRR and SMMR data were digitally merged to a polar stereographic projection with an effective pixel size of 5 sq km. With this data set, two unconventional methods of classifying the imagery for the analysis of polar clouds and surfaces were examined: one based on fuzzy sets theory and another based on a trained neural network. An algorithm for cloud detection was developed from an early test version of the ISCCP algorithm. This algorithm includes the identification of surface types with passive microwave, then temporal tests at each pixel location in the cloud detection phase. Cloud maps and clear sky radiance composites for 5 day periods are produced. Algorithm testing and validation was done with both actural AVHRR/SMMR data, and simulated imagery. From this point in the algorithm, groups of cloud pixels are examined for their spectral and textural characteristics, and a procedure is developed for the analysis of cloud patterns utilizing albedo, IR temperature, and texture. In a completion of earlier work, empirical analyses of arctic cloud cover were explored through manual interpretations of DMSP imagery and compared to U.S. Air Force 3D-nephanalysis. Comparisons of observed cloudiness from existing climatologies to patterns computed by the GISS climate model were also made.

  7. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Maslanik, J. A.; Key, J. R.

    1987-01-01

    A definition is undertaken of the spectral and spatial characteristics of clouds and surface conditions in the polar regions, and to the creation of calibrated, geometrically correct data sets suitable for quantitative analysis. Ways are explored in which this information can be applied to cloud classifications as new methods or as extensions to existing classification schemes. A methodology is developed that uses automated techniques to merge Advanced Very High Resolution Radiometer (AVHRR) and Scanning Multichannel Microwave Radiometer (SMMR) data, and to apply first-order calibration and zenith angle corrections to the AVHRR imagery. Cloud cover and surface types are manually interpreted, and manual methods are used to define relatively pure training areas to describe the textural and multispectral characteristics of clouds over several surface conditions. The effects of viewing angle and bidirectional reflectance differences are studied for several classes, and the effectiveness of some key components of existing classification schemes is tested.

  8. D Land Cover Classification Based on Multispectral LIDAR Point Clouds

    NASA Astrophysics Data System (ADS)

    Zou, Xiaoliang; Zhao, Guihua; Li, Jonathan; Yang, Yuanxi; Fang, Yong

    2016-06-01

    Multispectral Lidar System can emit simultaneous laser pulses at the different wavelengths. The reflected multispectral energy is captured through a receiver of the sensor, and the return signal together with the position and orientation information of sensor is recorded. These recorded data are solved with GNSS/IMU data for further post-processing, forming high density multispectral 3D point clouds. As the first commercial multispectral airborne Lidar sensor, Optech Titan system is capable of collecting point clouds data from all three channels at 532nm visible (Green), at 1064 nm near infrared (NIR) and at 1550nm intermediate infrared (IR). It has become a new source of data for 3D land cover classification. The paper presents an Object Based Image Analysis (OBIA) approach to only use multispectral Lidar point clouds datasets for 3D land cover classification. The approach consists of three steps. Firstly, multispectral intensity images are segmented into image objects on the basis of multi-resolution segmentation integrating different scale parameters. Secondly, intensity objects are classified into nine categories by using the customized features of classification indexes and a combination the multispectral reflectance with the vertical distribution of object features. Finally, accuracy assessment is conducted via comparing random reference samples points from google imagery tiles with the classification results. The classification results show higher overall accuracy for most of the land cover types. Over 90% of overall accuracy is achieved via using multispectral Lidar point clouds for 3D land cover classification.

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

    SciTech Connect

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

    1988-12-01

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

  10. Statistical analysis of multivariate atmospheric variables. [cloud cover

    NASA Technical Reports Server (NTRS)

    Tubbs, J. D.

    1979-01-01

    Topics covered include: (1) estimation in discrete multivariate distributions; (2) a procedure to predict cloud cover frequencies in the bivariate case; (3) a program to compute conditional bivariate normal parameters; (4) the transformation of nonnormal multivariate to near-normal; (5) test of fit for the extreme value distribution based upon the generalized minimum chi-square; (6) test of fit for continuous distributions based upon the generalized minimum chi-square; (7) effect of correlated observations on confidence sets based upon chi-square statistics; and (8) generation of random variates from specified distributions.

  11. Use of cloud and radiation testbed measurements to evaluate cloud cover and convective parameterizations

    SciTech Connect

    Walcek, C.J.; Hu, Q.

    1995-04-01

    We have used temperature and humidity soundings and radiation measurements from the Atmospheric Radiation Measurement (ARM) Cloud and Radiation Testbed (CART) site in northern Oklahoma to evaluate an improved cloud cover algorithm. We have also used a new single-column model cumulus parameterization to estimate convective heating and moistening tendencies at the CART site. Our earlier analysis of cloud cover showed that relatively dry atmospheres contain small cloud amounts. We have found numerous periods during 1993 where maximum relative humidities within any layer of the atmosphere over the CART site are well below 60-80%, yet clouds are clearly reducing shortwave irradiance measured by a rotating shadowband radiometer. These ARM measurements support our earlier findings that most current climate models probably underestimate cloud coverage when relative humidities fall below the threshold humidities where clear skies are assumed. We have applied a {open_quotes}detraining-plume{close_quotes} model of cumulus convection to the June 1993 intensive observation period (16-25 June 1993). This model was previously verified with GARP Atlantic Tropical Experiment (GATE) measurements. During the June intensive observing period (IOP), relative humidities over the CART site are typically 20% less than tropical Atlantic GATE relative humidities. Our convective model calculates that evaporation of convectively induced cloud and rainwater plays a much more important role in the heating and moistening convective tendencies at the drier CART location. In particular, we predict that considerable cooling and moistening in the lower troposphere should occur due to the evaporation of convectively initiated precipitation.

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

    NASA Technical Reports Server (NTRS)

    Larsen, P. A.

    1972-01-01

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

  13. Estimating errors in fractional cloud cover obtained with infrared threshold methods

    SciTech Connect

    Chang, Fu-Lung; Coakley, J.A. Jr. )

    1993-05-20

    The authors address the question of detecting cloud coverage from satellite imagery. The International Satellite Cloud Climatology Project (ISCCP), and NIMBUS-7 have constructed cloud climatologies, but they differ substantially in the global mean cloud cover. Here the authors address problems in the application of threshold methods to the infrared detection of cloud cover. They look in particular at single-layered cloud cover, and compare the threshold IR detection method with a spatial coherence method. One of the problems is that the pixel size of satellite imagery, namely 4-8km on a side is not particularly small compared to cloud features, or even breaks in cloud cover, and there can be severe error in estimating cloud cover because of this difficulty.

  14. Atmospheric Soundings from AIRS/AMSU in Partial Cloud Cover

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Atlas, Robert

    2005-01-01

    Simultaneous use of AIRS/AMSU-A observations allow for the determination of accurate atmospheric soundings under partial cloud cover conditions. The methodology involves the determination of the radiances AIRS would have seen if the AIRS fields of view were clear, called clear column radiances, and use of these radiances to infer the atmospheric and surface conditions giving rise to these clear column radiances. Susskind et al. demonstrate via simulation that accurate temperature soundings and clear column radiances can be derived from AIRS/AMSU-A observations in cases of up to 80% partial cloud cover, with only a small degradation in accuracy compared to that obtained in clear scenes. Susskind and Atlas show that these findings hold for real AIRS/AMSU-A soundings as well. For data assimilation purposes, this small degradation in accuracy is more than offset by a significant increase in spatial coverage (roughly 50% of global cases were accepted, compared to 3.6% of the global cases being diagnosed as clear), and assimilation of AIRS temperature soundings in partially cloudy conditions resulted in a larger improvement in forecast skill than when AIRS soundings were assimilated only under clear conditions. Alternatively, derived AIRS clear column radiances under partial cloud cover could also be used for data assimilation purposes. Further improvements in AIRS sounding methodology have been made since the results shown in Susskind and Atlas . A new version of the AIRS/AMSU-A retrieval algorithm, Version 4.0, was delivered to the Goddard DAAC in February 2005 for production of AIRS derived products, including clear column radiances. The major improvement in the Version 4.0 retrieval algorithm is with regard to a more flexible, parameter dependent, quality control. Results are shown of the accuracy and spatial distribution of temperature-moisture profiles and clear column radiances derived from AIRS/AMSU-A as a function of fractional cloud cover using the Version 4

  15. Investigating a solar influence on cloud cover using the North American Regional Reanalysis data

    NASA Astrophysics Data System (ADS)

    Krahenbuhl, Daniel Scott

    2015-06-01

    The controversial connection between cosmic rays, solar activity, and cloud cover is investigated using a climatological reconstructed reanalysis product: the North American Regional Reanalysis which provides high-resolution, low, mid-level, high, and total cloud cover data over a Lambert conformal conic projection permitting land/ocean discrimination. Pearson's product-moment regional correlations were obtained between monthly cloud cover data and solar variability indicators, cosmic ray neutron monitors, several climatological indices, including the Atlantic Multidecadal Oscillation (AMO), and between cloud layers. Regions of the mid-latitude oceans exhibited a positive correlation with cosmic ray flux. Additionally, this maritime low cloud cover exhibits the only failed correlation significance with other altitudes. The cross correlation reveals that cloud cover is positively correlated everywhere but for ocean low cloud cover, supporting the unique response of the marine layer. The results of this investigation suggest that with the assumption that solar forcing does impact cloud cover, measurements of solar activity exhibits a slightly higher correlation than GCRs. The only instance where GCRs exhibit a positive regional correlation with cloud cover is for maritime low clouds. The AMO exerts the greatest control of cloud cover in the NARR domain.

  16. Winter sky brightness & cloud cover over Dome A

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Moore, A. M.; Fu, J.; Ashley, M.; Cui, X.; Feng, L.; Gong, X.; Hu, Z.; Laurence, J.; LuongVan, D.; Riddle, R. L.; Shang, Z.; Sims, G.; Storey, J.; Tothill, N.; Travouillon, T.; Wang, L.; Yang, H.; Yang, J.; Zhou, X.; Zhu, Z.; Burton, M. G.

    2014-01-01

    At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical Observatories. The Gattini DomeA project was created to measure the optical sky brightness and large area cloud cover of the winter-time sky above this high altitude Antarctic site. The wide field camera and multi-filter system was installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in January 2008. This automated wide field camera consists of an Apogee U4000 interline CCD coupled to a Nikon fish-eye lens enclosed in a heated container with glass window. The system contains a filter mechanism providing a suite of standard astronomical photometric filters (Bessell B, V, R), however, the absence of tracking systems, together with the ultra large field of view 85 degrees) and strong distortion have driven us to seek a unique way to build our data reduction pipeline. We present here the first measurements of sky brightness in the photometric B, V, and R band, cloud cover statistics measured during the 2009 winter season and an estimate of the transparency. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based location. A ~0.2 magnitude agreement of our simultaneous test at Palomar Observatory with NSBM(National Sky Brightness Monitor), as well as an 0.04 magnitude photometric accuracy for typical 6th magnitude stars limited by the instrument design, indicating we obtained reasonable results based on our ~7mm effective aperture fish-eye lens.

  17. Rise in the frequency of cloud cover in LANDSAT data for the period 1973 to 1981. [Brazil

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Mendonca, F. J.; Neto, G. C.

    1983-01-01

    Percentages of cloud cover in LANDSAT imagery were used to calculate the cloud cover monthly average statistic for each LANDSAT scene in Brazil, during the period of 1973 to 1981. The average monthly cloud cover and the monthly minimum cloud cover were also calculated for the regions of north, northeast, central west, southeast and south, separately.

  18. Quantifying Seasonal Variation in Cloud Cover with Predictive Models

    NASA Astrophysics Data System (ADS)

    Srivastava, A. N.; Nemani, R. R.

    2005-12-01

    An important problem that arises in many earth science problems is that of breaking down an observed signal into several components, including a seasonal component and a component that contains the signal of interest. Usually, a model is used to separate the signal into these components. This research presentation attempts to quantify the degree of variation induced into this process by the model itself. The larger the degree of variation due to the model, the lower the confidence we can have in our results and the subsequent scientific interpretation of the results. In order to address this question, we consider the following scenario, where the end goal is to build a predictive model to estimate the yearly cloud cover over the Amazon region based on a sample of 12 multi-spectral image cubes from MODIS. These multi-spectral image cubes are at 500 m resolution at 6 channels at the following bandwidths (Channel 1: 620-670, Channel 2: 841-876, Channel 3: 459-479, Channel 4: 545-645, Channel 5: 1230-1250, Channel 6: 1628-1652. All bandwidths are in microns). These six channels are useful for characterizing land, cloud, and aerosol content in the scene. We will model the nonlinear relationships between Channels 1-5 and Channel 6 using regression techniques. Channel 6, operating at about 1.6 microns, is well suited to distinguish clouds from the background scene. This paper discusses the results of a novel experiment, in which we compare the performance of two predictive models drawn from one model class known as Gaussian Processes (GP), but built with two different data sets. The first GP is built using data sampled from the entire set of 12 image cubes, whereas the second model is built using only those data for a particular season. We compare the performance of these two models using a variety of statistical techniques to determine whether the single GP model is capable of modeling the variation in the data observed across seasons. The second model, which is built

  19. Antarctica Cloud Cover for October 2003 from GLAS Satellite Lidar Profiling

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Palm, S. P.; Hart, W. D.

    2005-01-01

    Seeing clouds in polar regions has been a problem for the imagers used on satellites. Both clouds and snow and ice are white, which makes clouds over snow hard to see. And for thermal infrared imaging both the surface and the clouds cold. The Geoscience Laser Altimeter System (GLAS) launched in 2003 gives an entirely new way to see clouds from space. Pulses of laser light scatter from clouds giving a signal that is separated in time from the signal from the surface. The scattering from clouds is thus a sensitive and direct measure of the presence and height of clouds. The GLAS instrument orbits over Antarctica 16 times a day. All of the cloud observations for October 2003 were summarized and compared to the results from the MODIS imager for the same month. There are two basic cloud types that are observed, low stratus with tops below 3 km and high cirrus form clouds with cloud top altitude and thickness tending at 12 km and 1.3 km respectively. The average cloud cover varies from over 93 % for ocean and coastal regions to an average of 40% over the East Antarctic plateau and 60-90% over West Antarctica. When the GLAS monthly average cloud fractions are compared to the MODIS cloud fraction data product, differences in the amount of cloud cover are as much as 40% over the continent. The results will be used to improve the way clouds are detected from the imager observations. These measurements give a much improved understanding of distribution of clouds over Antarctica and may show how they are changing as a result of global warming.

  20. North Island, New Zealand under heavy Cloud Cover

    NASA Technical Reports Server (NTRS)

    1991-01-01

    North Island, New Zealand (37.0S, 179.0E) is in the foreground (obscured partially by clouds). The disorganized cloud mass to the north is thought to be associated with a tropical wave, in the early stages of formation and embedded in the southern equuatorial trough.

  1. Multiple Satellite Observations of Cloud Cover in Extratropical Cyclones

    NASA Technical Reports Server (NTRS)

    Naud, Catherine M.; Booth, James F.; Posselt, Derek J.; van den Heever, Susan C.

    2013-01-01

    Using cloud observations from NASA Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and CloudSat-CALIPSO, composites of cloud fraction in southern and northern hemisphere extratropical cyclones are obtained for cold and warm seasons between 2006 and 2010, to assess differences between these three data sets, and between summer and winter cyclones. In both hemispheres and seasons, over the open ocean, the cyclone-centered cloud fraction composites agree within 5% across the three data sets, but behind the cold fronts, or over sea ice and land, the differences are much larger. To supplement the data set comparison and learn more about the cyclones, we also examine the differences in cloud fraction between cold and warm season for each data set. The difference in cloud fraction between cold and warm season southern hemisphere cyclones is small for all three data sets, but of the same order of magnitude as the differences between the data sets. The cold-warm season contrast in northern hemisphere cyclone cloud fractions is similar for all three data sets: in the warm sector, the cold season cloud fractions are lower close to the low, but larger on the equator edge than their warm season counterparts. This seasonal contrast in cloud fraction within the cyclones warm sector seems to be related to the seasonal differences in moisture flux within the cyclones. Our analysis suggests that the three different data sets can all be used confidently when studying the warm sector and warm frontal zone of extratropical cyclones but caution should be exerted when studying clouds in the cold sector.

  2. Cooling Earth's temperature by seeding marine stratocumulus clouds for increasing cloud cover by closing open cells

    NASA Astrophysics Data System (ADS)

    Daniel, R.

    2008-12-01

    The transition from open to closed cellular convection in marine stratocumulus is very sensitive to small concentrations of cloud condensation nuclei (CCN) aerosols. Addition of small amounts of CCN (about 100 cm-3) to the marine boundary layer (MBL) can close the open cells and by that increase the cloud cover from about 40% to nearly 100%, with negative radiative forcing exceeding 100 wm-2. We show satellite measurements that demonstrate this sensitivity by inadvertent experiments of old and diluted ship tracks. With the methodology suggested by Salter and Latham for spraying sub-micron sea water drops that serve as CCN, it is possible to close sufficiently large area of open cells for achieving the negative radiative forcing that is necessary to balance the greenhouse gases positive forcing. We show calculations of the feasibility of such an undertaking, and suggest that this is an economically feasible method with the least potential risks, when compared to seeding marine stratocumulus for enhancing their albedo or with seeding the stratosphere with bright or dark aerosols. Global Circulation models coupled with the ocean and the ice are necessary to calculate the impact and the possible side effects.

  3. The impact of clouds, land use and snow cover on climate in the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Betts, Alan K.; Desjardins, Raymond L.; Worth, Devon E.

    2016-03-01

    This study uses 55 years of hourly observations of air temperature, relative humidity, daily precipitation, snow cover and cloud cover from 15 climate stations across the Canadian Prairies to analyze biosphere-atmosphere interactions. We will provide examples of the coupling between climate, snow cover, clouds, and land use. Snow cover acts as a fast climate switch. With the first snow fall, air temperature falls by 10 °C, and a similar increase in temperature occurs with snow melt. Climatologically, days with snow cover are 10 °C cooler than days with no snow cover in Alberta. However the interannual variability has a larger range, so that for every 10 % decrease in days with snow cover, the mean October to April climate is warmer by 1.4 to 1.5 °C. Snow cover also transforms the coupling between clouds and the diurnal cycle of air temperature from a boundary layer regime dominated by shortwave cloud forcing in the warm season to one dominated by longwave cloud forcing with snow cover. Changing agricultural land use in the past thirty years, specifically the reduction of summer fallowing, has cooled and moistened the growing season climate and increased summer precipitation. These hourly climate data provide a solid observational basis for understanding land surface coupling, which can be used to improve the representation of clouds and land-surface processes in atmospheric models.

  4. Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming

    NASA Astrophysics Data System (ADS)

    Abe, Manabu; Nozawa, Toru; Ogura, Tomoo; Takata, Kumiko

    2016-11-01

    This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere-ocean general circulation model MIROC5. Arctic sea ice has been substantially retreating since the 1980s, particularly in September, under simulated global warming conditions. The simulated sea ice reduction is consistent with satellite observations. On the other hand, Arctic cloud cover has been increasing in October, with about a 1-month lag behind the sea ice reduction. The delayed response leads to extensive sea ice reductions because the heat and moisture fluxes from the underlying open ocean into the atmosphere are enhanced. Sensitivity experiments with the atmospheric part of MIROC5 clearly show that sea ice reduction causes increases in cloud cover. Arctic cloud cover increases primarily in the lower troposphere, but it decreases in the near-surface layers just above the ocean; predominant temperature rises in these near-surface layers cause drying (i.e., decreases in relative humidity), despite increasing moisture flux. Cloud radiative forcing due to increases in cloud cover in autumn brings an increase in the surface downward longwave radiation (DLR) by approximately 40-60 % compared to changes in clear-sky surface DLR in fall. These results suggest that an increase in Arctic cloud cover as a result of reduced sea ice coverage may bring further sea ice retreat and enhance the feedback processes of Arctic warming.

  5. Traffic sign detection in MLS acquired point clouds for geometric and image-based semantic inventory

    NASA Astrophysics Data System (ADS)

    Soilán, Mario; Riveiro, Belén; Martínez-Sánchez, Joaquín; Arias, Pedro

    2016-04-01

    Nowadays, mobile laser scanning has become a valid technology for infrastructure inspection. This technology permits collecting accurate 3D point clouds of urban and road environments and the geometric and semantic analysis of data became an active research topic in the last years. This paper focuses on the detection of vertical traffic signs in 3D point clouds acquired by a LYNX Mobile Mapper system, comprised of laser scanning and RGB cameras. Each traffic sign is automatically detected in the LiDAR point cloud, and its main geometric parameters can be automatically extracted, therefore aiding the inventory process. Furthermore, the 3D position of traffic signs are reprojected on the 2D images, which are spatially and temporally synced with the point cloud. Image analysis allows for recognizing the traffic sign semantics using machine learning approaches. The presented method was tested in road and urban scenarios in Galicia (Spain). The recall results for traffic sign detection are close to 98%, and existing false positives can be easily filtered after point cloud projection. Finally, the lack of a large, publicly available Spanish traffic sign database is pointed out.

  6. Cloud cover typing from environmental satellite imagery. Discriminating cloud structure with Fast Fourier Transforms (FFT)

    NASA Technical Reports Server (NTRS)

    Logan, T. L.; Huning, J. R.; Glackin, D. L.

    1983-01-01

    The use of two dimensional Fast Fourier Transforms (FFTs) subjected to pattern recognition technology for the identification and classification of low altitude stratus cloud structure from Geostationary Operational Environmental Satellite (GOES) imagery was examined. The development of a scene independent pattern recognition methodology, unconstrained by conventional cloud morphological classifications was emphasized. A technique for extracting cloud shape, direction, and size attributes from GOES visual imagery was developed. These attributes were combined with two statistical attributes (cloud mean brightness, cloud standard deviation), and interrogated using unsupervised clustering amd maximum likelihood classification techniques. Results indicate that: (1) the key cloud discrimination attributes are mean brightness, direction, shape, and minimum size; (2) cloud structure can be differentiated at given pixel scales; (3) cloud type may be identifiable at coarser scales; (4) there are positive indications of scene independence which would permit development of a cloud signature bank; (5) edge enhancement of GOES imagery does not appreciably improve cloud classification over the use of raw data; and (6) the GOES imagery must be apodized before generation of FFTs.

  7. Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming

    NASA Astrophysics Data System (ADS)

    Abe, M.; Nozawa, T.; Ogura, T.; Takata, K.

    2015-06-01

    This study investigates the effect of sea ice reduction on Arctic cloud cover in historical simulations with the coupled atmosphere-ocean general circulation model MIROC5. During simulated global warming since the 1970s, the Arctic sea ice extent has reduced substantially, particularly in September. This simulated reduction is consistent with satellite observation results. However, the Arctic cloud cover increases significantly during October at grids with significant reductions in sea ice because of the enhanced heat and moisture flux from the underlying ocean. Cloud fraction increases in the lower troposphere. However, the cloud fraction in the surface thin layers just above the ocean decreases despite the increased moisture because the surface air temperature rises strikingly in the thin layers and the relative humidity decreases. As the cloud cover increases, the cloud radiative effect in surface downward longwave radiation (DLR) increases by approximately 40-60 % compared to a change in clear-sky surface DLR. These results suggest that an increase in the Arctic cloud cover as a result of a reduction in sea ice could further melt the sea ice and enhance the feedback processes of the Arctic amplification in future projections.

  8. Improved identification of clouds and ice/snow covered surfaces in SCIAMACHY observations

    NASA Astrophysics Data System (ADS)

    Krijger, J. M.; Tol, P.; Istomina, L. G.; Schlundt, C.; Schrijver, H.; Aben, I.

    2011-10-01

    In the ultra-violet, visible and near infra-red wavelength range the presence of clouds can strongly affect the satellite-based passive remote sensing observation of constituents in the troposphere, because clouds effectively shield the lower part of the atmosphere. Therefore, cloud detection algorithms are of crucial importance in satellite remote sensing. However, the detection of clouds over snow/ice surfaces is particularly difficult in the visible wavelengths as both clouds an snow/ice are both white and highly reflective. The SCIAMACHY Polarisation Measurement Devices (PMD) Identification of Clouds and Ice/snow method (SPICI) uses the SCIAMACHY measurements in the wavelength range between 450 nm and 1.6 μm to make a distinction between clouds and ice/snow covered surfaces, specifically developed to identify cloud-free SCIAMACHY observations. For this purpose the on-board SCIAMACHY PMDs are used because they provide higher spatial resolution compared to the main spectrometer measurements. In this paper we expand on the original SPICI algorithm (Krijger et al., 2005a) to also adequately detect clouds over snow-covered forests which is inherently difficult because of the similar spectral characteristics. Furthermore the SCIAMACHY measurements suffer from degradation with time. This must be corrected for adequate performance of SPICI over the full SCIAMACHY time range. Such a correction is described here. Finally the performance of the new SPICI algorithm is compared with various other datasets, such as from FRESCO, MICROS and AATSR, focusing on the algorithm improvements.

  9. Investigation of a cloud-cover modification to SPCTRAL2, SERI's simple model for cloudless-sky, spectral solar irradiance

    SciTech Connect

    Bird, R.E.; Riordan, C.J.; Myers, D.R.

    1987-06-01

    This report summarizes the investigation of a cloud-cover modification to SPCTRAL2, SERI's simple model for cloudless-sky, spectral solar irradiance. Our approach was to develop a modifier that relies on commonly acquired meteorological and broadband-irradiance data rather than detailed cloud properties that are generally not available. The method was to normalize modeled, cloudless-sky spectral irradiance to a measured broadband-irradiance value under cloudy skies, and then to compare the normalized, modeled data with measured spectral-irradiance data to empirically derive spectral modifiers that improve the agreement between modeled and measured data. Results indicate the possible form of the spectral corrections; however, we must analyze additional data to develop a spectral transmission function for cloudy-sky conditions.

  10. Variation of arctic cloud cover in summer. Progress report, April 15, 1981-October 1, 1982

    SciTech Connect

    Kukla, G.J.

    1982-10-01

    The largest impact of increasing CO/sub 2/ should occur in the high latitudes according to climate models. However, an appropriate data base on cloud distribution and optical thickness is needed in order to improve and test the models as well as to enable the future detection of the CO/sub 2/ climate impact in high latitudes. Cloud cover over the Arctic Basin in late spring and summer of 1979 was charted in three day intervals based on NOAA and DMSP imagery. Three cloud types were recognized based on visually determined optical thickness. They are thick opaque stratus, thin transparent stratus, through which surface features are identifiable, and thin cirrus or fog. While 50 to 60% of the Arctic Basin was found to have stratus cloud, only about half this amount was of the optically thick type. This differs considerably from earlier estimates. Moreover, the day to day variability of cloud cover was found to be large. A comparison of cloud distribution with reconstructed pressure patterns show that the cloud distribution can be used to improve the charts. Ratios determined for cloud and cloud free conditions over both snow and open water were found to be useful in making numerical estimates of the optical thickness of clouds. Calibration of cloud type with the mean optical thickness is underway. Also tested was the detection of the cloud height from the width of the shadow. If the 1979 conditions were typical of recent years, substantial revisions will be needed in climate models assessing the CO/sub 2/ impact on climate.

  11. Observation of Sea Ice Surface Thermal States Under Cloud Cover

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Perovich, D. K.; Gow, A. J.; Kwok, R.; Barber, D. G.; Comiso, J. C.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Clouds interfere with the distribution of short-wave and long-wave radiations over sea ice, and thereby strongly affect the surface energy balance in polar regions. To evaluate the overall effects of clouds on climatic feedback processes in the atmosphere-ice-ocean system, the challenge is to observe sea ice surface thermal states under both clear sky and cloudy conditions. From laboratory experiments, we show that C-band radar (transparent to clouds) backscatter is very sensitive to the surface temperature of first-year sea ice. The effect of sea ice surface temperature on the magnitude of backscatter change depends on the thermal regimes of sea ice thermodynamic states. For the temperature range above the mirabilite (Na2SO4.10H20) crystallization point (-8.2 C), C-band data show sea ice backscatter changes by 8-10 dB for incident angles from 20 to 35 deg at both horizontal and vertical polarizations. For temperatures below the mirabilite point but above the crystallization point of MgCl2.8H2O (-18.0 C), relatively strong backwater changes between 4-6 dB are observed. These backscatter changes correspond to approximately 8 C change in temperature for both cases. The backscattering mechanism is related to the temperature which determines the thermodynamic distribution of brine volume in the sea ice surface layer. The backscatter is positively correlated to temperature and the process is reversible with thermodynamic variations such as diurnal insolation effects. From two different dates in May 1993 with clear and overcast conditions determined by the Advanced Very High Resolution Radiometer (AVHRR), concurrent Earth Resources Satellite 1 (ERS-1) C-band ice observed with increases in backscatter over first-year sea ice, and verified by increases in in-situ sea ice surface temperatures measured at the Collaborative-Interdisciplinary Cryosphere Experiment (C-ICE) site.

  12. Comparisons of cloud cover and cloud fractions using remote-sensing retrievals

    SciTech Connect

    Krueger, S K; Rodriguez, D

    1999-05-18

    The DOE's Atmospheric Radiation Measurement (ARM) Program employs both upward- and downward-looking remote-sensing instruments to measure the horizontal and vertical distributions of clouds across its Southern Great Plains (SGP) site. No single instrument is capable of completely determining these distributions over the scales of interest to ARM's Single Column Modeling (SCM) and Instantaneous Radiative Flux (IRF) groups; these groups embody the primary strategies through which ARM expects to achieve its objectives of developing and testing cloud formation (USDOE, 1996). Collectively, however, the data from ARM's cloud-detecting instruments offer the potential for such a three-dimensional characterization. Data intercomparisons, like the ones illustrated here, are steps in this direction. Specifically, they are valuable because they help: provide a measure of uncertainty in ARM's measurement capabilities, calibrate retrieval methods and refine algorithms and concepts. In the process, we are forced to think of meaningful ways in which measurements from different instruments can be compared and, perhaps, combined. While the ultimate goal of this particular effort is to develop the ability to accurately characterize cloud fields in three dimensions over time at the SGP site, along the way we will address such questions as ''which source, or combination of cloud data sources, offers a best estimate product?'' and ''how can cloud observations be used to evaluate the representation of clouds in numerical models?''. Examples of some initial comparisons, involving satellite, millimeter cloud radar, whole sky imager and ceilometer data, are provided herein.

  13. Trends and uncertainties in U.S. cloud cover from weather stations and satellite data

    NASA Astrophysics Data System (ADS)

    Free, M. P.; Sun, B.; Yoo, H. L.

    2014-12-01

    Cloud cover data from ground-based weather observers can be an important source of climate information, but the record of such observations in the U.S. is disrupted by the introduction of automated observing systems and other artificial shifts that interfere with our ability to assess changes in cloudiness at climate time scales. A new dataset using 54 National Weather Service (NWS) and 101 military stations that continued to make human-augmented cloud observations after the 1990s has been adjusted using statistical changepoint detection and visual scrutiny. The adjustments substantially reduce the trends in U.S. mean total cloud cover while increasing the agreement between the cloud cover time series and those of physically related climate variables such as diurnal temperature range and number of precipitation days. For 1949-2009, the adjusted time series give a trend in U.S. mean total cloud of 0.11 ± 0.22 %/decade for the military data, 0.55 ± 0.24 %/decade for the NWS data, and 0.31 ± 0.22 %/decade for the combined dataset. These trends are less than half those in the original data. For 1976-2004, the original data give a significant increase but the adjusted data show an insignificant trend of -0.17 (military stations) to 0.66 %/decade (NWS stations). The differences between the two sets of station data illustrate the uncertainties in the U.S. cloud cover record. We compare the adjusted station data to cloud cover time series extracted from several satellite datasets: ISCCP (International Satellite Cloud Climatology Project), PATMOS-x (AVHRR Pathfinder Atmospheres Extended) and CLARA-a1 (CM SAF cLoud Albedo and RAdiation), and the recently developed PATMOS-x diurnally corrected dataset. Like the station data, satellite cloud cover time series may contain inhomogeneities due to changes in the observing systems and problems with retrieval algorithms. Overall we find good agreement between interannual variability in most of the satellite data and that in our

  14. Effects of Digitization and JPEG Compression on Land Cover Classification Using Astronaut-Acquired Orbital Photographs

    NASA Technical Reports Server (NTRS)

    Robinson, Julie A.; Webb, Edward L.; Evangelista, Arlene

    2000-01-01

    Studies that utilize astronaut-acquired orbital photographs for visual or digital classification require high-quality data to ensure accuracy. The majority of images available must be digitized from film and electronically transferred to scientific users. This study examined the effect of scanning spatial resolution (1200, 2400 pixels per inch [21.2 and 10.6 microns/pixel]), scanning density range option (Auto, Full) and compression ratio (non-lossy [TIFF], and lossy JPEG 10:1, 46:1, 83:1) on digital classification results of an orbital photograph from the NASA - Johnson Space Center archive. Qualitative results suggested that 1200 ppi was acceptable for visual interpretive uses for major land cover types. Moreover, Auto scanning density range was superior to Full density range. Quantitative assessment of the processing steps indicated that, while 2400 ppi scanning spatial resolution resulted in more classified polygons as well as a substantially greater proportion of polygons < 0.2 ha, overall agreement between 1200 ppi and 2400 ppi was quite high. JPEG compression up to approximately 46:1 also did not appear to have a major impact on quantitative classification characteristics. We conclude that both 1200 and 2400 ppi scanning resolutions are acceptable options for this level of land cover classification, as well as a compression ratio at or below approximately 46:1. Auto range density should always be used during scanning because it acquires more of the information from the film. The particular combination of scanning spatial resolution and compression level will require a case-by-case decision and will depend upon memory capabilities, analytical objectives and the spatial properties of the objects in the image.

  15. MODIS Snow Cover Mapping Decision Tree Technique: Snow and Cloud Discrimination

    NASA Technical Reports Server (NTRS)

    Riggs, George A.; Hall, Dorothy K.

    2010-01-01

    Accurate mapping of snow cover continues to challenge cryospheric scientists and modelers. The Moderate-Resolution Imaging Spectroradiometer (MODIS) snow data products have been used since 2000 by many investigators to map and monitor snow cover extent for various applications. Users have reported on the utility of the products and also on problems encountered. Three problems or hindrances in the use of the MODIS snow data products that have been reported in the literature are: cloud obscuration, snow/cloud confusion, and snow omission errors in thin or sparse snow cover conditions. Implementation of the MODIS snow algorithm in a decision tree technique using surface reflectance input to mitigate those problems is being investigated. The objective of this work is to use a decision tree structure for the snow algorithm. This should alleviate snow/cloud confusion and omission errors and provide a snow map with classes that convey information on how snow was detected, e.g. snow under clear sky, snow tinder cloud, to enable users' flexibility in interpreting and deriving a snow map. Results of a snow cover decision tree algorithm are compared to the standard MODIS snow map and found to exhibit improved ability to alleviate snow/cloud confusion in some situations allowing up to about 5% increase in mapped snow cover extent, thus accuracy, in some scenes.

  16. The impact of European forests on cloud cover: an observation-based study

    NASA Astrophysics Data System (ADS)

    Melsen, L. A.; Teuling, R.; Vila-Guerau Arellano, J.; Nabuurs, G. J.; Miralles, D. G.; Taylor, C.; Stegehuis, A.; Meirink, J. F.

    2015-12-01

    The impact of temperate forests on their environment is uncertain [1]. While forests generally have a lower albedo, the flux partitioning over forests and its relation to weather conditions is still poorly understood [2,3], complicating modeling attempts. Effects of land surface conditions on boundary-layer humidity and cloud formation can also be very non-linear [4]. Furthermore, the study of hydrological and climate impacts of temperate European forests is complicated because forests are fragmented and often can be found on hilly terrain, making it impossible to attribute differences in cloud cover directly to forest cover. In this study, we analyse 10 years (2004-2013) of cloud cover data from the SEVIRI instrument aboard the Meteosat Second Generation satellite platform at a 15-minute temporal resolution [5]. We focus on two regions in France where large forests are found which satisfy the following criteria: a) absence of strong topography, and b) presence of sharp contrast between forest and non-forest regions. Cloud occurrence is expressed by the fraction of the daytime that clouds are detected within a ˜6 km MSG pixel. We find that in particular in summer and late summer, clouds are more likely to occur over forest than over the surrounding non-forest land (order of 20%). An opposite signal, but of weaker magnitude, is found in spring, when clouds are less likely to develop over forest. Difference in cloud occurrence is consistent with MODIS-derived differences in EVI, which reflects a more pronounced soil moisture reduction in the non-forested areas. In addition to investigating seasonal and diurnal patterns, we also investigate the effects of windthrow on cloud occurrence. In 2009, storm Klaus caused extensive damage in southern France, resulting in a large-scale disturbance of the forest cover conditions. This disturbance lead to a significantly lower cloud cover over the forest region in the period after the storm in comparison to the period before the

  17. Extension of four-dimensional atmospheric models. [and cloud cover data bank

    NASA Technical Reports Server (NTRS)

    Fowler, M. G.; Lisa, A. S.; Tung, S. L.

    1975-01-01

    The cloud data bank, the 4-D atmospheric model, and a set of computer programs designed to simulate meteorological conditions for any location above the earth are described in turns of space vehicle design and simulation of vehicle reentry trajectories. Topics discussed include: the relationship between satellite and surface observed cloud cover using LANDSAT 1 photographs and including the effects of cloud shadows; extension of the 4-D model to the altitude of 52 km; and addition of the u and v wind components to the 4-D model of means and variances at 1 km levels from the surface to 25 km. Results of the cloud cover analysis are presented along with the stratospheric model and the tropospheric wind profiles.

  18. Extrasolar Storms: Mapping Cloud Cover Evolution with Joint HST-Spitzer Observations

    NASA Astrophysics Data System (ADS)

    Apai, Daniel; Extrasolar Storms Team

    2017-01-01

    Observations of directly imaged and transiting exoplanets and brown dwarfs reveal the wide-spread presence of condensate clouds. These clouds profoundly influence the energy transport through ultracool atmospheres and impact their pressure-temperature profiles. Yet, the structure and properties of these cloud layers remain mostly unexplored and pose one of the great challenges to our understanding ultracool atmospheres. I will show how using HST and Spitzer jointly -- by exploiting their photometric stability and sensitivity and combining their wavelength ranges -- allows us to address this challenge. With time-resolved spectroscopy and photometry of rotating brown dwarfs - rotational phase mapping — we are exploring the longitudinal structure of condensate clouds and with multiple epoch observations we are following the evolution of the cloud cover. These new observations are opening a new window on the dynamics of ultracool atmospheres.

  19. Sensitivity Study of Cloud Cover and Ozone Modeling to Microphysics Parameterization

    NASA Astrophysics Data System (ADS)

    Wałaszek, Kinga; Kryza, Maciej; Szymanowski, Mariusz; Werner, Małgorzata; Ojrzyńska, Hanna

    2017-02-01

    Cloud cover is a significant meteorological parameter influencing the amount of solar radiation reaching the ground surface, and therefore affecting the formation of photochemical pollutants, most of all tropospheric ozone (O3). Because cloud amount and type in meteorological models are resolved by microphysics schemes, adjusting this parameterization is a major factor determining the accuracy of the results. However, verification of cloud cover simulations based on surface data is difficult and yields significant errors. Current meteorological satellite programs provide many high-resolution cloud products, which can be used to verify numerical models. In this study, the Weather Research and Forecasting model (WRF) has been applied for the area of Poland for an episode of June 17th-July 4th, 2008, when high ground-level ozone concentrations were observed. Four simulations were performed, each with a different microphysics parameterization: Purdue Lin, Eta Ferrier, WRF Single-Moment 6-class, and Morrison Double-Moment scheme. The results were then evaluated based on cloud mask satellite images derived from SEVIRI data. Meteorological variables and O3 concentrations were also evaluated. The results show that the simulation using Morrison Double-Moment microphysics provides the most and Purdue Lin the least accurate information on cloud cover and surface meteorological variables for the selected high ozone episode. Those two configurations were used for WRF-Chem runs, which showed significantly higher O3 concentrations and better model-measurements agreement of the latter.

  20. A simulation study exploring the effects of sensor spatial resolution on estimates of cloud cover from satellites.

    NASA Technical Reports Server (NTRS)

    Shenk, W. E.; Salomonson, V. V.

    1972-01-01

    Investigation of the effects of sensor spatial resolution on estimating the amount of clouds covering the earth by simulating various cloud distributions and sizes, and measuring the known cloud amount with resolution of different sizes using a cloud-no cloud threshold technique often applied in automatic data processing. Cloud amount statistics have been tabulated for a three-orders-of-magnitude range in the ratio (R) of areal cloud size to areal resolution size for seven cloud amounts between 6 and 90%. Three different cloud patterns were used. These were 1) a regularly spaced pattern of homogeneous dots arranged in rows and columns (to simulate cloud streets), 2) a randomly spaced pattern of the same dots (to simulate randomly oriented cumulus clouds), and 3) a heterogeneous cloud size distribution irregularly spaced (to simulate a view of different cloud types and sizes). Two cloud amount estimation techniques were tested. Cloud amounts of 100% (method 1) and 50% (method 2) were assigned to partially filled resolution elements. Using criteria applicable to some studies carried out in the past, it is shown that cloud amount estimations can be in error by as much as 86 and 38%, respectively, for the two methods. Nomograms have been developed which subtantially improve the estimate of the true cloud cover for R less than 100, provided that R can be determined.

  1. NAO-related Variability in Arctic Storm Activity and its Effect on Cloud Cover

    NASA Astrophysics Data System (ADS)

    Previdi, M.; Veron, D. E.

    2005-12-01

    Variability in Arctic and sub-Arctic storm activity on intraseasonal, interannual and decadal timescales is associated primarily with the North Atlantic Oscillation (NAO). NAO-related changes in storminess affect a wide range of sensible weather, including air temperature, precipitation and wind. We focus on a less often examined climate impact of these storm changes, their effect on cloud cover. The NAO modulation of storminess in the high latitude North Atlantic is studied using composites of regional climate model simulations representative of NAO extremes. The associated changes in cloud cover and their role in producing the mean surface air temperature response to NAO variability are then discussed.

  2. Comparisons of cloud cover estimates and cloud fraction profiles from ARM's cloud-detecting instruments and GOES-8 data

    SciTech Connect

    Krueger, S K; Rodriguez, D

    1999-05-07

    The DOE's Atmospheric Radiation Measurement (ARM) Program employs both upward- and downward-looking remote-sensing instruments to measure the horizontal and vertical distributions of clouds across its Southern Great Plains (SGP) site. No single instrument is capable of completely determining these distributions over the scales of interest to ARM's Single Column Modeling (SCM) and Instantaneous Radiative Flux (IRF) groups; these groups embody the primary strategies through which ARM expects to achieve its objectives of developing and testing cloud formation parameterizations (USDOE, 1996). Collectively, however, the data from ARM's cloud-detecting instruments offer the potential for such a three-dimensional characterization. Data intercomparisons, like the ones illustrated in this paper, are steps in this direction. Examples of some initial comparisons, involving satellite, millimeter cloud radar, whole sky imager and ceilometer data, are provided herein. that many of the lessons learned can later be adapted to cloud data at the Boundary and Extended Facilities. Principally, we are concerned about: (1) the accuracy of various estimates of cloud properties at a single point, or within a thin vertical column, above the CF over time, and (2) the accuracy of various estimates of cloud properties over the Cloud and Radiation Testbed (CART) site, which can then be reduced to single, representative profiles over time. In the former case, the results are usable in the IRF and SCM strategies; in the latter case, they satisfy SCM needs specifically. The Whole Sky Imager (WSI) and ceilometer data used in one study were collected at the SGP CF between October 1 and December 31, 1996 (Shields, et. al., 1990). This three-month period, corresponding to the first set of WSI data released by ARM's Experiment Center, was sufficiently long to reveal important trends (Rodriguez, 1998).

  3. Development and Evaluation of a Cloud-Gap-Filled MODIS Daily Snow-Cover Product

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Riggs, George A.; Foster, James L.; Kumar, Sujay V.

    2010-01-01

    The utility of the Moderate Resolution Imaging Spectroradiometer (MODIS) snow-cover products is limited by cloud cover which causes gaps in the daily snow-cover map products. We describe a cloud-gap-filled (CGF) daily snowcover map using a simple algorithm to track cloud persistence, to account for the uncertainty created by the age of the snow observation. Developed from the 0.050 resolution climate-modeling grid daily snow-cover product, MOD10C1, each grid cell of the CGF map provides a cloud-persistence count (CPC) that tells whether the current or a prior day was used to make the snow decision. Percentage of grid cells "observable" is shown to increase dramatically when prior days are considered. The effectiveness of the CGF product is evaluated by conducting a suite of data assimilation experiments using the community Noah land surface model in the NASA Land Information System (LIS) framework. The Noah model forecasts of snow conditions, such as snow-water equivalent (SWE), are updated based on the observations of snow cover which are obtained either from the MOD1 OC1 standard product or the new CGF product. The assimilation integrations using the CGF maps provide domain averaged bias improvement of -11 %, whereas such improvement using the standard MOD1 OC1 maps is -3%. These improvements suggest that the Noah model underestimates SWE and snow depth fields, and that the assimilation integrations contribute to correcting this systematic error. We conclude that the gap-filling strategy is an effective approach for increasing cloud-free observations of snow cover.

  4. Three-dimensional rendering of computer-generated holograms acquired from point-clouds on light field displays

    NASA Astrophysics Data System (ADS)

    Symeonidou, Athanasia; Blinder, David; Ceulemans, Beerend; Munteanu, Adrian; Schelkens, Peter

    2016-09-01

    Holograms, either optically acquired or simulated numerically from 3D datasets, such as point clouds, have special rendering requirements for display. Evaluating the quality of hologram generation techniques is not straightforward, since high-quality holographic display technologies are still immature, In this paper we present a framework for three-dimensional rendering of colour computer-generated holograms (CGHs) acquired from point-clouds, on high-end light field displays. This allows for the rendering of holographic content with horizontal parallax and wide viewing angle. We deploy prior work, namely a fast CGH method that inherently handles occlusion problems to acquire high quality colour holograms from point clouds. Our experiments showed that rendering holograms with the proposed framework provides 3D effect with depth disparity and horizontal-only with wide viewing angle. Therefore, it allows for the evaluation of CGH techniques regarding functional properties such as depth cues and efficient occlusion handling.

  5. Cloud cover archiving on a global scale - A discussion of principles

    NASA Technical Reports Server (NTRS)

    Henderson-Sellers, A.; Hughes, N. A.; Wilson, M.

    1981-01-01

    Monitoring of climatic variability and climate modeling both require a reliable global cloud data set. Examination is made of the temporal and spatial variability of cloudiness in light of recommendations made by GARP in 1975 (and updated by JOC in 1978 and 1980) for cloud data archiving. An examination of the methods of comparing cloud cover frequency curves suggests that the use of the beta distribution not only facilitates objective comparison, but also reduces overall storage requirements. A specific study of the only current global cloud climatology (the U.S. Air Force's 3-dimensional nephanalysis) over the United Kingdom indicates that discussion of methods of validating satellite-based data sets is urgently required.

  6. Filling of Cloud-Induced Gaps for Land Use and Land Cover Classifications Around Refugee Camps

    NASA Astrophysics Data System (ADS)

    Braun, Andreas; Hagensieker, Ron; Hochschild, Volker

    2016-08-01

    Clouds cover is one of the main constraints in the field of optical remote sensing. Especially the use of multispectral imagery is affected by either fully obscured data or parts of the image which remain unusable. This study compares four algorithms for the filling of cloud induced gaps in classified land cover products based on Markov Random Fields (MRF), Random Forest (RF), Closest Spectral Fit (CSF) operators. They are tested on a classified image of Sentinel-2 where artificial clouds are filled by information derived from a scene of Sentinel-1. The approaches rely on different mathematical principles and therefore produced results varying in both pattern and quality. Overall accuracies for the filled areas range from 57 to 64 %. Best results are achieved by CSF, however some classes (e.g. sands and grassland) remain critical through all approaches.

  7. Accuracy of Geophysical Parameters Derived from AIRS/AMSU as a Function of Fractional Cloud Cover

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Barnet, Chris; Blaisdell, John; Iredell, Lena; Keita, Fricky; Kouvaris, Lou; Molnar, Gyula; Chahine, Moustafa

    2006-01-01

    AIRS was launched on EOS Aqua on May 4,2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of lK, and layer precipitable water with an rms error of 20 percent, in cases with up to 80 percent effective cloud cover. The basic theory used to analyze Atmospheric InfraRed Sounder/Advanced Microwave Sounding Unit/Humidity Sounder Brazil (AIRS/AMSU/HSB) data in the presence of clouds, called the at-launch algorithm, was described previously. Pre-launch simulation studies using this algorithm indicated that these results should be achievable. Some modifications have been made to the at-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small and the RMS accuracy of lower tropospheric temperature retrieved with 80 percent cloud cover is about 0.5 K poorer than for clear cases. HSB failed in February 2003, and consequently HSB channel radiances are not used in the results shown in this paper. The AIRS/AMSU retrieval algorithm described in this paper, called Version 4, become operational at the Goddard DAAC (Distributed Active Archive Center) in April 2003 and is being used to analyze near-real time AIRS/AMSU data. Historical AIRS/AMSU data, going backwards from March 2005 through September 2002, is also being analyzed by the DAAC using the Version 4 algorithm.

  8. Spatial and temporal patterns of cloud cover and fog inundation in coastal California: Ecological implications

    USGS Publications Warehouse

    Rastogi, Bharat; Williams, A. Park; Fischer, Douglas T.; Iacobellis, Sam F.; McEachern, Kathryn; Carvalho, Leila; Jones, Charles Leslie; Baguskas, Sara A.; Still, Christopher J.

    2016-01-01

    The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in coastal California where forests are frequently shaded by low-lying clouds or immersed in fog during otherwise warm and dry summer months. Summer fog and stratus can ameliorate summer drought stress and enhance soil water budgets, and often have different spatial and temporal patterns. Here we use remote sensing datasets to characterize the spatial and temporal patterns of cloud cover over California’s northern Channel Islands. We found marine stratus to be persistent from May through September across the years 2001-2012. Stratus clouds were both most frequent and had the greatest spatial extent in July. Clouds typically formed in the evening, and dissipated by the following early afternoon. We present a novel method to downscale satellite imagery using atmospheric observations and discriminate patterns of fog from those of stratus and help explain patterns of fog deposition previously studied on the islands. The outcomes of this study contribute significantly to our ability to quantify the occurrence of coastal fog at biologically meaningful spatial and temporal scales that can improve our understanding of cloud-ecosystem interactions, species distributions and coastal ecohydrology.

  9. Comparisons of cloud cover evaluated from LANDSAT imagery and meteorological stations across the British Isles

    NASA Technical Reports Server (NTRS)

    Barrett, E. C. (Principal Investigator); Grant, C. K.

    1976-01-01

    The author has identified the following significant results. This stage of the study has confirmed the initial supposition that LANDSAT data could be analyzed to provide useful data on cloud amount, and that useful light would be thrown thereby on the performance of the ground observer of this aspect of the state of the sky. This study, in comparison with previous studies of a similar nature using data from meteorological satellites, has benefited greatly from the much higher resolution data provided by LANDSAT. This has permitted consideration of not only the overall performance of the surface observer in estimating total cloud cover, but also his performance under different sky conditions.

  10. Accuracy of Geophysical Parameters Derived from AIRS/AMSU as a Function of Fractional Cloud Cover

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Barnet, Chris; Blaisdell, John; Iredell, Lena; Keita, Fricky; Kouvaris, Lou; Molnar, Gyula; Chahine, Moustafa

    2005-01-01

    AIRS was launched on EOS Aqua on May 4,2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of 1K, and layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. The basic theory used to analyze AIRS/AMSU/HSB data in the presence of clouds, called the at-launch algorithm, was described previously. Pre-launch simulation studies using this algorithm indicated that these results should be achievable. Some modifications have been made to the at-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. HSB failed in February 2005, and consequently HSB channel radiances are not used in the results shown in this paper. The AIRS/AMSU retrieval algorithm described in this paper, called Version 4, become operational at the Goddard DAAC in April 2005 and is being used to analyze near-real time AIRS/AMSU data. Historical AIRS/AMSU data, going backwards from March 2005 through September 2002, is also being analyzed by the DAAC using the Version 4 algorithm.

  11. Assessment of cloud cover in climate models and reanalysis databases with ISCCP over the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Enriquez, Aaron; Calbo, Josep; Gonzalez, Josep-Abel

    2013-04-01

    Clouds are an important regulator of climate due to their influence on the water balance of the atmosphere and their interaction with solar and infrared radiation. At any time, clouds cover a great percentage of the Earth's surface but their distribution is very irregular along time and space, which makes the evaluation of their influence on climate a difficult task. At present there are few studies related to cloud cover comparing current climate models with observational data. In this study, the database of monthly cloud cover provided by the International Satellite Cloud Climatology Project (ISCCP) has been chosen as a reference against which we compare the output of CMIP5 climate models and reanalysis databases, on the domain South-Europe-Mediterranean (SEM) established by the Intergovernmental Panel on Climate Change (IPCC) [1]. The study covers the period between 1984 and 2009, and the performance of cloud cover estimations for seasons has also been studied. To quantify the agreement between the databases we use two types of statistics: bias and SkillScore, which is based on the probability density functions (PDFs) of the databases [2]. We also use Taylor diagrams to visualize the statistics. Results indicate that there are areas where the models accurately describe what it is observed by ISCCP, for some periods of the year (e.g. Northern Africa, for autumn), compared to other areas and periods for which the agreement is lower (Iberian Peninsula in winter and the Black Sea for the summer months). However these differences should be attributed not only to the limitations of climate models, but possibly also to the data provided by ISCCP. References [1] Intergovernmental Panel on Climate Change (2007) Fourth Assessment Report: Climate Change 2007: Working Group I Report: The Physical Science Basis. [2] Ranking the AR4 climate models over the Murray Darling Basin using simulated maximum temperature, minimum temperature and precipitation. Int J Climatol 28

  12. Validation of On-board Cloud Cover Assessment Using EO-1

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Miller, Jerry; Griffin, Michael; Burke, Hsiao-hua

    2003-01-01

    The purpose of this NASA Earth Science Technology Office funded effort was to flight validate an on-board cloud detection algorithm and to determine the performance that can be achieved with a Mongoose V flight computer. This validation was performed on the EO-1 satellite, which is operational, by uploading new flight code to perform the cloud detection. The algorithm was developed by MIT/Lincoln Lab and is based on the use of the Hyperion hyperspectral instrument using selected spectral bands from 0.4 to 2.5 microns. The Technology Readiness Level (TRL) of this technology at the beginning of the task was level 5 and was TRL 6 upon completion. In the final validation, an 8 second (0.75 Gbytes) Hyperion image was processed on-board and assessed for percentage cloud cover within 30 minutes. It was expected to take many hours and perhaps a day considering that the Mongoose V is only a 6-8 MIP machine in performance. To accomplish this test, the image taken had to have level 0 and level 1 processing performed on-board before the cloud algorithm was applied. For almost all of the ground test cases and all of the flight cases, the cloud assessment was within 5% of the correct value and in most cases within 1-2%.

  13. Thirty Years of Cloud Cover Patterns from Satellite Data: Fog in California's Central Valley and Coast

    NASA Astrophysics Data System (ADS)

    Waller, E.; Baldocchi, D. D.

    2012-12-01

    In an effort to assess long term trends in winter fog in the Central Valley of California, custom maps of daily cloud cover from an approximately 30 year record of AVHRR (1981-1999) and MODIS (2000-2012) satellite data were generated. Spatial rules were then used to differentiate between fog and general cloud cover. Differences among the sensors (e.g., spectral content, spatial resolution, overpass time) presented problems of consistency, but concurrent climate station data were used to resolve systematic differences in products, and to confirm long term trends. The frequency and extent of Central Valley ("Tule") fog appear to have some periodic oscillation, but also appear to be on the decline, especially in the Sacramento Valley and in the "shoulder" months of November and February. These results may have strong implications for growers of fruit and nut trees in the Central Valley dependent on winter chill hours that are augmented by the foggy daytime conditions. Conclusions about long term trends in fog are limited to daytime patterns, as results are primarily derived from reflectance-based products. Similar analyses of daytime cloud cover are performed on other areas of concern, such as the coastal fog belt of California. Large area and long term patterns here appear to have periodic oscillation similar to that for the Central Valley. However, the relatively coarse spatial resolution of the AVHRR LTDR (Long Term Data Record) data (~5-km) may be limiting for fine-scale analysis of trends.

  14. Satellite estimation of photosynthetically active radiation in Southeast Asia: Impacts of smoke and cloud cover

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hideki; Matsunaga, Tsuneo; Hoyano, Akira; Aoki, Masatoshi; Komori, Daisuke; Boonyawat, Samakkee

    2004-02-01

    Since large-scale variations in photosynthetically active radiation (PAR) influence the terrestrial carbon sources and sinks through the plant photosynthesis variations, large-scale evaluation of PAR is required. In the present study a simple PAR estimation model was developed for Southeast Asia, where large-scale forest fires occurred during El Niño years. The model considered the smoke aerosol released by forest fires using satellite-based smoke detection methods. A comparison study with ground-based solar radiation data for Malaysia and Thailand indicated that the current model could estimate monthly PAR with 10% (root-mean-square) accuracy and would successfully trace the seasonal and year-to-year variations in PAR, including the forest fire periods. During the peak-smoke month in Indonesia, September 1997, the reduction of PAR by smoke reached 63-75% in the center of the Kalimantan and Sumatra Islands. From the analyses of the smoke and cloud cover impacts on PAR in 1997-1999, annual PAR variations were found to be mostly regulated by smoke variations on the Malay Peninsula, Sumatra, and Kalimantan Islands and cloud cover variations on the Indo-China Peninsula. Thus annual variations in PAR changed with location. These variations did not simply correlate with year-to-year variations in cloud cover associated with the El Niño and La Niña cycle, but exhibited more complicated spatial variations due to the existence of smoke in Southeast Asia.

  15. Simultaneous colour visualizations of multiple ALS point cloud attributes for land cover and vegetation analysis

    NASA Astrophysics Data System (ADS)

    Zlinszky, András; Schroiff, Anke; Otepka, Johannes; Mandlburger, Gottfried; Pfeifer, Norbert

    2014-05-01

    LIDAR point clouds hold valuable information for land cover and vegetation analysis, not only in the spatial distribution of the points but also in their various attributes. However, LIDAR point clouds are rarely used for visual interpretation, since for most users, the point cloud is difficult to interpret compared to passive optical imagery. Meanwhile, point cloud viewing software is available allowing interactive 3D interpretation, but typically only one attribute at a time. This results in a large number of points with the same colour, crowding the scene and often obscuring detail. We developed a scheme for mapping information from multiple LIDAR point attributes to the Red, Green, and Blue channels of a widely used LIDAR data format, which are otherwise mostly used to add information from imagery to create "photorealistic" point clouds. The possible combinations of parameters are therefore represented in a wide range of colours, but relative differences in individual parameter values of points can be well understood. The visualization was implemented in OPALS software, using a simple and robust batch script, and is viewer independent since the information is stored in the point cloud data file itself. In our case, the following colour channel assignment delivered best results: Echo amplitude in the Red, echo width in the Green and normalized height above a Digital Terrain Model in the Blue channel. With correct parameter scaling (but completely without point classification), points belonging to asphalt and bare soil are dark red, low grassland and crop vegetation are bright red to yellow, shrubs and low trees are green and high trees are blue. Depending on roof material and DTM quality, buildings are shown from red through purple to dark blue. Erroneously high or low points, or points with incorrect amplitude or echo width usually have colours contrasting from terrain or vegetation. This allows efficient visual interpretation of the point cloud in planar

  16. Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?

    SciTech Connect

    Jeong, M-J.; Li, Z.

    2005-03-18

    Aerosol measurements over the Southern Great Plains (SGP) Cloud And Radiation Test bed (CART) site under Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program characterize the temporal variability, vertical distribution, and optical properties of aerosols in the region. They were made by the Cimel sunphotometer and Multifilter Rotating Shadow-band Radiometer (MFRSR), Raman Lidar, In situ Aerosol Profiling (IAP) flights, and the Aerosol Observing System (AOS). The spatial variability of aerosols relies a network of MFRSR at the Central Facility (CF) and Extended Facilities (EF), together with satellite remote sensing. The current state-of-art satellite-based estimates over land--e.g., MODerate resolution Imaging Scanner (MODIS) aerosol optical thickness--still suffer from large uncertainties. Contamination due to sub-pixel and/or thin cirrus clouds is believed to be one of the major sources of uncertainties. Retrievals near clouds are discouraged to use, which reduces considerably the amount of useful data. In this regard, cloud is considered as an artifact. However, cloud could have a real impact on AOT by changing humidity, which affects aerosol through the aerosol swelling effect. As a preliminary study, we first investigate the effects of cloud cover and humidity on the retrievals of AOT from ground-based Cimel sunphotometer measurements, in order to help us sort out the real influence and artifact. In general, it is very difficult to verify and quantify the effects of cloud on satellite retrieval of aerosol quantities. Speculation and warning of cloud contamination have been made whenever there is a correlation between the retrieved AOT and cloud fraction or their spatial variabilities, while it has also been argued that aerosol humidification effect (AHE) might be at work. The ample measurements available from ARM over the SGP region may allow us to unravel this complex issue. Our ultimate goals are to (1) evaluate various effects on the

  17. An Automated Algorithm for Producing Land Cover Information from Landsat Surface Reflectance Data Acquired Between 1984 and Present

    NASA Astrophysics Data System (ADS)

    Rover, J.; Goldhaber, M. B.; Holen, C.; Dittmeier, R.; Wika, S.; Steinwand, D.; Dahal, D.; Tolk, B.; Quenzer, R.; Nelson, K.; Wylie, B. K.; Coan, M.

    2015-12-01

    Multi-year land cover mapping from remotely sensed data poses challenges. Producing land cover products at spatial and temporal scales required for assessing longer-term trends in land cover change are typically a resource-limited process. A recently developed approach utilizes open source software libraries to automatically generate datasets, decision tree classifications, and data products while requiring minimal user interaction. Users are only required to supply coordinates for an area of interest, land cover from an existing source such as National Land Cover Database and percent slope from a digital terrain model for the same area of interest, two target acquisition year-day windows, and the years of interest between 1984 and present. The algorithm queries the Landsat archive for Landsat data intersecting the area and dates of interest. Cloud-free pixels meeting the user's criteria are mosaicked to create composite images for training the classifiers and applying the classifiers. Stratification of training data is determined by the user and redefined during an iterative process of reviewing classifiers and resulting predictions. The algorithm outputs include yearly land cover raster format data, graphics, and supporting databases for further analysis. Additional analytical tools are also incorporated into the automated land cover system and enable statistical analysis after data are generated. Applications tested include the impact of land cover change and water permanence. For example, land cover conversions in areas where shrubland and grassland were replaced by shale oil pads during hydrofracking of the Bakken Formation were quantified. Analytical analysis of spatial and temporal changes in surface water included identifying wetlands in the Prairie Pothole Region of North Dakota with potential connectivity to ground water, indicating subsurface permeability and geochemistry.

  18. A Satellite Survey of Cloud Cover and Water Vapor in the Southwestern USA and Northern Mexico

    NASA Astrophysics Data System (ADS)

    Carrasco, E.; Avila, R.; Erasmus, A.; Djorgovski, S. G.; Walker, A. R.; Blum, R.

    2017-03-01

    Cloud cover and water vapor conditions in the southwestern USA and northern Mexico were surveyed as a preparatory work for the Thirty Meter Telescope (TMT) in situ site testing program. Although the telescope site is already selected, the TMT site testing team decided to make public these results for its usefulness for the community. Using 58 months of meteorological satellite observations between 1993 July and 1999 September, different atmospheric parameters were quantified from data of the 10.7 μm and of 6.7 μm windows. In particular, cloud cover and water vapor conditions were identified in preferred areas. As a result of the aerial analysis, 15 sites of existing and potential telescope were selected, compared, and ranked in terms of their observing quality. The clearest sites are located along the spine of the Baja peninsula and into southern California on mountain peaks above the temperature inversion layer. A steep gradient of cloudiness was observed along the coast where coastal cloud and fog are trapped below the inversion layer. Moving from west to east over the continent, a significant increase in cloudiness was observed. The analysis shows that San Pedro Mártir, San Gorgonio Mountain and San Jacinto Peak have the largest fraction of clear sky conditions (∼74%). The site with the optimal combination of clear skies and low precipitable water vapor is Boundary Peak, Nevada. An approach based in satellite data provided a reliable method for sites comparison.

  19. Statistics of link blockage due to cloud cover for free-space optical communications using NCDC surface weather observation data

    NASA Technical Reports Server (NTRS)

    Slobin, S. D.; Piazzolla, S.

    2002-01-01

    Cloud opacity is one of the main atmospheric physical phenomena that can jeopardize the successful completion of an optical link between a spacecraft and a ground station. Hence, the site location chosen for a telescope used for optical communications must rely on knowledge of weather and cloud cover statistics for the geographical area where the telescope itself is located.

  20. Influence of cloud fraction and snow cover to the variation of surface UV radiation at King Sejong station, Antarctica

    NASA Astrophysics Data System (ADS)

    Lee, Yun Gon; Koo, Ja-Ho; Kim, Jhoon

    2015-10-01

    This study investigated how cloud fraction and snow cover affect the variation of surface ultraviolet (UV) radiation by using surface Erythemal UV (EUV) and Near UV (NUV) observed at the King Sejong Station, Antarctica. First the Radiative Amplification Factor (RAF), the relative change of surface EUV according to the total-column ozone amount, is compared for different cloud fractions and solar zenith angles (SZAs). Generally, all cloudy conditions show that the increase of RAF as SZA becomes larger, showing the larger effects of vertical columnar ozone. For given SZA cases, the EUV transmission through mean cloud layer gradually decreases as cloud fraction increases, but sometimes the maximum of surface EUV appears under partly cloudy conditions. The high surface EUV transmittance under broken cloud conditions seems due to the re-radiation of scattered EUV by cloud particles. NUV transmission through mean cloud layer also decreases as cloud amount increases but the sensitivity to the cloud fraction is larger than EUV. Both EUV and NUV radiations at the surface are also enhanced by the snow cover, and their enhancement becomes higher as SZA increases implying the diurnal variation of surface albedo. This effect of snow cover seems large under the overcast sky because of the stronger interaction between snow surface and cloudy sky.

  1. The influence of cloud cover index on the accuracy of solar irradiance model estimates

    NASA Astrophysics Data System (ADS)

    Martins, F. R.; Silva, S. A. B.; Pereira, E. B.; Abreu, S. L.

    2008-04-01

    Cloud cover index ( CCI) obtained from satellite images contains information on cloud amount and their optical thickness. It is the chief climate data for the assessment of solar energy resources in most radiative transfer models, particularly for the model BRASIL-SR that is currently operational at CPTEC. The wide range of climate environments in Brazil turns CCI determination into a challenging activity and great effort has been directed to develop new methods and procedures to improve the accuracy of these estimations from satellite images (Martins 2001; Martins et al. 2003a; Ceballos et al. 2004). This work demonstrates the influence of CCI determination methods on estimates of surface solar irradiances obtained by the model BRASIL-SR comparing deviations among ground data and model results. Three techniques using visible and/or thermal infrared images of GOES-8 were employed to generate the CCI for input into the model BRASIL-SR. The ground-truth data was provided by the solar radiation station located at Caicó/PE, in Brazilian Northeast region, which is part of the UNEP/GEF project SWERA (Solar and Wind Energy Resources Assessment). Results have shown that the application of the bi-spectral techniques have reduced mean bias error up to 66% and root mean square error up to 50% when compared to the usual technique for CCI determination based on the straightforward determination of month-by-month extremes for maximum and minimum cloud states.

  2. Development of the Landsat Data Continuity Mission Cloud Cover Assessment Algorithms

    USGS Publications Warehouse

    Scaramuzza, Pat; Bouchard, M.A.; Dwyer, J.L.

    2012-01-01

    The upcoming launch of the Operational Land Imager (OLI) will start the next era of the Landsat program. However, the Automated Cloud-Cover Assessment (CCA) (ACCA) algorithm used on Landsat 7 requires a thermal band and is thus not suited for OLI. There will be a thermal instrument on the Landsat Data Continuity Mission (LDCM)-the Thermal Infrared Sensor-which may not be available during all OLI collections. This illustrates a need for CCA for LDCM in the absence of thermal data. To research possibilities for full-resolution OLI cloud assessment, a global data set of 207 Landsat 7 scenes with manually generated cloud masks was created. It was used to evaluate the ACCA algorithm, showing that the algorithm correctly classified 79.9% of a standard test subset of 3.95 109 pixels. The data set was also used to develop and validate two successor algorithms for use with OLI data-one derived from an off-the-shelf machine learning package and one based on ACCA but enhanced by a simple neural network. These comprehensive CCA algorithms were shown to correctly classify pixels as cloudy or clear 88.5% and 89.7% of the time, respectively.

  3. Automatic registration of unordered point clouds acquired by Kinect sensors using an overlap heuristic

    NASA Astrophysics Data System (ADS)

    Weber, T.; Hänsch, R.; Hellwich, O.

    2015-04-01

    This paper proposes and evaluates a pipeline to automatically register point clouds captured by depth sensors like the Microsoft Kinect. The method neither makes assumptions about the view order of the sensors, nor uses any kind of other task-dependent prior knowledge. All point clouds within the input set are aligned in a common, global coordinate system by a successive application of pairwise registration steps. The order of the individual transformations is automatically derived from a global point cloud graph, which uses the overlap of two individual point clouds to establish a weighted link between them. The experiments prove the generality of the proposed approach by applying it to data from a single but moving sensor, multiple Kinects that run simultaneously, as well as laser scanning data. The obtained accuracies in terms of the mean nearest point neighbor distance are below 0.01% of the maximum point distance of the reference data in all cases.

  4. Comparison of satellite-derived and observer-based determinations of cloud cover amount at the SGP CART site

    SciTech Connect

    Liaw, Y.P.; Cook, D.R.; Sisterson, D.L.; Gao, W.

    1995-06-01

    Cloud-climate feedback is one of the most important factors in predicting the timing and magnitude of global climate change and its regional effects. Recent satellite measurements indicate that global effects of clouds on solar and infrared radiation are large. The experimental objective of the Atmospheric Radiation Measurement (ARM) Program is to characterize, empically, the radiative processes in the Earth`s atmosphere with improved resolution and accuracy. Therefore, the effective treatment of cloud formation and cloud properties is crucial for reliable climate prediction. This study focuses on the analysis of cloud cover data for the ARM Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site central facility. The data set was obtained from the Advanced Very High Resolution Radiometer (AVHRR) on National Oceanic and Atmospheric Administration (NOAA) Satellites 11 and 12, and cloud observations made by SGP CART site operators. Such an analysis provides a basis for future evaluations with whole-sky cameras and provides a means of assessing the reliability of surface-based observations of cloud cover at the SGP CART site.

  5. Mobile Laser Scanning along Dieppe coastal cliffs: reliability of the acquired point clouds applied to rockfall assessments

    NASA Astrophysics Data System (ADS)

    Michoud, Clément; Carrea, Dario; Augereau, Emmanuel; Cancouët, Romain; Costa, Stéphane; Davidson, Robert; Delacourt, Chirstophe; Derron, Marc-Henri; Jaboyedoff, Michel; Letortu, Pauline; Maquaire, Olivier

    2013-04-01

    Dieppe coastal cliffs, in Normandy, France, are mainly formed by sub-horizontal deposits of chalk and flintstone. Largely destabilized by an intense weathering and the Channel sea erosion, small and large rockfalls are regularly observed and contribute to retrogressive cliff processes. During autumn 2012, cliff and intertidal topographies have been acquired with a Terrestrial Laser Scanner (TLS) and a Mobile Laser Scanner (MLS), coupled with seafloor bathymetries realized with a multibeam echosounder (MBES). MLS is a recent development of laser scanning based on the same theoretical principles of aerial LiDAR, but using smaller, cheaper and portable devices. The MLS system, which is composed by an accurate dynamic positioning and orientation (INS) devices and a long range LiDAR, is mounted on a marine vessel; it is then possible to quickly acquire in motion georeferenced LiDAR point clouds with a resolution of about 15 cm. For example, it takes about 1 h to scan of shoreline of 2 km long. MLS is becoming a promising technique supporting erosion and rockfall assessments along the shores of lakes, fjords or seas. In this study, the MLS system used to acquire cliffs and intertidal areas of the Cap d'Ailly was composed by the INS Applanix POS-MV 320 V4 and the LiDAR Optech Ilirs LR. On the same day, three MLS scans with large overlaps (J1, J21 and J3) have been performed at ranges from 600 m at 4 knots (low tide) up to 200 m at 2.2 knots (up tide) with a calm sea at 2.5 Beaufort (small wavelets). Mean scan resolutions go from 26 cm for far scan (J1) to about 8.1 cm for close scan (J3). Moreover, one TLS point cloud on this test site has been acquired with a mean resolution of about 2.3 cm, using a Riegl LMS Z390i. In order to quantify the reliability of the methodology, comparisons between scans have been realized with the software Polyworks™, calculating shortest distances between points of one cloud and the interpolated surface of the reference point cloud. A Mat

  6. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, Li; Xia, Xiangao; Wang, Pucai; Fei, Ye

    2015-04-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCgrd) were firstly compared with ground observations (TCCsat) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsatranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat - TCCgrdand visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrdover the NCP.

  7. Do aerosols impact ground observation of total cloud cover over the North China Plain?

    NASA Astrophysics Data System (ADS)

    Sun, L.; Xia, X.; Wang, P.; Fei, Y.

    2014-06-01

    Ground observation of the total cloud cover (TCC) showed a significant downward trend during the past half century over the North China Plain (NCP). The objective of this paper is to examine whether aerosols have impacted the surface observations of TCC by human observers. TCC observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua (TCCsat) were firstly compared with ground observations (TCCgrd) at 201 synoptic stations over the NCP. Results showed that both data sets were in good agreement. The correlation coefficient between TCCgrd and TCCsat ranged from 0.80 in winter to 0.90 in summer. The relationship between TCCsat-TCCgrd and visibility was then analyzed, which showed no significant correlation. Finally, long-term trends of TCCgrd and visibility were not correlated. These results indicated that aerosols likely did not impact the long-term trend of TCCgrd over the NCP.

  8. High-resolution stochastic downscaling of climate models: simulating wind advection, cloud cover and precipitation

    NASA Astrophysics Data System (ADS)

    Peleg, Nadav; Fatichi, Simone; Burlando, Paolo

    2015-04-01

    A new stochastic approach to generate wind advection, cloud cover and precipitation fields is presented with the aim of formulating a space-time weather generator characterized by fields with high spatial and temporal resolution (e.g., 1 km x 1 km and 5 min). Its use is suitable for stochastic downscaling of climate scenarios in the context of hydrological, ecological and geomorphological applications. The approach is based on concepts from the Advanced WEather GENerator (AWE-GEN) presented by Fatichi et al. (2011, Adv. Water Resour.), the Space-Time Realizations of Areal Precipitation model (STREAP) introduced by Paschalis et al. (2013, Water Resour. Res.), and the High-Resolution Synoptically conditioned Weather Generator (HiReS-WG) presented by Peleg and Morin (2014, Water Resour. Res.). Advection fields are generated on the basis of the 500 hPa u and v wind direction variables derived from global or regional climate models. The advection velocity and direction are parameterized using Kappa and von Mises distributions respectively. A random Gaussian fields is generated using a fast Fourier transform to preserve the spatial correlation of advection. The cloud cover area, total precipitation area and mean advection of the field are coupled using a multi-autoregressive model. The approach is relatively parsimonious in terms of computational demand and, in the context of climate change, allows generating many stochastic realizations of current and projected climate in a fast and efficient way. A preliminary test of the approach is presented with reference to a case study in a complex orography terrain in the Swiss Alps.

  9. Regional cloud cover change associated with global climate change: Case studies for three regions of the United States

    SciTech Connect

    Croke, M.S. ); Cess, R.D.; Hameed, S. . Marine Sciences Research Center)

    1999-07-01

    Land-based observations of cloud cover, for the period 1900--87 and averaged over three geographical regions of the United States (coastal southwest, coastal northeast, and southern plains), show strong positive correlations with one estimate of global mean surface temperature, a finding consistent with prior investigations that suggest cloud cover over land has increased during global warm periods relative to cold periods. It is also found that the strengths of three permanent high/low pressure systems (North Pacific high, Icelandic low, and Azores high) are negatively correlated with global mean surface temperature, suggesting a possible connection between regional cloud cover, for certain locations, and the strengths of adjacent high/low pressure systems. Specifically, for the regions considered it is suggested that the coastal southwest cloud cover is related to changes in the strength of the subtropical North Pacific high, that for the southern plains also to the strength of the North Pacific high, and that for the coastal northeast to the strength of the Icelandic low. Thus the climate-induced change in cloud cover for certain regions appears related, at least in part, to climate-induced change in the strengths of adjacent high/low pressure systems, and plausible physical explanations for this relation are provided for the three regions that have been studied. This does not, of course, provide a direct physical cause-and-effect explanation for the changes in regional cloud cover, because the mechanisms that cause the intensities of the high/low pressure systems to change are not understood.

  10. The Impact of Changing Cloud Cover on the High Arctic's Primary Cooling-to-space Windows

    NASA Astrophysics Data System (ADS)

    Mariani, Zen; Rowe, Penny; Strong, Kimberly; Walden, Von; Drummond, James

    2014-05-01

    In the Arctic, most of the infrared energy emitted by the surface escapes to space in two atmospheric windows at 10 and 20 μm. As the Arctic warms, the 20 μm cooling-to-space window becomes increasingly opaque (or "closed"), trapping more surface infrared radiation in the atmosphere, with implications for the Arctic's radiative energy balance. Since 2006, the Canadian Network for the Detection of Atmospheric Change (CANDAC) has measured downwelling infrared radiance with an Atmospheric Emitted Radiance Interferometer (AERI) at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Canada, providing the first long-term measurements of the 10 and 20 μm windows in the high Arctic. In this work, measurements of the distribution of downwelling 10 and 20 µm brightness temperatures at Eureka are separated based on cloud cover, providing a comparison to an existing climatology from the Southern Great Plains (SGP). Measurements of the downwelling radiance at both 10 and 20 μm exhibit strong seasonal variability as a result of changes in temperature and water vapour, in addition to variability with cloud cover. When separated by season, brightness temperatures in the 20 µm window are found to be independent of cloud thickness in the summertime, indicating that this window is closed in the summer. Radiance trends in three-month averages are positive and are significantly larger (factor > 5) than the trends detected at the SGP, indicating that changes in the downwelling radiance are accelerated in the high Arctic compared to lower latitudes. This statistically significant increase (> 5% / yr) in radiance at 10 μm occurs only when the 20 μm window is mostly transparent, or "open" (i.e., in all seasons except summer), and may have long-term consequences, particularly as warmer temperatures and increased water vapour "close" the dirty window for a prolonged period. These surface-based measurements of radiative forcing can be used to quantify changes in

  11. Estimation of total cloud cover from solar radiation observations at Lake Rotorua, New Zealand

    SciTech Connect

    Luo, Liancong; Hamilton, David; Han, Boping

    2010-03-15

    The DYRESM-CAEDYM model is a valuable tool for simulating water temperature for biochemical studies in aquatic ecosystem. The model requires inputs of surface short-wave radiation and long-wave radiation or total cloud cover fraction (TC). Long-wave radiation is often not measured directly so a method to determine TC from commonly measured short-wave solar irradiance (E{sub 0}) and theoretical short-wave solar irradiance under a clear sky (E{sub c}) has broad application. A more than 17-year (15 November 1991 to 20 February 2009) hourly solar irradiance data set was used to estimate the peak solar irradiance for each ordinal date over one year, which was assumed to be representative of solar irradiance in the absence of cloud. Comparison between these daily observed values and the modelled clear-sky solar radiation over one year was in close agreement (Pearson correlation coefficient, r = 0.995 and root mean squared error, RMSE = 12.54 W m{sup -2}). The downloaded hourly cloudiness measurements from 15 November 1991 to 20 February 2009 was used to calculate the daily values for this period and then the calculated daily values over the 17 years were used to calculate the average values for each ordinal date over one year. A regression equation between (1 - E{sub 0}/E{sub c}) and TC produced a correlation coefficient value of 0.99 (p > 0.01, n = 71). The validation of this cloud cover estimation model was conducted with observed short-wave solar radiation and TC at two sites. Values of TC derived from the model at the Lake Rotorua site gave a reasonable prediction of the observed values (RMSE = 0.10, r = 0.86, p > 0.01, n = 61). The model was also tested at Queenstown (South Island of New Zealand) and it provided satisfactory results compared to the measurements (RMSE = 0.16, r = 0.67, p > 0.01, n = 61). Therefore the model's good performance and broad applicability will contribute to the DYRESM-CAEDYM accuracy of water temperature simulation when long-wave radiation

  12. A comparison of ground and satellite observations of cloud cover to saturation pressure differences during a cold air outbreak

    SciTech Connect

    Alliss, R.J.; Raman, S.

    1996-04-01

    The role of clouds in the atmospheric general circulation and the global climate is twofold. First, clouds owe their origin to large-scale dynamical forcing, radiative cooling in the atmosphere, and turbulent transfer at the surface. In addition, they provide one of the most important mechanisms for the vertical redistribution of momentum and sensible and latent heat for the large scale, and they influence the coupling between the atmosphere and the surface as well as the radiative and dynamical-hydrological balance. In existing diagnostic cloudiness parameterization schemes, relative humidity is the most frequently used variable for estimating total cloud amount or stratiform cloud amount. However, the prediction of relative humidity in general circulation models (GCMs) is usually poor. Even for the most comprehensive GCMs, the predicted relative humidity may deviate greatly from that observed, as far as the frequency distribution of relative humidity is concerned. Recently, there has been an increased effort to improve the representation of clouds and cloud-radiation feedback in GCMs, but the verification of cloudiness parameterization schemes remains a severe problem because of the lack of observational data sets. In this study, saturation pressure differences (as opposed to relative humidity) and satellite-derived cloud heights and amounts are compared with ground determinations of cloud cover over the Gulf Stream Locale (GSL) during a cold air outbreak.

  13. Feature-constrained registration of building point clouds acquired by terrestrial and airborne laser scanners

    NASA Astrophysics Data System (ADS)

    Wu, Hangbin; Scaioni, Marco; Li, Hanyan; Li, Nan; Lu, Minfeng; Liu, Chun

    2014-01-01

    Point-cloud registration is usually accomplished on the basis of several corresponding features to compute the parameters of the transformation model. However, common point features are difficult to select because airborne laser scanner (ALS) and terrestrial laser scanner (TLS) point clouds of the same object have be aligned due to the different sensing positions and sampling modes. Taking building profile features as objects, a registration method based on feature constraints is proposed here. The standard six-parameter rigid-body transformation adopted for alignment of laser scans is replaced by a two-step transformation: horizontal registration based on a two-dimensional similarity transformation and vertical registration based on a simple vertical shift. First, the feature-line and feature-plane equation parameters are obtained from both the airborne and terrestrial point clouds. Second, the plane transformation parameters are computed after projecting the extracted features onto a horizontal reference plane. Finally, the elevation transformation parameter is calculated by comparing the heights of flat features. The ALS and TLS datasets of two buildings (Shanghai Pudong International Conference Center and Shanghai Ocean Aquarium, China) were used to evaluate the robustness and accuracy. The results show that the proposed feature-constrained method works well for registration between two datasets. Five checkpoints and one overlap zone for the Pudong International Conference Center were selected to evaluate the accuracy and resulted in accuracies of 0.15 to 0.5 m in the horizontal direction and 0.20 m in the vertical direction.

  14. Partial covering of the emission regions of Q 0528-250 by intervening H2 clouds

    NASA Astrophysics Data System (ADS)

    Klimenko, V. V.; Balashev, S. A.; Ivanchik, A. V.; Ledoux, C.; Noterdaeme, P.; Petitjean, P.; Srianand, R.; Varshalovich, D. A.

    2015-03-01

    We present an analysis of the molecular hydrogen absorption system at zabs = 2.811 in the spectrum of the blazar Q 0528-250. We demonstrate that the molecular cloud does not cover the background source completely. The partial coverage reveals itself as a residual flux at the bottom of the saturated H2 absorption lines. This amounts to about (2.22 ± 0.54) per cent of the continuum and does not depend on the wavelength. This value is small and it explains why this effect has not been detected in previous studies of this quasar spectrum. However, it is robustly detected and is significantly higher than the zero-flux level at the bottom of the saturated lines of the Lyα forest, (-0.21 ± 0.22) per cent. The presence of the residual flux could be caused by unresolved quasar multicomponents, by light scattered by dust and/or by jet-cloud interaction. The H2 absorption system is very well described by a two-component model without the inclusion of additional components when we take partial coverage into account. The derived total column densities in the H2 absorption components A and B are log N(H2)(cm-2) = 18.10 ± 0.02 and 17.82 ± 0.02, respectively. HD molecules are present only in component B. Given the column density, log N(HD) = 13.33 ± 0.02, we find N(HD)/2N(H2) = (1.48 ± 0.10) × 10- 5, significantly lower than previous estimations. We argue that it is crucial to take into account the partial coverage effects in any analysis of H2 bearing absorption systems, in particular when studying the physical state of the high-redshift interstellar medium.

  15. The effects of moon illumination, moon angle, cloud cover, and sky glow on night vision goggle flight performance

    NASA Astrophysics Data System (ADS)

    Loro, Stephen Lee

    This study was designed to examine moon illumination, moon angle, cloud cover, sky glow, and Night Vision Goggle (NVG) flight performance to determine possible effects. The research was a causal-comparative design. The sample consisted of 194 Fort Rucker Initial Entry Rotary Wing NVG flight students being observed by 69 NVG Instructor Pilots. The students participated in NVG flight training from September 1992 through January 1993. Data were collected using a questionnaire. Observations were analyzed using a Kruskal-Wallis one-way analysis of variance and a Wilcox matched pairs signed-ranks test for difference. Correlations were analyzed using Pearson's r. The analyses results indicated that performance at high moon illumination levels is superior to zero moon illumination, and in most task maneuvers, superior to >0%--50% moon illumination. No differences were found in performance at moon illumination levels above 50%. Moon angle had no effect on night vision goggle flight performance. Cloud cover and sky glow have selective effects on different maneuvers. For most task maneuvers, cloud cover does not affect performance. Overcast cloud cover had a significant effect on seven of the 14 task maneuvers. Sky glow did not affect eight out of 14 task maneuvers at any level of sky glow.

  16. Feature-constrained surface reconstruction approach for point cloud data acquired with 3D laser scanner

    NASA Astrophysics Data System (ADS)

    Wang, Yongbo; Sheng, Yehua; Lu, Guonian; Tian, Peng; Zhang, Kai

    2008-04-01

    Surface reconstruction is an important task in the field of 3d-GIS, computer aided design and computer graphics (CAD & CG), virtual simulation and so on. Based on available incremental surface reconstruction methods, a feature-constrained surface reconstruction approach for point cloud is presented. Firstly features are extracted from point cloud under the rules of curvature extremes and minimum spanning tree. By projecting local sample points to the fitted tangent planes and using extracted features to guide and constrain the process of local triangulation and surface propagation, topological relationship among sample points can be achieved. For the constructed models, a process named consistent normal adjustment and regularization is adopted to adjust normal of each face so that the correct surface model is achieved. Experiments show that the presented approach inherits the convenient implementation and high efficiency of traditional incremental surface reconstruction method, meanwhile, it avoids improper propagation of normal across sharp edges, which means the applicability of incremental surface reconstruction is greatly improved. Above all, appropriate k-neighborhood can help to recognize un-sufficient sampled areas and boundary parts, the presented approach can be used to reconstruct both open and close surfaces without additional interference.

  17. Increasing cloud cover in the 20th century: review and new findings in Spain

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, A.; Calbó, J.; Wild, M.

    2012-04-01

    Visual observations of clouds have been performed since the establishment of meteorological observatories during the early instrumental period, and have become more systematic and reliable after the mid-19th century due to the establishment of the first national weather services. During the last decades a large number of studies have documented the trends of the total cloud cover (TCC) and cloudy types; most of these studies are focused on the trends since the second half of the 20th century. Due to the lower reliability of former observations, and the fact that most of this data is not accessible in digital format, there is a lack of studies focusing on the trends of cloudiness since the mid-19th century. In the first part, this work attempts to review the previous studies analyzing TCC changes with information covering at least the first half of the 20th century. Then, the study analyses a database of cloudiness observations in Southern Europe (Spain) since the second third of the 19th century. Specifically, monthly TCC series were reconstructed since 1866 by means of a so-called parameter of cloudiness, calculated from the number of cloudless and overcast days. This estimated TCC series show a high interannual and decadal correlation with the observed TCC series originally measured in oktas. After assessing the temporal homogeneity of the estimated TCC series, the mean annual and seasonal series for the whole of Spain and several subregions were calculated. The mean annual TCC shows a general tendency to increase from the beginning of the series until the 1960s; at this point, the trend becomes negative. The linear trend for the annual mean series, estimated over the 1866-2010 period, is a highly remarkable (and statistically significant) increase of +0.44% per decade, which implies an overall increase of more than +6% during the analyzed period. These results are in line with the major part of the previous trends observed at many areas of the World, especially

  18. Increasing cloud cover in the 20th century: review and new findings in Spain

    NASA Astrophysics Data System (ADS)

    Sanchez-Lorenzo, A.; Calbó, J.; Wild, M.

    2012-07-01

    Visual observations of clouds have been performed since the establishment of meteorological observatories during the early instrumental period, and have become more systematic and reliable after the mid-19th century due to the establishment of the first national weather services. During the last decades a large number of studies have documented the trends of the total cloud cover (TCC) and cloudy types; most of these studies focus on the trends since the second half of the 20th century. Due to the lower reliability of former observations, and the fact that most of this data is not accessible in digital format, there is a lack of studies focusing on the trends of cloudiness since the mid-19th century. In the first part, this work attempts to review previous studies analyzing TCC changes with information covering at least the first half of the 20th century. Then, the study analyses a database of cloudiness observations in Southern Europe (Spain) since the second half of the 19th century. Specifically, monthly TCC series were reconstructed since 1866 by means of a so-called parameter of cloudiness, calculated from the number of cloudless and overcast days. These estimated TCC series show a high interannual and decadal correlation with the observed TCC series originally measured in oktas. After assessing the temporal homogeneity of the estimated TCC series, the mean annual and seasonal series for the whole of Spain and several subregions were calculated. The mean annual TCC shows a general tendency to increase from the beginning of the series until the 1960s; at this point, the trend becomes negative. The linear trend for the annual mean series, estimated over the 1866-2010 period, is a highly remarkable (and statistically significant) increase of +0.44% per decade, which implies an overall increase of more than +6% during the analyzed period. These results are in line with the majority of the trends observed in many areas of the world in previous studies, especially

  19. The cloud cover fraction obtained from a ground CCD camera and its effect on a radiative transfer model

    NASA Astrophysics Data System (ADS)

    Souza, M. P.; Pereira, E. B.; Martins, F. R.; Chagas, R. C.; Freitas, W. S., Jr.

    2003-04-01

    Clouds are the major factor that rules the solar irradiance over Earth's surface. They interact with solar radiation in the shortwave spectra and with terrestrial radiation emitted by Earth's surface in the longwave range. Information about cloud cover is a very important input data for radiative transfer models and great effort is being made to improve methods to get this information. This paper reports the effects on a radiative transfer model by using the simple cloud fraction obtained by a ground set CCD camera instead of the satellite derived cloud index. The BRASIL-SR model is a radiative transfer model that calculates surface solar irradiance, using a normalized cloud index determined by statistical analyses of satellites images and from climatological values of temperature and albedo. Cloud fraction was obtained from digital images collected by a ground set CCD (Charge Coupled Device) camera, in the visible range (0.4mm - 0.7mm) as RGB (Red - Green - Blue) compositions. The method initially transforms the image attributes from the RGB space to the IHS (Intensity - Hue - Saturation) space. The algorithm defines threshold values for the saturation component of the IHS system to classify a pixel as cloudy or clear sky. Clear skies are identified by high values of saturation in the visible range while cloudy condition presents a mixture of several wavelengths and consequently lower saturation values. Results from the CCD camera and from the satellite were compared with the Kt and Kd from pyranometer data obtained from a local BSRN radiation station at Florianópolis (27º 28'S, 48º 29'W) and show that cloud fraction is only a poor information about the cloud sky status since it does not bear any information on the cloud optical depth which is needed in most radiative transfer models such as the one used in this paper (the BRASIL-SR).

  20. Characterizing spatial and temporal patterns of cloud cover and fog inundation for the Northern Channel islands of California

    NASA Astrophysics Data System (ADS)

    Rastogi, Bharat

    The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in a variety of ecosystems in different climates. This is especially true for California's Channel Islands, where forests are frequently shaded by low-lying clouds or immersed in fog during warm and dry summer months. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon and water budgets in these semi-arid environments by reducing solar insolation and raising relative humidity and thus reducing evapotranspiration, while also potentially supplying water directly to the landscape from fog-drip. While summertime fog and stratus cover in California's Channel Islands can ameliorate summer drought stress and enhance soil water budgets, they often have different spatial and temporal patterns. These differing patterns and the resulting shifts in relative ecological importance of fog and stratus are understudied. The overall objective of this study is to map spatial and temporal distributions of daytime cloud cover frequency for the California Channel Islands, and to predict probabilities of surface cloud (fog) contact and immersion for these islands. The results of this research are significant for water balance modeling, help explain vegetation patterns on the islands, and better identify locations where native vegetation restoration efforts are likely to be most successful.

  1. Cloud cover and type over the former USSR, 1936-83; trends derived from the RIHMI-WDC 223-station 6- and 3-hourly meteorological database

    SciTech Connect

    Kaiser, D.P.; Razuvaev, V.N.

    1995-07-01

    This paper presents trends analyses of sky cover data from the former U.S.S.R. for the period 1936-83. Observations of total cloud amount, low cloud amount, and low-, middle-, and high-cloud type from 223 stations were obtained from a database of 6- and 3-hourly meteorological observations compiled at the Research Institute of Hydrometeorological Information - World Data Centre in Obninsk, Russia. Station data were averaged over various-sized grid boxes and linear trends in seasonal mean total cloud amount, low cloud amount, frequency of occurrence of cirrus clouds, cirrus amount, and frequency of clear sky were computed for the period 1936-83.

  2. Equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) in 14 horses associated with ingestion of Maple leaves (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum).

    PubMed

    van der Kolk, J H; Wijnberg, I D; Westermann, C M; Dorland, L; de Sain-van der Velden, M G M; Kranenburg, L C; Duran, M; Dijkstra, J A; van der Lugt, J J; Wanders, R J A; Gruys, E

    2010-01-01

    This case-series describes fourteen horses suspected of equine acquired multiple acyl-CoA dehydrogenase deficiency (MADD) also known as atypical myopathy of which seven cases were confirmed biochemically with all horses having had access to leaves of the Maple tree (Acer pseudoplatanus) covered with European tar spot (Rhytisma acerinum). Assessment of organic acids, glycine conjugates, and acylcarnitines in urine was regarded as gold standard in the biochemical diagnosis of equine acquired multiple acyl-CoA dehydrogenase deficiency.

  3. On the relationships among cloud cover, mixed-phase partitioning, and planetary albedo in GCMs

    NASA Astrophysics Data System (ADS)

    McCoy, Daniel T.; Tan, Ivy; Hartmann, Dennis L.; Zelinka, Mark D.; Storelvmo, Trude

    2016-06-01

    In this study, it is shown that CMIP5 global climate models (GCMs) that convert supercooled water to ice at relatively warm temperatures tend to have a greater mean-state cloud fraction and more negative cloud feedback in the middle and high latitude Southern Hemisphere. We investigate possible reasons for these relationships by analyzing the mixed-phase parameterizations in 26 GCMs. The atmospheric temperature where ice and liquid are equally prevalent (T5050) is used to characterize the mixed-phase parameterization in each GCM. Liquid clouds have a higher albedo than ice clouds, so, all else being equal, models with more supercooled liquid water would also have a higher planetary albedo. The lower cloud fraction in these models compensates the higher cloud reflectivity and results in clouds that reflect shortwave radiation (SW) in reasonable agreement with observations, but gives clouds that are too bright and too few. The temperature at which supercooled liquid can remain unfrozen is strongly anti-correlated with cloud fraction in the climate mean state across the model ensemble, but we know of no robust physical mechanism to explain this behavior, especially because this anti-correlation extends through the subtropics. A set of perturbed physics simulations with the Community Atmospheric Model Version 4 (CAM4) shows that, if its temperature-dependent phase partitioning is varied and the critical relative humidity for cloud formation in each model run is also tuned to bring reflected SW into agreement with observations, then cloud fraction increases and liquid water path (LWP) decreases with T5050, as in the CMIP5 ensemble.

  4. Experimental evaluation of ALS point cloud ground extraction over different land cover in the Malopolska Province

    NASA Astrophysics Data System (ADS)

    Korzeniowska, Karolina; Mandlburger, Gottfried; Klimczyk, Agata

    2013-04-01

    The paper presents an evaluation of different terrain point extraction algorithms for Airborne Laser Scanning (ALS) point clouds. The research area covers eight test sites in the Małopolska Province (Poland) with varying point density between 3-15points/m² and surface as well as land cover characteristics. In this paper the existing implementations of algorithms were considered. Approaches based on mathematical morphology, progressive densification, robust surface interpolation and segmentation were compared. From the group of morphological filters, the Progressive Morphological Filter (PMF) proposed by Zhang K. et al. (2003) in LIS software was evaluated. From the progressive densification filter methods developed by Axelsson P. (2000) the Martin Isenburg's implementation in LAStools software (LAStools, 2012) was chosen. The third group of methods are surface-based filters. In this study, we used the hierarchic robust interpolation approach by Kraus K., Pfeifer N. (1998) as implemented in SCOP++ (Trimble, 2012). The fourth group of methods works on segmentation. From this filtering concept the segmentation algorithm available in LIS was tested (Wichmann V., 2012). The main aim in executing the automatic classification for ground extraction was operating in default mode or with default parameters which were selected by the developers of the algorithms. It was assumed that the default settings were equivalent to the parameters on which the best results can be achieved. In case it was not possible to apply an algorithm in default mode, a combination of the available and most crucial parameters for ground extraction were selected. As a result of these analyses, several output LAS files with different ground classification were achieved. The results were described on the basis of qualitative and quantitative analyses, both being in a formal description. The classification differences were verified on point cloud data. Qualitative verification of ground extraction was

  5. Time-cumulated visible and infrared histograms used as descriptor of cloud cover

    NASA Technical Reports Server (NTRS)

    Seze, G.; Rossow, W.

    1987-01-01

    To study the statistical behavior of clouds for different climate regimes, the spatial and temporal stability of VIS-IR bidimensional histograms is tested. Also, the effect of data sampling and averaging on the histogram shapes is considered; in particular the sampling strategy used by the International Satellite Cloud Climatology Project is tested.

  6. Procedures for gathering ground truth information for a supervised approach to a computer-implemented land cover classification of LANDSAT-acquired multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Joyce, A. T.

    1978-01-01

    Procedures for gathering ground truth information for a supervised approach to a computer-implemented land cover classification of LANDSAT acquired multispectral scanner data are provided in a step by step manner. Criteria for determining size, number, uniformity, and predominant land cover of training sample sites are established. Suggestions are made for the organization and orientation of field team personnel, the procedures used in the field, and the format of the forms to be used. Estimates are made of the probable expenditures in time and costs. Examples of ground truth forms and definitions and criteria of major land cover categories are provided in appendixes.

  7. Object Based Image Analysis Combining High Spatial Resolution Imagery and Laser Point Clouds for Urban Land Cover

    NASA Astrophysics Data System (ADS)

    Zou, Xiaoliang; Zhao, Guihua; Li, Jonathan; Yang, Yuanxi; Fang, Yong

    2016-06-01

    With the rapid developments of the sensor technology, high spatial resolution imagery and airborne Lidar point clouds can be captured nowadays, which make classification, extraction, evaluation and analysis of a broad range of object features available. High resolution imagery, Lidar dataset and parcel map can be widely used for classification as information carriers. Therefore, refinement of objects classification is made possible for the urban land cover. The paper presents an approach to object based image analysis (OBIA) combing high spatial resolution imagery and airborne Lidar point clouds. The advanced workflow for urban land cover is designed with four components. Firstly, colour-infrared TrueOrtho photo and laser point clouds were pre-processed to derive the parcel map of water bodies and nDSM respectively. Secondly, image objects are created via multi-resolution image segmentation integrating scale parameter, the colour and shape properties with compactness criterion. Image can be subdivided into separate object regions. Thirdly, image objects classification is performed on the basis of segmentation and a rule set of knowledge decision tree. These objects imagery are classified into six classes such as water bodies, low vegetation/grass, tree, low building, high building and road. Finally, in order to assess the validity of the classification results for six classes, accuracy assessment is performed through comparing randomly distributed reference points of TrueOrtho imagery with the classification results, forming the confusion matrix and calculating overall accuracy and Kappa coefficient. The study area focuses on test site Vaihingen/Enz and a patch of test datasets comes from the benchmark of ISPRS WG III/4 test project. The classification results show higher overall accuracy for most types of urban land cover. Overall accuracy is 89.5% and Kappa coefficient equals to 0.865. The OBIA approach provides an effective and convenient way to combine high

  8. SACR ADVance 3-D Cartesian Cloud Cover (SACR-ADV-3D3C) product

    DOE Data Explorer

    Meng Wang, Tami Toto, Eugene Clothiaux, Katia Lamer, Mariko Oue

    2017-03-08

    SACR-ADV-3D3C remaps the outputs of SACRCORR for cross-wind range-height indicator (CW-RHI) scans to a Cartesian grid and reports reflectivity CFAD and best estimate domain averaged cloud fraction. The final output is a single NetCDF file containing all aforementioned corrected radar moments remapped on a 3-D Cartesian grid, the SACR reflectivity CFAD, a profile of best estimate cloud fraction, a profile of maximum observable x-domain size (xmax), a profile time to horizontal distance estimate and a profile of minimum observable reflectivity (dBZmin).

  9. NH4SH and cloud cover in the atmospheres of the giant planets

    NASA Astrophysics Data System (ADS)

    Ibragimov, K. Iu.; Solodovnik, A. A.

    1991-02-01

    The probability of the formation of NH4SH and (NH4)2S is examined on the basis of the Le Chatelier principle. It is shown that it is very doubtful if NH4SH can be created in the atmospheres of the giant planets in quantities sufficient for cloud formation. Thus (NH4)2S is considered as a more likely candidate for cloud formation in the atmospheres of these planets, inasmuch as the conditions for its production there are more favorable.

  10. Solar signal at regional scale: a study of possible solar impact upon cloud cover and associated climatic parameters in Romania

    NASA Astrophysics Data System (ADS)

    Sfica, Lucian; Iordache, Iulian; Voiculescu, Mirela

    2016-04-01

    consistent arguments for existing solar influence upon climate at global or hemispherical scale. Solar trademark was identified in pressure fields at tropospheric or stratospheric level, atmospheric circulation pattern, temperature variation or cloud cover, on different timescales. However, these are less clear at regional or local. In our study we try to investigate the solar impact upon the climate parameters on the level of Romanian territory. The ROCADA database (Bîrsan et al., 2014) was used for climate data for Romania. The database covers the 1961-2013 period for 9 climate parameters out of which we will focus on those which may help in understanding the cloud cover response to solar triggers: mean air temperature, maximum air temperature, minimum air temperature, relative humidity, cloud cover, atmospheric pressure, precipitation amount and sunshine duration. The data base is downloadable on a gridded dataset at daily level with a spatial resolution of 0,1 degree. For solar data a couple of proxy solar data were selected from NASA daily database - omniweb.gsfc.nasa.gov - concerning terrestrial magnetic field (BY, BZ), electric field (EF), solar wind speed (SW) or the more classical proxy of sunspots number. Climate Data Operator is used for extracting gridded data and ArcGis 10.3.1 and Qgis software packages for mapping the results. Data were statistically treated in order to eliminate the trend and the effect of seasonality. The results were organized for monthly, seasonal and yearly level. The methodology for detection of the solar signal on climate variables relies on interpreting the correlation maps between climate variables and solar proxies. Also, a composite analysis on the basis of separation of high and low solar activity at monthly level was performed. The main results leads to the idea that the solar signal can be detected primarly in the temporal variation of atmospheric pressure (positive correlation with solar wind speed), soil temperature

  11. Effects of cover crops on the microbial community and its ability to suppress disease and acquire nutrients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover crops are able to provide a field with a microbial biomass that is able perform important ecological functions for that field. Studies show that cover crops are able to increase soil microbial biomass, suppress disease and weeds, and improve soil and water quality. Siderophores are an importan...

  12. Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

    DTIC Science & Technology

    2013-09-30

    a drop or balloon sonde, which is low cost but cannot be guided, and a typical UAV, which provides guidance flexibility but uses costly avionics and...by incorporating the proposed IR sensors and ground­sky temperature difference algorithm into a tethered balloon borne payload (Figure 6).This...ceilometer was used to provide a cloud base reference measurement, as well as visual markings of altitudes where the balloon and its payload disappeared

  13. Stabilization of Global Temperature and Polar Sea-ice cover via seeding of Maritime Clouds

    NASA Astrophysics Data System (ADS)

    Chen, Jack; Gadian, Alan; Latham, John; Launder, Brian; Neukermans, Armand; Rasch, Phil; Salter, Stephen

    2010-05-01

    The marine cloud albedo enhancement (cloud whitening) geoengineering technique (Latham1990, 2002, Bower et al. 2006, Latham et al. 2008, Salter et al. 2008, Rasch et al. 2009) involves seeding maritime stratocumulus clouds with seawater droplets of size (at creation) around 1 micrometer, causing the droplet number concentration to increase within the clouds, thereby enhancing their albedo and possibly longevity. GCM modeling indicates that (subject to satisfactory resolution of specified scientific and technological problems) the technique could produce a globally averaged negative forcing of up to about -4W/m2, adequate to hold the Earth's average temperature constant as the atmospheric carbon dioxide concentration increases to twice the current value. This idea is being examined using GCM modeling, LES cloud modeling, technological development (practical and theoretical), and analysis of data from the recent, extensive VOCALS field study of marine stratocumulus clouds. We are also formulating plans for a possible limited-area field test of the technique. Recent general circulation model computations using a fully coupled ocean-atmosphere model indicate that increasing cloud reflectivity by seeding maritime boundary layer clouds may compensate for some effects on climate of increasing greenhouse gas concentrations. The chosen seeding strategy (one of many possible scenarios), when employed in an atmosphere where the CO2 concentration is doubled, can restore global averages of temperature, precipitation and polar sea-ice to present day values, but not simultaneously. The response varies nonlinearly with the extent of seeding, and geoengineering generates local changes to important climatic features. Our computations suggest that for the specimen cases examined there is no appreciable reduction of rainfall over land, as a consequence of seeding. This result is in agreement with one separate study but not another. Much further work is required to explain these

  14. Cloud cover index obtained from satellite data and its role on reliability of surface solar radiation assessment.

    NASA Astrophysics Data System (ADS)

    Martins, F. R.; Pereira, E. B.; Abreu, S. L.

    Cloud cover index (CCI) is a very important input data for radiative transfer models and great effort is being made to its determination from satellite images with high confidence. Cloud cover index is obtained from a linear relation between the clear and overcast radiances values measured in the visible range by satellite over a specific time period for each image pixel. The major key to obtain reliable CCI values is to correctly characterize clear skies and overcast skies from satellite images. This may be a complex and uncertain task in some circumstances. The importance of CCI becomes evident when it is used as input data to map surface solar irradiation over large continental areas such as over the Brazilian territory, with a wide range of climatic environments. Brazilian Northeast area presents a low annual precipitation (less than 700mm) and large insolation (about 120 clear sky days/year). In contrast, precipitation is high in the Amazonian region and it may occur long time periods (more than 30 days) with the sky cloudy at a specific daytime during the wet season (from November to April). The majority of the established methodologies to obtain CCI values from satellite images fail under any of these circumstances. Besides that, the comparison of CCI values obtained from satellite images with ground data is unfeasible in face of the different fields of view, and the subjectivity associated with observer in ground measurements, besides the lack of information on cloud optical thickness in ground data. This work describes two techniques to obtain CCI information using visible (0.52-0.75mm) and infrared (10.2-11.2mm) data from GOES satellite in order to maximize the reliability of CCI input data to BRASIL-SR radiative transfer model. The new techniques are based on statistical and geometry analyses for each pixel of satellite data. The BRASIL-SR model is a radiative transfer model that evaluates surface solar irradiation over Brazilian territory using

  15. Cloud cover and UV index estimates in Chile from satellite-derived and ground-based data

    NASA Astrophysics Data System (ADS)

    Damiani, A.; Cordero, R. R.; Cabrera, S.; Laurenza, M.; Rafanelli, C.

    2014-03-01

    Data of Lambertian equivalent reflectivity (LER) in ultraviolet (UV)-A range recorded by Total Ozone Mapping Spectrometer (TOMS) series aboard Nimbus 7 and Earth Probe and by Ozone Monitoring Instrument (OMI) on EOS Aura have been analyzed over eight Chilean locations spanning from about 18° to 62° S (i.e. including Profesor Julio Escudero station, Antarctic peninsula), covering years 1978-2011. Generally the distribution of the reflectivity is similar for both TOMS datasets. A slightly better agreement has been found for the most southern locations while a small discordance appears for northern locations. The latter could be partly due to actual differences in the cloud cover conditions. On the other hand, OMI LER data differ from TOMS ones in almost all locations. Daily cloud modification factor (CMF) values from ground-based global solar irradiance measurements have been compared with OMI LER-based CMF data. The northernmost and southernmost locations characterized by prevalent clear sky and winter snow conditions, respectively, showed the worse agreement with a correlation coefficient r = 0.63 and 0.71, while other stations showed a better correlation (i.e. r = 0.83 and r = 85). Clear sky ground UV index values for Santiago de Chile have been estimated for years 1979-2011 by means of an empirical reconstruction model based on data recorded by a multichannel radiometer. It allowed computing a ground-based CMF for years 1996-2011 and comparing it with satellite data. Results show that OMI CMF based on gridded cell LER data introduces significant differences with respect to equivalent TOMS CMF. On the contrary, the use of overpass LER data allows to evaluate changes in cloudiness and, by using the model, reconstructing the actual UV index. Nevertheless, LER CMF overestimates actual cloud cover conditions in winter. The trend in reconstructed satellite (ground) based UV index during summer months is + 3.3 ± 0.9% (+ 11.9 ± 2.5%)/decade for years 1979-2011 (1997

  16. Cloud cover climatologies in the Mediterranean obtained from satellites, surface observations, reanalyses, and CMIP5 simulations: validation and future scenarios

    NASA Astrophysics Data System (ADS)

    Enriquez-Alonso, Aaron; Sanchez-Lorenzo, Arturo; Calbó, Josep; González, Josep-Abel; Norris, Joel R.

    2016-07-01

    Clouds are an important regulator of climate due to their connection to the water balance of the atmosphere and their interaction with solar and infrared radiation. In this study, monthly total cloud cover (TCC) records from different sources have been inter-compared on annual and seasonal basis for the Mediterranean region and the period 1984-2005. Specifically, gridded databases from satellite projects (ISCCP, CLARA, PATMOS-x), from reanalysis products (ERA-Interim, MERRA), and from surface observations over land (EECRA) and ocean (ICOADS) have been examined. Then, simulations from 44 climate runs of the Coupled Model Intercomparison Project phase 5 corresponding to the historical scenario have been compared against the observations. Overall, we find good agreement between the mean values of TCC estimated from the three satellite products and from surface observations, while reanalysis products show much lower values across the region. Nevertheless, all datasets show similar behavior regarding the annual cycle of TCC. In addition, our results indicate an underestimation of TCC from climate model simulations as compared to the satellite products, especially during summertime, although the annual cycle is well simulated by most models. This result is quite general and apparently independent of the cloud parameterizations included in each particular model. Equally, similar results are obtained if the ISCCP simulator included in the Cloud Feedback Model Intercomparison Project Observation Simulator Package is considered, despite only few models provide the post-processed results. Finally, GCM projections of TCC over the Mediterranean are presented. These projections predict a reduction of TCC during the 21st century in the Mediterranean. Specifically, for an extreme emission scenario (RCP8.5) the projected relative rate of TCC decrease is larger than 10 % by the end of the century.

  17. Spatial and temporal characteristics of global cloud cover as observed from the Nimbus-7 satellite

    NASA Technical Reports Server (NTRS)

    Stowe, L. L.; Pellegrino, P. P.; Hwang, P. H.; Bhartia, P. K.; Eck, T. F.

    1986-01-01

    The spatial and temporal characteristics of the total cloud amount (TCA) were determined on the bases of 2 yr of data collected by Nimbus-7. The instruments used were the 11.5 microns channel of the Temperature Humidity IR radiometer and the 0.38 micron channel of the Total Ozone Mapping Spectrometer. Comparisons were made between long-term averages and large variations during the El Nino/Southern Oscillation event of 1982/83. Separate attention was also given to the TCA for the Northern and Southern Hemispheres, and to TCA averages over specific large-scale global features such as deserts.

  18. The effects of cloud radiative forcing on an ocean-covered planet

    NASA Technical Reports Server (NTRS)

    Randall, David A.

    1990-01-01

    Cumulus anvil clouds, whose importance has been emphasized by observationalists in recent years, exert a very powerful influence on deep tropical convection by tending to radiatively destabilize the troposphere. In addition, they radiatively warm the column in which they reside. Their strong influence on the simulated climate argues for a much more refined parameterization in the General Circulation Model (GCM). For Seaworld, the atmospheric cloud radiative forcing (ACRF) has a powerful influence on such basic climate parameters as the strength of the Hadley circulation, the existence of a single narrow InterTropical Convergence Zone (ITCZ), and the precipitable water content of the atmosphere. It seems likely, however, that in the real world the surface CRF feeds back negatively to suppress moist convection and the associated cloudiness, and so tends to counteract the effects of the ACRF. Many current climate models have fixed sea surface temperatures but variable land-surface temperatures. The tropical circulations of such models may experience a position feedback due to ACRF over the oceans, and a negative or weak feedback due to surface CRF over the land. The overall effects of the CRF on the climate system can only be firmly established through much further analysis, which can benefit greatly from the use of a coupled ocean-atmospheric model.

  19. Cloud cover anomalies at middle latitudes: Links to troposphere dynamics and solar variability

    NASA Astrophysics Data System (ADS)

    Veretenenko, S.; Ogurtsov, M.

    2016-11-01

    In this work we study links between low cloud anomalies (LCA) at middle latitudes of the Northern and Southern hemispheres and galactic cosmic ray (GCR) variations used as a proxy of solar variability on the decadal time scale. It was shown that these links are not direct, but realized through GCR/solar activity phenomena influence on the development of extratropical baric systems (cyclones and troughs) which form cloud field. The violation of a positive correlation between LCA and GCR intensity which was observed in the 1980s-1990s occurred simultaneously in the Northern and Southern hemispheres in the early 2000s and coincided with the sign reversal of GCR effects on troposphere circulation. It was suggested that a possible reason for the correlation reversal between cyclonic activity at middle latitudes and GCR fluxes is the change of the stratospheric polar vortex intensity which influences significantly the troposphere-stratosphere coupling. The evidences for a noticeable weakening of the polar vortices in the Arctic and Antarctic stratosphere in the early 2000s are provided. The results obtained suggest an important role of the polar vortex evolution as a reason for a temporal variability of solar activity effects on the lower atmosphere.

  20. A Study of the Role of Clouds in the Relationship Between Land Use/Land Cover and the Climate and Air Quality of the Atlanta Area

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.; Hafner, Jan

    2001-01-01

    The goal of Project ATLANTA is to derive a better scientific understanding of how land cover changes associated with urbanization affect climate and air quality. In this project the role that clouds play in this relationship was studied. Through GOES satellite observations and RAMS modeling of the Atlanta area, we found that in Atlanta (1) clouds are more frequent than in the surrounding rural areas; (2) clouds cool the surface by shading and thus tend to counteract the warming effect of urbanization; (3) clouds reflect sunlight, which might other wise be used to produce ozone; and (4) clouds decrease biogenic emission of ozone precursors, and they probably decrease ozone concentration. We also found that mesoscale modeling of clouds, especially of small, summertime clouds, needs to be improved and that coupled mesoscale and air quality models are needed to completely understand the mediating role that clouds play in the relationship between land use/land cover change and the climate and air quality of Atlanta. It is strongly recommended that more cities be studied to strengthen and extend these results.

  1. Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

    DTIC Science & Technology

    2014-09-30

    Cover in the Beaufort and Chukchi Seas Dale A. Lawrence and James Maslanik Aerospace Engineering Sciences University of Colorado Boulder, CO...OBJECTIVES The main objective of the University of Colorado portion of the project is to adapt an existing low cost, expendable small unmanned...University of Colorado ,325 Broadway,Boulder,CO,80305 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS

  2. Geologic Mapping and Mineral Resource Assessment of the Healy and Talkeetna Mountains Quadrangles, Alaska Using Minimal Cloud- and Snow-Cover ASTER Data

    USGS Publications Warehouse

    Hubbard, Bernard E.; Rowan1, Lawrence C.; Dusel-Bacon, Cynthia; Eppinger, Robert G.

    2007-01-01

    On July 8, 2003, ASTER acquired satellite imagery of a 60 km-wide swath of parts of two 1:250,000 Alaska quadrangles, under favorable conditions of minimal cloud- and snow-cover. Rocks from eight different lithotectonic terranes are exposed within the swath of data, several of which define permissive tracts for various mineral deposit types such as: volcanic-hosted massive sulfides (VMS) and porphyry copper and molybdenum. Representative rock samples collected from 13 different lithologic units from the Bonnifield mining district within the Yukon-Tanana terrane (YTT), plus hydrothermally altered VMS material from the Red Mountain prospect, were analyzed to produce a spectral library spanning the VNIR-SWIR (0.4 - 2.5 ?m) through the TIR (8.1 - 11.7 ?m). Comparison of the five-band ASTER TIR emissivity and decorrelation stretch data to available geologic maps indicates that rocks from the YTT display the greatest range and diversity of silica composition of the mapped terranes, ranging from mafic rocks to silicic quartzites. The nine-band ASTER VNIR-SWIR reflectance data and spectral matched-filter processing were used to map several lithologic sequences characterized by distinct suites of minerals that exhibit diagnostic spectral features (e.g. chlorite, epidote, amphibole and other ferrous-iron bearing minerals); other sequences were distinguished by their weathering characteristics and associated hydroxyl- and ferric-iron minerals, such as illite, smectite, and hematite. Smectite, kaolinite, opaline silica, jarosite and/or other ferric iron minerals defined narrow (< 250 m diameter) zonal patterns around Red Mountain and other potential VMS targets. Using ASTER we identified some of the known mineral deposits in the region, as well as mineralogically similar targets that may represent potential undiscovered deposits. Some known deposits were not identified and may have been obscured by vegetation- or snow-cover, or were too small to be resolved.

  3. Evaluation and Applications of Cloud Climatologies from CALIOP

    NASA Technical Reports Server (NTRS)

    Winker, David; Getzewitch, Brian; Vaughan, Mark

    2008-01-01

    Clouds have a major impact on the Earth radiation budget and differences in the representation of clouds in global climate models are responsible for much of the spread in predicted climate sensitivity. Existing cloud climatologies, against which these models can be tested, have many limitations. The CALIOP lidar, carried on the CALIPSO satellite, has now acquired over two years of nearly continuous cloud and aerosol observations. This dataset provides an improved basis for the characterization of 3-D global cloudiness. Global average cloud cover measured by CALIOP is about 75%, significantly higher than for existing cloud climatologies due to the sensitivity of CALIOP to optically thin cloud. Day/night biases in cloud detection appear to be small. This presentation will discuss detection sensitivity and other issues associated with producing a cloud climatology, characteristics of cloud cover statistics derived from CALIOP data, and applications of those statistics.

  4. Common summertime total cloud cover and aerosol optical depth weekly variabilities over Europe: Sign of the aerosol indirect effects?

    NASA Astrophysics Data System (ADS)

    Georgoulias, A. K.; Kourtidis, K. A.; Alexandri, G.; Rapsomanikis, S.; Sanchez-Lorenzo, A.

    2015-02-01

    In this study, the summer total cloud cover (TCC) weekly cycle over Europe is investigated using MODIS and ISCCP satellite data in conjunction with aerosol optical depth (AOD) MODIS data. Spatial weekly patterns are examined at a 1° × 1° (MODIS) and 250 × 250 km2 (ISCCP) resolution. Despite the noise in the TCC weekly cycle patterns, their large-scale features show similarities with the AOD550 patterns. Regions with a positive (higher values during midweek) weekly cycle appear over Central Europe, while a strong negative (higher values during weekend) weekly plume appears over the Iberian Peninsula and the North-Eastern Europe. The TCC weekly variability exhibits a very good agreement with the AOD550 weekly variability over Central, South-Western Europe and North-Eastern Europe and a moderate agreement for Central Mediterranean. The MODIS derived TCC weekly variability shows reasonable agreement with the independent ISCCP observations, thus supporting the credibility of the results. TCC and AOD550 correlations exhibit a strong slope for the total of the 6 regions investigated in this work with the slopes being higher for regions with common TCC-AOD550 weekly variabilities. The slope is much stronger for AOD550 values less than 0.2 for Central and South-Western Europe, in line with previous studies around the world. Possible scenarios that could explain the common weekly variability of aerosols and cloud cover through the aerosol indirect effects are discussed here also taking into account the weekly variability appearing in ECA&D E-OBS rainfall data.

  5. Changes in Seasonal Cloud Cover over the Arctic Seas from Satellite and Surface Observations

    NASA Technical Reports Server (NTRS)

    Schweiger, Axel J.

    2004-01-01

    Winter and spring changes in cloudiness are compared over the arctic seas (ocean areas north of 60 degrees N) from the TOVS (TIROS Operational Vertical Sounder) Polar Pathfinder retrievals and two separate datasets derived from the Advanced Very High Resolution Radiometer (AVHRR). All satellite products exhibit significant decreases in cloud fraction over the arctic seas during winter (December, January, February) on the order of 5 %/ decade. An equally striking increase in spring (March, April, May) cloudiness is evident from the TOVS Pathfinder (TPP) and the extended AVHRR Polar Pathfinder (APP-x) projects. In the Central Arctic these positive trends can be as large as 15 %/decade. Surface observations from the Russian drifting meteorological stations are consistent with satellite-observed changes during the 1980s. Negative trends in spring cloudiness reported by Comiso [2003] are in conflict with these findings. Spring changes in cloudiness are associated with changes in the atmospheric circulation. These dramatic, large-scale changes may have substantial impacts on the surface energy balance.

  6. Orbital and cloud cover sampling analyses for multisatellite earth radiation budget experiments

    NASA Technical Reports Server (NTRS)

    Harrison, E. F.; Minnis, P.; Gibson, G. G.

    1983-01-01

    Computer simulations have been performed to determine the geographical and temporal coverage of various satellite orbits and scanning and nonscanning radiometers for earth radiation budget measurements. These results were used to simulate the sampling of a diurnally varying cloud and radiation field for several different satellite systems to estimate errors in regional monthly mean reflected radiation. The combined results indicate that coincient observations with a minimum of one sun-synchronous satellite and a midinclined orbit satellite are needed to obtain the required regional, zonal, and global coverage with sufficient temporal sampling for obtaining accurate estimates of monthly mean reflected solar radiation. Overall, the best sampling capability and lowest errors were obtained with a three-satellite system, i.e., two sun-synchronous satellites with different equatorial crossing times combined with either a 46 or 57-deg orbit satellite. The results from these analyses have been used in defining a joint NASA-NOAA multisatellite mission for an earth radiation budget experiment.

  7. Detection and assessment of cloud cover and precipitation parameters using data of scanning radiometers of polar-orbiting and geostationary meteorological satellites

    NASA Astrophysics Data System (ADS)

    Volkova, E. V.; Uspensky, A. B.

    2016-12-01

    Two multispectral threshold techniques have been developed and tested for the automatic classification of AVHRR/NOAA and SEVIRI/Meteosat-10 data. They provide day-and-night detection and the assessment of cloud-cover parameters, as well as the discrimination of precipitation zones and severe weather phenomena. The validation of output information products, which has been performed with ground-based conventional meteorological observations and radar data, as well as with independent satellite-based estimates of cloud cover and precipitation parameters, confirms the feasibility of developed techniques and reasonable accuracy of output products. Therefore, the technique is concurrent to those implemented in current foreign satellite centers.

  8. Development and comparison of HP-41C software to predict solar irradiation of tilted surfaces, based upon cloud cover factors

    SciTech Connect

    Nawrocki, A.D.; Anderson, S.P.

    1982-01-01

    Summarized is a comparison between predicted and measured solar radiation and cloud cover data from NOAA weather stations and Solar Energy Meterological Research and Training Sites at various locations throughout the US, based upon a semiempirical method which was used recently to generate synthetic insolation data for correlation with measured solar performance under the SUEDE program. This method is unique, since it predicts irradiation of a tilted surface from sky cover estimates by weather observers, using a modified ASHRAE method to compute direct and diffuse insolation on a clear day. Data comparisons were made using an HP-41C programmable calculator, card reader, printer, and eight magnetic cards. Although a more detailed study with a larger data base is desirable, these particular findings, using hourly summations to obtain monthly averages in 1980, indicate that approximately -5 to 15% difference between measured and calculated monthly results is typical of continental US sites. A sensitivity study indicated that monthly percentage differences are reduced by centering ASHRAE constants and earth declination on the 15th day of each month instead of the 21st day.

  9. Analyzing the Effect of Intraseasonal Meteorological Variability and Land Cover on Aerosol-Cloud Interactions During the Amazonian Biomass Burning Season

    NASA Technical Reports Server (NTRS)

    TenHoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

    2010-01-01

    pasture is not correlated with aerosol loading, supporting the assumption that temporal variation of column water vapor is primarily a function of the larger-scale meteorology. However, a difference in the response of cloud fraction to increasing AOD is observed between forest and pasture. This suggests that dissimilarities between other meteorological factors, such as atmospheric stability, are likely to have an impact on aerosol-cloud correlations between different land-cover types.

  10. Temporal variability of total cloud cover at a Mediterranean megacity in the 20th century: Evidence from visual observations and climate models

    NASA Astrophysics Data System (ADS)

    Founda, Dimitra; Giannakopoulos, Christos; Pierros, Fragiskos

    2013-04-01

    Cloud cover is one of the major factors that determine the radiation budget and the climate system of the Earth. Moreover, the response of clouds has always been an important source of uncertainty in global climate models. Visual surface observations of clouds have been conducted at the National Observatory of Athens (NOA) since the mid 19th century. The historical archive of cloud reports at NOA since 1860 has been digitized and updated, spanning now a period of one and a half century. Mean monthly values of total cloud cover were derived by averaging subdaily observations of cloud cover (3 observations/day). Changes in observational practice (e.g. from 1/10 to 1/8 units) were considered, however, subjective measures of cloud cover from trained observers introduces some kind of uncertainty in the time series. Data before 1884 were considered unreliable, so the analysis was restricted to the series from 1884 to 2012. The time series of total cloud cover at NOA is validated and correlated with historical time series of other (physically related) variables such as the total sunshine duration as well as DTR (Diurnal Temperature Range) which are independently measured. Trend analysis was performed on the mean annual and seasonal series of total cloud cover from 1884-2012. The mean annual values show a marked temporal variability with sub periods of decreasing and increasing tendencies, however, the overall linear trend is positive and statistically significant (p <0.001) amounting to +2% per decade and implying a total increase of almost 25% for the whole analysed period. These results are in agreement qualitatively with the trends reported in other studies worldwide, especially concerning the period before the mid 20th century. On a seasonal basis, spring and summer series present outstanding positive long term trends, while in winter and autumn total cloud cover reveals also positive but less pronounced long term trends Additionally, an evaluation of cloud cover and

  11. Surface Energy Exchange in a Tropical Montane Cloud Forest Environment: Flux Partitioning, and Seasonal and Land Cover-Related Variations

    NASA Astrophysics Data System (ADS)

    Holwerda, F.; Alvarado-Barrientos, M. S.; González-Martínez, T.

    2015-12-01

    Relationships between seasonal climate, land cover and surface energy exchange in tropical montane cloud forest (TMCF) environments are poorly understood. Yet, understanding these linkages is essential to evaluating the impacts of land use and climate change on the functioning of these unique ecosystems. In central Veracruz, Mexico, TMCF occurs between 1100 and 2500 m asl. The canopy of this forest consists of a mix of deciduous and broadleaved-evergreen tree species, the former of which shed their leaves for a short period during the dry season. The aim of this study was to quantify the surface energy balance, and seasonal variations therein, for TMCF, as well as for shaded coffee (CO) and sugarcane (SU), two important land uses that have replaced TMCF at lower elevations. Sensible (H) and latent heat (LE) fluxes were measured using eddy covariance and sap flow methods. Other measurements included: micrometeorological variables, soil heat flux, soil moisture and vegetation characteristics. Partitioning of available energy (A) into H and LE showed important seasonal changes as well as differences among land covers. During the wet-season month of July, average midday Bowen ratios for sunny days were lowest and least variable among land covers: 0.5 in TMCF and SU versus 0.7 in CO. However, because of higher A, along with lower Bowen ratio with respect to CO, LE over TMCF was ca. 20% higher compared to CO and SU. During the late dry-season months of March and April, average midday Bowen ratios for sunny days were generally much higher and more variable among land covers. The higher Bowen ratios indicated a reduction of LE under the drier conditions prevailing (low soil moisture and high VPD), something rarely observed in TMCFs. Moreover, because some trees were still partially leafless in March, LE over TMCF was about half that over CO and SU, suggesting an important effect of phenology on energy exchange of this TMCF. Observed differences between seasons and land

  12. Use of satellite data in runoff forecasting in the heavily forested, cloud-covered Pacific Northwest. [Upper Snake, Boise, Dworshak, Libby and Hungry Horse River Basins

    NASA Technical Reports Server (NTRS)

    Dillard, J. P.; Orwig, C. F. (Principal Investigator)

    1980-01-01

    The author has identified the following significant results. Satellite-derived snow cover data improves forecasts of stream flow but not at a statistically significant amount and should not be used exclusively because of persistent cloud cover. Based upon reconstruction runs, satellite data can be used to augment snow-flight data in the Upper Snake, Boise, Dworshak, and Hungry Horse basins. Satellite data does not compare well with aerial snow-flight data in the Libby basin.

  13. Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

    SciTech Connect

    Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; Long, Charles N.; Kalashnikova, Olga; Alpert, Pinhas

    2015-07-09

    Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOT asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-year period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.

  14. Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

    DOE PAGES

    Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; ...

    2015-07-09

    Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOTmore » asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-year period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.« less

  15. A Study of the Role of Clouds in the Relationship Between Land Use/Land Cover and the Climate and Air Quality of the Atlanta Area

    NASA Technical Reports Server (NTRS)

    Kidder, Stanley Q.; Hafner, Jan

    1997-01-01

    The goal of Project ATLANTA is to derive a better scientific understanding of how land cover changes associated with urbanization affect local and regional climate and air quality. Clouds play a significant role in this relationship. Using GOES images, we found that in a 63-day period (5 July-5 September 1996) there were zero days which were clear for the entire daylight period. Days which are cloud-free in the morning become partly cloudy with small cumulus clouds in the afternoon in response to solar heating. This result casts doubt on the applicability of California-style air quality models which run in perpetual clear skies. Days which are clear in the morning have higher ozone than those which are cloudy in the morning. Using the RAMS model, we found that urbanization increases the skin surface temperature by about 1.0-1.5 C on average under cloudy conditions, with an extreme of +3.5 C. Clouds cool the surface due to their shading effect by 1.5-2.0 C on average, with an extreme of 5.0 C. RAMS simulates well the building stage of the cumulus cloud field, but does poorly in the decaying phase. Next year's work: doing a detailed cloud climatology and developing improved RAMS cloud simulations.

  16. Effect of cloud cover and surface type on earth's radiation budget derived from the first year of ERBE data

    NASA Technical Reports Server (NTRS)

    Gibson, G. G.; Denn, F. M.; Young, D. F.; Harrison, E. F.; Minnis, P.; Barkstrom, B. R.

    1990-01-01

    One year of ERBE data is analyzed for variations in outgoing LW and absorbed solar flux. Differences in land and ocean radiation budgets as well as differences between clear-sky and total scenes, including clouds, are studied. The variation of monthly average radiative parameters is examined for February 1985 through January 1986 for selected study regions and on zonal and global scales. ERBE results show significant seasonal variations in both outgoing LW and absorbed SW flux, and a pronounced difference between oceanic and continental surfaces. The main factors determining cloud radiative forcing in a given region are solar insolation, cloud amount, cloud type, and surface properties. The strongest effects of clouds are found in the midlatitude storm tracks over the oceans. Over much of the globe, LW warming is balanced by SW cooling. The annual-global average net cloud forcing shows that clouds have a net cooling effect on the earth for the year.

  17. Variability and trend of diurnal temperature range in China and their relationship to total cloud cover and sunshine duration

    NASA Astrophysics Data System (ADS)

    Xia, X.

    2013-05-01

    This study aims to investigate the effect of total cloud cover (TCC) and sunshine duration (SSD) in the variation of diurnal temperature range (DTR) in China during 1954-2009. As expected, the inter-annual variation of DTR was mainly determined by TCC. Analysis of trends of 30-year moving windows of DTR and TCC time series showed that TCC changes could account for that of DTR in some cases. However, TCC decreased during 1954-2009, which did not support DTR reduction across China. DTRs under sky conditions such as clear, cloudy and overcast showed nearly the same decreasing rate that completely accounted for the overall DTR reduction. Nevertheless, correlation between SSD and DTR was weak and not significant under clear sky conditions in which aerosol direct radiative effect should be dominant. Furthermore, 30-60% of DTR reduction was associated with DTR decrease under overcast conditions in south China. This implies that aerosol direct radiative effect appears not to be one of the main factors determining long-term changes in DTR in China.

  18. Singular Value Decomposition Analysis of Cloud Fraction Cover and Sea Ice Concentration over the Arctic Region, 1982-2009

    NASA Astrophysics Data System (ADS)

    Boccolari, Mauro; Parmiggiani, Flavio

    2016-08-01

    In this study, the coupled spatial and temporal variability between seasonal data of Cloud Fraction Cover (CFC) and Sea Ice Concentration (SIC) in the Arctic Ocean for the 1982-2009 period were investigated by using the Singular Value Decomposition (SVD) method.The spatial patterns of CFCs related to the first mode of co-variability, identify the maximum covariance, for all seasons, in the Barents Sea and in the Arctic Ocean Canada, while the SIC and 'found in the Chukchi Sea in autumn (in according to the maximum sea ice melting) and the Barents sea during both the winter and spring.CFC spatial patterns related to the first mode of co- variability, locate maximum covariance, for all seasons, in the Barents Sea and in the Canadian side of the Arctic Ocean, while for SIC is found in the Chukchi Sea during autumn (corresponding to the maximum sea ice melting) and in the Barents Sea during both the winter and spring.Finally, the correlation between the seasonal time series of expansion coefficients derived from the SVD analysis, for both CFC and SIC fields, with the seasonal time series of some relevant climate indices for the Arctic (NAO, AO, PDO and PNA). Statistically significant values for both fields were found during summer with the AO, and during autumn with the PNA.

  19. A study of National Lightning Detection Network responses to natural lightning based on ground truth data acquired at LOG with emphasis on cloud discharge activity

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Rakov, V. A.; Tran, M. D.; Nag, A.

    2016-12-01

    The U.S. National Lightning Detection Network (NLDN) detection efficiency (DE) and classification accuracy (CA) for cloud discharge (IC) activity (identified here by a sequence of non-return-stroke-type electric field pulses not accompanied by channels to ground) were evaluated using optical and electric field data acquired at the LOG (Lightning Observatory in Gainesville), Florida. Our ground truth "IC events" include 26 "isolated IC events" (complete IC flashes), 58 "IC events before first return stroke," and 69 "IC events after first return stroke." For the total of 153 IC events, 33% were detected by the NLDN, and the classification accuracy was 86%. For complete IC flashes, the detection efficiency and classification accuracy were 73% and 95%, respectively, and the average number of NLDN-reported cloud pulses was 2.9 per detected event. For 24 preliminary breakdown pulse trains in CG flashes, the detection efficiency and classification accuracy were 46% and 82%, respectively. We have additionally estimated the DE and CA for return strokes in CG flashes. Irrespective of stroke order and polarity, the DE was 92% (339/367), and the CA was also 92% (312/339). The DEs for negative first and subsequent strokes were 98% and 90%, respectively.

  20. Origin and causes of the mammoth steppe: a story of cloud cover, woolly mammal tooth pits, buckles, and inside-out Beringia

    NASA Astrophysics Data System (ADS)

    Dale Guthrie, R.

    2001-01-01

    To account for the vastness of the northern arid steppes during Glacial episodes, I propose the proximate key variable was simply frequent clear skies. This hitherto under-emphasized point is the hub which best explains many questions. Low maritime cloud cover best accounts for today's tundra, and in a related way, the cloudy Polar Front accounts for the whole of the taiga. Even during Glacial maxima, the proximity of the sea to the Bering isthmus created intermittent maritime cloud cover. This regional cloud cover produced an ecological interruption, or buckle, of the arid steppe belt. While this Beringian mesic buckle did not serve as an intercontinental ecological barrier to most steppe-adapted species, it does seem to have limited the distributions of woolly rhinos, camels, American kiangs, short-faced bears, badgers, and some others. At the beginning of the Holocene, this narrow refugium seems to have been a source of some mesic-adapted species which colonized westward into the now tundra vegetation of northern Asia and eastward into northern North America. This Holocene expansion from a limited and regional Pleistocene refugium created our present misconceptions about Beringia. The mid-strait mesic ecological conditions were the exception to the more extensive, arid-adapted, communities of the Mammoth Steppe.

  1. The effect of a sub-grid statistical cloud-cover scheme applied to the COSMO local numerical weather prediction model over the wider geographical domain of Greece

    NASA Astrophysics Data System (ADS)

    Avgoustoglou, Euripides; Tzeferi, Theodora

    2015-01-01

    The COSMO model uses operationally two sub-grid schemes for the evaluation of stratus clouds. A semi-empirical scheme based on relative humidity is used in the radiation module while a statistical scheme is used in the turbulence module. The objective is to investigate the possibility of the implementation of the statistical scheme also in the radiation module. The relative impact is presented in reference to a spring test case with synoptic conditions that favor stratiform clouds. The domain considered is the wider Balkan region around the Hellenic geographical area and is characterized by comparable sea and land partitions. This particular domain choice gives rise to a strong coexistence of continental as well as marine clouds which is one of the most challenging features regarding the operational use of numerical weather prediction models by the Hellenic Meteorological Service. The results are evaluated through direct comparisons with satellite data as well as the observed 2-m temperatures for an approximate total of fifty Greek synoptic meteorological stations. The implementation of the statistical scheme led to an underestimation of low cloud-cover by the model in contrast to the implementation of the default relative-humidity scheme, while regarding medium cloud-cover the situation was reversed. Also, the daily 2-meter minimum and maximum temperatures were slightly better simulated, but not conclusively, when the statistical scheme was implemented in the radiation module. Although the statistical scheme cannot in its present form replace operationally the relative-humidity scheme in the radiation module, it is an important asset to COSMO model invoking valuable insight to the physics of the model and can be used as a basis to support the ongoing research in this crucial area of atmospheric sciences.

  2. Modeling halogen chemistry in the marine boundary layer 2. Interactions with sulfur and the cloud-covered MBL

    NASA Astrophysics Data System (ADS)

    von Glasow, Roland; Sander, Rolf; Bott, Andreas; Crutzen, Paul J.

    2002-09-01

    A companion paper presented a numerical one-dimensional model of the marine boundary layer (MBL) including chemical reactions in the gas and aqueous phase, focusing on the reaction cycles of halogen compounds. In this paper we study interactions between halogen and sulfur chemistry. HOCl and HOBr were found to be generally more important than H2O2 or O3 in the oxidation of S(IV) in sea salt aerosols in the cloud-free MBL. The inclusion of halogen chemistry lead to an increase in the oxidation of DMS of roughly 63%. This additional oxidation is caused by BrO. The model was also expanded for the study of the cloudy MBL. We found that the effects of stratiform clouds on the evolution and diurnal cycle of halogen species are widespread; they are not restricted to cloud layers. The diurnal variation of gas and aqueous phase bromine was the opposite of that in cloud-free runs. Oxidation of S(IV) by HOBr and HOCl was important for cloud droplets, too. However, the relative importance of these oxidants changed compared to the cloud-free runs.

  3. Land cover and forest formation distributions for St. Kitts, Nevis, St. Eustatius, Grenada and Barbados from decision tree classification of cloud-cleared satellite imagery

    USGS Publications Warehouse

    Helmer, E.H.; Kennaway, T.A.; Pedreros, D.H.; Clark, M.L.; Marcano-Vega, H.; Tieszen, L.L.; Ruzycki, T.R.; Schill, S.R.; Carrington, C.M.S.

    2008-01-01

    Satellite image-based mapping of tropical forests is vital to conservation planning. Standard methods for automated image classification, however, limit classification detail in complex tropical landscapes. In this study, we test an approach to Landsat image interpretation on four islands of the Lesser Antilles, including Grenada and St. Kitts, Nevis and St. Eustatius, testing a more detailed classification than earlier work in the latter three islands. Secondly, we estimate the extents of land cover and protected forest by formation for five islands and ask how land cover has changed over the second half of the 20th century. The image interpretation approach combines image mosaics and ancillary geographic data, classifying the resulting set of raster data with decision tree software. Cloud-free image mosaics for one or two seasons were created by applying regression tree normalization to scene dates that could fill cloudy areas in a base scene. Such mosaics are also known as cloud-filled, cloud-minimized or cloud-cleared imagery, mosaics, or composites. The approach accurately distinguished several classes that more standard methods would confuse; the seamless mosaics aided reference data collection; and the multiseason imagery allowed us to separate drought deciduous forests and woodlands from semi-deciduous ones. Cultivated land areas declined 60 to 100 percent from about 1945 to 2000 on several islands. Meanwhile, forest cover has increased 50 to 950%. This trend will likely continue where sugar cane cultivation has dominated. Like the island of Puerto Rico, most higher-elevation forest formations are protected in formal or informal reserves. Also similarly, lowland forests, which are drier forest types on these islands, are not well represented in reserves. Former cultivated lands in lowland areas could provide lands for new reserves of drier forest types. The land-use history of these islands may provide insight for planners in countries currently considering

  4. Reliable Averages and Risky Extremes - Analysis of spatio-temporal variability in solar irradiance and persistent cloud cover patterns over Switzerland

    NASA Astrophysics Data System (ADS)

    Kahl, Annelen; Nguyen, Viet-Anh; Sarrasin, Karine; Lehning, Michael

    2016-04-01

    With the perspective of Switzerland's phase-out from nuclear energy, solar energy potential may take a leading role for the country's future in renewable energy. Unlike nuclear power stations, photovoltaic (PV) production is prone to intermittency as it depends on the immediate solar irradiance, which fluctuates in space and time. If a large percentage of Switzerland's electricity was to be derived from solar radiation, stochastic fluctuations pose a risk to the robust supply and healthy function of the electricity network. For most efficient PV planning and siting, it is hence imperative to understand and quantify this variability in solar radiation, in order to anticipate average production as well as worst-case scenarios. Based on 12 years of satellite derived, spatially distributed data of daily average surface incoming shortwave radiation (SIS) this work analyses standard statistics, spatial correlation patterns and extreme conditions of cloud cover over Switzerland. Having compared different irradiance products, we decided to use the SIS product captured on the Meteosat Second Generation satellites, because it provides the most reliable snow/cloud discrimination, which is essential for spatial analysis over alpine terrain. Particularly in regions with high elevation differences, correlation between cloud cover and elevation undergo an annual cycle. In winter more clouds are found in the valleys, while in summer convective clouds dominate at higher elevations. The highest average irradiance values occur in the southern parts of the country, and make the cantons of Vallais, Tessin and Grison ideal candidate locations for PV installations. Simultaneously the Tessin shows a higher risk of periods with long lasting cloud cover, which would discourage from relying too much on solar power in that area. However looking at the question of suitability by studying spatial and temporal correlations of extremes, we see that the Tessin appears to be comparably decoupled

  5. Spatial and Temporal Inter-Relationships Between Anomalies of Temperature, Moisture, Cloud Cover, and OLR as Observed by AIRS/AMSU on Aqua

    NASA Technical Reports Server (NTRS)

    Susskind, Joel

    2008-01-01

    AIRS/AMSU is the advanced IR/MW atmospheric sounding system launched on EOS Aqua in May 2002. Products derived from AIRS/AMSU include surface skin temperature and atmospheric temperature profiles; atmospheric humidity profiles, percent cloud cover and cloud top pressure, and OLR. Near real time products, stating with September 2002, have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. Results in this paper included products through April 2008. The time period studied is marked by a substantial warming trend of Northern Hemisphere Extropical land surface skin temperatures, as well as pronounced El Nino - La Nina episodes. These both influence the spatial and temporal anomaly patterns of atmospheric temperature and moisture profiles, as well as of cloud cover and Clear Sky and All Sky OLR The relationships between temporal and spatial anomalies of these parameters over this time period, as determined from AIRS/AMSU observations, are shown below, with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. The ability to match this data represents a good test of a model's response to El Nino.

  6. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2013-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Atmospheric Profiles, Clouds , and the Evolution of Sea Ice...sea ice retreats further, changes in lower atmospheric temperature, humidity, winds, and clouds are likely to result from changed sea ice...how changes in sea ice and sea surface conditions in the SIZ affect changes in cloud properties and cover. • Determine the role additional atmospheric

  7. Sky cover

    NASA Astrophysics Data System (ADS)

    Gerth, Jordan J.

    Of all of the standard meteorological parameters collected and observed daily, sky cover is not only one of the most complex, but the one that is fairly ambiguously defined and difficult to quantify. Despite that, the implications of how cloud fraction and sky cover are understood not only impact daily weather forecasts, but also present challenges to assessing the state of the earth's climate system. Part of the reason for this is the lack of observational methods for verifying the skill of clouds represented and parameterized in numerical models. While human observers record sky cover as part of routine duties, the spatial coverage of such observations in the United States is relatively sparse. There is greater spatial coverage of automated observations, and essentially complete coverage from geostationary weather satellites that observe the Americas. A good analysis of sky cover reconciles differences between manual observations, automated observations, and satellite observations, through an algorithm that accounts for the strengths and weaknesses of each dataset. This work describes the decision structure for trusting and weighting these similar observations. Some of the issues addressed include: human and instrument error resulting from approximations and estimations, a deficiency in high cloud detectability using surface-based ceilometers, poorly resolved low cloud using infrared channels on space-based radiometers during overnight hours, and decreased confidence in satellite-detected cloud during stray light periods. Using the blended sky cover analysis as the best representation of cloudiness, it is possible to compare the analysis to numerical model fields in order to assess the performance of the model and the parameterizations therein, as well as confirm or uncover additional relationships between sky cover and pertinent fields using an optimization methodology. The optimizer minimizes an affine expression of adjusted fields to the "truth" sky cover

  8. Complex Clouds

    Atmospheric Science Data Center

    2013-04-16

    ...     View Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired ... corner, the edge of the Antarctic coastline and some sea ice can be seen through some thin, high cirrus clouds. The right-hand panel ...

  9. A Simple Solar, Spectral Model for Studying the Effects of Cloud Cover and Surface Albedo on the Incoming Solar Radiation.

    DTIC Science & Technology

    1986-01-01

    designed for particular locations ( Barbaro , 1979), clear sky cases only (Bird, 1984), for slopes of different orientation (Temps and Coulson, 1977...not desirable. In late 1982, a volcano (El Chichon) erupted in Mexico and spewed ash and other constituents into the atmosphere. The volcanic cloud...April 1981, pp. 889-894. Barbaro , S.; Coppolino, S.; Leone, C.; and Sinagra, E. "An Atmospheric Model For computing Direct and Diffuse Solar Radiation

  10. Cloud Computing

    DTIC Science & Technology

    2009-11-12

    Eucalyptus Systems • Provides an open-source application that can be used to implement a cloud computing environment on a datacenter • Trying to establish an...Summary Cloud Computing is in essence an economic model • It is a different way to acquire and manage IT resources There are multiple cloud providers...edgeplatform.html • Amazon Elastic Compute Cloud (EC2): http://aws.amazon.com/ec2/ • Amazon Simple Storage Solution (S3): http://aws.amazon.com/s3/ • Eucalyptus

  11. Point cloud generation from aerial image data acquired by a quadrocopter type micro unmanned aerial vehicle and a digital still camera.

    PubMed

    Rosnell, Tomi; Honkavaara, Eija

    2012-01-01

    The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems' SOCET SET classical commercial photogrammetric software and another is built using Microsoft(®)'s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation.

  12. Point Cloud Generation from Aerial Image Data Acquired by a Quadrocopter Type Micro Unmanned Aerial Vehicle and a Digital Still Camera

    PubMed Central

    Rosnell, Tomi; Honkavaara, Eija

    2012-01-01

    The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems’ SOCET SET classical commercial photogrammetric software and another is built using Microsoft®’s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation. PMID:22368479

  13. DoD Cloud Computing Strategy Needs Implementation Plan and Detailed Waiver Process

    DTIC Science & Technology

    2014-12-04

    specialists to use when acquiring cloud services. The matrix contains 21 issues specific to cloud computing that should be addressed in cloud computing...No. DODIG-2015-045 D E C E M B E R 4 , 2 0 1 4 DoD Cloud Computing Strategy Needs Implementation Plan and Detailed Waiver Process Report...REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE DoD Cloud Computing Strategy Needs Implementation Plan and Detailed

  14. A 10-Year Climatology of Cloud Cover and Vertical Distribution Derived from Both Surface and GOES Observations Over the DOE ARM SGP Site

    NASA Technical Reports Server (NTRS)

    Xi, Baike; Dong, Xiquan; Minnis, P.; Khaiyer, M.

    2010-01-01

    Analysis of a decade of ARM radar-lidar and GOES observations at the SGP site reveal that 0.5 and 4-hr averages of the surface cloud fraction correspond closely to 0.5deg and 2.5deg averages of GOES cloudiness, respectively. The long-term averaged surface and GOES cloud fractions agree to within 0.5%. Cloud frequency increases and cloud amount decreases as the temporal and spatial averaging scales increase. Clouds occurred most often during winter and spring. Single-layered clouds account for 61.5% of the total cloud frequency. There are distinct bimodal vertical distributions of clouds with a lower peak around 1 km and an upper one that varies from 7.5 to 10.8 km between winter and summer, respectively. The frequency of occurrence for nighttime GOES high-cloud tops agree well with the surface observations, but are underestimated during the day.

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

    NASA Astrophysics Data System (ADS)

    Lee, Kuan-Yi; Lin, Chao-Hung

    2016-06-01

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

  16. Remote Sensing and In-Situ Observations of Arctic Mixed-Phase and Cirrus Clouds Acquired During Mixed-Phase Arctic Cloud Experiment: Atmospheric Radiation Measurement Uninhabited Aerospace Vehicle Participation

    SciTech Connect

    McFarquhar, G.M.; Freer, M.; Um, J.; McCoy, R.; Bolton, W.

    2005-03-18

    The Atmospheric Radiation Monitor (ARM) uninhabited aerospace vehicle (UAV) program aims to develop measurement techniques and instruments suitable for a new class of high altitude, long endurance UAVs while supporting the climate community with valuable data sets. Using the Scaled Composites Proteus aircraft, ARM UAV participated in Mixed-Phase Arctic Cloud Experiment (M-PACE), obtaining unique data to help understand the interaction of clouds with solar and infrared radiation. Many measurements obtained using the Proteus were coincident with in-situ observations made by the UND Citation. Data from M-PACE are needed to understand interactions between clouds, the atmosphere and ocean in the Arctic, critical interactions given large-scale models suggest enhanced warming compared to lower latitudes is occurring.

  17. A TWO-COMPONENT POWER LAW COVERING NEARLY FOUR ORDERS OF MAGNITUDE IN THE POWER SPECTRUM OF SPITZER FAR-INFRARED EMISSION FROM THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Block, David L.; Puerari, Ivanio; Elmegreen, Bruce G.; Bournaud, Frederic

    2010-07-20

    Power spectra of Large Magellanic Cloud (LMC) emission at 24, 70, and 160 {mu}m observed with the Spitzer Space Telescope have a two-component power-law structure with a shallow slope of -1.6 at low wavenumber, k, and a steep slope of -2.9 at high k. The break occurs at k {sup -1} {approx} 100-200 pc, which is interpreted as the line-of-sight thickness of the LMC disk. The slopes are slightly steeper for longer wavelengths, suggesting the cooler dust emission is smoother than the hot emission. The power spectrum (PS) covers {approx}3.5 orders of magnitude, and the break in the slope is in the middle of this range on a logarithmic scale. Large-scale driving from galactic and extragalactic processes, including disk self-gravity, spiral waves, and bars, presumably causes the low-k structure in what is effectively a two-dimensional geometry. Small-scale driving from stellar processes and shocks causes the high-k structure in a three-dimensional geometry. This transition in dimensionality corresponds to the observed change in PS slope. A companion paper models the observed power law with a self-gravitating hydrodynamics simulation of a galaxy like the LMC.

  18. The Oort cloud

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  19. Sr/Ca and stable isotopes in a coral from the Venezuelan coast: A record of 20th-century changes in SST, SSS and cloud cover?

    NASA Astrophysics Data System (ADS)

    Hetzinger, S.; Pfeiffer, M.; Dullo, W.; Zinke, J.; Garbe-Schoenberg, C.

    2011-12-01

    We present a record of monthly δ18O and Sr/Ca variations in coral aragonite from a massive Diploria strigosa colony retrieved from a coastal NW-Venezuelan reef site (10.55°N, 67.24°W; 1940-2004). Linear regression of coral proxies to high resolution satellite sea surface temperature (SST) data (NASA OBPG MODIS-Aqua, 9-km resolution) demonstrates that both geochemical proxies record seasonal temperature variability in ambient seawater (Sr/Ca: r=-0.68 monthly, r=-0.60 annual; δ18O: r=-0.57 monthly, r=-0.46 annual; 1985-2004). On longer time scales both proxies record local as well as regional SST dynamics in the southeastern Caribbean and northern North Tropical Atlantic. A statistically significant relationship is observed between coral δ18O and local air temperature (r=-0.56; 1951-2002), while correspondence of δ18O to SST products (e.g. ERSST, SODA reanalysis) is lower than for Sr/Ca ratios. However, coral δ18O is a function of both temperature and δ18Oseawater and δ18Oseawater in turn is dependent on salinity. A comparison of δ18O to sea surface salinity (SSS) data confirms the existence of a strong salinity component in coral δ18O on annual and longer time scales (SODA reanalysis, r=0.65 for annual means, r=0.84 for 3-year average; 1958-2001). A decreasing trend from the mid-1980s onwards is evident in both SSS and coral δ18O, corresponding to trends seen in other Caribbean studies. Further, both geochemical proxies show a significant negative correlation to cloud cover averaged over a regional box (r=-0.66 for Sr/Ca; r=-0.48 for δ18O; 1941-2003). A significant drop in cloud cover is seen around the year 1947, which is displayed in both proxies as a distinct positive peak and coincides with a drop in instrumental SST. Interestingly, a marked decrease in annual coral growth rate is observed in the uppermost years of the core (1999 to 2004), as well as a reduced seasonal amplitude in δ18O variability and a trend to more negative δ18O-values at the

  20. The Clouds of Isidore

    NASA Technical Reports Server (NTRS)

    2002-01-01

    of viewing angle as well as the height field. Note that over the short distances (2.2 kilometers) that the local albedo product is generated, values can be greater than 1.0 due to contributions from cloud sides. Areas where albedo could not be retrieved are shown in dark gray.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. These data products were generated from a portion of the imagery acquired during Terra orbit 14669. The panels cover an area of about 380 kilometers x 704 kilometers, and utilize data from blocks 70 to 79within World Reference System-2 path 17.

    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 Institute of Technology.

  1. Changes in cloud and aerosol cover (1980-2006) from reflectivity time series using SeaWiFS, N7-TOMS, EP-TOMS, SBUV-2, and OMI radiance data

    NASA Astrophysics Data System (ADS)

    Herman, J. R.; Labow, G.; Hsu, N. C.; Larko, D.

    2009-01-01

    The amount of solar radiation reflected back to space or reaching the Earth's surface is primarily governed by the amount of cloud cover and, to a much lesser extent, by Rayleigh scattering, aerosols, and various absorbing gases (e.g., O3, NO2, H2O). A useful measure of the effect of cloud plus aerosol cover is given by the amount that the 331 nm Lambert Equivalent Reflectivity (LER) of a scene exceeds the surface reflectivity for snow/ice-free scenes after Rayleigh scattering has been removed. Twenty-eight years of reflectivity data are available by overlapping data from several satellites: N7 (Nimbus 7, TOMS; 331 nm) from 1979 to 1992, SBUV-2 series (Solar Backscatter Ultraviolet, NOAA; 331 nm) 1985 to 2007, EP (Earth-Probe, TOMS; 331 nm) 1997 to 2006, SW (SeaWiFS; 412 nm) 1998 to 2006, and OMI (Ozone Measuring Instrument; 331 nm) 2004-2007. Only N7 and SW have a sufficiently long data record, Sun-synchronous orbits, and are adequately calibrated for long-term reflectivity trend estimation. Reflectivity data derived from these instruments and the SBUV-2 series are compared during the overlapping years. Key issues in determining long-term reflectivity changes that have occurred during the N7 and SW operating periods are discussed. The largest reflectivity changes in the 412 nm SW LER and 331 nm EP LER are found to occur near the equator and are associated with a large El Nino-Southern Oscillation event. Most other changes that have occurred are regional, such as the apparent cloud decrease over northern Europe since 1998. The fractional occurrence (fraction of days) of high reflectivity values over Hudson Bay, Canada (snow/ice and clouds) appears to have decreased when comparing reflectivity data from 1980 to 1992 to 1997-2006, suggesting shorter duration of ice in Hudson Bay since 1980.

  2. Changes in Cloud and Aerosol Cover (1980-2006) from Reflectivity Time Series Using SeaWiFS, N7-TOMS, EP-TOMS, SBUV-2, and OMI Radiance Data

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Labow, G.; Hsu, N. C.; Larko, D.

    2009-01-01

    The amount of solar radiation reflected back to space or reaching the Earth's surface is primarily governed by the amount of cloud cover and, to a much lesser extent, by Rayleigh scatteri ng, aerosols, and various absorbing gases (e.g., O3, NO2, H2O). A useful measure of the effect of cloud plus aerosol cover is given by the amount that the 331 run Lambert Equivalent Reflectivity (LER) ofa scene exceeds the surfuce reflectivity for snow/ice-free scenes after Rayleigh scattering has been removed. Twenty-eight years of reflectivity data are available by overlapping data from several satellites: N7 (Nimbus 7, TOMS; 331 nm) from 1979 to 1992, SBUV-2 series (Solar Backscatter Ultraviolet, NOAA; 331 nm) 1985 to 2007, EP (Earth-Probe, TOMS; 331 nm) 1997 to 2006, SW (SeaWiFS; 412 nm) 1998 to 2006, and OMI (Ozone Measuring Instrument; 331 nm) 2004-2007. Only N7 and SW have a sufficiently long data record, Sun-synchronous orbits, and are adequately calibrated for long-term reflectivity trend estimation. Reflectivity data derived from these instruments and the SBUV-2 series are compared during the overlapping years. Key issues in determining long-term reflecti vity changes that have occurred during the N7 and SW operating periods are discussed. The largest reflectivity changes in the 412 nm SW LER and 331 nm EP LER are found to occur near the equator and are associated with a large EI Nino-Southern Oscillation event. Most other changes that have occurred are regional, such as the apparent cloud decrease over northern Europe since 1998. The fractional occurrence (fraction of days) of high reflectivity values over Hudson Bay, Canada (snow/ice and clouds) appears to have decreased when comparing reflectivity data from 1980 to 1992 to 1997-2006, suggesting shorter duration of ice in Hudson Bay since 1980.

  3. Acquired hyperpigmentations*

    PubMed Central

    Cestari, Tania Ferreira; Dantas, Lia Pinheiro; Boza, Juliana Catucci

    2014-01-01

    Cutaneous hyperpigmentations are frequent complaints, motivating around 8.5% of all dermatological consultations in our country. They can be congenital, with different patterns of inheritance, or acquired in consequence of skin problems, systemic diseases or secondary to environmental factors. The vast majority of them are linked to alterations on the pigment melanin, induced by different mechanisms. This review will focus on the major acquired hyperpigmentations associated with increased melanin, reviewing their mechanisms of action and possible preventive measures. Particularly prominent aspects of diagnosis and therapy will be emphasized, with focus on melasma, post-inflammatory hyperpigmentation, periorbital pigmentation, dermatosis papulosa nigra, phytophotodermatoses, flagellate dermatosis, erythema dyschromicum perstans, cervical poikiloderma (Poikiloderma of Civatte), acanthosis nigricans, cutaneous amyloidosis and reticulated confluent dermatitis PMID:24626644

  4. Cloud Formation

    NASA Astrophysics Data System (ADS)

    Graham, Mark Talmage

    2004-05-01

    Cloud formation is crucial to the heritage of modern physics, and there is a rich literature on this important topic. In 1927, Charles T.R. Wilson was awarded the Nobel Prize in physics for applications of the cloud chamber.2 Wilson was inspired to study cloud formation after working at a meteorological observatory on top of the highest mountain in Scotland, Ben Nevis, and testified near the end of his life, "The whole of my scientific work undoubtedly developed from the experiments I was led to make by what I saw during my fortnight on Ben Nevis in September 1894."3 To form clouds, Wilson used the sudden expansion of humid air.4 Any structure the cloud may have is spoiled by turbulence in the sudden expansion, but in 1912 Wilson got ion tracks to show up by using strobe photography of the chamber immediately upon expansion.5 In the interim, Millikan's study in 1909 of the formation of cloud droplets around individual ions was the first in which the electron charge was isolated. This study led to his famous oil drop experiment.6 To Millikan, as to Wilson, meteorology and physics were professionally indistinct. With his meteorological physics expertise, in WWI Millikan commanded perhaps the first meteorological observation and forecasting team essential to military operation in history.7 But even during peacetime meteorology is so much of a concern to everyone that a regular news segment is dedicated to it. Weather is the universal conversation topic, and life on land could not exist as we know it without clouds. One wonders then, why cloud formation is never covered in physics texts.

  5. Dissipation of Titans north polar cloud at northern spring equinox

    USGS Publications Warehouse

    Le, Mouelic S.; Rannou, P.; Rodriguez, S.; Sotin, C.; Griffith, C.A.; Le, Corre L.; Barnes, J.W.; Brown, R.H.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.; Tobie, G.

    2012-01-01

    Saturns Moon Titan has a thick atmosphere with a meteorological cycle. We report on the evolution of the giant cloud system covering its north pole using observations acquired by the Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft. A radiative transfer model in spherical geometry shows that the clouds are found at an altitude between 30 and 65 km. We also show that the polar cloud system vanished progressively as Titan approached equinox in August 2009, revealing at optical wavelengths the underlying sea known as Kraken Mare. This decrease of activity suggests that the north-polar downwelling has begun to shut off. Such a scenario is compared with the Titan global circulation model of Rannou et al. (2006), which predicts a decrease of cloud coverage in northern latitudes at the same period of time. ?? 2011 Elsevier Ltd. All rights reserved.

  6. Limits to Cloud Susceptibility

    NASA Technical Reports Server (NTRS)

    Coakley, James A., Jr.

    2002-01-01

    1-kilometer AVHRR observations of ship tracks in low-level clouds off the west coast of the U S. were used to determine limits for the degree to which clouds might be altered by increases in anthropogenic aerosols. Hundreds of tracks were analyzed to determine whether the changes in droplet radii, visible optical depths, and cloud top altitudes that result from the influx of particles from underlying ships were consistent with expectations based on simple models for the indirect effect of aerosols. The models predict substantial increases in sunlight reflected by polluted clouds due to the increases in droplet numbers and cloud liquid water that result from the elevated particle concentrations. Contrary to the model predictions, the analysis of ship tracks revealed a 15-20% reduction in liquid water for the polluted clouds. Studies performed with a large-eddy cloud simulation model suggested that the shortfall in cloud liquid water found in the satellite observations might be attributed to the restriction that the 1-kilometer pixels be completely covered by either polluted or unpolluted cloud. The simulation model revealed that a substantial fraction of the indirect effect is caused by a horizontal redistribution of cloud water in the polluted clouds. Cloud-free gaps in polluted clouds fill in with cloud water while the cloud-free gaps in the surrounding unpolluted clouds remain cloud-free. By limiting the analysis to only overcast pixels, the current study failed to account for the gap-filling predicted by the simulation model. This finding and an analysis of the spatial variability of marine stratus suggest new ways to analyze ship tracks to determine the limit to which particle pollution will alter the amount of sunlight reflected by clouds.

  7. Use of cloud observations and mesoscale meteorology models to evaluate and improve cloud parameterizations

    SciTech Connect

    Walcek, C.J.

    1992-10-30

    This research program utilizes satellite and surface-derived cloud observations together with standard meteorological measurements to evaluate and improve our ability to accurately diagnose cloud coverage. Results are to be used to compliment existing or future parameterizations of cloud effects in general circulation models, since nearly all cloud parameterizations must specify a fractional area of cloud coverage when calculating radiative or dynamic cloud effects, and current parameterizations rely on rather crude cloud cover estimates. We have compiled and reviewed a list of formulations used by various climate research groups to specify cloud cover. We find considerable variability between formulations used by various climate and meteorology models, and under some conditions, one formulation will produce a zero cloud amount, while an alternate formulation calculates 95% cloud cover under the same environmental conditions. All formulations hypothesize that cloud cover is predominantly determined by the average relative humidity, although some formulations allow local temperature lapse rates and vertical velocities to influence cloud amount.

  8. Mapping known and potential mineral occurrences and host rocks in the Bonnifield Mining District using minimal cloud- and snow-cover ASTER data: Chapter E in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    USGS Publications Warehouse

    Hubbard, Bernard E.; Dusel-Bacon, Cynthia; Rowan, Lawrence C.; Eppinger, Robert G.; Gough, Larry P.; Day, Warren C.

    2007-01-01

    On July 8, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor acquired satellite imagery of a 60-kilometer-wide swath covering a portion of the Bonnifield mining district within the southernmost part of the Tintina Gold Province, Alaska, under unusually favorable conditions of minimal cloud and snow cover. Although rocks from more than eight different lithotectonic terranes are exposed within the extended swath of data, we focus on volcanogenic massive sulfides (VMS) and porphyry deposits within the Yukon-Tanana terrane (YTT), the largest Mesozoic accretionary terrane exposed between the Denali fault system to the south of Fairbanks and the Tintina fault system to the north of Fairbanks. Comparison of thermal-infrared region (TIR) decorrelation stretch data to available geologic maps indicates that rocks from the YTT contain a wide range of rock types ranging in composition from mafic metavolcanic rocks to felsic rock types such as metarhyolites, pelitic schists, and quartzites. The nine-band ASTER visible-near-infrared region--short-wave infrared region (VNIR-SWIR) reflectance data and spectral matched-filter processing were used to map hydrothermal alteration patterns associated with VMS and porphyry deposit types. In particular, smectite, kaolinite, opaline silica, jarosite and (or) other ferric iron minerals defined narrow (less than 250-meter diameter) zonal patterns around Red Mountain and other potential VMS targets. Using ASTER we identified some of the known mineral deposits in the region, as well as mineralogically similar targets that may represent potential undiscovered deposits. Some known deposits were not identified and may have been obscured by vegetation or snow cover or were too small to be resolved.

  9. Cirrus cloud detection from airborne imaging spectrometer data using the 1.38 micron water vapor band

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Goetz, Alexander F. H.; Wiscombe, Warren J.

    1993-01-01

    Using special images acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at 20 km altitude, we show that wavelengths close to the center of the strong 1.38 micron water vapor band are useful for detecting thin cirrus clouds. The detection makes use of the fact that cirrus clouds are located above almost all the atmospheric water vapor. Because of the strong water vapor absorption in the lower atmosphere, AVIRIS channels near 1.38 micron receive little scattered solar radiance from the surface of low level clouds. When cirrus clouds are present, however, these channels receive large amounts of scattered solar radiance from the cirrus clouds. Our ability to determine cirrus cloud cover using space-based remote sensing will be improved if channels near the center of the 1.38 micron water vapor band are added to future satellites.

  10. GEOS-5 Modeled Clouds

    NASA Video Gallery

    This visualization shows clouds from a simulation using the Goddard Earth Observing System Model, Verison 5 (GEOS-5). The global atmospheric simulation covers a period from Feb 3, 2010 through Feb ...

  11. Land cover mapping of North and Central America—Global Land Cover 2000

    USGS Publications Warehouse

    Latifovic, Rasim; Zhu, Zhi-Liang

    2004-01-01

    The Land Cover Map of North and Central America for the year 2000 (GLC 2000-NCA), prepared by NRCan/CCRS and USGS/EROS Data Centre (EDC) as a regional component of the Global Land Cover 2000 project, is the subject of this paper. A new mapping approach for transforming satellite observations acquired by the SPOT4/VGTETATION (VGT) sensor into land cover information is outlined. The procedure includes: (1) conversion of daily data into 10-day composite; (2) post-seasonal correction and refinement of apparent surface reflectance in 10-day composite images; and (3) extraction of land cover information from the composite images. The pre-processing and mosaicking techniques developed and used in this study proved to be very effective in removing cloud contamination, BRDF effects, and noise in Short Wave Infra-Red (SWIR). The GLC 2000-NCA land cover map is provided as a regional product with 28 land cover classes based on modified Federal Geographic Data Committee/Vegetation Classification Standard (FGDC NVCS) classification system, and as part of a global product with 22 land cover classes based on Land Cover Classification System (LCCS) of the Food and Agriculture Organisation. The map was compared on both areal and per-pixel bases over North and Central America to the International Geosphere–Biosphere Programme (IGBP) global land cover classification, the University of Maryland global land cover classification (UMd) and the Moderate Resolution Imaging Spectroradiometer (MODIS) Global land cover classification produced by Boston University (BU). There was good agreement (79%) on the spatial distribution and areal extent of forest between GLC 2000-NCA and the other maps, however, GLC 2000-NCA provides additional information on the spatial distribution of forest types. The GLC 2000-NCA map was produced at the continental level incorporating specific needs of the region.

  12. Satellite Studies of Cirrus Clouds for Project Fire

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Examine global cloud climatologies for evidence of human caused changes in cloud cover and their effect on the Earth's heat budget through radiative processes. Quantify climatological changes in global cloud cover and estimate their effect on the Earth's heat budget. Improve our knowledge of global cloud cover and its changes through the merging of several satellite data sets.

  13. Facial plastic surgery area acquisition method based on point cloud mathematical model solution.

    PubMed

    Li, Xuwu; Liu, Fei

    2013-09-01

    It is one of the hot research problems nowadays to find a quick and accurate method of acquiring the facial plastic surgery area to provide sufficient but irredundant autologous or in vitro skin source for covering extensive wound, trauma, and burnt area. At present, the acquisition of facial plastic surgery area mainly includes model laser scanning, point cloud data acquisition, pretreatment of point cloud data, three-dimensional model reconstruction, and computation of area. By using this method, the area can be computed accurately, but it is hard to control the random error, and it requires a comparatively longer computation period. In this article, a facial plastic surgery area acquisition method based on point cloud mathematical model solution is proposed. This method applies symmetric treatment to the point cloud based on the pretreatment of point cloud data, through which the comparison diagram color difference map of point cloud error before and after symmetry is obtained. The slicing mathematical model of facial plastic area is got through color difference map diagram. By solving the point cloud data in this area directly, the facial plastic area is acquired. The point cloud data are directly operated in this method, which can accurately and efficiently complete the surgery area computation. The result of the comparative analysis shows the method is effective in facial plastic surgery area.

  14. Cloud Arcs in the Western Pacific

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

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

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

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

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

  15. Search Cloud

    MedlinePlus

    ... this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this page, ... chest pa and lateral Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  16. Diurnal Variations of Clouds in Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Wu, Qiaoyan; Ruan, Zhenxin

    2016-04-01

    Using 14 years (2000-2013) of pixel-resolution infrared (IR) brightness temperature data and best track data, this study estimates the diurnal variations of convective systems in tropical cyclones (TCs) in the western North Pacific. The very cold cloud cover (IR brightness temperatures < 208 K) of TCs reaches a maximum areal extent in the early morning (0000-0300 LST) and then decreases after the sunrise. The decrease of very cold cloud cover is followed by an increase of cloud cover between 208 K and 240 K with a maximum areal extent in the afternoon (1500-1800 LST). TC IR cloud top temperatures < 240 K have minimum values in the morning (0300-0600 LST) , while TC IR cloud top temperatures > 240 K have mean minimum values in the afternoon (1500-1800 LST). The out-of-phase relation between different cloud conditions with IR cloud top temperatures < 240 K and IR cloud top temperatures > 240 K lead to radius-averaged IR temperature show two minima within a day. Different diurnal evolution under different cloud conditions suggests that TC convective systems are better described in terms of both areal extent and cloud-top temperature. The maximum cloud cover with IR cloud top temperatures colder than 208 K in the morning and the maximum cloud cover with IR cloud top temperatures between 208 K and 240 K in the afternoon suggest that two different mechanisms might be involved with the diurnal variations of these two types of TC cloud conditions.

  17. Gravity Waves Ripple over Marine Stratocumulus Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    In this natural-color image from the Multi-angle Imaging SpectroRadiometer (MISR), a fingerprint-like gravity wave feature occurs over a deck of marine stratocumulus clouds. Similar to the ripples that occur when a pebble is thrown into a still pond, such 'gravity waves' sometimes appear when the relatively stable and stratified air masses associated with stratocumulus cloud layers are disturbed by a vertical trigger from the underlying terrain, or by a thunderstorm updraft or some other vertical wind shear. The stratocumulus cellular clouds that underlie the wave feature are associated with sinking air that is strongly cooled at the level of the cloud-tops -- such clouds are common over mid-latitude oceans when the air is unperturbed by cyclonic or frontal activity. This image is centered over the Indian Ocean (at about 38.9o South, 80.6o East), and was acquired on October 29, 2003.

    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 orbit 20545. The image covers an area of 245 kilometers x 378 kilometers, and uses data from blocks 121 to 122 within World Reference System-2 path 134.

    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 Institute of Technology.

  18. Cloud recognition from ground-based solar radiation measurements: preliminary results

    NASA Astrophysics Data System (ADS)

    Calbo, Josep; Gonzalez, Josep-Abel

    1998-12-01

    Despite cloud recognition techniques that can routinely identify cloud classes form satellite images, observation of clouds from the ground is still needed to acquire a complete description of cloud climatology. Solar radiation in a given site is one of the meteorological magnitudes that are most affected by cloud cover. Presently, the number of stations where both global and diffuse total solar radiation is measured is growing, due basically to energetic applications of solar radiation. Global and diffuse hourly irradiation, along with some measure of the temporal variability of solar radiation, are used in this paper to describe the sky condition, and to classify it into several cloud types. A classical maximum likelihood method is applied for clustering data. One year of solar radiation data and cloud observations at a site in Catalonia, Spain is used to illustrate the ability of solar radiation measurements to describe cloud types. Preliminary results of the above methodology show that three clusters appear using global and diffuse hourly irradiation only. Fog, stratus, and stratocumulus from the first group. A second group includes altocumulus alone or mixed with other clouds, as well as scattered cumulus congestus. In a third group, we find clear skies, cirrus and scattered cumulus. Especially in this third group, variability of solar radiation within an hour helps to separate different situations.

  19. Architectural Implications of Cloud Computing

    DTIC Science & Technology

    2011-10-24

    Mellon University Final Thoughts 1 Cloud Computing is in essence an economic model • It is a different way to acquire and manage IT resources...Cloud (EC2): http://aws.amazon.com/ec2/ • Amazon Simple Storage Solution (S3): http://aws.amazon.com/s3/ • Eucalyptus Systems: http

  20. Cloud Interactions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

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

  1. Acquired Cystic Kidney Disease

    MedlinePlus

    ... They Work Kidney Disease A-Z Acquired Cystic Kidney Disease What is acquired cystic kidney disease? Acquired cystic kidney disease happens when a ... cysts. What are the differences between acquired cystic kidney disease and polycystic kidney disease? Acquired cystic kidney ...

  2. Snow Clouds Stream off Lake Michigan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Sea-viewing Wide Field-of-view Sensor (SeaWiFS) true-color image of Lake Michigan shows a lake effect where clear dry air moves eastward from Wisconsin, picking up moisture as it traverses the lake and forming dense clouds by the time it reaches Lake Michigan's eastern shore. The scene was acquired on January 17, 2002. Note the newly-fallen snow that covers Wisconsin, Michigan, and northern Illinois. The southern edge of the snow line extends to just south of the Chicago area. Chicago sits on the southwestern shore of Lake Michigan. Except for cloudy areas in the west and east and around Lake Superior, the entire Canadian portion of the broader image can be seen to be snow covered as well. Lake Winnipeg (upper left) and James Bay (upper right of center) are frozen over. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  3. JINR cloud infrastructure evolution

    NASA Astrophysics Data System (ADS)

    Baranov, A. V.; Balashov, N. A.; Kutovskiy, N. A.; Semenov, R. N.

    2016-09-01

    To fulfil JINR commitments in different national and international projects related to the use of modern information technologies such as cloud and grid computing as well as to provide a modern tool for JINR users for their scientific research a cloud infrastructure was deployed at Laboratory of Information Technologies of Joint Institute for Nuclear Research. OpenNebula software was chosen as a cloud platform. Initially it was set up in simple configuration with single front-end host and a few cloud nodes. Some custom development was done to tune JINR cloud installation to fit local needs: web form in the cloud web-interface for resources request, a menu item with cloud utilization statistics, user authentication via Kerberos, custom driver for OpenVZ containers. Because of high demand in that cloud service and its resources over-utilization it was re-designed to cover increasing users' needs in capacity, availability and reliability. Recently a new cloud instance has been deployed in high-availability configuration with distributed network file system and additional computing power.

  4. Waves on White: Ice or Clouds?

    NASA Technical Reports Server (NTRS)

    2005-01-01

    snow or ice-covered surfaces is important in order to adequately characterize the radiation balance of the polar regions. However, detecting clouds using spaceborne detectors over snow and ice surfaces is notoriously difficult, because the surface may often be as bright and as cold as the overlying clouds, and because polar atmospheric temperature inversions sometimes mean that clouds are warmer than the underlying snow or ice surface. The Angular Signature Cloud Mask (ASCM) was developed based on the Band-Differenced Angular Signature (BDAS) approach, introduced by Di Girolamo and Davies (1994) and updated for MISR application by Di Girolamo and Wilson (2003). BDAS uses both spectral and angular changes in reflectivity to distinguish clouds from the background, and the ASCM calculates the difference between the 446 and 866 nanometer reflectances at MISR's two most oblique cameras that view forward-scattered light. New land thresholds for the ASCM are planned for delivery later this year.

    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. This image area covers about 277 kilometers by 421 kilometers in the interior of the East Antarctic ice sheet. These data products were generated from a portion of the imagery acquired during Terra orbit 26584 and utilize data from within blocks 159 to 161 within World Reference System-2 path 63.

    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 Institute of Technology.

  5. Martian Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

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

  6. Cumulus cloud properties derived using Landsat satellite data

    NASA Technical Reports Server (NTRS)

    Wielicki, B. A.; Welch, R. M.

    1986-01-01

    Landsat Multispectral Scanner (MSS) digital data are used to remotely sense cumulus cloud properties such as cloud fraction and cloud reflectance, along with the distribution of cloud number and cloud fraction as a function of cloud size. The analysis is carried out for four cumulus fields covering regions approximately 150 km square. Results for these initial cloud fields indicate that: (1) the common intuitive model of clouds as nearly uniform reflecting surfaces is a poor representation of cumulus clouds, (2) the cumulus clouds were often multicelled, even for clouds as small as 1 km in diameter, (3) cloud fractional coverage derived using a simple reflectance threshold is sensitive to the chosen threshold even for 57-meter resolution Landsat data, (4) the sensitivity of cloud fraction to changes in satellite sensor resolution is less sensitive than suggested theoretically, and (5) the Landsat derived cloud size distributions show encouraging similarities among the cloud fields examined.

  7. Continuous Change Detection and Classification (CCDC) of Land Cover Using All Available Landsat Data

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Woodcock, C. E.

    2012-12-01

    A new algorithm for Continuous Change Detection and Classification (CCDC) of land cover using all available Landsat data is developed. This new algorithm is capable of detecting many kinds of land cover change as new images are collected and at the same time provide land cover maps for any given time. To better identify land cover change, a two step cloud, cloud shadow, and snow masking algorithm is used for eliminating "noisy" observations. Next, a time series model that has components of seasonality, trend, and break estimates the surface reflectance and temperature. The time series model is updated continuously with newly acquired observations. Due to the high variability in spectral response for different kinds of land cover change, the CCDC algorithm uses a data-driven threshold derived from all seven Landsat bands. When the difference between observed and predicted exceeds the thresholds three consecutive times, a pixel is identified as land cover change. Land cover classification is done after change detection. Coefficients from the time series models and the Root Mean Square Error (RMSE) from model fitting are used as classification inputs for the Random Forest Classifier (RFC). We applied this new algorithm for one Landsat scene (Path 12 Row 31) that includes all of Rhode Island as well as much of Eastern Massachusetts and parts of Connecticut. A total of 532 Landsat images acquired between 1982 and 2011 were processed. During this period, 619,924 pixels were detected to change once (91% of total changed pixels) and 60,199 pixels were detected to change twice (8% of total changed pixels). The most frequent land cover change category is from mixed forest to low density residential which occupies more than 8% of total land cover change pixels.

  8. Brute Force Matching Between Camera Shots and Synthetic Images from Point Clouds

    NASA Astrophysics Data System (ADS)

    Boerner, R.; Kröhnert, M.

    2016-06-01

    3D point clouds, acquired by state-of-the-art terrestrial laser scanning techniques (TLS), provide spatial information about accuracies up to several millimetres. Unfortunately, common TLS data has no spectral information about the covered scene. However, the matching of TLS data with images is important for monoplotting purposes and point cloud colouration. Well-established methods solve this issue by matching of close range images and point cloud data by fitting optical camera systems on top of laser scanners or rather using ground control points. The approach addressed in this paper aims for the matching of 2D image and 3D point cloud data from a freely moving camera within an environment covered by a large 3D point cloud, e.g. a 3D city model. The key advantage of the free movement affects augmented reality applications or real time measurements. Therefore, a so-called real image, captured by a smartphone camera, has to be matched with a so-called synthetic image which consists of reverse projected 3D point cloud data to a synthetic projection centre whose exterior orientation parameters match the parameters of the image, assuming an ideal distortion free camera.

  9. Study of clouds and dust aerosols in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    Chen-Chen, H.; Pérez-Hoyos, S.; Sánchez-Lavega, A.

    2017-03-01

    Observation of Mars’ atmosphere has evolved to a state of permanent monitoring of its main components. In this work, we focus on the study of clouds and dust aerosols in the Martian atmosphere by means of spacecraft observations, particularly VMC on-board Mars Express, and surface vehicles, mainly cameras on the MSL rover. Orbiting instrument observations provide a general view of the planet, which allows covering a huge area in a short time. This is very interesting, for example, to study global dust events in Mars. On the other hand, ground-based instruments are better suited to analyse local properties of dust particles from in-situ acquired first hand data.

  10. Covering Crime.

    ERIC Educational Resources Information Center

    Gest, Ted; Krajicek, David; Hackney, Suzette; Moore, Melissa

    2003-01-01

    Presents four brief articles on covering crime. Notes that reporting on crimes requires special skills for student reporters, editors, and photographers. Explains how to gain access to scenes, to develop journalistic ethics, and how to cover crime and its victims. Discusses the relation of race and ethnic issues to crime, and how visual…

  11. Sky Cover from MFRSR Observations

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Berg, Larry K.; Flynn, Connor J.; Long, Charles N.

    2011-07-01

    The diffuse all-sky surface irradiances measured at two nearby wavelengths in the visible spectral range and their model clear-sky counterparts are two main components of a new method for estimating the fractional sky cover of different cloud types, including cumulus clouds. The performance of this method is illustrated using 1-min resolution data from ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR). The MFRSR data are collected at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during the summer of 2007 and represent 13 days with cumulus clouds. Good agreement is obtained between estimated values of the fractional sky cover and those provided by a well-established independent method based on broadband observations.

  12. Use of cloud observations and mesoscale meteorology models to evaluate and improve cloud parameterizations. Technical progress report, 1 December 1991--30 November 1992

    SciTech Connect

    Walcek, C.J.

    1992-10-30

    This research program utilizes satellite and surface-derived cloud observations together with standard meteorological measurements to evaluate and improve our ability to accurately diagnose cloud coverage. Results are to be used to compliment existing or future parameterizations of cloud effects in general circulation models, since nearly all cloud parameterizations must specify a fractional area of cloud coverage when calculating radiative or dynamic cloud effects, and current parameterizations rely on rather crude cloud cover estimates. We have compiled and reviewed a list of formulations used by various climate research groups to specify cloud cover. We find considerable variability between formulations used by various climate and meteorology models, and under some conditions, one formulation will produce a zero cloud amount, while an alternate formulation calculates 95% cloud cover under the same environmental conditions. All formulations hypothesize that cloud cover is predominantly determined by the average relative humidity, although some formulations allow local temperature lapse rates and vertical velocities to influence cloud amount.

  13. Cloud Spirals and Outflow in Tropical Storm Katrina

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes.

    Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction. The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center. The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the

  14. Multi-layer Clouds Over the South Indian Ocean

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The complex structure and beauty of polar clouds are highlighted by these images acquired by the Multi-angle Imaging SpectroRadiometer (MISR) on April 23, 2003. These clouds occur at multiple altitudes and exhibit a noticeable cyclonic circulation over the Southern Indian Ocean, to the north of Enderbyland, East Antarctica.

    The image at left was created by overlying a natural-color view from MISR's downward-pointing (nadir) camera with a color-coded stereo height field. MISR retrieves heights by a pattern recognition algorithm that utilizes multiple view angles to derive cloud height and motion. The opacity of the height field was then reduced until the field appears as a translucent wash over the natural-color image. The resulting purple, cyan and green hues of this aesthetic display indicate low, medium or high altitudes, respectively, with heights ranging from less than 2 kilometers (purple) to about 8 kilometers (green). In the lower right corner, the edge of the Antarctic coastline and some sea ice can be seen through some thin, high cirrus clouds.

    The right-hand panel is a natural-color image from MISR's 70-degree backward viewing camera. This camera looks backwards along the path of Terra's flight, and in the southern hemisphere the Sun is in front of this camera. This perspective causes the cloud-tops to be brightly outlined by the sun behind them, and enhances the shadows cast by clouds with significant vertical structure. An oblique observation angle also enhances the reflection of light by atmospheric particles, and accentuates the appearance of polar clouds. The dark ocean and sea ice that were apparent through the cirrus clouds at the bottom right corner of the nadir image are overwhelmed by the brightness of these clouds at the oblique view.

    The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude

  15. Indirect and Semi-Direct Aerosol Campaign: The Impact of Arctic Aerosols on Clouds

    SciTech Connect

    McFarquhar, Greg; Ghan, Steven J.; Verlinde, J.; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Mengistu; Brooks, Sarah D.; Cziczo, Daniel J.; Dubey, Manvendra K.; Fan, Jiwen; Flynn, Connor J.; Gultepe, Ismail; Hubbe, John M.; Gilles, Mary K.; Laskin, Alexander; Lawson, Paul; Leaitch, W. R.; Liu, Peter S.; Liu, Xiaohong; Lubin, Dan; Mazzoleni, Claudio; Macdonald, A. M.; Moffet, Ryan C.; Morrison, H.; Ovchinnikov, Mikhail; Shupe, Matthew D.; Turner, David D.; Xie, Shaocheng; Zelenyuk, Alla; Bae, Kenny; Freer, Matthew; Glen, Andrew

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the arctic boundary layer in the vicinity of Barrow, Alaska was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) sponsored by the Department of Energy Atmospheric Radiation Measurement (ARM) and Atmospheric Science Programs. The primary aim of ISDAC was to examine indirect effects of aerosols on clouds that contain both liquid and ice water. The experiment utilized the ARM permanent observational facilities at the North Slope of Alaska (NSA) in Barrow. These include a cloud radar, a polarized micropulse lidar, and an atmospheric emitted radiance interferometer as well as instruments specially deployed for ISDAC measuring aerosol, ice fog, precipitation and spectral shortwave radiation. The National Research Council of Canada Convair-580 flew 27 sorties during ISDAC, collecting data using an unprecedented 42 cloud and aerosol instruments for more than 100 hours on 12 different days. Data were obtained above, below and within single-layer stratus on 8 April and 26 April 2008. These data enable a process-oriented understanding of how aerosols affect the microphysical and radiative properties of arctic clouds influenced by different surface conditions. Observations acquired on a heavily polluted day, 19 April 2008, are enhancing this understanding. Data acquired in cirrus on transit flights between Fairbanks and Barrow are improving our understanding of the performance of cloud probes in ice. Ultimately the ISDAC data will be used to improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and to determine the extent to which long-term surface-based measurements can provide retrievals of aerosols, clouds, precipitation and radiative heating in the Arctic.

  16. Cloud observations with Nimbus-7 satellite data

    NASA Technical Reports Server (NTRS)

    Stowe, L. L.; Hwang, P. H.; Bhartia, P. K.; Eck, T. F.

    1983-01-01

    A Nimbus-7 Cloud Data Processing Team was established in 1982 in order to implement cloud-related studies for as long as the spacecraft's Temperature Humidity IR radiometer and Total Ozone Mapping Spectrometer continue to operate. It will soon be possible to correlate the Nimbus-7 cloud cover information with International Satellite Cloud Climatology results. The production of validated Nimbus-7 cloud products was scheduled to begin in November, 1983; each year of Nimbus-7 cloud data should take about four months to produce.

  17. CO observations of dark clouds in Lupus

    NASA Technical Reports Server (NTRS)

    Murphy, D. C.; Cohen, R.; May, J.

    1986-01-01

    C-12O observations covering 170 square degrees toward the southern T Association Lupus have revealed the presence of an extended physically related complex of dark clouds which have recently formed low mass stars. The estimated mass of the clouds (about 30,000 solar masses) is comparable to that of the nearby Ophiuchus dust clouds. The Lupus clouds are projected onto a gap between two subgroups of the Scorpio-Centaurus OB association suggesting that this long accepted subgrouping may require reinterpretation.

  18. Cloud Radiative Effect in dependence on Cloud Type

    NASA Astrophysics Data System (ADS)

    Aebi, Christine; Gröbner, Julian; Kämpfer, Niklaus; Vuilleumier, Laurent

    2015-04-01

    Radiative transfer of energy in the atmosphere and the influence of clouds on the radiation budget remain the greatest sources of uncertainty in the simulation of climate change. Small changes in cloudiness and radiation can have large impacts on the Earth's climate. In order to assess the opposing effects of clouds on the radiation budget and the corresponding changes, frequent and more precise radiation and cloud observations are necessary. The role of clouds on the surface radiation budget is studied in order to quantify the longwave, shortwave and the total cloud radiative forcing in dependence on the atmospheric composition and cloud type. The study is performed for three different sites in Switzerland at three different altitude levels: Payerne (490 m asl), Davos (1'560 m asl) and Jungfraujoch (3'580 m asl). On the basis of data of visible all-sky camera systems at the three aforementioned stations in Switzerland, up to six different cloud types are distinguished (Cirrus-Cirrostratus, Cirrocumulus-Altocumulus, Stratus-Altostratus, Cumulus, Stratocumulus and Cumulonimbus-Nimbostratus). These cloud types are classified with a modified algorithm of Heinle et al. (2010). This cloud type classifying algorithm is based on a set of statistical features describing the color (spectral features) and the texture of an image (textural features) (Wacker et al. (2015)). The calculation of the fractional cloud cover information is based on spectral information of the all-sky camera data. The radiation data are taken from measurements with pyranometers and pyrgeometers at the different stations. A climatology of a whole year of the shortwave, longwave and total cloud radiative effect and its sensitivity to integrated water vapor, cloud cover and cloud type will be calculated for the three above-mentioned stations in Switzerland. For the calculation of the shortwave and longwave cloud radiative effect the corresponding cloud-free reference models developed at PMOD/WRC will be

  19. Cloud/climate sensitivity experiments

    NASA Technical Reports Server (NTRS)

    Roads, J. O.; Vallis, G. K.; Remer, L.

    1982-01-01

    A study of the relationships between large-scale cloud fields and large scale circulation patterns is presented. The basic tool is a multi-level numerical model comprising conservation equations for temperature, water vapor and cloud water and appropriate parameterizations for evaporation, condensation, precipitation and radiative feedbacks. Incorporating an equation for cloud water in a large-scale model is somewhat novel and allows the formation and advection of clouds to be treated explicitly. The model is run on a two-dimensional, vertical-horizontal grid with constant winds. It is shown that cloud cover increases with decreased eddy vertical velocity, decreased horizontal advection, decreased atmospheric temperature, increased surface temperature, and decreased precipitation efficiency. The cloud field is found to be well correlated with the relative humidity field except at the highest levels. When radiative feedbacks are incorporated and the temperature increased by increasing CO2 content, cloud amounts decrease at upper-levels or equivalently cloud top height falls. This reduces the temperature response, especially at upper levels, compared with an experiment in which cloud cover is fixed.

  20. Cloud Computing

    SciTech Connect

    Pete Beckman and Ian Foster

    2009-12-04

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

  1. Distinguishing Clouds from Ice over the East Siberian Sea, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As a consequence of its capability to retrieve cloud-top elevations, stereoscopic observations from the Multi-angle Imaging SpectroRadiometer (MISR) can discriminate clouds from snow and ice. The central portion of Russia's East Siberian Sea, including one of the New Siberian Islands, Novaya Sibir, are portrayed in these views from data acquired on May 28, 2002.

    The left-hand image is a natural color view from MISR's nadir camera. On the right is a height field retrieved using automated computer processing of data from multiple MISR cameras. Although both clouds and ice appear white in the natural color view, the stereoscopic retrievals are able to identify elevated clouds based on the geometric parallax which results when they are observed from different angles. Owing to their elevation above sea level, clouds are mapped as green and yellow areas, whereas land, sea ice, and very low clouds appear blue and purple. Purple, in particular, denotes elevations very close to sea level. The island of Novaya Sibir is located in the lower left of the images. It can be identified in the natural color view as the dark area surrounded by an expanse of fast ice. In the stereo map the island appears as a blue region indicating its elevation of less than 100 meters above sea level. Areas where the automated stereo processing failed due to lack of sufficient spatial contrast are shown in dark gray. The northern edge of the Siberian mainland can be found at the very bottom of the panels, and is located a little over 250 kilometers south of Novaya Sibir. Pack ice containing numerous fragmented ice floes surrounds the fast ice, and narrow areas of open ocean are visible.

    The East Siberian Sea is part of the Arctic Ocean and is ice-covered most of the year. The New Siberian Islands are almost always covered by snow and ice, and tundra vegetation is very scant. Despite continuous sunlight from the end of April until the middle of August, the ice between the island and the

  2. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2015-09-30

    retreat of the SIZ. As sea ice retreats further, changes in lower atmospheric temperature, humidity, winds , and clouds are likely to result from changed...obtain atmospheric profiles of temperature, humidity, and winds from the time of ice edge retreat in spring to advance in fall. Transects following...aerial vehicles (Glidersonde, SmartSonde) designed to obtain detailed high-vertical-resolution temperature, humidity and wind profiles and cloud

  3. Preparatory studies of zero-g cloud drop coalescence experiment

    NASA Technical Reports Server (NTRS)

    Telford, J. W.; Keck, T. S.

    1979-01-01

    Experiments to be performed in a weightless environment in order to study collision and coalescence processes of cloud droplets are described. Rain formation in warm clouds, formation of larger cloud drops, ice and water collision processes, and precipitation in supercooled clouds are among the topics covered.

  4. Can Clouds replace Grids? Will Clouds replace Grids?

    NASA Astrophysics Data System (ADS)

    Shiers, J. D.

    2010-04-01

    The world's largest scientific machine - comprising dual 27km circular proton accelerators cooled to 1.9oK and located some 100m underground - currently relies on major production Grid infrastructures for the offline computing needs of the 4 main experiments that will take data at this facility. After many years of sometimes difficult preparation the computing service has been declared "open" and ready to meet the challenges that will come shortly when the machine restarts in 2009. But the service is not without its problems: reliability - as seen by the experiments, as opposed to that measured by the official tools - still needs to be significantly improved. Prolonged downtimes or degradations of major services or even complete sites are still too common and the operational and coordination effort to keep the overall service running is probably not sustainable at this level. Recently "Cloud Computing" - in terms of pay-per-use fabric provisioning - has emerged as a potentially viable alternative but with rather different strengths and no doubt weaknesses too. Based on the concrete needs of the LHC experiments - where the total data volume that will be acquired over the full lifetime of the project, including the additional data copies that are required by the Computing Models of the experiments, approaches 1 Exabyte - we analyze the pros and cons of Grids versus Clouds. This analysis covers not only technical issues - such as those related to demanding database and data management needs - but also sociological aspects, which cannot be ignored, neither in terms of funding nor in the wider context of the essential but often overlooked role of science in society, education and economy.

  5. [Multifractal cloud properties data assessment

    SciTech Connect

    Gautier, C.; Ricchiazzi, P.; Peterson, P.; Lavallee, D. ); Frouin, R.; Lubin, D. ); Lovejoy, S. ); Schertzer, D. )

    1992-05-06

    Our group has been very active over the last year, analyzing a number of data sets to characterize multifractal cloud properties and assess the effects of clouds on surface radiation properties (spectral and broadband). The data sets analyzed include: AVHRR observations of clouds over the ocean, SPOT observations of clouds over the ocean, SSM/I observations of clouds over the ocean, pyranometer data with all-sky photographs, pyrgeometer data all-sky photographs, and spectral surface irradiance all-sky photographs. A number of radiative transfer computations have been performed to help in the interpretation of these observations or provide theoretical guidance for their analysis. Finally 4 number of radiative transfer models have been acquired and tested to prepare for the interpretation of ARM/CART data.

  6. Cover Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover crops are great tools to improve soil quality and health, and great tools to increase carbon sequestration. They are nutrient management tools that can help scavenge nitrate, cycle nitrogen to the following crop, mine NO3 from groundwater, and increase nitrogen use efficiency of cropping syste...

  7. Comparison of point clouds derived from aerial image matching with data from airborne laser scanning. (Polish Title: Porównanie wóaściwości chmury punktów wygenerowanej metodą dopasowania obrazów zdjęć lotniczych z danymi z lotniczego skanowania)

    NASA Astrophysics Data System (ADS)

    Dominik, W.

    2014-12-01

    The aim of this study was to investigate the properties of point clouds derived from aerial image matching and to compare them with point clouds from airborne laser scanning. A set of aerial images acquired in years 2010-2013 over the city of Elblag were used for the analysis. Images were acquired with the use of three digital cameras: DMC II 230, DMC I and DigiCAM60 with a GSD varying from 4.5 cm to 15 cm. Eight sets of images that were used in the study were acquired at different stages of the growing season - from March to December. Two LiDAR point clouds were used for the comparison - one with a density of 1.3 p/m2 and a second with a density of 10 p/m2. Based on the input images point clouds were created with the use of the semi-global matching method. The properties of the obtained point clouds were analyzed in three ways: - by the comparison of the vertical accuracy of point clouds with reference to a terrain profile surveyed on bare ground with GPS-RTK method - by visual assessment of point cloud profiles generated both from SGM and LiDAR point clouds - by visual assessment of a digital surface model generated from a SGM point cloud with reference to a digital surface model generated from a LiDAR point cloud. The conducted studies allowed a number of observations about the quality of SGM point clouds to be formulated with respect to different factors. The main factors having influence on the quality of SGM point clouds are GSD and base/height ratio. The essential problem related to SGM point clouds are areas covered with vegetation where SGM point clouds are visibly worse in terms of both accuracy and the representation of terrain surface. It is difficult to expect that in these areas SGM point clouds could replace LiDAR point clouds. This leads to a general conclusion that SGM point clouds are less reliable, more unpredictable and are dependent on more factors than LiDAR point clouds. Nevertheless, SGM point clouds generated with appropriate parameters can

  8. The use of MISR Multiangle Image Data to Visualize Cloud Morphology and Motion

    NASA Astrophysics Data System (ADS)

    Realmuto, V. J.; Moroney, C. M.; Davies, R.

    2002-12-01

    The Multiangle Imaging SpectroRadiometer (MISR), currently orbiting the Earth aboard NASA's Terra spacecraft, acquires image data at 9 distinct viewing angles simultaneously. This multiangle imaging is accomplished through the use of 9 cameras, with one camera providing a nadir view and the remaining cameras providing views 26.1, 45.6, 60.0, and 70.5 degrees fore and aft of nadir. Each camera, in turn, measures scene radiance in 4 spectral bands (red, green, blue, and near infrared). One of the objectives of the MISR mission is to infer the physical properties of atmospheric aerosols, clouds, and land cover (including snow, ice, and vegetation) from angular variations in scene radiance. One step in the operational processing of MISR data is to map these data into a Space Oblique Mercator projection. As a result of this projection, features at elevations above or below the reference ellipsoid (WGS 84) exhibit an apparent displacement, known as parallax or disparity, in the off-nadir images. The disparities exhibited by clouds can be used to estimate the height of the clouds, and cloud-top height maps are an operational MISR data product. Although the 9 MISR cameras acquire data simultaneously, approximately 7 minutes are required to obtain a suite of fore- and aft-viewing images that depict the same scene. This time lag allows MISR to capture the motion of clouds due to winds, and maps of wind direction and wind speed are operational data products. Visualization of the cloud properties measured by MISR presents several unique challenges, such as registration of the angular distribution of radiance above a cloud with its surface morphology and depiction of cloud motion independent of the disparity resulting from cloud height. We will present some of the tools and animation techniques developed to address these challenges. For example, MISR_Shift is an interactive tool that allows us to evaluate the effects of changes (or uncertainties) in cloud height and wind speed

  9. EVOLUTIONARY COMPUTATION AND POST-WILDFIRE LAND-COVER MAPPING WITH MULTISPECTRAL IMAGERY.

    SciTech Connect

    Brumby, Steven P.; Koch, S. W.; Hansen, L. A.

    2001-01-01

    The Cerro Grande Los Alamos wildfire devastated approximately 43,000 acres (17,500 ha) of forested land, and destroyed over 200 structures in the town of Los Alamos. The need to monitor the continuing impact of the fire on the local environment has led to the application of a number of advanced remote sensing technologies. During and after the fire, remote-sensing data was acquired fiorn a variety of aircraft- and satellite-based sensors, including Landsat 7 Enhanced Thematic Mapper (ETM+). We now report on the application of a machine learning technique io the automated classification of land cover using multispectral imagery. We apply a hybrid gertelic programminghupervised classification technique to evolve automatic feature extraction algorithms. We use a software package we have developed at Los Alamos National Laboratory, called GENIE, to carry out this evolution. We use multispectral imagery fiom the Landsat 7 ETM+ instrument fiom before and after the wildfire. Using an existing land cover classification based on a Landsat 5 TM scene for our training data, we evolve algorithms that distinguish a range of land cover categories, along with clouds and cloud shadows. The details of our evolved classification are compared to the manually produced land-cover classification. Keywords: Feature Extraction, Genetic programming, Supervised classification, Multi-spectral imagery, Land cover, Wildfire.

  10. Lightweight Electronic Camera for Research on Clouds

    NASA Technical Reports Server (NTRS)

    Lawson, Paul

    2006-01-01

    "Micro-CPI" (wherein "CPI" signifies "cloud-particle imager") is the name of a small, lightweight electronic camera that has been proposed for use in research on clouds. It would acquire and digitize high-resolution (3- m-pixel) images of ice particles and water drops at a rate up to 1,000 particles (and/or drops) per second.

  11. Marine Cloud Brightening

    SciTech Connect

    Latham, John; Bower, Keith; Choularton, Tom; Coe, H.; Connolly, P.; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Philip J.; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Robert

    2012-09-07

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could - subject to satisfactory resolution of technical and scientific problems identified herein - have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seedparticle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

  12. Marine cloud brightening.

    PubMed

    Latham, John; Bower, Keith; Choularton, Tom; Coe, Hugh; Connolly, Paul; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Phillip; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Rob

    2012-09-13

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could-subject to satisfactory resolution of technical and scientific problems identified herein-have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud-albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action.

  13. Acquired Idiopathic Generalized Anhidrosis.

    PubMed

    Gangadharan, Geethu; Criton, Sebastian; Surendran, Divya

    2015-01-01

    Acquired idiopathic generalized anhidrosis is a rare condition, where the exact pathomechanism is unknown. We report a case of acquired idiopathic generalized anhidrosis in a patient who later developed lichen planus. Here an autoimmune-mediated destruction of sweat glands may be the probable pathomechanism.

  14. LABORATORY-ACQUIRED MYCOSES

    DTIC Science & Technology

    laboratory- acquired mycoses . Insofar as possible, the etiological fungus, type of laboratory, classification of personnel, type of work conducted, and other...pertinent data have been listed in this study. More than 288 laboratory- acquired mycoses are described here, including 108 cases of

  15. The Nimbus-7 Global Cloud Climatology

    NASA Technical Reports Server (NTRS)

    Hwang, Paul H.; Kyle, H. Lee; Stowe, Larry L.; Pellegrino, P. P.; Yeh, H. Y. Michael

    1988-01-01

    The Nimbus-7 Global Cloud Climatology (N7GCC) has been produced from measurements made between April 1979 and March 1985 using the Temperature Humidity IR Radiometer and the Total Ozone Mapping Spectrometer on the Nimbus-7 satellite. The N7GCC gives, near local noon and midnight, the fractional area covered by high-level, middle-level, and low-altitude clouds, and the total fractional area covered by all clouds. Statistics for cirrus, deep convective, and warm low-altitude clouds and the cloud and clear-sky radiances with correlative surface temperatures are also included. The N7GCC is compared with other cloud data sets, including the International Satellite Cloud Climatology Project.

  16. SatCam: A mobile application for coordinated ground/satellite observation of clouds and validation of satellite-derived cloud mask products.

    NASA Astrophysics Data System (ADS)

    Gumley, L.; Parker, D.; Flynn, B.; Holz, R.; Marais, W.

    2011-12-01

    SatCam is an application for iOS devices that allows users to collect observations of local cloud and surface conditions in coordination with an overpass of the Terra, Aqua, or NPP satellites. SatCam allows users to acquire images of sky conditions and ground conditions at their location anywhere in the world using the built-in iPhone or iPod Touch camera at the same time that the satellite is passing overhead and viewing their location. Immediately after the sky and ground observations are acquired, the application asks the user to rate the level of cloudiness in the sky (Completely Clear, Mostly Clear, Partly Cloudy, Overcast). For the ground observation, the user selects their assessment of the surface conditions (Urban, Green Vegetation, Brown Vegetation, Desert, Snow, Water). The sky condition and surface condition selections are stored along with the date, time, and geographic location for the images, and the images are uploaded to a central server. When the MODIS (Terra and Aqua) or VIIRS (NPP) imagery acquired over the user location becomes available, a MODIS or VIIRS true color image centered at the user's location is delivered back to the SatCam application on the user's iOS device. SSEC also proposes to develop a community driven SatCam website where users can share their observations and assessments of satellite cloud products in a collaborative environment. SSEC is developing a server side data analysis system to ingest the SatCam user observations, apply quality control, analyze the sky images for cloud cover, and collocate the observations with MODIS and VIIRS satellite products (e.g., cloud mask). For each observation that is collocated with a satellite observation, the server will determine whether the user scored a "hit", meaning their sky observation and sky assessment matched the automated cloud mask obtained from the satellite observation. The hit rate will be an objective assessment of the accuracy of the user's sky observations. Users with

  17. Empirical and modeled synoptic cloud climatology of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Crane, R. G.

    1985-01-01

    A daily climatology of the atmospheric circulation of the Arctic and the associated cloud conditions were determined. These are used for comparisons with the variability of general circulation model, generated circulation, and cloud cover for the same region.

  18. Science in the clouds: UAVs and cloud computing methods for spatial diffuse pollution risk assessment (Invited)

    NASA Astrophysics Data System (ADS)

    Reaney, S. M.

    2010-12-01

    The processes related to diffuse pollution can be understood within a 'source -> mobilisation -> pathway -> impact' framework. Recently our ability to monitor the impact section of this framework has significantly increased. This has been achieved through the measurement of flow and water quality (e.g. Nitrogen and Phosphorus) on a continuous 10 minute basis. However, our ability to observe and understand the 'source', 'mobilisation' and 'pathway' sections has not progressed at the same rate. This lack of information of the source term is due to the larger spatial areas involved and the difficulty in performing repeat surveys. Within an agricultural catchment, there are two key, temporally dynamic factors that affect the diffuse pollution export [source-mobilisation-pathway]: 1. vegetation cover and 2. agricultural management. These factors influence the amount of bare soil, vulnerable to erosion (source) and the creation of flow pathways, for example, due to tractor wheelings (tram lines). Information on these factors could be acquired through the use of satellite remote sensing or light aircraft based aerial photography. However, to acquire images on a fine temporal scale (monthly) there are significant cost and practical barriers (e.g. cloud cover). A potential solution to the problem could be the use of small semi- autonomous helicopters (UAV) and is the approach that has been investigated in this research. The UAV helicopter that has been used in this research is a Microdrones MD4-200 and is capable of autonomously flying a pre-programmed route and acquiring images at set locations at heights of up to 120 metres. The use of the pre-programmed routes enables the acquisition of repeat images at the same locations. These images contain information on the vegetation cover that can be extracted with the use of standard image processing techniques. However, the images also contain a large amount of implicit information that may help to explain water quality trends

  19. Automatic classification of clouds on Meteosat imagery - Application to high-level clouds

    NASA Technical Reports Server (NTRS)

    Desbois, M.; Seze, G.; Szejwach, G.

    1982-01-01

    A statistical classification method based on clustering on three-dimensional histograms is applied to the three channels of the Meteosat imagery. The results of this classification are studied for different cloud cover cases over tropical regions. For high-level cloud classes, it is shown that the bidimensional IR-water vapor histogram allows one to deduce the cloud top temperature even for semi-transparent clouds.

  20. The Relationship Between Surface Temperature Anomaly Time Series and those of OLR, Water Vapor, and Cloud Cover as Observed Using Nine Years of AIRS Version-5 Level-3 Products

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Molnar, Gyula; Iredell, Lena

    2011-01-01

    Outline: (1) Comparison of AIRS and CERES anomaly time series of outgoing longwave radiation (OLR) and OLR(sub CLR), i.e. Clear Sky OLR (2) Explanation of recent decreases in global and tropical mean values of OLR (3) AIRS "Short-term" Longwave Cloud Radiative Feedback -- A new product

  1. Acquired inflammatory demyelinating neuropathies.

    PubMed

    Ensrud, E R; Krivickas, L S

    2001-05-01

    The acquired demyelinating neuropathies can be divided into those with an acute onset and course and those with a more chronic course. The acute neuropathies present as Guillain-Barré syndrome and include acute inflammatory demyelinating polyradiculoneuropathy (AIDP), Miller Fisher syndrome, acute motor axonal neuropathy (AMAN), acute motor and sensory axonal neuropathy (AMSAN), and acute pandysautonomia. The chronic neuropathies are collectively known as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and include MADSAM (multifocal acquired demyelinating sensory and motor neuropathy, also know as Lewis-Sumner syndrome) and DADS (distal acquired demyelinating symmetric neuropathy) as variants. The clinical features, pathology, pathogenesis, diagnosis, treatment, rehabilitation, and prognosis of these neuropathies are discussed.

  2. Parameterization of clouds and radiation in climate models

    SciTech Connect

    Roeckner, E.

    1995-09-01

    Clouds are a very important, yet poorly modeled element in the climate system. There are many potential cloud feedbacks, including those related to cloud cover, height, water content, phase change, and droplet concentration and size distribution. As a prerequisite to studying the cloud feedback issue, this research reports on the simulation and validation of cloud radiative forcing under present climate conditions using the ECHAM general circulation model and ERBE top-of-atmosphere radiative fluxes.

  3. Acquired color vision deficiency.

    PubMed

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  4. A Flexible Cloud Generator

    NASA Astrophysics Data System (ADS)

    Benassi, A.; Deguy, S.; Szczap, F.

    2001-05-01

    In this work we propose a flexible cloud generating model as well as a software. This model depends upon 5 quantities: -the cloud fractional coverage -the spectral slope -the mean value -the variance -the internal heterogeneity (intermittency). All these quantities are independantly identifiable on the base of mathematical proofs. This model also depends on a given function, called "morphlet", and on the law of a random variables family. In order to get a positive water contain inside the cloud,we ask the morphlet and the random variables to be positives. The structure of the model is hierarchycal. The vertebral column of this model is a tree: the basic encoding tree of the space where the cloud lives. At each edge of the tree is attached: -a Bernoulli random variable,this for tuning the fractional cover and the intermittency, -a rate of energy loose,giving the spectral slope, -a dilated morphlet. The word flexible is justified by the fact that we can choose to modify some objets on the basic tree in order to adjust the caracteristics of the desired cloud.

  5. Marine cloud brightening

    PubMed Central

    Latham, John; Bower, Keith; Choularton, Tom; Coe, Hugh; Connolly, Paul; Cooper, Gary; Craft, Tim; Foster, Jack; Gadian, Alan; Galbraith, Lee; Iacovides, Hector; Johnston, David; Launder, Brian; Leslie, Brian; Meyer, John; Neukermans, Armand; Ormond, Bob; Parkes, Ben; Rasch, Phillip; Rush, John; Salter, Stephen; Stevenson, Tom; Wang, Hailong; Wang, Qin; Wood, Rob

    2012-01-01

    The idea behind the marine cloud-brightening (MCB) geoengineering technique is that seeding marine stratocumulus clouds with copious quantities of roughly monodisperse sub-micrometre sea water particles might significantly enhance the cloud droplet number concentration, and thereby the cloud albedo and possibly longevity. This would produce a cooling, which general circulation model (GCM) computations suggest could—subject to satisfactory resolution of technical and scientific problems identified herein—have the capacity to balance global warming up to the carbon dioxide-doubling point. We describe herein an account of our recent research on a number of critical issues associated with MCB. This involves (i) GCM studies, which are our primary tools for evaluating globally the effectiveness of MCB, and assessing its climate impacts on rainfall amounts and distribution, and also polar sea-ice cover and thickness; (ii) high-resolution modelling of the effects of seeding on marine stratocumulus, which are required to understand the complex array of interacting processes involved in cloud brightening; (iii) microphysical modelling sensitivity studies, examining the influence of seeding amount, seed-particle salt-mass, air-mass characteristics, updraught speed and other parameters on cloud–albedo change; (iv) sea water spray-production techniques; (v) computational fluid dynamics studies of possible large-scale periodicities in Flettner rotors; and (vi) the planning of a three-stage limited-area field research experiment, with the primary objectives of technology testing and determining to what extent, if any, cloud albedo might be enhanced by seeding marine stratocumulus clouds on a spatial scale of around 100×100 km. We stress that there would be no justification for deployment of MCB unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favour of such action

  6. Cloud Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Moncrieff, Mitchell; Einaud, Franco (Technical Monitor)

    2001-01-01

    Numerical cloud models have been developed and applied extensively to study cloud-scale and mesoscale processes during the past four decades. The distinctive aspect of these cloud models is their ability to treat explicitly (or resolve) cloud-scale dynamics. This requires the cloud models to be formulated from the non-hydrostatic equations of motion that explicitly include the vertical acceleration terms since the vertical and horizontal scales of convection are similar. Such models are also necessary in order to allow gravity waves, such as those triggered by clouds, to be resolved explicitly. In contrast, the hydrostatic approximation, usually applied in global or regional models, does allow the presence of gravity waves. In addition, the availability of exponentially increasing computer capabilities has resulted in time integrations increasing from hours to days, domain grids boxes (points) increasing from less than 2000 to more than 2,500,000 grid points with 500 to 1000 m resolution, and 3-D models becoming increasingly prevalent. The cloud resolving model is now at a stage where it can provide reasonably accurate statistical information of the sub-grid, cloud-resolving processes poorly parameterized in climate models and numerical prediction models.

  7. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

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

  8. Cloud Control

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  9. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

    ...   View Larger Image Stratus clouds are common in the Arctic during the summer months, and are important modulators of ... from MISR's two most obliquely forward-viewing cameras. The cold, stable air causes the clouds to persist in stratified layers, and this ...

  10. A updated view of the Venusian cloud system: synthesis of Venus Express results

    NASA Astrophysics Data System (ADS)

    Satoh, Takehiko

    Physics and chemistry of planet-covering clouds of Venus are the major targets of ESA's Venus Express. The planet is entirely covered by layers of cloud and haze (amount to a total optical thickness of few tens) which are thought to control planet's heat balance, climate, and atmospheric dynamics. Until the time of Pioneer Venus, our knowledge was limited only to "remotely sensible" upper cloud/haze layer or to a few locations where descent probes made direct measurements in the atmosphere. The situation, however, has changed since discovery of so-called atmospheric "windows" (Allen and Crawford, 1984) in the infrared spectrum of Venus. The "windows" are wavelengths of relatively weak CO2 absorption (1.74 and 2.3 µm, for example) at which infrared radiation originating from deeper levels of Venus atmosphere can escape to the space through the dense clouds and atmosphere. Usefulness of observations in these windows to remotely sense the deeper atmosphere was demonstrated during Galileo's flyby (Carlson et al., 1991) although the data were not many. Venus Express is the first spacecraft to fully utilize these windows. VIRTIS utilizes near-infrared windows (distributed in 1 2.4-µm range) to sense clouds and gases in the middle to lower atmosphere. The VIRTIS data have revealed great variability of cloud opacity: particle size and number density of aerosols have been derived with higher accuracy and greater spatial coverage than previous studies. The vertical extent of lower cloud layer (the source of main opacity at 1.74 µm) is found to show discontinuous change at higher latitudes near so-called cold polar collar. SPICAV/SOIR, sensitive to upper haze and near cloud top as it utilizes a lay of light (from a star or the Sun) which grazes the atmosphere, also has found semi-periodic change in aerosol opacity with a large amplitude. Ultraviolet images acquired with VMC show fine structures of clouds (patches, cells, and waves) and their rapid changes. A remarkable

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  12. Nimbus-7 global cloud climatology. II - First year results

    NASA Technical Reports Server (NTRS)

    Stowe, Larry L.; Yeh, H. Y. Michael; Wellemeyer, Charlie G.; Eck, Thomas F.; Kyle, H. Lee

    1989-01-01

    Results are presented on the analysis of the Nimbus-7 satellite data set obtained on regional and seasonal variations in global cloud cover. Four midseason months (April, July, and October 1979 and January 1980) were analyzed for the total cloud amount, the cloud amounts at high, middle, and low altitudes, the cirrus and deep convective clouds, and the cloud and clear-sky 11.5 micron-derived radiances; in addition, noon versus midnight cloud amounts were examined. The Nimbus-7 data are compared with three previously published cloud climatologies, and the differences among these data sets are discussed.

  13. Fuzzy cloud concepts for assessing radiation feedbacks

    SciTech Connect

    Hanson, H.

    1995-09-01

    The importance of clouds in the climate system is well-known but poorly understood. Modeling and observational studies have suggested that there may be positive feedbacks associated with certain cloud processes, but it is not known how strong these feedbacks are in the context of the overall system. Examples include ice microphysics feedback, as shown by Liou`s model, and the relationship between SST and cloud cover in the tropics, which is the focus of this research. 2 refs., 3 figs.

  14. Acquired hypofibrinogenemia: current perspectives

    PubMed Central

    Besser, Martin W; MacDonald, Stephen G

    2016-01-01

    Acquired hypofibrinogenemia is most frequently caused by hemodilution and consumption of clotting factors. The aggressive replacement of fibrinogen has become one of the core principles of modern management of massive hemorrhage. The best method for determining the patient’s fibrinogen level remains controversial, and particularly in acquired dysfibrinogenemia, could have major therapeutic implications depending on which quantification method is chosen. This review introduces the available laboratory and point-of-care methods and discusses the relative advantages and limitations. It also discusses current strategies for the correction of hypofibrinogenemia. PMID:27713652

  15. Community-acquired pneumonia.

    PubMed

    Falguera, M; Ramírez, M F

    2015-11-01

    This article not only reviews the essential aspects of community-acquired pneumonia for daily clinical practice, but also highlights the controversial issues and provides the newest available information. Community-acquired pneumonia is considered in a broad sense, without excluding certain variants that, in recent years, a number of authors have managed to delineate, such as healthcare-associated pneumonia. The latter form is nothing more than the same disease that affects more frail patients, with a greater number of risk factors, both sharing an overall common approach.

  16. Acquired Brain Injury Program.

    ERIC Educational Resources Information Center

    Schwartz, Stacey Hunter

    This paper reviews the Acquired Brain Injury (ABI) Program at Coastline Community College (California). The ABI Program is a two-year, for-credit educational curriculum designed to provide structured cognitive retraining for adults who have sustained an ABI due to traumatic (such as motor vehicle accident or fall) or non-traumatic(such as…

  17. Cloud Statistics for NASA Climate Change Studies

    NASA Technical Reports Server (NTRS)

    Wylie, Donald P.

    1999-01-01

    The Principal Investigator participated in two field experiments and developed a global data set on cirrus cloud frequency and optical depth to aid the development of numerical models of climate. Four papers were published under this grant. The accomplishments are summarized: (1) In SUCCESS (SUbsonic aircraft: Contrail & Cloud Effects Special Study) the Principal Investigator aided weather forecasters in the start of the field program. A paper also was published on the clouds studied in SUCCESS and the use of the satellite stereographic technique to distinguish cloud forms and heights of clouds. (2) In SHEBA (Surface Heat Budget in the Arctic) FIRE/ACE (Arctic Cloud Experiment) the Principal Investigator provided daily weather and cloud forecasts for four research aircraft crews, NASA's ER-2, UCAR's C-130, University of Washington's Convert 580, and the Canadian Atmospheric Environment Service's Convert 580. Approximately 105 forecasts were written. The Principal Investigator also made daily weather summaries with calculations of air trajectories for 54 flight days in the experiment. The trajectories show where the air sampled during the flights came from and will be used in future publications to discuss the origin and history of the air and clouds sampled by the aircraft. A paper discussing how well the FIRE/ACE data represent normal climatic conditions in the arctic is being prepared. (3) The Principal Investigator's web page became the source of information for weather forecasting by the scientists on the SHEBA ship. (4) Global Cirrus frequency and optical depth is a continuing analysis of global cloud cover and frequency distribution are being made from the NOAA polar orbiting weather satellites. This analysis is sensitive to cirrus clouds because of the radiative channels used. During this grant three papers were published which describe cloud frequencies, their optical properties and compare the Wisconsin FM Cloud Analysis to other global cloud data such as

  18. Automatic Cloud Detection from Multi-Temporal Satellite Images: Towards the Use of PLÉIADES Time Series

    NASA Astrophysics Data System (ADS)

    Champion, N.

    2012-08-01

    Contrary to aerial images, satellite images are often affected by the presence of clouds. Identifying and removing these clouds is one of the primary steps to perform when processing satellite images, as they may alter subsequent procedures such as atmospheric corrections, DSM production or land cover classification. The main goal of this paper is to present the cloud detection approach, developed at the French Mapping agency. Our approach is based on the availability of multi-temporal satellite images (i.e. time series that generally contain between 5 and 10 images) and is based on a region-growing procedure. Seeds (corresponding to clouds) are firstly extracted through a pixel-to-pixel comparison between the images contained in time series (the presence of a cloud is here assumed to be related to a high variation of reflectance between two images). Clouds are then delineated finely using a dedicated region-growing algorithm. The method, originally designed for panchromatic SPOT5-HRS images, is tested in this paper using time series with 9 multi-temporal satellite images. Our preliminary experiments show the good performances of our method. In a near future, the method will be applied to Pléiades images, acquired during the in-flight commissioning phase of the satellite (launched at the end of 2011). In that context, this is a particular goal of this paper to show to which extent and in which way our method can be adapted to this kind of imagery.

  19. Aphelion water-ice cloud mapping and property retrieval using the OMEGA imaging spectrometer onboard Mars Express

    NASA Astrophysics Data System (ADS)

    Madeleine, J.-B.; Forget, F.; Spiga, A.; Wolff, M. J.; Montmessin, F.; Vincendon, M.; Jouglet, D.; Gondet, B.; Bibring, J.-P.; Langevin, Y.; Schmitt, B.

    2012-05-01

    Mapping of the aphelion clouds over the Tharsis plateau and retrieval of their particle size and visible opacity are made possible by the OMEGA imaging spectrometer aboard Mars Express. Observations cover the period from MY26 Ls = 330° to MY29 Ls = 180° and are acquired at various local times, ranging from 8 AM to 6 PM. Cloud maps of the Tharsis region constructed using the 3.1 μm ice absorption band reveal the seasonal and diurnal evolution of aphelion clouds. Four distinct types of clouds are identified: morning hazes, topographically controlled hazes, cumulus clouds and thick hazes. The location and time of occurrence of these clouds are analyzed and their respective formation process is discussed. An inverse method for retrieving cloud particle size and opacity is then developed and can only be applied to thick hazes. The relative error of these measurements is less than 30% for cloud particle size and 20% for opacity. Two groups of particles can be distinguished. The first group is found over flat plains and is composed of relatively small particles, ranging in size from 2 to 3.5 μm. The second group is characterized by particle sizes of ˜5 μm which appear to be quite constant over Ls and local time. It is found west of Ascraeus and Pavonis Mons, and near Lunae Planum. These regions are preferentially exposed to anabatic winds, which may control the formation of these particles and explain their distinct properties. The water ice column is equal to 2.9 pr.μm on average, and can reach 5.2 pr.μm in the thickest clouds of Tharsis.

  20. Clouds over Mars!

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is the first color image ever taken from the surface of Mars of an overcast sky. Featured are pink stratus clouds coming from the northeast at about 15 miles per hour (6.7 meters/second) at an approximate height of ten miles (16 kilometers) above the surface. The clouds consist of water ice condensed on reddish dust particles suspended in the atmosphere. Clouds on Mars are sometimes localized and can sometimes cover entire regions, but have not yet been observed to cover the entire planet. The image was taken about an hour and forty minutes before sunrise by the Imager for Mars Pathfinder (IMP) on Sol 16 at about ten degrees up from the eastern Martian horizon.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages and Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  1. Hospital-acquired thrombocytopenia.

    PubMed

    McMahon, Christine M; Cuker, Adam

    2014-10-01

    The development of thrombocytopenia is common in hospitalized patients and is associated with increased mortality. Frequent and important causes of thrombocytopenia in hospitalized patients include etiologies related to the underlying illness for which the patient is admitted, such as infection and disseminated intravascular coagulation, and iatrogenic etiologies such as drug-induced immune thrombocytopenia, heparin-induced thrombocytopenia, posttransfusion purpura, hemodilution, major surgery, and extracorporeal circuitry. This review presents a brief discussion of the pathophysiology, distinguishing clinical features, and management of these etiologies, and provides a diagnostic approach to hospital-acquired thrombocytopenia that considers the timing and severity of the platelet count fall, the presence of hemorrhage or thrombosis, the clinical context, and the peripheral blood smear. This approach may offer guidance to clinicians in distinguishing among the various causes of hospital-acquired thrombocytopenia and providing management appropriate to the etiology.

  2. Desmosomes in acquired disease

    PubMed Central

    Stahley, Sara N.; Kowalczyk, Andrew P.

    2015-01-01

    Desmosomes are cell-cell junctions that mediate adhesion and couple the intermediate filament cytoskeleton to sites of cell-cell contact. This architectural arrangement functions to integrate adhesion and cytoskeletal elements of adjacent cells. The importance of this robust adhesion system is evident in numerous human diseases, both inherited and acquired, that occur when desmosome function is compromised. This review focuses on autoimmune and infectious diseases that impair desmosome function. In addition, we discuss emerging evidence that desmosomal genes are often misregulated in cancer. The emphasis of our discussion is placed on how human diseases inform our understanding of basic desmosome biology, and in turn, how fundamental advances in the cell biology of desmosomes may lead to new treatments for acquired diseases of the desmosome. PMID:25795143

  3. Desmosomes in acquired disease.

    PubMed

    Stahley, Sara N; Kowalczyk, Andrew P

    2015-06-01

    Desmosomes are cell-cell junctions that mediate adhesion and couple the intermediate filament cytoskeleton to sites of cell-cell contact. This architectural arrangement integrates adhesion and cytoskeletal elements of adjacent cells. The importance of this robust adhesion system is evident in numerous human diseases, both inherited and acquired, which occur when desmosome function is compromised. This review focuses on autoimmune and infectious diseases that impair desmosome function. In addition, we discuss emerging evidence that desmosomal genes are often misregulated in cancer. The emphasis of our discussion is placed on the way in which human diseases can inform our understanding of basic desmosome biology and in turn, the means by which fundamental advances in the cell biology of desmosomes might lead to new treatments for acquired diseases of the desmosome.

  4. Jupiter Clouds in Depth

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site] 619 nm [figure removed for brevity, see original site] 727 nm [figure removed for brevity, see original site] 890 nm

    Images from NASA's Cassini spacecraft using three different filters reveal cloud structures and movements at different depths in the atmosphere around Jupiter's south pole.

    Cassini's cameras come equipped with filters that sample three wavelengths where methane gas absorbs light. These are in the red at 619 nanometer (nm) wavelength and in the near-infrared at 727 nm and 890 nm. Absorption in the 619 nm filter is weak. It is stronger in the 727 nm band and very strong in the 890 nm band where 90 percent of the light is absorbed by methane gas. Light in the weakest band can penetrate the deepest into Jupiter's atmosphere. It is sensitive to the amount of cloud and haze down to the pressure of the water cloud, which lies at a depth where pressure is about 6 times the atmospheric pressure at sea level on the Earth). Light in the strongest methane band is absorbed at high altitude and is sensitive only to the ammonia cloud level and higher (pressures less than about one-half of Earth's atmospheric pressure) and the middle methane band is sensitive to the ammonia and ammonium hydrosulfide cloud layers as deep as two times Earth's atmospheric pressure.

    The images shown here demonstrate the power of these filters in studies of cloud stratigraphy. The images cover latitudes from about 15 degrees north at the top down to the southern polar region at the bottom. The left and middle images are ratios, the image in the methane filter divided by the image at a nearby wavelength outside the methane band. Using ratios emphasizes where contrast is due to methane absorption and not to other factors, such as the absorptive properties of the cloud particles, which influence contrast at all wavelengths.

    The most prominent feature seen in all three filters is the polar stratospheric haze that makes Jupiter

  5. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    SciTech Connect

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Menqistu; Brooks, Sarah D.; Cziczo, Dan; Dubey, Manvendra K.; Fan, Jiwen; Flynn, Connor; Gultepe, Ismail; Hubbe, John; Gilles, Mary K.; Laskin, Alexander; Lawson, Paul; Leaitch, W. Richard; Liu, Peter; Liu, Xiaohong; Lubin, Dan; Mazzoleni, Claudio; Macdonald, Ann -Marie; Moffet, Ryan C.; Morrison, Hugh; Ovchinnikov, Mikhail; Ronfeld, Debbie; Shupe, Matthew D.; Xie, Shaocheng; Zelenyuk, Alla; Bae, Kenny; Freer, Matt; Glen, Andrew

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41 stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.

  6. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    DOE PAGES

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; ...

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41more » stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.« less

  7. Utilizing Multiple Datasets for Snow Cover Mapping

    NASA Technical Reports Server (NTRS)

    Tait, Andrew B.; Hall, Dorothy K.; Foster, James L.; Armstrong, Richard L.

    1999-01-01

    Snow-cover maps generated from surface data are based on direct measurements, however they are prone to interpolation errors where climate stations are sparsely distributed. Snow cover is clearly discernable using satellite-attained optical data because of the high albedo of snow, yet the surface is often obscured by cloud cover. Passive microwave (PM) data is unaffected by clouds, however, the snow-cover signature is significantly affected by melting snow and the microwaves may be transparent to thin snow (less than 3cm). Both optical and microwave sensors have problems discerning snow beneath forest canopies. This paper describes a method that combines ground and satellite data to produce a Multiple-Dataset Snow-Cover Product (MDSCP). Comparisons with current snow-cover products show that the MDSCP draws together the advantages of each of its component products while minimizing their potential errors. Improved estimates of the snow-covered area are derived through the addition of two snow-cover classes ("thin or patchy" and "high elevation" snow cover) and from the analysis of the climate station data within each class. The compatibility of this method for use with Moderate Resolution Imaging Spectroradiometer (MODIS) data, which will be available in 2000, is also discussed. With the assimilation of these data, the resolution of the MDSCP would be improved both spatially and temporally and the analysis would become completely automated.

  8. Reflected fluxes for broken clouds over a Lambertian surface

    NASA Technical Reports Server (NTRS)

    Welch, Ronald M.; Wielicki, Bruce A.

    1989-01-01

    Reflected fluxes are calculated for broken cloudiness (i.e., nonplane parallel) as a function of cloud cover, cloud optical depth, solar zenith angle and surface albedo. These calculations extend previous results for broken cloud reflected fluxes over a black surface. The present study demonstrates that not only radiances but also radiative fluxes over high albedo surfaces may be decreased by the presence of broken cloudiness. Conventional wisdom states that cloud radiances (brightnesses) are always greater than the background. While most cloud retrieval schemes are built around this assumption, it is incorrect for clouds over high albedo surfaces such as found in polar regions. However, the most startling and counterintuitive conclusion of this study is that nonabsorbing finite clouds over a highly reflecting surface will decrease the system albedo. As a result, surface absorption is increased, the result of multiple scattering between surface and cloud layer, controlled by cloud morphology and cloud optical thickness. A simple parameterization of the effects of cloud contamination upon retrieved albedo is given in terms of solar zenith angle, cloud optical depth, surface albedo, cloud cover, and plane-parallel cloud albedo. In this way, the effects of broken cloudiness are modeled in terms of easily computed plane-parallel values.

  9. CLOUD CHEMISTRY.

    SciTech Connect

    SCHWARTZ,S.E.

    2001-03-01

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

  10. Neptune's clouds

    NASA Technical Reports Server (NTRS)

    1999-01-01

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

  11. Atmospheric Profiles, Clouds, and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

    DTIC Science & Technology

    2012-09-30

    Meric Srokosz, Alex West, Richard Wood, Axel Schweiger (2012), Assessment of Possibility and Impact of Rapid Climate Change in the Arctic Rep., 62 pp, UK MetOffice, Hadley Centre ...Ice Cover in the Beaufort and Chukchi Seas Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys Axel ...email: axel @apl.washington.edu Ron Lindsay Applied Physics Laboratory, University of Washington Jinlun Zhang Applied Physics Laboratory

  12. Our World: Cool Clouds

    NASA Video Gallery

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

  13. Modeling of Cloud/Radiation Processes for Large-Scale Clouds and Tropical Anvils

    DTIC Science & Technology

    1994-05-31

    three-dimensional, large-scale cloud model has been developed for the prediction of cloud cover, cloud liquid /ice water content (LWC/IWC), precipitation...specific humidity and temperature. Partial cloudiness is allowed to form when large-scale relative humidity is less than 100%. Both liquid and ice...phases are included in the model. The liquid phase processes consist of evaporation, condensation, autoconversion and precipitation. The ice phase

  14. Seasonal and Interannual Variability of Polar Stratospheric Cloud Optical Depth

    NASA Astrophysics Data System (ADS)

    Pitts, M. C.; Poole, L. R.; Thomason, L. W.; Damadeo, R. P.

    2013-12-01

    In addition to their important role in ozone depletion, polar stratospheric clouds (PSCs) may also impact stratospheric radiation and dynamics. Earlier studies indicated that PSCs could significantly affect radiative heating rates, but the magnitude and even the sign of the effect varied greatly from study to study, depending on many factors, e.g. PSC optical depth and underlying tropospheric cloud cover. A more recent study, which assumed nominal PSC conditions of 100% cloud fraction and visible optical depth of 0.01 for non-ice PSCs and 0.04 for ice PSCs, suggested that PSCs could produce significant perturbations to the radiative heating rates in the Antarctic stratosphere. A comprehensive evaluation of the radiative effects of PSCs requires more accurate knowledge of PSC characteristics over the entire polar region and throughout complete seasons. With the advent of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission in 2006, a more complete picture of PSC composition and occurrence is now emerging. The polarization-sensitive CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) lidar system onboard the CALIPSO spacecraft is acquiring, on average, over 300,000 backscatter profiles per day at latitudes poleward of 55° (including the polar night region up to 82°), providing a unique opportunity to examine the distribution of PSC optical depth on vortex-wide scales and over entire PSC seasons. In this paper, we describe an approach to calculate PSC optical depth from the CALIOP 532-nm attenuated backscatter measurements. We retrieve the PSC extinction profile downward from cloud top using a composition-dependent extinction-to-backscatter ratio and then integrate the extinction profile to derive PSC optical depth. We then examine this multi-year PSC optical depth record to determine the spatial and seasonal variability for the Arctic and Antarctic, respectively. Multi-year composites provide insight to the interannual

  15. Acquired Factor V Inhibitor

    PubMed Central

    Hirai, Daisuke; Yamashita, Yugo; Masunaga, Nobutoyo; Katsura, Toshiaki; Akao, Masaharu; Okuno, Yoshiaki; Koyama, Hiroshi

    2016-01-01

    Inhibitors directed against factor V rarely occur, and the clinical symptoms vary. We herein report the case of a patient who presented with a decreased factor V activity that had decreased to <3 %. We administered vitamin K and 6 units of fresh frozen plasma, but she thereafter developed an intracerebral hemorrhage. It is unclear whether surgery >10 years earlier might have caused the development of a factor V inhibitor. The treatment of acquired factor V inhibitors is mainly the transfusion of platelet concentrates and corticosteroids. Both early detection and the early initiation of the treatment of factor V inhibitor are thus considered to be important. PMID:27746446

  16. Martian Clouds Data Workshop

    NASA Technical Reports Server (NTRS)

    Lee, Steven (Editor)

    1987-01-01

    The major topics covered were a discussion of the structure of relational data base systems and features of the Britton Lee Relational Data Base Management System (RDBMS); a discussion of the workshop's objectives, approach, and research scenarios; and an overview of the Atmospheres Node User's Guide, which details the datasets stored on the Britton Lee, the structure of the query and data analysis system, and examples of the exact menu screens encountered. Also discussed were experience with the system, review of the system performance, and a strategy to produce queries and performance data retrievals of mutual interest. The goals were defined as examining correlations between cloud occurrence, water vapor abundance, and surface properties.

  17. Cloud Phase and the Surface Energy Balance of the Arctic; An Investigation of Mixed-Phase Clouds

    DTIC Science & Technology

    2008-03-01

    IWP - Column Integrated Ice Water Path LORAN - Long Range Navigation LowBase - Cloud Base Height (lidar) LowBaseT - Cloud Base...cloud base and top heights (Intrieri et al. 2002b) GPS/ LORAN atmospheric sounding radiosonde system 2 day-1 at 1200 and 2400 UTC.4 day-1 (addition...the other hand, the sensitivity of CFSW is dependent on the total insolation. Surface cooling is enhanced with increased cloud cover when SW shading

  18. Cloud Height Maps for Hurricanes Frances and Ivan

    NASA Technical Reports Server (NTRS)

    2004-01-01

    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

  19. MODIS Snow-Cover Products

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Riggs, George A.; Salomonson, Vinvent V.; DiGirolamo, Nicolo; Bayr, Klaus J.; Houser, Paul (Technical Monitor)

    2001-01-01

    On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. These products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to the currently available operation products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. Also the snow-mapping algorithms are automated which means that a consistent data set is generated for long-term climates studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the product. The snow product suite starts with a 500-m resolution swath snow-cover map which is gridded to the Integerized Sinusoidal Grid to produce daily and eight-day composite tile products. The sequence then proceeds to a climate-modeling grid product at 5-km spatial resolution, with both daily and eight-day composite products. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented. Near-term enhancements include daily snow albedo and fractional snow cover.

  20. [Acquired coagulant factor inhibitors].

    PubMed

    Nogami, Keiji

    2015-02-01

    Acquired coagulation factor inhibitors are an autoimmune disease causing bleeding symptoms due to decreases in the corresponding factor (s) which result from the appearance of autoantibodies against coagulation factors (inhibitor). This disease is quite different from congenital coagulation factor deficiencies based on genetic abnormalities. In recent years, cases with this disease have been increasing, and most have anti-factor VIII autoantibodies. The breakdown of the immune control mechanism is speculated to cause this disease since it is common in the elderly, but the pathology and pathogenesis are presently unclear. We herein describe the pathology and pathogenesis of factor VIII and factor V inhibitors. Characterization of these inhibitors leads to further analysis of the coagulation process and the activation mechanisms of clotting factors. In the future, with the development of new clotting examination method (s), we anticipate that further novel findings will be obtained in this field through inhibitor analysis. In addition, detailed elucidation of the coagulation inhibitory mechanism possibly leading to hemostatic treatment strategies for acquired coagulation factor disorders will be developed.

  1. Cloud types and the tropical Earth radiation budget, revised

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.; Kyle, H. Lee

    1989-01-01

    Nimbus-7 cloud and Earth radiation budget data are compared in a study of the effects of clouds on the tropical radiation budget. The data consist of daily averages over fixed 500 sq km target areas, and the months of July 1979 and January 1980 were chosen to show the effect of seasonal changes. Six climate regions, consisting of 14 to 24 target areas each, were picked for intensive analysis because they exemplified the range in the tropical cloud/net radiation interactions. The normal analysis was to consider net radiation as the independent variable and examine how cloud cover, cloud type, albedo and emitted radiation varied with the net radiation. Two recurring themes keep repeating on a local, regional, and zonal basis: the net radiation is strongly influenced by the average cloud type and amount present, but most net radiation values could be produced by several combinations of cloud types and amount. The regions of highest net radiation (greater than 125 W/sq m) tend to have medium to heavy cloud cover. In these cases, thin medium altitude clouds predominate. Their cloud tops are normally too warm to be classified as cirrus by the Nimbus cloud algorithm. A common feature in the tropical oceans are large regions where the total regional cloud cover varies from 20 to 90 percent, but with little regional difference in the net radiation. The monsoon and rain areas are high net radiation regions.

  2. Study of the transport parameters of cloud lightning plasmas

    SciTech Connect

    Chang, Z. S.; Yuan, P.; Zhao, N.

    2010-11-15

    Three spectra of cloud lightning have been acquired in Tibet (China) using a slitless grating spectrograph. The electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity of the cloud lightning, for the first time, are calculated by applying the transport theory of air plasma. In addition, we investigate the change behaviors of parameters (the temperature, the electron density, the electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity) in one of the cloud lightning channels. The result shows that these parameters decrease slightly along developing direction of the cloud lightning channel. Moreover, they represent similar sudden change behavior in tortuous positions and the branch of the cloud lightning channel.

  3. Tropical thermostats and low cloud clover

    SciTech Connect

    Miller, R.L.

    1997-03-01

    The ability of subtropical stratus low cloud cover to moderate amplify the tropical response to climate forcing such as increased CO{sub 2} is considered. Cloud radiative forcing over the subtropics is parameterized using an empirical relation between stratus cloud cover and the difference in potential temperature between 700 mb (a level that is above the trade inversion) and the surface. This relation includes the empirical negative correlation between SST and low cloud cover and is potentially a positive feedback to climate forcing. Since potential temperature above the trade inversion varies in unison across the Tropics as a result of the large-scale circulation and because moist convection relates tropospheric temperature within the convecting region to variations in surface temperature and moisture, the subtropical potential temperature at 700 mb depends upon surface conditions within the convecting region. As a result, subtropical stratus cloud cover and the associated feedback depend upon the entire tropical climate and not just the underlying SST. A simple tropical model is constructed, consisting of separate budgets of dry static energy and moisture for the convecting region (referred to as the {open_quotes}warm{close_quotes} pool) and the subtropical descending region (the {open_quotes}cold{close_quotes} pool). The cold pool is the location of stratus low clouds in the model. Dynamics is implicitly included through the assumption that temperature above the boundary layer is horizontally uniform as a result of the large-scale circulation. The tropropause and warm pool surface are shown to be connected by a moist adiabat in the limit of vanishingly narrow convective updrafts. Stratus low cloud cover is found to be a negative feedback, increasing in response to doubled CO{sub 2} and reducing the tropically averaged warming in comparison to the warming with low cloud cover held fixed. 72 refs., 13 figs., 2 tabs.

  4. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  5. Cloud Arcs

    Atmospheric Science Data Center

    2013-04-19

    ... a sinking motion elsewhere, are very common, the degree of organization exhibited here is relatively rare, as the wind field at different altitudes usually disrupts such patterns. The degree of self organization of this cloud image, whereby three or four such circular events ...

  6. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... one of a new generation of instruments flying aboard the NASA Earth Observing System's Terra satellite, views Earth with nine cameras ... of thin cirrus minutes after MISR imaged the cloud from space. At the same time, another NASA high-altitude jet, the WB-57, flew right ...

  7. Stochastic Radiative Transfer in Polar Mixed Phase Clouds

    NASA Astrophysics Data System (ADS)

    Brodie, J.; Veron, D. E.

    2004-12-01

    According to recent research, mixed phase clouds comprise one third of the overall annual cloud cover in the Arctic region. These clouds contain distinct regions of liquid water and ice, which have a different impact on radiation than single-phase clouds. Despite the prevalence of mixed phase clouds in the polar regions, many modern atmospheric general circulation models use single-phase clouds in their radiation routines. A stochastic approach to representating the transfer of shortwave radiation through a cloud layer where the distribution of the ice and liquid is governed by observed statistics is being assessed. Data from the Surface Heat Budget of the Arctic (SHEBA) program and the Atmospheric Radiation Measurement (ARM) program's North Slopes of Alaska Cloud and Radiation Testbed site will be used to determine the characteristic features of the cloud field and to evaluate the performance of this statistical model.

  8. Sahara Dust Cloud

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24

    A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean.

    These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward.

    In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005.

    In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie

    The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the

  9. Acquired epidermodysplasia verruciformis.

    PubMed

    Rogers, Heather D; Macgregor, Jennifer L; Nord, Kristin M; Tyring, Stephen; Rady, Peter; Engler, Danielle E; Grossman, Marc E

    2009-02-01

    Epidermodysplasia verruciformis (EV) is a rare autosomal recessive genodermatosis with an increased susceptibility to specific human papillomavirus (HPV) genotypes. Classically, this viral infection leads to the development of tinea versicolor-like macules on the trunk, neck, arms, and face during childhood, and over time, these lesions can progress to squamous cell carcinoma. More recently, an EV-like syndrome has been described in patients with impaired cell-mediated immunity. We describe two cases of EV-like syndrome in HIV-positive patients, review all previously reported cases of EV in patients with impaired cell-mediated immunity, introduce the term "acquired epidermodysplasia verruciformis" to describe EV developing in the immunocompromised host and examine the limited treatment options for these patients.

  10. AIDS: acquired immunodeficiency syndrome.

    PubMed Central

    Gilmore, N. J.; Beaulieu, R.; Steben, M.; Laverdière, M.

    1983-01-01

    Acquired immunodeficiency syndrome, or AIDS, is a new illness that occurs in previously healthy individuals. It is characterized by immunodeficiency, opportunistic infections and unusual malignant diseases. Life-threatening single or multiple infections with viruses, mycobacteria, fungi or protozoa are common. A rare neoplasm, Kaposi's sarcoma, has developed in approximately one third of patients with AIDS. More than 800 cases of AIDS have been reported in North America, over 24 of them in Canada. The majority of patients are male homosexuals, although AIDS has also developed in abusers of intravenously administered drugs, Haitian immigrants, individuals with hemophilia, recipients of blood transfusions, prostitutes, and infants, spouses and partners of patients with AIDS. The cause of AIDS is unknown, but the features are consistent with an infectious process. Early diagnosis can be difficult owing to the nonspecific symptoms and signs of the infections and malignant diseases. Therefore, vigilance by physicians is of utmost importance. PMID:6342737

  11. AIDS: acquired immunodeficiency syndrome *

    PubMed Central

    Gilmore, N.J.; Beaulieu, R.; Steben, M.; Laverdière, M.

    1992-01-01

    Acquired immunodeficiency syndrome, or AIDS, is a new illness that occurs in previously healthy individuals. It is characterized by immunodeficiency, opportunistic infections and unusual malignant diseases. Life-threatening single or multiple infections with viruses, mycobacteria, fungi or protozoa are common. A rare neoplasm, Kaposi's sarcoma, has developed in approximately one third of patients with AIDS. More than 800 cases of AIDS have been reported in North America, over 24 of them in Canada. The majority of patients are male homosexuals, although AIDS has also developed in abusers of intravenously administered drugs, Haitian immigrants, individuals with hemophilia, recipients of blood transfusions, prostitutes, and infants, spouses and partners of patients with AIDS. The cause of AIDS is unknown, but the features are consistent with an infectious process. Early diagnosis can be difficult owing to the nonspecific symptoms and signs of the infections and malignant diseases. Therefore, vigilance by physicians is of the utmost importance. PMID:1544049

  12. Jupiter Clouds in Depth

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site] 619 nm [figure removed for brevity, see original site] 727 nm [figure removed for brevity, see original site] 890 nm

    Images from NASA's Cassini spacecraft using three different filters reveal cloud structures and movements at different depths in the atmosphere around Jupiter's south pole.

    Cassini's cameras come equipped with filters that sample three wavelengths where methane gas absorbs light. These are in the red at 619 nanometer (nm) wavelength and in the near-infrared at 727 nm and 890 nm. Absorption in the 619 nm filter is weak. It is stronger in the 727 nm band and very strong in the 890 nm band where 90 percent of the light is absorbed by methane gas. Light in the weakest band can penetrate the deepest into Jupiter's atmosphere. It is sensitive to the amount of cloud and haze down to the pressure of the water cloud, which lies at a depth where pressure is about 6 times the atmospheric pressure at sea level on the Earth). Light in the strongest methane band is absorbed at high altitude and is sensitive only to the ammonia cloud level and higher (pressures less than about one-half of Earth's atmospheric pressure) and the middle methane band is sensitive to the ammonia and ammonium hydrosulfide cloud layers as deep as two times Earth's atmospheric pressure.

    The images shown here demonstrate the power of these filters in studies of cloud stratigraphy. The images cover latitudes from about 15 degrees north at the top down to the southern polar region at the bottom. The left and middle images are ratios, the image in the methane filter divided by the image at a nearby wavelength outside the methane band. Using ratios emphasizes where contrast is due to methane absorption and not to other factors, such as the absorptive properties of the cloud particles, which influence contrast at all wavelengths.

    The most prominent feature seen in all three filters is the polar stratospheric haze that makes Jupiter

  13. Use of cloud observations and mesoscale meteorology models to evaluate and improve cloud parameterizations. Technical progress report, 1 October 1992--30 September 1993

    SciTech Connect

    Walcek, C.J.

    1993-09-30

    This research program utilizes satellite and surface-derived cloud observations together with standard meteorological measurements to evaluate and improve our ability to accurately diagnose cloud coverage. Results of this research will be used to compliment existing or future parameterizations of cloud effects in general circulation models, since nearly all cloud parameterizations must specify a fractional area of cloud coverage when calculating radiative or dynamic cloud effects, and current parameterizations rely on rather crude cloud cover estimates. During the first phase of this research program, our goal is to evaluate and improve the methods for calculating cloud cover within a mesoscale meteorology model. To accomplish this, a mesoscale meteorology model will be quantitatively evaluated using available cloud cover databases, including the US Air Force 3DNEPH and RTNEPH satellite-derived cloud fields, as well as CART data as they become available. During the second phase of this research, the cloud cover data and improved parameterizations of cloud coverage developed during the first phase will be incorporated into a mesoscale meteorology model. Model forecasts which utilize the observed cloud coverage and depth should be improved relative to forecasts which crudely specify cloud properties.

  14. The DC-8 Submillimeter-Wave Cloud Ice Radiometer

    NASA Technical Reports Server (NTRS)

    Walter, Steven; Batelaan, Paul; Siegel, Peter; Evans, K. Franklin; Evans, Aaron; Balachandra, Balu; Gannon, Jade; Guldalian, John; Raz, Guy; Shea, James; Smith, Christopher; Thomassen, John

    2000-01-01

    Submillimeter-wave cloud ice radiometry is an innovative technique for determining the amount of ice present in cirrus clouds, measuring median crystal size, and constraining crystal shape. The radiometer described in this poster is being developed to acquire data to validate radiometric retrievals of cloud ice at submillimeter wavelengths. The goal of this effort is to develop a technique to enable spaceborne characterization of cirrus, meeting key climate modeling and NASA measurement needs.

  15. Satellite discrimination of snow/cloud surfaces

    NASA Technical Reports Server (NTRS)

    Crane, R. G.; Anderson, M. R.

    1984-01-01

    Differentiation between cloud cover and snow surfaces using remotely sensed data is complicated by the similarity of their radiative temperatures, and also by their similar reflectances at visible wavelengths. A method of cloud analysis over snow-covered regions is presented, using 1.51-1.63 micron data from an experimental sensor on board a U.S. Air Force Defense Meteorological Satellite Program platform. At these wavelengths, snow appears relatively 'black' while clouds are highly reflective. The spatial structure of the 1.51-1.63 micron reflectivity fields over a continuous snow surface are examined. Plots of mean reflectance against coefficients of variation for 4 x 4 pixel areas reveals a cluster of points have low reflectivity and low variability, corresponding to snow-covered (cloud free) areas, and a similar cluster with high reflectances corresponding to 100 per cent cloud cover. For the case of a single layered cloud, the radiances associated with partially filled fields of view are also inferred.

  16. Clouds and snowmelt on the north slope of Alaska

    SciTech Connect

    Zhang, T.; Stamnes, K.; Bowling, S.A.

    1996-04-01

    Clouds have a large effect on the radiation field. Consequently, possible changes in cloud properties may have a very substantial impact on climate. Of all natural surfaces, seasonal snow cover has the highest surface albedo, which is one of the most important components of the climatic system. Interactions between clouds and seasonal snow cover are expected to have a significant effect on climate and its change at high latitudes. The purpose of this paper is to investigate the sensitivity of the surface cloud-radiative forcing during the period of snowmelt at high latitudes. The primary variables investigated are cloud liquid path (LWP) and droplet equivalent radius (r{sub e}). We will also examine the sensitivity of the surface radiative fluxes to cloud base height and cloud base temperature.

  17. Decadal Variability of West Coast Marine Stratus Clouds

    NASA Astrophysics Data System (ADS)

    Iacobellis, S.; Schwartz, R. E.; Gershunov, A.; Cayan, D. R.; Williams, P.

    2013-12-01

    Low frequency variability of West Coast summertime marine stratus clouds are investigated using six decades of observations at several coastal airport locations. The magnitude and direction of long-term trends in summertime marine stratus occurrence along the California coast depends strongly on the cloud base height threshold used to distinguish low clouds from higher clouds. In this study, marine stratus clouds are defined as having cloud base at or below 1000 meters. Using this threshold, a decreasing trend in marine stratus cloud frequency was found for Southern California during the 1950-2012 period. No significant trends were found in Northern California. When averaged over the summer season, the cloud data reveal that coastal stratus has substantial variation on multi-year time scales with typical changes of 10-15% from year to year and 5-7% from decade to decade. Low stratus cloud cover varies over long distances with coherent anomalies that extend from southern California to Oregon. The most important correlated modes of SST with cloud cover anomalies, via a canonical correlation analysis contains both local and remote SST linkages. The first mode is correlated with the PDO and also to Pacific atmospheric circulation patterns and coastal upwelling. There is also a linkage to sea surface temperature anomalies in the low latitude Pacific, suggesting that tropical-extratropical interactions may be involved in driving West Coast cloud cover.

  18. Progress towards a Venus reference cloud model

    NASA Astrophysics Data System (ADS)

    Wilson, Colin; Ignatiev, Nikolay; Marcq, Emmanuel

    Venus is completely enveloped by clouds. The main cloud layers stretch from altitudes of 48 - 75 km, with additional tenuous hazes found at altitudes 30 - 100 km. Clouds play a crucial role in governing atmospheric circulation, chemistry and climate on all planets, but particularly so on Venus due to the optical thickness of the atmosphere. The European Space Agency’s Venus Express (VEx) satellite has carried out a wealth of observations of Venus clouds since its arrival at Venus in April 2006. Many VEx observations are relevant to cloud science - from imagers and spectrometers to solar, stellar and radio occultation - each covering different altitude ranges, spectral ranges and atmospheric constituents. We have formed an International Team at the International Space Science Institute to bring together scientists from each of the relevant Venus Express investigation teams as well as from previous missions, as well as those developing computational and analytical models of clouds and hazes. The aims of the project are (1) to create self-consistent reference cloud/haze models which capture not only a mean cloud structure but also its main modes of variability; and (2) to bring together modelers and observers, to reach an understanding of clouds and hazes on Venus which matches all observables and is physically consistent. Our approach is to first to assemble an averaged cloud profile for low latitudes, showing how cloud number abundances and other observables vary as a function of altitude, consistent with all available observations. In a second step, we will expand this work to produce a reference cloud profile which varies with latitude and local solar time, as well as optical thickness of the cloud. We will present our status in progressing towards this goal. We acknowledge the support of the International Space Science Institute of Berne, Switzerland, in hosting our Team’s meetings.

  19. A Simple Model for the Cloud Adjacency Effect and the Apparent Bluing of Aerosols Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Wen, Guoyong; Coakley, James A., Jr.; Remer, Lorraine A.; Loeb,Norman G.; Cahalan, Robert F.

    2008-01-01

    In determining aerosol-cloud interactions, the properties of aerosols must be characterized in the vicinity of clouds. Numerous studies based on satellite observations have reported that aerosol optical depths increase with increasing cloud cover. Part of the increase comes from the humidification and consequent growth of aerosol particles in the moist cloud environment, but part comes from 3D cloud-radiative transfer effects on the retrieved aerosol properties. Often, discerning whether the observed increases in aerosol optical depths are artifacts or real proves difficult. The paper provides a simple model that quantifies the enhanced illumination of cloud-free columns in the vicinity of clouds that are used in the aerosol retrievals. This model is based on the assumption that the enhancement in the cloud-free column radiance comes from enhanced Rayleigh scattering that results from the presence of the nearby clouds. The enhancement in Rayleigh scattering is estimated using a stochastic cloud model to obtain the radiative flux reflected by broken clouds and comparing this flux with that obtained with the molecules in the atmosphere causing extinction, but no scattering.

  20. Spectral Dependence of MODIS Cloud Droplet Effective Radius Retrievals for Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Zhang, Zhibo; Platnick, Steven E.; Ackerman, Andrew S.; Cho, Hyoun-Myoung

    2014-01-01

    Low-level warm marine boundary layer (MBL) clouds cover large regions of Earth's surface. They have a significant role in Earth's radiative energy balance and hydrological cycle. Despite the fundamental role of low-level warm water clouds in climate, our understanding of these clouds is still limited. In particular, connections between their properties (e.g. cloud fraction, cloud water path, and cloud droplet size) and environmental factors such as aerosol loading and meteorological conditions continue to be uncertain or unknown. Modeling these clouds in climate models remains a challenging problem. As a result, the influence of aerosols on these clouds in the past and future, and the potential impacts of these clouds on global warming remain open questions leading to substantial uncertainty in climate projections. To improve our understanding of these clouds, we need continuous observations of cloud properties on both a global scale and over a long enough timescale for climate studies. At present, satellite-based remote sensing is the only means of providing such observations.

  1. Cloud Features Detected by MODIS But Not by CloudSat and CALIOP

    NASA Technical Reports Server (NTRS)

    Chan, Mark Aaron; Comiso, Josefino C.

    2011-01-01

    The ability to characterize the global cloud cover from space has been greatly enhanced by the availability of MODIS, CloudSat, and CALIOP data. The three sensors provide good complementary information about clouds. In this study, we investigated unexpected observations of certain types of clouds apparent in the MODIS data but not detected by CloudSat and CALIOP. Several examples are presented and generally these undetected clouds are geometrically thin, low-level clouds. In particular, they are located in the Arctic region and have optical thicknesses of less than 14, top height altitudes of below 2.5 km, and layer thickness of less than 1 km. CloudSat may miss such low-level clouds because of its coarse vertical resolution of about 500 m and it has limited sensitivity near the surface. Unexpectedly, CALIOP with a much higher vertical resolution of 30 m also misses these clouds and this is due to the cloud s geometrically thin nature and surface proximity.

  2. Clouds and Dust Storms

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

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

  3. Southern Clouds

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03026 Southern Clouds

    This image shows a system of clouds just off the margin of the South Polar cap. Taken during the summer season, these clouds contain both water-ice and dust.

    Image information: VIS instrument. Latitude 80.2S, Longitude 57.6E. 17 meter/pixel resolution.

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

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

  4. Linear Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  5. Characteristics of tropical thin cirrus clouds deduced from joint CloudSat and CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Haladay, Taryn; Stephens, Graeme

    2009-04-01

    The joint detection characteristics of both the CloudSat radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar are used to study tropical thin cirrus observed between 20°N and 20°S. The thin ice cloud category (TIC-1) of cirrus consists of those clouds detected by the lidar but not the radar whereas the TIC-2 cirrus category consists of clouds detected by both sensors. Tropical TIC-1 cirrus clouds between 20°N and 20°S are high, are optically thin, and have an approximate cloud cover in the defined region of 30%. Almost a third of this occurrence is in the form of single layers of cloudiness without any clouds below. These TIC-1 clouds also exhibit a marked seasonal variation, especially away from the equator, consistent with the shifts in annual cycle of convection with latitude. Lidar-based estimates of optical depth, uncorrected for multiple scattering, suggest that the TIC-1 optical depths range between 0.02 and 0.3. The ice water path of TIC-1 clouds is also estimated to be between 0.5 and 4 g m-2. The radiative properties of the TIC-1 clouds are also deduced from CloudSat flux data products at the top, at the bottom, and within the atmosphere. The influence of these clouds on the instantaneous reflected solar fluxes is determined to be less than 2 W m-2. The effects of TIC-1 clouds on the instantaneous outgoing longwave fluxes are estimated to be ˜20 W m-2, and the impact of these TIC-1 clouds on the tropics-wide average of the infrared heating is ˜4 W m-2.

  6. Smoke and Clouds over Russia

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Several mountain ranges and a portion of the Amur River are visible in this set of MISR images of Russia's far east Khabarovsk region. The images were acquired on May 13, 2001 during Terra orbit 7452. The view from MISR's 70-degree forward-looking camera is at the top left; the 26-degree forward-looking view is at the top right. The larger image at the bottom is a stereo 'anaglyph' created using the cameras at two intermediate angles. To view the stereo image in 3-D you need red/blue glasses with the red filter placed over your left eye. All of the images are oriented with north to the left to facilitate stereo viewing. Each image covers an area about 345 kilometers x 278 kilometers.

    The Amur River, in the upper right, and Lake Bolon, at the top center, are most prominent in the 26-degree view due to sunglint (mirror-like reflection of the Sun's rays by the water). The Amur River valley is a primary breeding ground for storks and cranes and a stopover for large numbers of migratory birds. About 20% of the Amur wetlands are protected by official conservation measures, but human development has converted large portions to agricultural uses. Other notable features in these images are several mountain chains, including the Badzhal'skiy to the left of center and the Bureiskiy in the lower left.

    Smoke plumes from several forest fires can be seen. They are especially apparent in the 70-degree view where the smoke's visibility is accentuated, in part, by the long slant path through the atmosphere. The largest plumes are in the lower left and upper right, with some smaller plumes above and to the right of the image centers. In the upper images the hazy region in the vicinity of these smaller plumes has the appearance of low-altitude smoke, but depth perception provided by the stereo anaglyph shows that it is actually a distinct layer of high-altitude cirrus clouds. Whether the cirrus is related to the fires is uncertain. It is possible, however, for the fires have

  7. Acquired aplastic anemia.

    PubMed

    Keohane, Elaine M

    2004-01-01

    Acquired aplastic anemia (AA) is a disorder characterized by a profound deficit of hematopoietic stem and progenitor cells, bone marrow hypocellularity, and peripheral blood pancytopenia. It primarily affects children, young adults, and those over 60 years of age. The majority of cases are idiopathic; however, idiosyncratic reactions to some drugs, chemicals, and viruses have been implicated in its etiology. An autoimmune T-cell reaction likely causes the stem cell depletion, but the precise mechanism, as well as the eliciting and target antigens, is unknown. Symptoms vary from severe life-threatening cytopenias to moderate or non-severe disease that does not require transfusion support. The peripheral blood typically exhibits pancytopenia, reticulocytopenia, and normocytic or macrocytic erythrocytes. The bone marrow is hypocellular and may exhibit dysplasia of the erythrocyte precursors. First line treatment for severe AA consists of hematopoietic stem cell transplantation in young patients with HLA identical siblings, while immunosuppression therapy is used for older patients and for those of any age who lack a HLA matched donor. Patients with AA have an increased risk of developing paroxysmal nocturnal hemoglobinuria (PNH), myelodysplastic syndrome (MDS), or acute leukemia. Further elucidation of the pathophysiology of this disease will result in a better understanding of the interrelationship among AA, PNH, and MDS, and may lead to novel targeted therapies.

  8. Acquired spatial dyslexia.

    PubMed

    Siéroff, E

    2015-08-10

    Acquired spatial dyslexia is a reading disorder frequently occurring after left or right posterior brain lesions. This article describes several types of spatial dyslexia with an attentional approach. After right posterior lesions, patients show left neglect dyslexia with errors on the left side of text, words, and non-words. The deficit is frequently associated with left unilateral spatial neglect. Severe left neglect dyslexia can be detected with unlimited exposure duration of words or non-words. Minor neglect dyslexia is detected with brief presentation of bilateral words, one in the left and one in the right visual field (phenomenon of contralesional extinction). Neglect dyslexia can be explained as a difficulty in orienting attention to the left side of verbal stimuli. With left posterior lesions, spatial dyslexia is also frequent but multiform. Right neglect dyslexia is frequent, but right unilateral spatial neglect is rare. Attentional dyslexia represents difficulty in selecting a stimulus, letter or word among other similar stimuli; it is a deficit of attentional selection, and the left hemisphere plays a crucial role in selection. Two other types of spatial dyslexia can be found after left posterior lesions: paradoxical ipsilesional extinction and stimulus-centred neglect dyslexia. Disconnections between left or right parietal attentional areas and the left temporal visual word form area could explain these deficits. Overall, a model of attention dissociating modulation, selection control, and selection positioning can help in understanding these reading disorders.

  9. Lake Effect Snow Covers Buffalo

    NASA Technical Reports Server (NTRS)

    2002-01-01

    An average of one foot of snow per day has fallen on Buffalo, New York, since Christmas Eve, resulting in a total of up to 5 feet from December 24-28. The snow fell very heavily, with accumulations of up to 3 inches per hour. Cold winds blowing along the surface of Lake Erie pick up warmth and moisture, which falls as snow as the warm air rises. This image was acquired by the Geostationary Operational Environmental Satellite (GOES), operated by NOAA, on December 27, 2001, at 12:32 p.m. EST. The scene shows thick bands of clouds extending from the eastern tip of Lake Erie and over Buffalo. The arrows show the wind direction, which is blowing down the length of the lake. Image and animation by Robert Simmon, based on data from the NASA GOES Project Science Office.

  10. Clouds at CTIO and the Dark Energy Survey

    SciTech Connect

    Neilsen, Jr., Eric

    2015-08-01

    An understanding of the weather patters at Cerro-Tololo Inter-American (CTIO) Observatory, the observing site for the Dark Energy Survey (DES), is important for assessing the efciency of DES operations in using observing time and for planning future operations. CTIO has maintained records of cloud-cover by quarters of nights since 1975. A comparison between these cloud records in the 2013-2014 DES observing season (DES year 1) and achieved observing efciency and exposure quality allows the DES collaboration to make better use of the historical records in survey planning. Plots and tables here relate human recorded cloud-cover to collection of good DES data, show the variation of typical cloud-cover by month, and evaluate the relationship between the El Niño weather pattern and cloud-cover at CTIO.

  11. MODIS Snow-Cover Products

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Riggs, George A.; Salomonson, Vincent V.; DiGirolamo, Nicole E.; Bayr, Klaus J.; Houser, Paul R. (Technical Monitor)

    2002-01-01

    On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. MODIS snow and ice products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to or enhancement of the currently-available operational products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. Also the snow-mapping algorithms are automated which means that a consistent data set may be generated for long-term climate studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the products. The MODIS snow product suite begins with a 500-m resolution, 2330-km swath snow-cover map which is then gridded to an integerized sinusoidal grid to produce daily and 8-day composite tile products. The sequence proceeds to a climate-modeling grid (CMG) product at about 5.6-km spatial resolution, with both daily and 8-day composite products. Each pixel of the CMG contains fraction of snow cover from 40 - 100%. Measured errors of commission in the CMG are low, for example, on the continent of Australia in the spring, they vary from 0.02 - 0.10%. Near-term enhancements include daily snow albedo and fractional snow cover. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented to show some early validation work.

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

    SciTech Connect

    Cotton, W.R.

    1994-01-18

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

  13. Observed and simulated temperature dependence of the liquid water path of low clouds

    SciTech Connect

    Del Genio, A.D.; Wolf, A.B.

    1996-04-01

    Data being acquired at the Atmospheric Radiation Measurement (ARM) Southern great Plains (SGP) Cloud and Radiation Testbed (CART) site can be used to examine the factors determining the temperature dependence of cloud optical thickness. We focus on cloud liquid water and physical thickness variations which can be derived from existing ARM measurements.

  14. Daytime Cloud Property Retrievals Over the Arctic from Multispectral MODIS Data

    NASA Technical Reports Server (NTRS)

    Spangenberg, Douglas A.; Trepte, Qing; Minnis, Patrick; Uttal, Taneil

    2004-01-01

    Improving climate model predictions over Earth's polar regions requires a complete understanding of polar clouds properties. Passive satellite remote sensing techniques can be used to retrieve macro and microphysical properties of polar cloud systems. However, over the Arctic, there is minimal contrast between clouds and the background snow surface observed in satellite data, especially for visible wavelengths. This makes it difficult to identify clouds and retrieve their properties from space. Variable snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds further complicate cloud property identification. For this study, the operational Clouds and the Earth s Radiant Energy System (CERES) cloud mask is first used to discriminate clouds from the background surface in Terra Moderate Resolution Imaging Spectroradiometer (MODIS) data. A solar-infrared infrared nearinfrared technique (SINT) first used by Platnick et al. (2001) is used here to retrieve cloud properties over snow and ice covered regions.

  15. Clinical laboratory data: acquire, analyze, communicate, liberate.

    PubMed

    Azzazy, Hassan M E; Elbehery, Ali H A

    2015-01-01

    The availability of portable healthcare devices, which can acquire and transmit medical data to remote experts would dramatically affect healthcare in areas with poor infrastructure. Smartphones, which feature touchscreen computer capabilities and sophisticated cameras, have become widely available with over billion units shipped in 2013. In the clinical laboratory, smartphones have recently brought the capabilities of key instruments such as spectrophotometers, fluorescence analyzers and microscopes into the palm of the hand. Several research groups have developed sensitive and low-cost smartphone-based diagnostic assay prototypes for testing cholesterol, albumin, vitamin D, tumor markers, and the detection of infectious agents. This review covers the use of smartphones to acquire, analyze, communicate, and liberate clinical laboratory data. Smartphones promise to dramatically improve the quality and quantity of healthcare offered in resource-limited areas.

  16. Acquired reactive perforating collagenosis

    PubMed Central

    Fei, Chengwen; Wang, Yao; Gong, Yu; Xu, Hui; Yu, Qian; Shi, Yuling

    2016-01-01

    Abstract Background: Reactive perforating collagenosis (RPC) is a rare form of transepithelial elimination, in which altered collagen is extruded through the epidermis. There are 2 types of RPC, acquired RPC (ARPC) and inherited RPC, while the latter is extremely rare. Here we report on 1 case of ARPC. Methods: A 73-year-old female was presented with strongly itchy papules over her back and lower limbs for 3 months. She denied the history of oozing or vesiculation. A cutaneous examination showed diffusely distributed multiple well-defined keratotic papules, 4 to 10 mm in diameter, on the bilateral lower limbs and back as well as a few papules on her chest and forearm. Scratching scars were over the resolved lesions while Koebner phenomenon was negative. The patient had a history of type 2 diabetes for 15 years. Laboratory examinations showed elevated blood glucose level. Skin lesion biopsy showed a well-circumscribed area of necrosis filled with a keratotic plug. Parakeratotic cells and lymphocytic infiltration could be seen in the necrosed area. In dermis, sparse fiber bundles were seen perforating the epidermis. These degenerated fiber bundles were notarized as collagen fiber by elastic fiber stain, suggesting a diagnosis of RPC. Results: Then a diagnosis of ARPC was made according to the onset age and the history of diabetes mellitus. She was treated with topical application of corticosteroids twice a day and oral antihistamine once a day along with compound glycyrrhizin tablets 3 times a day. And the blood glucose was controlled in a satisfying range. Two months later, a significant improvement was seen in this patient. Conclusion: Since there is no efficient therapy to RPC, moreover, ARPC is considered to be associated with some systemic diseases, the management of the coexisting disease is quite crucial. The patient in this case received a substantial improvement due to the control of blood glucose and application of compound glycyrrhizin tablets. PMID

  17. Snow cover dynamic in the Atlas Chain (Morocco) using daily MODIS products over the last decade

    NASA Astrophysics Data System (ADS)

    Marchane, Ahmed; Jarlan, Lionel; Hanich, Lahoucine; Boudhar, Abdelghani; Gascoin, Simon; Le page, Michel; Tavernier, Adrien; Filali, Nourredine; Berjamy, Brahim; Khabba, Said; Chehbouni, Ghani

    2014-05-01

    Over semi-arid areas, snow cover in the mountains represents an important source of water for many people living downstream. This study evaluates the daily MODIS snow covered area products over the 7 catchments with a rain-snow functioning covering the Atlas chain in Morocco. To this objective, more than 4600 daily MODIS images from September 2000 to June 2013 have been processed based on a spatio-temporal filtering algorithm aiming at reducing the cloud coverage and the problem of discrimination between snow and cloud. The number of pixel identified as cloud is reduced by 96% from 22.6% to 0.8%. In a second step, the ability of the product to detect snow is tested against 5 stations of automatic snow depth measurements covering 22 complete seasons. The overall accuracy is equal to 90%. Although slightly lower than previously published validation studies, this is fairly good considering the highly varying dynamic of the snow cover in the region characterized by period of complete ablation even during the core of the winter due to high incoming radiation. The timing of the seasonal snow is also correctly detected with 11.4 days and 9.4 days of average errors with almost no bias for the onset date and the ablation date, respectively and 18.2 days on the snow cover duration. The processed fractional snow cover is also tested against a series of 19 clear images acquired by the FORMOSAT sensor at 8-m resolution from February to June 2009 in the Tensift catchment (Marrakech). The comparison of the two datasets results in a correlation coefficient of r=0.94 and an average low bias of 3.96 km² but some differences are observed during the very end of the ablation phase. Finally, the processed snow cover products provide insights into spatio-temporal variability of snow cover in the region which is analyzed through seasonal indicators including onset and melt-out date, the snow cover duration (SCD) and the maximum snow cover extent: (1) the dynamic is characterized by a

  18. The relationship between interannual and long-term cloud feedbacks

    SciTech Connect

    Zhou, Chen; Zelinka, Mark D.; Dessler, Andrew E.; Klein, Stephen A.

    2015-12-11

    The analyses of Coupled Model Intercomparison Project phase 5 simulations suggest that climate models with more positive cloud feedback in response to interannual climate fluctuations also have more positive cloud feedback in response to long-term global warming. Ensemble mean vertical profiles of cloud change in response to interannual and long-term surface warming are similar, and the ensemble mean cloud feedback is positive on both timescales. However, the average long-term cloud feedback is smaller than the interannual cloud feedback, likely due to differences in surface warming pattern on the two timescales. Low cloud cover (LCC) change in response to interannual and long-term global surface warming is found to be well correlated across models and explains over half of the covariance between interannual and long-term cloud feedback. In conclusion, the intermodel correlation of LCC across timescales likely results from model-specific sensitivities of LCC to sea surface warming.

  19. Clouds at Barbados are representative of clouds across the trade wind regions in observations and climate models.

    PubMed

    Medeiros, Brian; Nuijens, Louise

    2016-05-31

    Trade wind regions cover most of the tropical oceans, and the prevailing cloud type is shallow cumulus. These small clouds are parameterized by climate models, and changes in their radiative effects strongly and directly contribute to the spread in estimates of climate sensitivity. This study investigates the structure and variability of these clouds in observations and climate models. The study builds upon recent detailed model evaluations using observations from the island of Barbados. Using a dynamical regimes framework, satellite and reanalysis products are used to compare the Barbados region and the broader tropics. It is shown that clouds in the Barbados region are similar to those across the trade wind regions, implying that observational findings from the Barbados Cloud Observatory are relevant to clouds across the tropics. The same methods are applied to climate models to evaluate the simulated clouds. The models generally capture the cloud radiative effect, but underestimate cloud cover and show an array of cloud vertical structures. Some models show strong biases in the environment of the Barbados region in summer, weakening the connection between the regional biases and those across the tropics. Even bearing that limitation in mind, it is shown that covariations of cloud and environmental properties in the models are inconsistent with observations. The models tend to misrepresent sensitivity to moisture variations and inversion characteristics. These model errors are likely connected to cloud feedback in climate projections, and highlight the importance of the representation of shallow cumulus convection.

  20. Clouds at Barbados are representative of clouds across the trade wind regions in observations and climate models

    NASA Astrophysics Data System (ADS)

    Medeiros, Brian; Nuijens, Louise

    2016-05-01

    Trade wind regions cover most of the tropical oceans, and the prevailing cloud type is shallow cumulus. These small clouds are parameterized by climate models, and changes in their radiative effects strongly and directly contribute to the spread in estimates of climate sensitivity. This study investigates the structure and variability of these clouds in observations and climate models. The study builds upon recent detailed model evaluations using observations from the island of Barbados. Using a dynamical regimes framework, satellite and reanalysis products are used to compare the Barbados region and the broader tropics. It is shown that clouds in the Barbados region are similar to those across the trade wind regions, implying that observational findings from the Barbados Cloud Observatory are relevant to clouds across the tropics. The same methods are applied to climate models to evaluate the simulated clouds. The models generally capture the cloud radiative effect, but underestimate cloud cover and show an array of cloud vertical structures. Some models show strong biases in the environment of the Barbados region in summer, weakening the connection between the regional biases and those across the tropics. Even bearing that limitation in mind, it is shown that covariations of cloud and environmental properties in the models are inconsistent with observations. The models tend to misrepresent sensitivity to moisture variations and inversion characteristics. These model errors are likely connected to cloud feedback in climate projections, and highlight the importance of the representation of shallow cumulus convection.

  1. Clouds at Barbados are representative of clouds across the trade wind regions in observations and climate models

    PubMed Central

    Nuijens, Louise

    2016-01-01

    Trade wind regions cover most of the tropical oceans, and the prevailing cloud type is shallow cumulus. These small clouds are parameterized by climate models, and changes in their radiative effects strongly and directly contribute to the spread in estimates of climate sensitivity. This study investigates the structure and variability of these clouds in observations and climate models. The study builds upon recent detailed model evaluations using observations from the island of Barbados. Using a dynamical regimes framework, satellite and reanalysis products are used to compare the Barbados region and the broader tropics. It is shown that clouds in the Barbados region are similar to those across the trade wind regions, implying that observational findings from the Barbados Cloud Observatory are relevant to clouds across the tropics. The same methods are applied to climate models to evaluate the simulated clouds. The models generally capture the cloud radiative effect, but underestimate cloud cover and show an array of cloud vertical structures. Some models show strong biases in the environment of the Barbados region in summer, weakening the connection between the regional biases and those across the tropics. Even bearing that limitation in mind, it is shown that covariations of cloud and environmental properties in the models are inconsistent with observations. The models tend to misrepresent sensitivity to moisture variations and inversion characteristics. These model errors are likely connected to cloud feedback in climate projections, and highlight the importance of the representation of shallow cumulus convection. PMID:27185925

  2. Acquired immune deficiency syndrome: review.

    PubMed

    Scully, C; Cawson, R A; Porter, S R

    1986-07-19

    Acquired immunodeficiency syndrome (AIDS) is reviewed for dental practitioners, with an emphasis on oral findings; the clinical course, diagnosis, reporting, treatment, prognosis, transmission, and epidemiology are also covered. HIV infection has an incubation period that may be associated with glandular fever, a prodrome called AIDS-Related Complex (ARC) characterized by lymphadenopathy, low fever, weight loss, night sweats, diarrhea, oral candidosis, nonproductive cough and recurrent infections. AIDS is characterized by opportunistic infections. Over 50% present with pneumocystis carinii pneumonia, 21% with Kaposi's sarcoma, and 6% have both. The AIDS virus causes direct neurological symptoms in some cases. Oral candidosis (thrush) in a young male without a local cause such as xerostomia or immune suppression is strongly suggestive of AIDS. Other oral manifestations are severe herpes simplex, varicella-zoster, Epstein-Barr virus, cytomegalovirus, venereal warts, aphthous ulceration, mycobacterial oral ulcers, oral histoplasmosis, sinusitis and osteomyelitis of the jaw. Hairy leukoplakia, usually seen on the lateral border of the tongue, is probably caused by Epstein-Barr virus. Kaposi's sarcoma, an endothelial cell tumor, is characteristic of AIDS, and in 50% of patients is oral or perioral. Cervical lymph node enlargement will be seen in those with ARC as well as AIDS. No guidelines have been issued by the Department of Health and Social Security for dental surgeons in the UK for reporting AIDS cases. Although HIV virions have been isolated from saliva, there are no known incidents of transmission via saliva. HIV is less likely to be transmitted by needle stick injuries than, for example hepatitis B (25% risk), especially if the blood is from a carrier rather than a full blown AIDS case.

  3. Long Term Cloud Property Datasets From MODIS and AVHRR Using the CERES Cloud Algorithm

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Bedka, Kristopher M.; Doelling, David R.; Sun-Mack, Sunny; Yost, Christopher R.; Trepte, Qing Z.; Bedka, Sarah T.; Palikonda, Rabindra; Scarino, Benjamin R.; Chen, Yan; Hong, Gang; Bhatt, Rajendra

    2015-01-01

    Cloud properties play a critical role in climate change. Monitoring cloud properties over long time periods is needed to detect changes and to validate and constrain models. The Clouds and the Earth's Radiant Energy System (CERES) project has developed several cloud datasets from Aqua and Terra MODIS data to better interpret broadband radiation measurements and improve understanding of the role of clouds in the radiation budget. The algorithms applied to MODIS data have been adapted to utilize various combinations of channels on the Advanced Very High Resolution Radiometer (AVHRR) on the long-term time series of NOAA and MetOp satellites to provide a new cloud climate data record. These datasets can be useful for a variety of studies. This paper presents results of the MODIS and AVHRR analyses covering the period from 1980-2014. Validation and comparisons with other datasets are also given.

  4. Lidar Observations of the Optical Properties and 3-Dimensional Structure of Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.

    1996-01-01

    The scientific research conducted under this grant have been reported in a series of journal articles, dissertations, and conference proceedings. This report consists of a compilation of these publications in the following areas: development and operation of a High Spectral Resolution Lidar, cloud physics and cloud formation, mesoscale observations of cloud phenomena, ground-based and satellite cloud cover observations, impact of volcanic aerosols on cloud formation, visible and infrared radiative relationships as measured by satellites and lidar, and scattering cross sections.

  5. Do clouds save the great barrier reef? satellite imagery elucidates the cloud-SST relationship at the local scale.

    PubMed

    Leahy, Susannah M; Kingsford, Michael J; Steinberg, Craig R

    2013-01-01

    Evidence of global climate change and rising sea surface temperatures (SSTs) is now well documented in the scientific literature. With corals already living close to their thermal maxima, increases in SSTs are of great concern for the survival of coral reefs. Cloud feedback processes may have the potential to constrain SSTs, serving to enforce an "ocean thermostat" and promoting the survival of coral reefs. In this study, it was hypothesized that cloud cover can affect summer SSTs in the tropics. Detailed direct and lagged relationships between cloud cover and SST across the central Great Barrier Reef (GBR) shelf were investigated using data from satellite imagery and in situ temperature and light loggers during two relatively hot summers (2005 and 2006) and two relatively cool summers (2007 and 2008). Across all study summers and shelf positions, SSTs exhibited distinct drops during periods of high cloud cover, and conversely, SST increases during periods of low cloud cover, with a three-day temporal lag between a change in cloud cover and a subsequent change in SST. Cloud cover alone was responsible for up to 32.1% of the variation in SSTs three days later. The relationship was strongest in both El Niño (2005) and La Niña (2008) study summers and at the inner-shelf position in those summers. SST effects on subsequent cloud cover were weaker and more variable among study summers, with rising SSTs explaining up to 21.6% of the increase in cloud cover three days later. This work quantifies the often observed cloud cooling effect on coral reefs. It highlights the importance of incorporating local-scale processes into bleaching forecasting models, and encourages the use of remote sensing imagery to value-add to coral bleaching field studies and to more accurately predict risks to coral reefs.

  6. Do Clouds Save the Great Barrier Reef? Satellite Imagery Elucidates the Cloud-SST Relationship at the Local Scale

    PubMed Central

    Leahy, Susannah M.; Kingsford, Michael J.; Steinberg, Craig R.

    2013-01-01

    Evidence of global climate change and rising sea surface temperatures (SSTs) is now well documented in the scientific literature. With corals already living close to their thermal maxima, increases in SSTs are of great concern for the survival of coral reefs. Cloud feedback processes may have the potential to constrain SSTs, serving to enforce an “ocean thermostat” and promoting the survival of coral reefs. In this study, it was hypothesized that cloud cover can affect summer SSTs in the tropics. Detailed direct and lagged relationships between cloud cover and SST across the central Great Barrier Reef (GBR) shelf were investigated using data from satellite imagery and in situ temperature and light loggers during two relatively hot summers (2005 and 2006) and two relatively cool summers (2007 and 2008). Across all study summers and shelf positions, SSTs exhibited distinct drops during periods of high cloud cover, and conversely, SST increases during periods of low cloud cover, with a three-day temporal lag between a change in cloud cover and a subsequent change in SST. Cloud cover alone was responsible for up to 32.1% of the variation in SSTs three days later. The relationship was strongest in both El Niño (2005) and La Niña (2008) study summers and at the inner-shelf position in those summers. SST effects on subsequent cloud cover were weaker and more variable among study summers, with rising SSTs explaining up to 21.6% of the increase in cloud cover three days later. This work quantifies the often observed cloud cooling effect on coral reefs. It highlights the importance of incorporating local-scale processes into bleaching forecasting models, and encourages the use of remote sensing imagery to value-add to coral bleaching field studies and to more accurately predict risks to coral reefs. PMID:23894649

  7. Remote sensing of smoke, clouds, and fire using AVIRIS data

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Kaufman, Yorman J.; Green, Robert O.

    1993-01-01

    Clouds remain the greatest element of uncertainty in predicting global climate change. During deforestation and biomass burning processes, a variety of atmospheric gases, including CO2 and SO2, and smoke particles are released into the atmosphere. The smoke particles can have important effects on the formation of clouds because of the increased concentration of cloud condensation nuclei. They can also affect cloud albedo through changes in cloud microphysical properties. Recently, great interest has arisen in understanding the interaction between smoke particles and clouds. We describe our studies of smoke, clouds, and fire using the high spatial and spectral resolution data acquired with the NASA/JPL Airborne Visible/Infrared Imaging Spectrometer (AVIRIS).

  8. Intercomparison between Nimbus-7 cirrus cloud data and ERB measurements

    NASA Technical Reports Server (NTRS)

    Yeh, H. Y. M.; Eck, T. F.; Wellemeyer, C. G.; Bhartia, P. K.; Hwang, P. H.

    1986-01-01

    Nimbus-7 and Earth Radiation Budget (ERB) data were compared with the quantity of high, thin cirrus clouds over a 6 yr period. Three separate data analysis techniques are described which were used to derive cloud cover and total upwelling radiance values from the satellite data. Zonal average cirrus clouds amounts are compared with surface observations and SAGE satellite data, and comparisons are made between the cloud amount estimates made with ERB data and data from other Nimbus-7 instruments. All Nimbus-7 instrumental data indicated cloud amounts and frequency of occurrence patterns which were commensurate with surface observations, except in high latitude zones.

  9. Global cloud climatology from surface observations

    SciTech Connect

    Warren, S.

    1995-09-01

    Surface weather observations from stations on land and ships in the ocean are used to obtain the global distribution, at 5{sup o}x5{sup o} latitude-longitude resolution, of total cloud cover and the average amounts of the different cloud types: cumulus, cumulonimbus, stratus, stratocumulus, nimbostratus, altostratus, altocumulus, cirrus, cirrostratus, cirrocumulus, and fog. Diurnal and seasonal variations are derived, as well as interannual variations and multi-year trends. 3 refs., 3 figs.

  10. Integrating Network Management for Cloud Computing Services

    DTIC Science & Technology

    2015-06-01

    Integrating Network Management For Cloud Computing Services Peng Sun A Dissertation Presented to the Faculty of Princeton University in Candidacy for...2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Integrating Network Management for Cloud Computing Services... integrate the management of various network components. With commercial deployment, our operational experiences feed back into revision of the

  11. Ammonia Ice Clouds on Jupiter

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The top cloud layer on Jupiter is thought to consist of ammonia ice, but most of that ammonia 'hides' from spectrometers. It does not absorb light in the same way ammonia does. To many scientists, this implies that ammonia churned up from lower layers of the atmosphere 'ages' in some way after it condenses, possibly by being covered with a photochemically generated hydrocarbon mixture. The New Horizons Linear Etalon Imaging Spectral Array (LEISA), the half of the Ralph instrument that is able to 'see' in infrared wavelengths that are absorbed by ammonia ice, spotted these clouds and watched them evolve over five Jupiter days (about 40 Earth hours). In these images, spectroscopically identified fresh ammonia clouds are shown in bright blue. The largest cloud appeared as a localized source on day 1, intensified and broadened on day 2, became more diffuse on days 3 and 4, and disappeared on day 5. The diffusion seemed to follow the movement of a dark spot along the boundary of the oval region. Because the source of this ammonia lies deeper than the cloud, images like these can tell scientists much about the dynamics and heat conduction in Jupiter's lower atmosphere.

  12. Quantitative Measures of Immersion in Cloud and the Biogeography of Cloud Forests

    NASA Technical Reports Server (NTRS)

    Lawton, R. O.; Nair, U. S.; Ray, D.; Regmi, A.; Pounds, J. A.; Welch, R. M.

    2010-01-01

    Sites described as tropical montane cloud forests differ greatly, in part because observers tend to differ in their opinion as to what constitutes frequent and prolonged immersion in cloud. This definitional difficulty interferes with hydrologic analyses, assessments of environmental impacts on ecosystems, and biogeographical analyses of cloud forest communities and species. Quantitative measurements of cloud immersion can be obtained on site, but the observations are necessarily spatially limited, although well-placed observers can examine 10 50 km of a mountain range under rainless conditions. Regional analyses, however, require observations at a broader scale. This chapter discusses remote sensing and modeling approaches that can provide quantitative measures of the spatiotemporal patterns of cloud cover and cloud immersion in tropical mountain ranges. These approaches integrate remote sensing tools of various spatial resolutions and frequencies of observation, digital elevation models, regional atmospheric models, and ground-based observations to provide measures of cloud cover, cloud base height, and the intersection of cloud and terrain. This combined approach was applied to the Monteverde region of northern Costa Rica to illustrate how the proportion of time the forest is immersed in cloud may vary spatially and temporally. The observed spatial variation was largely due to patterns of airflow over the mountains. The temporal variation reflected the diurnal rise and fall of the orographic cloud base, which was influenced in turn by synoptic weather conditions, the seasonal movement of the Intertropical Convergence Zone and the north-easterly trade winds. Knowledge of the proportion of the time that sites are immersed in clouds should facilitate ecological comparisons and biogeographical analyses, as well as land use planning and hydrologic assessments in areas where intensive on-site work is not feasible.

  13. Intensification of convective extremes driven by cloud-cloud interaction

    NASA Astrophysics Data System (ADS)

    Moseley, Christopher; Hohenegger, Cathy; Berg, Peter; Haerter, Jan O.

    2016-10-01

    In a changing climate, a key role may be played by the response of convective-type cloud and precipitation to temperature changes. Yet, it is unclear if convective precipitation intensities will increase mainly due to thermodynamic or dynamical processes. Here we perform large eddy simulations of convection by imposing a realistic diurnal cycle of surface temperature. We find convective events to gradually self-organize into larger cloud clusters and those events occurring late in the day to produce the highest precipitation intensities. Tracking rain cells throughout their life cycles, we show that events which result from collisions respond strongly to changes in boundary conditions, such as temperature changes. Conversely, events not resulting from collisions remain largely unaffected by the boundary conditions. Increased surface temperature indeed leads to more interaction between events and stronger precipitation extremes. However, comparable intensification occurs when leaving temperature unchanged but simply granting more time for self-organization. These findings imply that the convective field as a whole acquires a memory of past precipitation and inter-cloud dynamics, driving extremes. For global climate model projections, our results suggest that the interaction between convective clouds must be incorporated to simulate convective extremes and the diurnal cycle more realistically.

  14. Clouds and the Near-Earth Environment: Possible Links

    NASA Astrophysics Data System (ADS)

    Condurache-Bota, Simona; Voiculescu, Mirela; Dragomir, Carmelia

    2015-12-01

    Climate variability is a hot topic not only for scientists and policy-makers, but also for each and every one of us. The anthropogenic activities are considered to be responsible for most climate change, however there are large uncertainties about the magnitude of effects of solar variability and other extraterrestrial influences, such as galactic cosmic rays on terrestrial climate. Clouds play an important role due to feedbacks of the radiation budget: variation of cloud cover/composition affects climate, which, in turn, affects cloud cover via atmospheric dynamics and sea temperature variations. Cloud formation and evolution are still under scientific scrutiny, since their microphysics is still not understood. Besides atmospheric dynamics and other internal climatic parameters, extraterrestrial sources of cloud cover variation are considered. One of these is the solar wind, whose effect on cloud cover might be modulated by the global atmospheric electrical circuit. Clouds height and composition, their seasonal variation and latitudinal distribution should be considered when trying to identify possible mechanisms by which solar energy is transferred to clouds. The influence of the solar wind on cloud formation can be assessed also through the ap index - the geomagnetic storm index, which can be readily connected with interplanetary magnetic field, IMF structure. This paper proposes to assess the possible relationship between both cloud cover and solar wind proxies, as the ap index, function of cloud height and composition and also through seasonal studies. The data covers almost three solar cycles (1984-2009). Mechanisms are looked for by investigating observed trends or correlation at local/seasonal scale

  15. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  16. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  17. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  18. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  19. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Acquiring and acquired persons. 801.2 Section 801.2 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENTS AND INTERPRETATIONS UNDER THE HART-SCOTT-RODINO ANTITRUST IMPROVEMENTS ACT OF 1976 COVERAGE RULES § 801.2...

  20. Dynamic resource allocation engine for cloud-based real-time video transcoding in mobile cloud computing environments

    NASA Astrophysics Data System (ADS)

    Adedayo, Bada; Wang, Qi; Alcaraz Calero, Jose M.; Grecos, Christos

    2015-02-01

    The recent explosion in video-related Internet traffic has been driven by the widespread use of smart mobile devices, particularly smartphones with advanced cameras that are able to record high-quality videos. Although many of these devices offer the facility to record videos at different spatial and temporal resolutions, primarily with local storage considerations in mind, most users only ever use the highest quality settings. The vast majority of these devices are optimised for compressing the acquired video using a single built-in codec and have neither the computational resources nor battery reserves to transcode the video to alternative formats. This paper proposes a new low-complexity dynamic resource allocation engine for cloud-based video transcoding services that are both scalable and capable of being delivered in real-time. Firstly, through extensive experimentation, we establish resource requirement benchmarks for a wide range of transcoding tasks. The set of tasks investigated covers the most widely used input formats (encoder type, resolution, amount of motion and frame rate) associated with mobile devices and the most popular output formats derived from a comprehensive set of use cases, e.g. a mobile news reporter directly transmitting videos to the TV audience of various video format requirements, with minimal usage of resources both at the reporter's end and at the cloud infrastructure end for transcoding services.

  1. Shocked clouds in the Cygnus Loop

    NASA Technical Reports Server (NTRS)

    Raymond, John C.

    1994-01-01

    This grant covers the analysis of ROSAT PSPC and HRI images of the Cygnus Loop, an elderly supernova remnant. The project, as proposed, includes not only the usual analysis of ROSAT data; the ROSAT data is being combined with optical and UV data, and new model calculations are being performed. The status is reported on optical imagery, echelle data, IUE data, ROSAT data, and the grain model. The major question being addressed is whether the blastwave-cloud interaction in the feature known as XA is basically a converging shock in a fairly large cloud or turbulent stripping of material from the edges of a smaller cloud.

  2. Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3

    DOE PAGES

    Prather, M. J.

    2015-05-27

    A new approach for modeling photolysis rates (J values) in atmospheres with fractional cloud cover has been developed and implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observed statistics for the vertical correlation of cloud layers, Cloud-J 7.3 provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations represented by four quadrature atmospheres produces mean J values in an atmospheric column with root-mean-square errors of 4% or less compared with 10–20% errors using simpler approximations. Cloud-Jmore » is practical for chemistry-climate models, requiring only an average of 2.8 Fast-J calls per atmosphere, vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections is also incorporated into Cloud-J.« less

  3. Photolysis rates in correlated overlapping cloud fields: Cloud-J 7.3c

    DOE PAGES

    Prather, M. J.

    2015-08-14

    A new approach for modeling photolysis rates (J values) in atmospheres with fractional cloud cover has been developed and is implemented as Cloud-J – a multi-scattering eight-stream radiative transfer model for solar radiation based on Fast-J. Using observations of the vertical correlation of cloud layers, Cloud-J 7.3c provides a practical and accurate method for modeling atmospheric chemistry. The combination of the new maximum-correlated cloud groups with the integration over all cloud combinations by four quadrature atmospheres produces mean J values in an atmospheric column with root mean square (rms) errors of 4 % or less compared with 10–20 % errorsmore » using simpler approximations. Cloud-J is practical for chemistry–climate models, requiring only an average of 2.8 Fast-J calls per atmosphere vs. hundreds of calls with the correlated cloud groups, or 1 call with the simplest cloud approximations. Another improvement in modeling J values, the treatment of volatile organic compounds with pressure-dependent cross sections, is also incorporated into Cloud-J.« less

  4. Crater Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  5. Snow covers detection using terrestrial photography. Application to a mountain catchment in Alps region (France).

    NASA Astrophysics Data System (ADS)

    Barth, Thierry; Saulnier, Georges-Marie; Malet, Emmanuel

    2010-05-01

    In August 2005, a significant mudflow leaded to major impacts damages at the Sainte-Agnes village located downstream the Vorz torrent (35 km2, elevations ranging from 1248m and 2977m, Alps region, France). To meet the demand of populations and civil authorities a research program was launched to both monitor and model these regions to help to quantify water resources and vulnerability to such hazardous events, including their probable evolutions do to climatic changes. This communication focuses on one of the several forcing variables of the water cycle in mountainous regions: the snow covering. Indeed, its controls a significant part of the future available water resources and may strongly interact with liquid precipitations during snow melting season. Usual sensors such as remote sensing cannot easily quantify accurately the snow covering for small mountainous catchment at hydrological models spatial and temporal resolutions (typically Dx < 50m, Dx= 30'-1h). Consequently, we decided to develop a specific monitoring system based on terrestrial photos. Two cameras were installed within the catchment at two different elevations (1950m and 2250m). Each camera acquires pictures every 2-3 hours from 8.00am to 8.00pm. Thus, a lot of data on snow covering are acquired at a minimal costs. The first step of this technique is to place the cameras at "optimal location", i.e. able to see a large surface of the catchment with various elevations and aspects. This position must also be reached by direct solar radiation to recharge the embedded solar panel. A 2 or 3 hours sampling time-step was chosen for pictures shots (depending to available energy and memory capacity of camera). Indeed it allows observing all the day and offers an accurate sampling of the melting period. First major difficulty of this technique is the retro mapping of the 2D pictures from the camera on the 3D Digital Terrain Model to distribute the snow covering by elevation and aspects. The second difficulty

  6. Cloud-Top Entrainment in Stratocumulus Clouds

    NASA Astrophysics Data System (ADS)

    Mellado, Juan Pedro

    2017-01-01

    Cloud entrainment, the mixing between cloudy and clear air at the boundary of clouds, constitutes one paradigm for the relevance of small scales in the Earth system: By regulating cloud lifetimes, meter- and submeter-scale processes at cloud boundaries can influence planetary-scale properties. Understanding cloud entrainment is difficult given the complexity and diversity of the associated phenomena, which include turbulence entrainment within a stratified medium, convective instabilities driven by radiative and evaporative cooling, shear instabilities, and cloud microphysics. Obtaining accurate data at the required small scales is also challenging, for both simulations and measurements. During the past few decades, however, high-resolution simulations and measurements have greatly advanced our understanding of the main mechanisms controlling cloud entrainment. This article reviews some of these advances, focusing on stratocumulus clouds, and indicates remaining challenges.

  7. Cumulus cloud field morphology and spatial patterns derived from high spatial resolution Landsat imagery

    NASA Technical Reports Server (NTRS)

    Sengupta, S. K.; Welch, R. M.; Navar, M. S.; Berendes, T. A.; Chen, D. W.

    1990-01-01

    Using high-spatial-resolution Landsat MSS imagery, the cumulus cloud morphology, cloud nearest-neighbor distributions, and cloud clumping scales were investigated. It is shown that the cloud-size distribution can be represented by a mixture of two power laws; clouds of diameters less than 1 km have power-law slope range of 1.4-2.3, while larger clouds have slopes from 2.1 to 4.75. The break in power-law slope occurs at the cloud size that makes the largest contribution to cloud cover. Results suggest that larger clouds grow at the expense of smaller clouds. It was also found that the cloud inhomogeneities have significant impact on radiative fluxes.

  8. Studies in the use of cloud type statistics in mission simulation

    NASA Technical Reports Server (NTRS)

    Fowler, M. G.; Willand, J. H.; Chang, D. T.; Cogan, J. L.

    1974-01-01

    A study to further improve NASA's global cloud statistics for mission simulation is reported. Regional homogeneity in cloud types was examined; most of the original region boundaries defined for cloud cover amount in previous studies were supported by the statistics on cloud types and the number of cloud layers. Conditionality in cloud statistics was also examined with special emphasis on temporal and spatial dependencies, and cloud type interdependence. Temporal conditionality was found up to 12 hours, and spatial conditionality up to 200 miles; the diurnal cycle in convective cloudiness was clearly evident. As expected, the joint occurrence of different cloud types reflected the dynamic processes which form the clouds. Other phases of the study improved the cloud type statistics for several region and proposed a mission simulation scheme combining the 4-dimensional atmospheric model, sponsored by MSFC, with the global cloud model.

  9. Cloud fractional coverage: A key uncertainty in current climate models

    SciTech Connect

    Walcek, C.J.

    1996-12-31

    Climate models being used to study global warming use highly uncertain and widely divergent methods for calculating fractional cloudiness, which plays a significant role in regulating global albedo and climate. In this study the author compares cloud cover formulations used by various climate models with observations of fractional cloudiness and related meteorology derived from surface reports, upper atmospheric soundings, and satellites. He found that relative humidity is the best single predictor of cloud coverage, in agreement with most climate model formulations. However, the precise functional relationships used by climate models to estimate cloud coverage disagree significantly with observed cloud relationships. In the middle troposphere, most climate models probably underestimate cloud coverage since they specify zero cloud amounts when relative humidities are below 60--80%, while observed cloud amounts range from 20--60% at these height and humidity ranges. At humidities close to saturation, current algorithms probably overestimate cloud coverage. Cloud fractional cover observations compiled in this study suggest that at any level in the atmosphere, cloud amount decreases exponentially as humidity falls below 100%, and there is no evidence for critical humidities below which no clouds exist.

  10. A prototype for automation of land-cover products from Landsat Surface Reflectance Data Records

    NASA Astrophysics Data System (ADS)

    Rover, J.; Goldhaber, M. B.; Steinwand, D.; Nelson, K.; Coan, M.; Wylie, B. K.; Dahal, D.; Wika, S.; Quenzer, R.

    2014-12-01

    Landsat data records of surface reflectance provide a three-decade history of land surface processes. Due to the vast number of these archived records, development of innovative approaches for automated data mining and information retrieval were necessary. Recently, we created a prototype utilizing open source software libraries for automatically generating annual Anderson Level 1 land cover maps and information products from data acquired by the Landsat Mission for the years 1984 to 2013. The automated prototype was applied to two target areas in northwestern and east-central North Dakota, USA. The approach required the National Land Cover Database (NLCD) and two user-input target acquisition year-days. The Landsat archive was mined for scenes acquired within a 100-day window surrounding these target dates, and then cloud-free pixels where chosen closest to the specified target acquisition dates. The selected pixels were then composited before completing an unsupervised classification using the NLCD. Pixels unchanged in pairs of the NLCD were used for training decision tree models in an iterative process refined with model confidence measures. The decision tree models were applied to the Landsat composites to generate a yearly land cover map and related information products. Results for the target areas captured changes associated with the recent expansion of oil shale production and agriculture driven by economics and policy, such as the increase in biofuel production and reduction in Conservation Reserve Program. Changes in agriculture, grasslands, and surface water reflect the local hydrological conditions that occurred during the 29-year span. Future enhancements considered for this prototype include a web-based client, ancillary spatial datasets, trends and clustering algorithms, and the forecasting of future land cover.

  11. T-Check in System-of-Systems Technologies: Cloud Computing

    DTIC Science & Technology

    2010-09-01

    Provides developers with tools to build their own cloud computing infrastructures [3tera 2010] Eucalyptus Systems: Provides an open-source...for cloud computing [ Eucalyptus 2010]. 5 The National Institute of Standards and Technology (NIST) defines two additional types of cloud...40 | CMU/SEI-2010-TN-009 5 Conclusions and Open Questions Cloud computing is in essence an economic model—a different way to acquire and manage

  12. Automatic Cloud Bursting under FermiCloud

    SciTech Connect

    Wu, Hao; Shangping, Ren; Garzoglio, Gabriele; Timm, Steven; Bernabeu, Gerard; Kim, Hyun Woo; Chadwick, Keith; Jang, Haengjin; Noh, Seo-Young

    2013-01-01

    Cloud computing is changing the infrastructure upon which scientific computing depends from supercomputers and distributed computing clusters to a more elastic cloud-based structure. The service-oriented focus and elasticity of clouds can not only facilitate technology needs of emerging business but also shorten response time and reduce operational costs of traditional scientific applications. Fermi National Accelerator Laboratory (Fermilab) is currently in the process of building its own private cloud, FermiCloud, which allows the existing grid infrastructure to use dynamically provisioned resources on FermiCloud to accommodate increased but dynamic computation demand from scientists in the domains of High Energy Physics (HEP) and other research areas. Cloud infrastructure also allows to increase a private cloud’s resource capacity through “bursting” by borrowing or renting resources from other community or commercial clouds when needed. This paper introduces a joint project on building a cloud federation to support HEP applications between Fermi National Accelerator Laboratory and Korea Institution of Science and Technology Information, with technical contributions from the Illinois Institute of Technology. In particular, this paper presents two recent accomplishments of the joint project: (a) cloud bursting automation and (b) load balancer. Automatic cloud bursting allows computer resources to be dynamically reconfigured to meet users’ demands. The load balance algorithm which the cloud bursting depends on decides when and where new resources need to be allocated. Our preliminary prototyping and experiments have shown promising success, yet, they also have opened new challenges to be studied

  13. Snow cover monitoring model and change over both time and space in pastoral area of northern China

    NASA Astrophysics Data System (ADS)

    Cui, Yan; Li, Suju; Wang, Ping; Zhang, Wei; Nie, Juan; Wen, Qi

    2014-11-01

    Snow disaster is a natural phenomenon owning to widespread snowfall for a long time and usually affect people's life, property and economic. During the whole disaster management circle, snow disaster in pastoral area of northern china which including Xinjiang, Inner Mongolia, Qinghai, Tibet has been paid more attention. Thus do a good job in snow cover monitoring then found snow disaster in time can help the people in disaster area to take effective rescue measures, which always been the central and local government great important work. Remote sensing has been used widely in snow cover monitoring for its wide range, high efficiency, less conditions, more methods and large information. NOAA/AVHRR data has been used for wide range, plenty bands information and timely acquired and act as an import data of Snow Cover Monitoring Model (SCMM). SCMM including functions list below: First after NOAA/AVHRR data has been acquired, geometric calibration, radiometric calibration and other pre-processing work has been operated. Second after band operation, four threshold conditions are used to extract snow spectrum information among water, cloud and other features in NOAA/AVHRR image. Third snow cover information has been analyzed one by one and the maximum snow cover from about twenty images in a week has been selected. Then selected image has been mosaic which covered the pastoral area of China. At last both time and space analysis has been carried out through this operational model ,such as analysis on the difference between this week and the same period of last year , this week and last week in three level regional. SCMM have been run successfully for three years, and the results have been take into account as one of the three factors which led to risk warning of snow disaster and analysis results from it always play an important role in disaster reduction and relief.

  14. Storm and Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Yesterday's storm front was moving westward, today's moves eastward. Note the thick cloud cover and beautifully delineated cloud tops.

    Image information: VIS instrument. Latitude 72.1, Longitude 308.3 East (51.7 West). 40 meter/pixel resolution.

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

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

  15. Leveraging LIDAR-derived Point Clouds for Topographic Characterization

    NASA Astrophysics Data System (ADS)

    Velasquez, C.; Glenn, N. F.; Ames, D. P.

    2010-12-01

    Velásquez, C. F., Glenn, N. F., Ames, D. P. Acquisition of accurate x, y and z coordinates of terrain information throughout large geographic areas is possible with Light Detection and Ranging (LiDAR) technology. The mass of points (or point cloud) remotely acquired with airborne LiDAR sensors, for instance, are used for the creation of quality digital models of terrain. Extraction of hydrological features such as channel networks from digital terrain models is a common task. This task is generally conducted by means of implementing software tools that analyze raster structures for representation of terrain surfaces. Exploring the feasibility of directly and effectively extracting land cover features from a point cloud deserves due attention given both the proliferation of LiDAR data availability and the potential for the information to overcome some disadvantages that are intrinsic to the raster structure. Pursuing an alternative mode to leveraging LiDAR data for hydrologic applications is, therefore, the subject motivating the current research. A methodology for extraction of concave-shaped terrain surfaces is proposed. These features, relevant to hydrological applications, are extracted by means of implementing a convolution operation that is conducted on the x, y, and z coordinates of the point cloud and with an adapted construct for a zero-sum kernel function. The mass of points that are topographically lower of what is referred to as a zero-crossing level appear to reasonably well delineate concave-shaped landforms. The proposed method is, therefore, of merit to further investigation.

  16. Aerosol-Cloud-Precipitation Interactions over Indo-Gangetic Basin

    NASA Technical Reports Server (NTRS)

    Tsay, S.-C.; Lau, K. .; Holben, B. N.; Hsu, N. C.; Bhartia, P. K.

    2005-01-01

    About 60% of world population reside in Asia, in term of which sheer population density presents a major environmental stress. Economic expansion in this region is, in fact, accompanied by increases in bio-fuel burning, industrial pollution, and land cover and land use changes. With a growth rate of approx. 8%/yr for Indian economy, more than 600 million people from Lahore, Pakistan to Calcutta, India over the Indo-Gangetic Basin have particularly witnessed increased frequencies of floods and droughts as well as a dramatic increase in atmospheric loading of aerosols (i.e., anthropogenic and natural aerosol) in recent decades. This regional change (e.g., aerosol, cloud, precipitation, etc.) will constitute a vital part of the global change in the 21st century. Better understanding of the impacts of aerosols in affecting monsoon climate and water cycles is crucial in providing the physical basis to improve monsoon climate prediction and for disaster mitigation. Based on climate model simulations, absorbing aerosols (dust and black carbon) play a critical role in affecting interannual and intraseasonal variability of the Indian monsoon. An initiative on the integrated (aerosols, clouds, and precipitation) measurements approach over the Indo-Gangetic Basin will be discussed. An array of ground-based (e.g., AERONET, MPLNET, SMART-COMMIT, etc.) and satellite (e.g., Terra, A-Train, etc.) sensors will be utilized to acquire aerosol characteristics, sources/sinks, and transport processes during the pre-monsoon (April-May, aerosol forcing) season, and to obtain cloud and precipitation properties during the monsoon (May-June, water cycle response) season. Close collaboration with other international programs, such as ABC, CLIVAR, GEWEX, and CEOP in the region is anticipated.

  17. Vehicle body cover

    SciTech Connect

    Hirose, T.

    1987-01-13

    This patent describes a vehicle body covered with a vehicle body cover which comprises: a front cover part, a rear cover part, a pair of side cover parts, and a roof cover part: the front cover part having portions adapted to cover only a hood, an area around a windshield and tops of front fenders of a vehicle body. The portion covering the hood is separated from the portions covering the tops of the fenders by cuts in the front cover part, the front cover part having an un-cut portion corresponding to a position at which the hood is hinged to the car body. The front cover part has a cut-out at a position corresponding to the windshield of the vehicle body and the front cover part has at least one cut-out at a position corresponding to where a rear view mirror is attached to the vehicle body; and the rear cover part having portions adapted to cover an area around a rear window, a trunk lid and a rear end of the vehicle body, the portion covering the trunk lid separated from the rest of the rear cover part by cuts corresponding to three sides of the trunk lid and an un-cut portion corresponding to a position at which the trunk lid is hinged to the vehicle body. The rear cover part has a hole at position corresponding to a trunk lid lock, a cut-out portion at a position corresponding to the rear window of the vehicle body, a cut-out at a position corresponding to a license plate of the vehicle body and cut-outs at positions corresponding to rear taillights of the vehicle body.

  18. Could cirrus clouds have warmed early Mars?

    NASA Astrophysics Data System (ADS)

    Ramirez, Ramses M.; Kasting, James F.

    2017-01-01

    The presence of the ancient valley networks on Mars indicates that the climate at 3.8 Ga was warm enough to allow substantial liquid water to flow on the martian surface for extended periods of time. However, the mechanism for producing this warming continues to be debated. One hypothesis is that Mars could have been kept warm by global cirrus cloud decks in a CO2sbnd H2O atmosphere containing at least 0.25 bar of CO2 (Urata and Toon, 2013). Initial warming from some other process, e.g., impacts, would be required to make this model work. Those results were generated using the CAM 3-D global climate model. Here, we use a single-column radioactive-convective climate model to further investigate the cirrus cloud warming hypothesis. Our calculations indicate that cirrus cloud decks could have produced global mean surface temperatures above freezing, but only if cirrus cloud cover approaches ∼75 - 100% and if other cloud properties (e.g., height, optical depth, particle size) are chosen favorably. However, at more realistic cirrus cloud fractions, or if cloud parameters are not optimal, cirrus clouds do not provide the necessary warming, suggesting that other greenhouse mechanisms are needed.

  19. The EOS CERES Global Cloud Mask

    NASA Technical Reports Server (NTRS)

    Berendes, T. A.; Welch, R. M.; Trepte, Q.; Schaaf, C.; Baum, B. A.

    1996-01-01

    To detect long-term climate trends, it is essential to produce long-term and consistent data sets from a variety of different satellite platforms. With current global cloud climatology data sets, such as the International Satellite Cloud Climatology Experiment (ISCCP) or CLAVR (Clouds from Advanced Very High Resolution Radiometer), one of the first processing steps is to determine whether an imager pixel is obstructed between the satellite and the surface, i.e., determine a cloud 'mask.' A cloud mask is essential to studies monitoring changes over ocean, land, or snow-covered surfaces. As part of the Earth Observing System (EOS) program, a series of platforms will be flown beginning in 1997 with the Tropical Rainfall Measurement Mission (TRMM) and subsequently the EOS-AM and EOS-PM platforms in following years. The cloud imager on TRMM is the Visible/Infrared Sensor (VIRS), while the Moderate Resolution Imaging Spectroradiometer (MODIS) is the imager on the EOS platforms. To be useful for long term studies, a cloud masking algorithm should produce consistent results between existing (AVHRR) data, and future VIRS and MODIS data. The present work outlines both existing and proposed approaches to detecting cloud using multispectral narrowband radiance data. Clouds generally are characterized by higher albedos and lower temperatures than the underlying surface. However, there are numerous conditions when this characterization is inappropriate, most notably over snow and ice of the cloud types, cirrus, stratocumulus and cumulus are the most difficult to detect. Other problems arise when analyzing data from sun-glint areas over oceans or lakes over deserts or over regions containing numerous fires and smoke. The cloud mask effort builds upon operational experience of several groups that will now be discussed.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  1. Multiple layer insulation cover

    DOEpatents

    Farrell, James J.; Donohoe, Anthony J.

    1981-11-03

    A multiple layer insulation cover for preventing heat loss in, for example, a greenhouse, is disclosed. The cover is comprised of spaced layers of thin foil covered fabric separated from each other by air spaces. The spacing is accomplished by the inflation of spaced air bladders which are integrally formed in the cover and to which the layers of the cover are secured. The bladders are inflated after the cover has been deployed in its intended use to separate the layers of the foil material. The sizes of the material layers are selected to compensate for sagging across the width of the cover so that the desired spacing is uniformly maintained when the cover has been deployed. The bladders are deflated as the cover is stored thereby expediting the storage process and reducing the amount of storage space required.

  2. Providing Diurnal Sky Cover Data at ARM Sites

    SciTech Connect

    Klebe, Dimitri I.

    2015-03-06

    The Solmirus Corporation was awarded two-year funding to perform a comprehensive data analysis of observations made during Solmirus’ 2009 field campaign (conducted from May 21 to July 27, 2009 at the ARM SGP site) using their All Sky Infrared Visible Analyzer (ASIVA) instrument. The objective was to develop a suite of cloud property data products for the ASIVA instrument that could be implemented in real time and tailored for cloud modelers. This final report describes Solmirus’ research and findings enabled by this grant. The primary objective of this award was to develop a diurnal sky cover (SC) data product utilizing the ASIVA’s infrared (IR) radiometrically-calibrated data and is described in detail. Other data products discussed in this report include the sky cover derived from ASIVA’s visible channel and precipitable water vapor, cloud temperature (both brightness and color), and cloud height inferred from ASIVA’s IR channels.

  3. An automated approach for mapping persistent ice and snow cover over high latitude regions

    USGS Publications Warehouse

    Selkowitz, David J.; Forster, Richard R.

    2016-01-01

    We developed an automated approach for mapping persistent ice and snow cover (glaciers and perennial snowfields) from Landsat TM and ETM+ data across a variety of topography, glacier types, and climatic conditions at high latitudes (above ~65°N). Our approach exploits all available Landsat scenes acquired during the late summer (1 August–15 September) over a multi-year period and employs an automated cloud masking algorithm optimized for snow and ice covered mountainous environments. Pixels from individual Landsat scenes were classified as snow/ice covered or snow/ice free based on the Normalized Difference Snow Index (NDSI), and pixels consistently identified as snow/ice covered over a five-year period were classified as persistent ice and snow cover. The same NDSI and ratio of snow/ice-covered days to total days thresholds applied consistently across eight study regions resulted in persistent ice and snow cover maps that agreed closely in most areas with glacier area mapped for the Randolph Glacier Inventory (RGI), with a mean accuracy (agreement with the RGI) of 0.96, a mean precision (user’s accuracy of the snow/ice cover class) of 0.92, a mean recall (producer’s accuracy of the snow/ice cover class) of 0.86, and a mean F-score (a measure that considers both precision and recall) of 0.88. We also compared results from our approach to glacier area mapped from high spatial resolution imagery at four study regions and found similar results. Accuracy was lowest in regions with substantial areas of debris-covered glacier ice, suggesting that manual editing would still be required in these regions to achieve reasonable results. The similarity of our results to those from the RGI as well as glacier area mapped from high spatial resolution imagery suggests it should be possible to apply this approach across large regions to produce updated 30-m resolution maps of persistent ice and snow cover. In the short term, automated PISC maps can be used to rapidly

  4. Global analysis of cloud field coverage and radiative properties, using morphological methods and MODIS observations

    NASA Astrophysics Data System (ADS)

    Bar-Or, R. Z.; Altaratz, O.; Koren, I.

    2011-01-01

    The recently recognized continuous transition zone between detectable clouds and cloud-free atmosphere ("the twilight zone") is affected by undetectable clouds and humidified aerosol. In this study, we suggest to distinguish cloud fields (including the detectable clouds and the surrounding twilight zone) from cloud-free areas, which are not affected by clouds. For this classification, a robust and simple-to-implement cloud field masking algorithm which uses only the spatial distribution of clouds, is presented in detail. A global analysis, estimating Earth's cloud field coverage (50° S-50° N) for 28 July 2008, using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, finds that while the declared cloud fraction is 51%, the global cloud field coverage reaches 88%. The results reveal the low likelihood for finding a cloud-free pixel and suggest that this likelihood may decrease as the pixel size becomes larger. A global latitudinal analysis of cloud fields finds that unlike oceans, which are more uniformly covered by cloud fields, land areas located under the subsidence zones of the Hadley cell (the desert belts), contain proper areas for investigating cloud-free atmosphere as there is 40-80% probability to detect clear sky over them. Usually these golden-pixels, with higher likelihood to be free of clouds, are over deserts. Independent global statistical analysis, using MODIS aerosol and cloud products, reveals a sharp exponential decay of the global mean aerosol optical depth (AOD) as a function of the distance from the nearest detectable cloud, both above ocean and land. Similar statistical analysis finds an exponential growth of mean aerosol fine-mode fraction (FMF) over oceans when the distance from the nearest cloud increases. A 30 km scale break clearly appears in several analyses here, suggesting this is a typical natural scale of cloud fields. This work shows different microphysical and optical properties of cloud fields, urging to separately

  5. Global analysis of cloud field coverage and radiative properties, using morphological methods and MODIS observations

    NASA Astrophysics Data System (ADS)

    Bar-Or, R. Z.; Altaratz, O.; Koren, I.

    2010-08-01

    The recently recognized continuous transition zone between detectable clouds and cloud-free atmosphere ("the twilight zone") is affected by undetectable clouds and humidified aerosol. In this study, we suggest to distinguish cloud fields (including the detectable clouds and the surrounding twilight zone) from cloud-free areas, which are not affected by clouds. For this classification, a robust and simple-to-implement cloud field masking algorithm which uses only the spatial distribution of clouds, is presented in detail. A global analysis, estimating Earth's cloud field coverage (50° S-50° N) for 28 July 2008, using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, finds that while the declared cloud fraction is 51%, the global cloud field coverage reaches 88%. The results reveal the low likelihood for finding a cloud free pixel and suggest that this likelihood may decrease as the pixel size becomes larger. A global latitudinal analysis of cloud fields finds that unlike oceans, which are more uniformly covered by cloud fields, land areas located under the subsidence zones of the Hadley cell (the desert belts), contain proper areas for investigating cloud free atmosphere as there is 40-80% probability to detect clear sky over them. Usually these golden-pixels, with higher likelihood to be free of clouds, are over deserts. Independent global statistical analysis, using MODIS aerosol and cloud products, reveals a sharp exponential decay of the global mean aerosol optical depth (AOD) as a function of the distance from the nearest detectable cloud, both above ocean and land. Similar statistical analysis finds an exponential growth of mean aerosol fine-mode fraction (FMF) over Oceans when the distance from the nearest cloud increases. A 30 km scale break clearly appears in several analyses here, suggesting this is a typical natural scale of cloud fields. This work shows different microphysical and optical properties of cloud fields, urging to separately

  6. Physical-chemical processes in a protoplanetary cloud

    NASA Technical Reports Server (NTRS)

    Lavrukhina, Avgusta K.

    1991-01-01

    Physical-chemical processes in a protoplanetary cloud are discussed. The following subject areas are covered: (1) characteristics of the chemical composition of molecular interstellar clouds; (2) properties and physico-chemical process in the genesis of interstellar dust grains; and (3) the isotope composition of volatiles in bodies of the Solar System.

  7. Global patterns of cloud optical thickness variation with temperature

    NASA Technical Reports Server (NTRS)

    Tselioudis, George; Rind, David; Rossow, William B.

    1990-01-01

    A global cloud climatology dataset is used to study patterns of cloud optical thickness variation with temperature. The data, which cover the period from July 1983 through June 1995, contain detailed information on the distribution of cloud radiative properties and their diurnal and seasonal variations, as well as information on the vertical distribution of temperature and humidity in the troposphere. For cold low clouds over land, the temperature coefficient of change in optical thickness has a value of about 0.04, which is similar to that deduced from Soviet aircraft observations and derived from thermodynamic considerations for the change of cloud liquid water with temperature. It is suggested that, in this cold-temperature range, cloud optical thickness variations are dominated by changes in the liquid water content of the cloud and that the liquid water content changes in accordance with the thermodynamic theory.

  8. Approaches to Observe Anthropogenic Aerosol-Cloud Interactions.

    PubMed

    Quaas, Johannes

    Anthropogenic aerosol particles exert an-quantitatively very uncertain-effective radiative forcing due to aerosol-cloud interactions via an immediate altering of cloud albedo on the one hand and via rapid adjustments by alteration of cloud processes and by changes in thermodynamic profiles on the other hand. Large variability in cloud cover and properties and the therefore low signal-to-noise ratio for aerosol-induced perturbations hamper the identification of effects in observations. Six approaches are discussed as a means to isolate the impact of anthropogenic aerosol on clouds from natural cloud variability to estimate or constrain the effective forcing. These are (i) intentional cloud modification, (ii) ship tracks, (iii) differences between the hemispheres, (iv) trace gases, (v) weekly cycles and (vi) trends. Ship track analysis is recommendable for detailed process understanding, and the analysis of weekly cycles and long-term trends is most promising to derive estimates or constraints on the effective radiative forcing.

  9. Classification by Using Multispectral Point Cloud Data

    NASA Astrophysics Data System (ADS)

    Liao, C. T.; Huang, H. H.

    2012-07-01

    Remote sensing images are generally recorded in two-dimensional format containing multispectral information. Also, the semantic information is clearly visualized, which ground features can be better recognized and classified via supervised or unsupervised classification methods easily. Nevertheless, the shortcomings of multispectral images are highly depending on light conditions, and classification results lack of three-dimensional semantic information. On the other hand, LiDAR has become a main technology for acquiring high accuracy point cloud data. The advantages of LiDAR are high data acquisition rate, independent of light conditions and can directly produce three-dimensional coordinates. However, comparing with multispectral images, the disadvantage is multispectral information shortage, which remains a challenge in ground feature classification through massive point cloud data. Consequently, by combining the advantages of both LiDAR and multispectral images, point cloud data with three-dimensional coordinates and multispectral information can produce a integrate solution for point cloud classification. Therefore, this research acquires visible light and near infrared images, via close range photogrammetry, by matching images automatically through free online service for multispectral point cloud generation. Then, one can use three-dimensional affine coordinate transformation to compare the data increment. At last, the given threshold of height and color information is set as threshold in classification.

  10. Desktop Cloud Visualization: the new technology to remote access 3D interactive applications in the Cloud.

    PubMed

    Torterolo, Livia; Ruffino, Francesco

    2012-01-01

    In the proposed demonstration we will present DCV (Desktop Cloud Visualization): a unique technology that allows users to remote access 2D and 3D interactive applications over a standard network. This allows geographically dispersed doctors work collaboratively and to acquire anatomical or pathological images and visualize them for further investigations.

  11. What Medicare Covers

    MedlinePlus

    ... your Medicare coverage — Original Medicare or a Medicare Advantage Plan (Part C). What Part A covers Medicare ... health plans cover Medicare health plans include Medicare Advantage, Medical Savings Account (MSA), Medicare Cost plans, PACE, ...

  12. CaFe interstellar clouds

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Kozak, M.; Gnaciński, P.; Galazutdinov, G. A.; Beletsky, Y.; Krełowski, J.

    2007-07-01

    A new kind of interstellar cloud is proposed. These are rare (just a few examples among ~300 lines of sight) objects with the CaI 4227-Å, FeI 3720-Å and 3860-Å lines stronger than those of KI (near 7699 Å) and NaI (near 3302 Å). We propose the name `CaFe' for these clouds. Apparently they occupy different volumes from the well-known interstellar HI clouds where the KI and ultraviolet NaI lines are dominant features. In the CaFe clouds we have not found either detectable molecular features (CH, CN) or diffuse interstellar bands which, as commonly believed, are carried by some complex, organic molecules. We have found the CaFe clouds only along sightlines toward hot, luminous (and thus distant) objects with high rates of mass loss. In principle, the observed gas-phase interstellar abundances reflect the combined effects of the nucleosynthetic history of the material, the depletion of heavy elements into dust grains and the ionization state of these elements which may depend on irradiation by neighbouring stars. Based on data collected using the Maestro spectrograph at the Terskol 2-m telescope, Russia; and on data collected using the ESO Feros spectrograph; and on data obtained from the ESO Science Archive Facility acquired with the UVES spectrograph, Chile. E-mail: `arctur'@rambler.ru (AB); marizak@astri.uni.torun.pl (MK); pg@iftia.univ.gda.pl (PG); gala@boao.re.kr (GAG); ybialets@eso.org (YB); jacek@astri.uni.torun.pl (JK)

  13. Organic Brain Syndromes: Conditions of Acquired Intellectual Deficit

    PubMed Central

    Roy, John R.

    1979-01-01

    The term 'organic brain syndrome' covers a multitude of ills, many of which are treatable conditions. Diagnosis must concentrate on defining which syndrome is involved; this article presents a diagnostic schema with illustrative case histories. Clinical aspects of acquired mental deficit are also outlined. The approach to organic brain syndromes is the classic medical observation of signs and symptoms. PMID:21297811

  14. Jovian clouds and haze

    NASA Astrophysics Data System (ADS)

    West, Robert A.; Baines, Kevin H.; Friedson, A. James; Banfield, Don; Ragent, Boris; Taylor, Fred W.

    Tropospheric clouds: thermochemical equilibrium theory and cloud microphysical theory, condensate cloud microphysics, tropospheric cloud and haze distribution - observations, results from the Galileo probe experiments, Galileo NIMS observations and results, Galileo SSE observations and results, recent analyses of ground-based and HST data; Tropospheric clouds and haze: optical and physical properties: partical composition, particle optical properties, size and shape, chromophores; Stratospheric haze: particle distribution, optical properties, size and shape, particle formation.

  15. Microsecond-scale electric field pulses in cloud lightning discharges

    NASA Technical Reports Server (NTRS)

    Villanueva, Y.; Rakov, V. A.; Uman, M. A.; Brook, M.

    1994-01-01

    From wideband electric field records acquired using a 12-bit digitizing system with a 500-ns sampling interval, microsecond-scale pulses in different stages of cloud flashes in Florida and New Mexico are analyzed. Pulse occurrence statistics and waveshape characteristics are presented. The larger pulses tend to occur early in the flash, confirming the results of Bils et al. (1988) and in contrast with the three-stage representation of cloud-discharge electric fields suggested by Kitagawa and Brook (1960). Possible explanations for the discrepancy are discussed. The tendency for the larger pulses to occur early in the cloud flash suggests that they are related to the initial in-cloud channel formation processes and contradicts the common view found in the atmospheric radio-noise literature that the main sources of VLF/LF electromagnetic radiation in cloud flashes are the K processes which occur in the final, or J type, part of the cloud discharge.

  16. An Observational Study of the Relationship between Cloud, Aerosol and Meteorology in Broken Low-Level Cloud Conditions

    NASA Technical Reports Server (NTRS)

    Loeb, Norman G.; Schuster, Gregory L.

    2008-01-01

    Global satellite analyses showing strong correlations between aerosol optical depth and 3 cloud cover have stirred much debate recently. While it is tempting to interpret the results as evidence of aerosol enhancement of cloud cover, other factors such as the influence of meteorology on both the aerosol and cloud distributions can also play a role, as both aerosols and clouds depend upon local meteorology. This study uses satellite observations to examine aerosol-cloud relationships for broken low-level cloud regions off the coast of Africa. The analysis approach minimizes the influence of large-scale meteorology by restricting the spatial and temporal domains in which the aerosol and cloud properties are compared. While distributions of several meteorological variables within 5deg 5deg latitude-longitude regions are nearly identical under low and high aerosol optical depth, the corresponding distributions of single-layer low cloud properties and top-of-atmosphere radiative fluxes differ markedly, consistent with earlier studies showing increased cloud cover with aerosol optical depth. Furthermore, fine-mode fraction and Angstrom Exponent are also larger in conditions of higher aerosol optical depth, even though no evidence of systematic latitudinal or longitudinal gradients between the low and high aerosol optical depth populations are observed. When the analysis is repeated for all 5deg 5deg latitude-longitude regions over the global oceans (after removing cases in which significant meteorological differences are found between the low and high aerosol populations), results are qualitatively similar to those off the coast of Africa.

  17. Characterization of Polar Stratospheric Clouds With Spaceborne Lidar: CALIPSO and the 2006 Antarctic Season

    NASA Technical Reports Server (NTRS)

    Pitts, Michael C.; Thomason, L. W.; Poole, Lamont R.; Winker, David M.

    2007-01-01

    The role of polar stratospheric clouds in polar ozone loss has been well documented. The CALIPSO satellite mission offers a new opportunity to characterize PSCs on spatial and temporal scales previously unavailable. A PSC detection algorithm based on a single wavelength threshold approach has been developed for CALIPSO. The method appears to accurately detect PSCs of all opacities, including tenuous clouds, with a very low rate of false positives and few missed clouds. We applied the algorithm to CALIPSO data acquired during the 2006 Antarctic winter season from 13 June through 31 October. The spatial and temporal distribution of CALIPSO PSC observations is illustrated with weekly maps of PSC occurrence. The evolution of the 2006 PSC season is depicted by time series of daily PSC frequency as a function of altitude. Comparisons with virtual solar occultation data indicate that CALIPSO provides a different view of the PSC season than attained with previous solar occultation satellites. Measurement-based time series of PSC areal coverage and vertically-integrated PSC volume are computed from the CALIPSO data. The observed area covered with PSCs is significantly smaller than would be inferred from a temperature-based proxy such as TNAT but is similar in magnitude to that inferred from TSTS. The potential of CALIPSO measurements for investigating PSC microphysics is illustrated using combinations of lidar backscatter coefficient and volume depolarization to infer composition for two CALIPSO PSC scenes.

  18. Cloud types and the tropical earth radiation budget

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.; Kyle, H. Lee

    1990-01-01

    Nimbus-7 cloud and earth radiation budget data are compared in a study of the effects of clouds on the tropical radiation budget. The data consist of daily averages over fixed 500 sq km target areas, and the months of July 1979 and January 1980 were chosen to show the effect of seasonal changes. Six climate regions, consisting of 14 to 24 target areas each, were picked for intensive analysis because they exemplified the range in the tropical cloud/net radiation interactions. It is found that the net radiation is strongly influenced by the average cloud type and amount present, but most net radiation values could be produced by several combinations of cloud types and amount. The regions of highest net radiation (greater than 125 W/sq m) tend to have medium to heavy cloud cover. In these cases, thin medium-altitude clouds predominate. Their cloud tops are normally too warm to be classified as cirrus by the Nimbus cloud algorithm. In the tropical oceans there are large regions where the total regional cloud cover varies from 20 to 90 percent, but with little regional difference in the net radiation. The monsoon and rain areas are high net radiation regions.

  19. Students as Ground Observers for Satellite Cloud Retrieval Validation

    NASA Technical Reports Server (NTRS)

    Chambers, Lin H.; Costulis, P. Kay; Young, David F.; Rogerson, Tina M.

    2004-01-01

    The Students' Cloud Observations On-Line (S'COOL) Project was initiated in 1997 to obtain student observations of clouds coinciding with the overpass of the Clouds and the Earth's Radiant Energy System (CERES) instruments on NASA's Earth Observing System satellites. Over the past seven years we have accumulated more than 9,000 cases worldwide where student observations are available within 15 minutes of a CERES observation. This paper reports on comparisons between the student and satellite data as one facet of the validation of the CERES cloud retrievals. Available comparisons include cloud cover, cloud height, cloud layering, and cloud visual opacity. The large volume of comparisons allows some assessment of the impact of surface cover, such as snow and ice, reported by the students. The S'COOL observation database, accessible via the Internet at http://scool.larc.nasa.gov, contains over 32,000 student observations and is growing by over 700 observations each month. Some of these observations may be useful for assessment of other satellite cloud products. In particular, some observing sites have been making hourly observations of clouds during the school day to learn about the diurnal cycle of cloudiness.

  20. Cover crops for Alabama

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover crops are grown to benefit the following crop as well as to improve the soil, but they are normally not intended for harvest. Selecting the right cover crops for farming operations can improve yields, soil and water conservation and quality, and economic productivity. Properly managed cover ...

  1. Cover crop water use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover crops are being widely promoted because of soil health benefits. However, semi-arid dryland production systems, chronically short of water for crop production, may not be able to profitably withstand the yield reduction that follows cover crops because of cover crop water use. Some studies sug...

  2. Ice Clouds

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Heavy water ice clouds almost completely obscure the surface in Vastitas Borealis.

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

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

    Image information: VIS instrument. Latitude 69.5, Longitude 283.6 East (76.4 West). 19 meter/pixel resolution.

  3. Cloud detection method for Chinese moderate high resolution satellite imagery (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhong, Bo; Chen, Wuhan; Wu, Shanlong; Liu, Qinhuo

    2016-10-01

    Cloud detection of satellite imagery is very important for quantitative remote sensing research and remote sensing applications. However, many satellite sensors don't have enough bands for a quick, accurate, and simple detection of clouds. Particularly, the newly launched moderate to high spatial resolution satellite sensors of China, such as the charge-coupled device on-board the Chinese Huan Jing 1 (HJ-1/CCD) and the wide field of view (WFV) sensor on-board the Gao Fen 1 (GF-1), only have four available bands including blue, green, red, and near infrared bands, which are far from the requirements of most could detection methods. In order to solve this problem, an improved and automated cloud detection method for Chinese satellite sensors called OCM (Object oriented Cloud and cloud-shadow Matching method) is presented in this paper. It firstly modified the Automatic Cloud Cover Assessment (ACCA) method, which was developed for Landsat-7 data, to get an initial cloud map. The modified ACCA method is mainly based on threshold and different threshold setting produces different cloud map. Subsequently, a strict threshold is used to produce a cloud map with high confidence and large amount of cloud omission and a loose threshold is used to produce a cloud map with low confidence and large amount of commission. Secondly, a corresponding cloud-shadow map is also produced using the threshold of near-infrared band. Thirdly, the cloud maps and cloud-shadow map are transferred to cloud objects and cloud-shadow objects. Cloud and cloud-shadow are usually in pairs; consequently, the final cloud and cloud-shadow maps are made based on the relationship between cloud and cloud-shadow objects. OCM method was tested using almost 200 HJ-1/CCD images across China and the overall accuracy of cloud detection is close to 90%.

  4. Cloud-screening for Africa using a geographically and seasonally variable infrared threshold

    NASA Technical Reports Server (NTRS)

    Eck, T. F.; Kalb, V. L.

    1991-01-01

    A spatially variable monthly, infrared cloud-threshold data base has been used to screen cloud-contaminated observations from radiances measured by the NOAA-9 AVHRR over Africa. Cloud-screening through a monthly average infrared threshold based on measured surface air temperature, which is geographically dependent, shows an improvement over using a seasonally and geographically independent thermal cloud threshold of 287 K. It is found that differences in cloud-screening for these two thresholds occur for cases of lower altitude clouds or subpixel clouds where the radiative temperature is higher than the 287 K infrared threshold, yet colder than the variable threshold developed by Stowe et al. (1988) for the Nimbus-7 global cloud climatology. The variable IR threshold is shown to be effective over persistently cloud-covered regions, such as the coastal region of the Gulf of Guinea, but may introduce some erroneous cloud identifications over mountains.

  5. Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

    SciTech Connect

    Wang, Zhien

    2010-06-29

    The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processes is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model simulations. The

  6. Clouds and Climate Change. Understanding Global Change: Earth Science and Human Impacts. Global Change Instruction Program.

    ERIC Educational Resources Information Center

    Shaw, Glenn E.

    The Global Change Instruction Program was designed by college professors to fill a need for interdisciplinary materials on the emerging science of global change. This instructional module introduces the basic features and classifications of clouds and cloud cover, and explains how clouds form, what they are made of, what roles they play in…

  7. Morphology of the cloud tops as observed by the Venus Express Monitoring Camera

    NASA Astrophysics Data System (ADS)

    Titov, Dmitrij V.; Markiewicz, Wojciech J.; Ignatiev, Nikolay I.; Song, Li; Limaye, Sanjay S.; Sanchez-Lavega, Agustin; Hesemann, Jonas; Almeida, Miguel; Roatsch, Thomas; Matz, Klaus-Dieter; Scholten, Frank; Crisp, David; Esposito, Larry W.; Hviid, Stubbe F.; Jaumann, Ralf; Keller, Horst U.; Moissl, Richard

    2012-02-01

    Since the discovery of ultraviolet markings on Venus, their observations have been a powerful tool to study the morphology, motions and dynamical state at the cloud top level. Here we present the results of investigation of the cloud top morphology performed by the Venus Monitoring Camera (VMC) during more than 3 years of the Venus Express mission. The camera acquires images in four narrow-band filters centered at 365, 513, 965 and 1010 nm with spatial resolution from 50 km at apocentre to a few hundred of meters at pericentre. The VMC experiment provides a significant improvement in the Venus imaging as compared to the capabilities of the earlier missions. The camera discovered new cloud features like bright "lace clouds" and cloud columns at the low latitudes, dark polar oval and narrow circular and spiral "grooves" in the polar regions, different types of waves at the high latitudes. The VMC observations revealed detailed structure of the sub-solar region and the afternoon convective wake, the bow-shape features and convective cells, the mid-latitude transition region and the "polar cap". The polar orbit of the satellite enables for the first time nadir viewing of the Southern polar regions and an opportunity to zoom in on the planet. The experiment returned numerous images of the Venus limb and documented global and local brightening events. VMC provided almost continuous monitoring of the planet with high temporal resolution that allowed one to follow changes in the cloud morphology at various scales. We present the in-flight performance of the instrument and focus in particular on the data from the ultraviolet channel, centered at the characteristic wavelength of the unknown UV absorber that yields the highest contrasts on the cloud top. Low latitudes are dominated by relatively dark clouds that have mottled and fragmented appearance clearly indicating convective activity in the sub-solar region. At ˜50° latitude this pattern gives way to streaky clouds

  8. Still from High-Clouds Jupiter Movie

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image is one of seven from the narrow-angle camera on NASA's Cassini spacecraft assembled as a brief movie of high-altitude cloud movements on Jupiter. It was taken in early October 2000.

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

    The area shown covers latitudes from 50 degrees north to 50 degrees south and a 100-degree sweep of longitude.

    Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

  9. The Aerosol, Clouds and Ecosystem (ACE) Mission

    NASA Astrophysics Data System (ADS)

    Schoeberl, M.; Remer, L.; Kahn, R.; Starr, D.; Hildebrand, P.; Colarco, P.; Diner, D.; Vane, D.; Im, E.; Behrenfeld, M.; Stephens, G.; Maring, H.; Bontempi, P.; Martins, J. V.

    2008-12-01

    The Aerosol, Clouds and Ecosystem (ACE) Mission is a second tier Decadal Survey mission designed to characterize the role of aerosols in climate forcing, especially their impact on precipitation and cloud formation. ACE also includes ocean biosphere measurements (chlorophyll and dissolved organic materials) which will be greatly improved by simultaneous measurements of aerosols. The nominal ACE payload includes lidar and multiangle spectropolarimetric polarimetric measurements of aerosols, radar measurements of clouds and multi-band spectrometer for the measurement of ocean ecosystems. An enhancement to ACE payload under consideration includes µ-wave radiometer measurements of cloud ice and water outside the nadir path of the radar/lidar beams. This talk will cover ACE instrument and science options, updates on the science team definition activity and science potential.

  10. Theoretical development of Monte Carlo codes for modeling cumulus cloud fields

    NASA Technical Reports Server (NTRS)

    Welch, R. M.

    1984-01-01

    Reflected fluxes are calculated for stratocumulus cloud fields as a function of skycover, cloud aspect ratio, and cloud shape. Cloud liquid water volume is held invariant as cloud shape is varied so that the results can be utilized more effectively by general circulation models and climate models. On the basis of required accuracy in the Earth Radiation Budget Experiment program, an order of magnitude value of 10 W/sq m is used to estimate significant differences between plane parallel and broken cloudiness. This limit is exceeded for cloud covers between 10% and 90%, indicating that plane paralel calculations are not satisfactory at most values of cloud cover. The choice of cloud shape also leads to large differences in reflected fluxes. These differences are traced to the anisotropic intensity pattern out the cloud sides, to the size and shape of the holes between clouds, and to variations in cloud area as viewed from the solar direction. An empirical relationship for effective cloud cover is given at solar zenith angle of theta = 60 deg. This relationship allows for the relatively accurate (delta F = 10 - 15 W/sq m.) computation of broken cloud field reflected fluxes from plane parallel calculations.

  11. Grids and clouds in the Czech NGI

    NASA Astrophysics Data System (ADS)

    Kundrát, Jan; Adam, Martin; Adamová, Dagmar; Chudoba, Jiří; Kouba, Tomáš; Lokajíček, Miloš; Mikula, Alexandr; Říkal, Václav; Švec, Jan; Vohnout, Rudolf

    2016-09-01

    There are several infrastructure operators within the Czech Republic NGI (National Grid Initiative) which provide users with access to high-performance computing facilities over a grid and cloud interface. This article focuses on those where the primary author has personal first-hand experience. We cover some operational issues as well as the history of these facilities.

  12. Sensitivity of PARASOL multi-angle photo-polarimetric aerosol retrievals to cloud contamination

    NASA Astrophysics Data System (ADS)

    Stap, F. A.; Hasekamp, O.; Röckmann, T.

    2014-10-01

    An important problem in satellite remote sensing of aerosols is related to the need to perform an adequate cloud screening. If a cloud screening is applied that is not strict enough, the ground scene has the probability of residual cloud cover which causes large errors on the retrieved aerosol parameters. On the other hand, if the cloud screening procedure is too strict, too many clear sky cases, especially near-cloud scenes, will falsely be flagged cloudy. The detrimental effects of cloud contamination as well as the importance of aerosol cloud interactions that can be studied in these near-cloud scenes call for new approaches to cloud screening. Multi-angle, multi-wavelength photo-polarimetric measurements have a unique capability to distinguish between scattering by (liquid) cloud droplets and aerosol particles. In this paper the sensitivity of aerosol retrievals from multi-angle, photo-polarimetric measurements to cloud contamination is investigated and the ability to intrinsically filter the cloud contaminated scenes based on a goodness-of-fit criteria is evaluated. Hereto, an aerosol retrieval algorithm is applied to a partially clouded, synthetic data-set including partial cloud cover as well as non-cloud screened POLDER-3/PARASOL observations It is found that a goodness-of-fit filter, together with a filter on the coarse mode refractive index (mrcoarse > 1.335) and a cirrus screening adequately reject the cloud contaminated scenes. No bias nor larger SD are found in the retrieved parameters for this intrinsic cloud filter compared to the parameters retrieved in a priori cloud screened data-set (using MODIS/AQUA cloud masks) of PARASOL observations. Moreover, less high aerosol load scenes are misinterpreted as cloud contaminated. The retrieved aerosol optical thickness, single scattering albedo and Ångström exponent show good agreement with AERONET observations. Furthermore, the synthetic retrievals give confidence in the ability of the algorithm to

  13. The Inner Oort Cloud Population

    NASA Astrophysics Data System (ADS)

    Sheppard, Scott; Trujillo, Chad

    2014-08-01

    The Kuiper Belt population has an outer edge at about 50 AU. Sedna and our recent discovery, 2012 VP113, are the only known objects with perihelion significantly beyond this edge at about 80 AU. These inner Oort cloud objects obtained their orbits when the solar system was vastly different from now. There are several theories as to the origin of these objects that can only be tested by finding several more. This population is likely larger than the Kuiper Belt but previous surveys did not go faint enough, did not have the required long cadence, or covered too small of sky area to find them. The dynamical and physical properties of objects in this region offer key constraints on the formation and evolution of our solar system. We propose to continue our survey with DECam in order to find several more inner Oort cloud objects to further constrain formation theories and thus learn about our Sun's formation environment and evolution.

  14. Persistent Oxygen Requirement beyond Prematurity: A Case of Acquired Pulmonary Vein Stenosis

    PubMed Central

    Richards, Bernadette; Ball, Molly K.

    2017-01-01

    Acquired pulmonary vein stenosis is a rare cardiac defect and diagnosis can often be challenging, as many cases present with refractory or prolonged oxygen requirement over the expected course. Comorbid conditions can cloud this diagnosis further. Prognosis is poor for most patients. We present a case of idiopathic acquired pulmonary vein stenosis and discuss diagnostics, treatment options, and the need for further collaborative studies. PMID:28392954

  15. Modeled Impact of Cirrus Cloud Increases Along Aircraft Flight Paths

    NASA Technical Reports Server (NTRS)

    Rind, David; Lonergan, P.; Shah, K.

    1999-01-01

    The potential impact of contrails and alterations in the lifetime of background cirrus due to subsonic airplane water and aerosol emissions has been investigated in a set of experiments using the GISS GCM connected to a q-flux ocean. Cirrus clouds at a height of 12-15km, with an optical thickness of 0.33, were input to the model "x" percentage of clear-sky occasions along subsonic aircraft flight paths, where x is varied from .05% to 6%. Two types of experiments were performed: one with the percentage cirrus cloud increase independent of flight density, as long as a certain minimum density was exceeded; the other with the percentage related to the density of fuel expenditure. The overall climate impact was similar with the two approaches, due to the feedbacks of the climate system. Fifty years were run for eight such experiments, with the following conclusions based on the stable results from years 30-50 for each. The experiments show that adding cirrus to the upper troposphere results in a stabilization of the atmosphere, which leads to some decrease in cloud cover at levels below the insertion altitude. Considering then the total effect on upper level cloud cover (above 5 km altitude), the equilibrium global mean temperature response shows that altering high level clouds by 1% changes the global mean temperature by 0.43C. The response is highly linear (linear correlation coefficient of 0.996) for high cloud cover changes between 0. 1% and 5%. The effect is amplified in the Northern Hemisphere, more so with greater cloud cover change. The temperature effect maximizes around 10 km (at greater than 40C warming with a 4.8% increase in upper level clouds), again more so with greater warming. The high cloud cover change shows the flight path influence most clearly with the smallest warming magnitudes; with greater warming, the model feedbacks introduce a strong tropical response. Similarly, the surface temperature response is dominated by the feedbacks, and shows

  16. Testing of Land Cover Classification from Multispectral Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Bakuła, K.; Kupidura, P.; Jełowicki, Ł.

    2016-06-01

    Multispectral Airborne Laser Scanning provides a new opportunity for airborne data collection. It provides high-density topographic surveying and is also a useful tool for land cover mapping. Use of a minimum of three intensity images from a multiwavelength laser scanner and 3D information included in the digital surface model has the potential for land cover/use classification and a discussion about the application of this type of data in land cover/use mapping has recently begun. In the test study, three laser reflectance intensity images (orthogonalized point cloud) acquired in green, near-infrared and short-wave infrared bands, together with a digital surface model, were used in land cover/use classification where six classes were distinguished: water, sand and gravel, concrete and asphalt, low vegetation, trees and buildings. In the tested methods, different approaches for classification were applied: spectral (based only on laser reflectance intensity images), spectral with elevation data as additional input data, and spectro-textural, using morphological granulometry as a method of texture analysis of both types of data: spectral images and the digital surface model. The method of generating the intensity raster was also tested in the experiment. Reference data were created based on visual interpretation of ALS data and traditional optical aerial and satellite images. The results have shown that multispectral ALS data are unlike typical multispectral optical images, and they have a major potential for land cover/use classification. An overall accuracy of classification over 90% was achieved. The fusion of multi-wavelength laser intensity images and elevation data, with the additional use of textural information derived from granulometric analysis of images, helped to improve the accuracy of classification significantly. The method of interpolation for the intensity raster was not very helpful, and using intensity rasters with both first and last return

  17. Global surface-based cloud observation for ISCCP

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Visual observations of cloud cover are hindered at night due to inadequate illumination of the clouds. This usually leads to an underestimation of the average cloud cover at night, especially for the amounts of middle and high clouds, in climatologies on surface observations. The diurnal cycles of cloud amounts, if based on all the surface observations, are therefore in error, but they can be obtained more accurately if the nighttime observations are screened to select those made under sufficient moonlight. Ten years of nighttime weather observations from the northern hemisphere in December were classified according to the illuminance of moonlight or twilight on the cloud tops, and a threshold level of illuminance was determined, above which the clouds are apparently detected adequately. This threshold corresponds to light from a full moon at an elevation angle of 6 degrees or from a partial moon at higher elevation, or twilight from the sun less than 9 degrees below the horizon. It permits the use of about 38% of the observations made with the sun below the horizon. The computed diurnal cycles of total cloud cover are altered considerably when this moonlight criterion is imposed. Maximum cloud cover over much of the ocean is now found to be at night or in the morning, whereas computations obtained without benefit of the moonlight criterion, as in our published atlases, showed the time of maximum to be noon or early afternoon in many regions. Cloud cover is greater at night than during the day over the open oceans far from the continents, particularly in summer. However, near noon maxima are still evident in the coastal regions, so that the global annual average oceanic cloud cover is still slightly greater during the day than at night, by 0.3%. Over land, where daytime maxima are still obtained but with reduced amplitude, average cloud cover is 3.3% greater during the daytime. The diurnal cycles of total cloud cover we obtain are compared with those of ISCCP for a

  18. 26 CFR 31.3121(j)-1 - Covered transportation service.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Covered transportation service. 31.3121(j)-1 Section 31.3121(j)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in...

  19. Optical Algorithm for Cloud Shadow Detection Over Water

    DTIC Science & Technology

    2013-02-01

    contextual information to detect cumulus clouds and cloud shadows in Landsat data," Int. J. Remote Sens., vol. 3, no. l.pp. 51-62,1982. [12] T...Betendes, S. K. Sengupta, R. M. Welch, B. A. Wielicki, and M. Navar, " Cumulus cloud base height estimation from high spatial resolution rr-r 740 IEEE...REPORT DATE (DD-MM-YYYY) 05-02-2013 2. REPORT TYPE Journal Article 3. DATES COVERED (From ■ To) 4. TITLE AND SUBTITLE Optical Algorithm for Cloud

  20. Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals

    DOE Data Explorer

    Shupe, Matthew

    2013-05-22

    Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May 2008). These time periods will be expanded in a future submission.

  1. Variations in Nimbus-7 cloud estimates. Part I: Zonal averages

    SciTech Connect

    Weare, B.C. )

    1992-12-01

    Zonal averages of low, middle, high, and total cloud amount estimates derived from measurements from Nimbus-7 have been analyzed for the six-year period April 1979 through March 1985. The globally and zonally averaged valued of six-year annual means and standard deviations of total cloud amount and a proxy of cloudtop height are illustrated. Separate means for day and night and land and sea are also shown. The globally averaged value of intra-annual variability of total cloud amount is greater than 7%, and that for cloud height is greater than 0.3 km. Those of interannual variability are more than one-third of these values. Important latitudinal differences in variability are illustrated. The dominant empirical orthogonal analyses of the intra-annual variations of total cloud amount and heights show strong annual cycles, indicating that in the tropics increases in total cloud amount of up to about 30% are often accompanied by increases in cloud height of up to 1.2 km. This positive link is also evident in the dominant empirical orthogonal function of interannual variations of a total cloud/cloud height complex. This function shows a large coherent variation in total cloud cover of about 10% coupled with changes in cloud height of about 1.1 km associated with the 1982-83 El Ni[tilde n]o-Southern Oscillation event. 14 refs. 12 figs., 2 tabs.

  2. Synergistic application of geometric and radiometric features of LiDAR data for urban land cover mapping.

    PubMed

    Qin, Yuchu; Li, Shihua; Vu, Tuong-Thuy; Niu, Zheng; Ban, Yifang

    2015-06-01

    Urban land cover map is essential for urban planning, environmental studies and management. This paper aims to demonstrate the potential of geometric and radiometric features derived from LiDAR waveform and point cloud data in urban land cover mapping with both parametric and non-parametric classification algorithms. Small footprint LiDAR waveform data acquired by RIEGL LMS-Q560 in Zhangye city, China is used in this study. A LiDAR processing chain is applied to perform waveform decomposition, range determination and radiometric characterization. With the synergic utilization of geometric and radiometric features derived from LiDAR data, urban land cover classification is then conducted using the Maximum Likelihood Classification (MLC), Support Vector Machines (SVM) and random forest algorithms. The results suggest that the random forest classifier achieved the most accurate result with overall classification accuracy of 91.82% and the kappa coefficient of 0.88. The overall accuracies of MLC and SVM are 84.02, and 88.48, respectively. The study suggest that the synergic utilization of geometric and radiometric features derived from LiDAR data can be efficiently used for urban land cover mapping, the non-parametric random forest classifier is a promising approach for the various features with different physical meanings.

  3. The Cloud Detection and UV Monitoring Experiment (CLUE)

    NASA Technical Reports Server (NTRS)

    Barbier, L.; Loh, E.; Sokolsky, P.; Streitmatter, R.

    2004-01-01

    We propose a large-area, low-power instrument to perform CLoud detection and Ultraviolet monitoring, CLUE. CLUE will combine the W detection capabilities of the NIGHTGLOW payload, with an array of infrared sensors to perform cloud slicing measurements. Missions such as EUSO and OWL which seek to measure UHE cosmic-rays at 1W20 eV use the atmosphere as a fluorescence detector. CLUE will provide several important correlated measurements for these missions, including: monitoring the atmospheric W emissions &om 330 - 400 nm, determining the ambient cloud cover during those W measurements (with active LIDAR), measuring the optical depth of the clouds (with an array of narrow band-pass IR sensors), and correlating LIDAR and IR cloud cover measurements. This talk will describe the instrument as we envision it.

  4. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. Armored geomembrane cover engineering.

    PubMed

    Foye, Kevin

    2011-06-01

    Geomembranes are an important component of modern engineered barriers to prevent the infiltration of stormwater and runoff into contaminated soil and rock as well as waste containment facilities--a function generally described as a geomembrane cover. This paper presents a case history involving a novel implementation of a geomembrane cover system. Due to this novelty, the design engineers needed to assemble from disparate sources the design criteria for the engineering of the cover. This paper discusses the design methodologies assembled by the engineering team. This information will aid engineers designing similar cover systems as well as environmental and public health professionals selecting site improvements that involve infiltration barriers.

  6. Armored Geomembrane Cover Engineering

    PubMed Central

    Foye, Kevin

    2011-01-01

    Geomembranes are an important component of modern engineered barriers to prevent the infiltration of stormwater and runoff into contaminated soil and rock as well as waste containment facilities—a function generally described as a geomembrane cover. This paper presents a case history involving a novel implementation of a geomembrane cover system. Due to this novelty, the design engineers needed to assemble from disparate sources the design criteria for the engineering of the cover. This paper discusses the design methodologies assembled by the engineering team. This information will aid engineers designing similar cover systems as well as environmental and public health professionals selecting site improvements that involve infiltration barriers. PMID:21776229

  7. National land cover dataset

    USGS Publications Warehouse

    ,

    2000-01-01

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency, has produced a land cover dataset for the conterminous United States on the basis of 1992 Landsat thematic mapper imagery and supplemental data. The National Land Cover Dataset (NLCD) is a component of the USGS Land Cover Characterization Program. The seamless NLCD contains 21 categories of land cover information suitable for a variety of State and regional applications, including landscape analysis, land management, and modeling nutrient and pesticide runoff. The NLCD is distributed by State as 30-meter resolution raster images in an Albers Equal-Area map projection.

  8. An Assessment of the World Wide Merged Cloud Analysis using Interactive Graphics

    DTIC Science & Technology

    2007-06-01

    and Cumulus Nimbus (CB) are recorded but the type of cloud was not compared in the study. The WWMCA also classifies clouds into one of nine types...WORLD WIDE MERGED CLOUD ANALYSIS USING INTERACTIVE GRAPHICS by Stephen J. Horsman II June 2007 Thesis Advisor: Karl D. Pfeiffer...REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE An Assessment of the World Wide Merged Cloud Analysis using Interactive

  9. Retrieval of Cloud Phase Using the Moderate Resolution Imaging Spectroradiometer Data during the Mixed-Phase Arctic Cloud Experiment

    SciTech Connect

    Spangenberg, D.; Minnis, P.; Shupe, M.; Uttal, T.; Poellot, M.

    2005-03-18

    Improving climate model predictions over Earth's polar regions requires a comprehensive knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface, making it difficult to detect clouds and retrieve their phase from space. Snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds make it even more difficult to determine cloud phase. Also, since determining cloud phase is the first step toward analyzing cloud optical depth, particle size, and water content, it is vital that the phase be correct in order to obtain accurate microphysical and bulk properties. Changes in these cloud properties will, in turn, affect the Arctic climate since clouds are expected to play a critical role in the sea ice albedo feedback. In this paper, the IR trispectral technique (IRTST) is used as a starting point for a WV and 11-{micro}m brightness temperature (T11) parameterization (WVT11P) of cloud phase using MODIS data. In addition to its ability to detect mixed-phase clouds, the WVT11P also has the capability to identify thin cirrus clouds overlying mixed or liquid phase clouds (multiphase ice). Results from the Atmospheric Radiation Measurement (ARM) MODIS phase model (AMPHM) are compared to the surface-based cloud phase retrievals over the ARM North Slope of Alaska (NSA) Barrow site and to in-situ data taken from University of North Dakota Citation (CIT) aircraft which flew during the Mixed-Phase Arctic Cloud Experiment (MPACE). It will be shown that the IRTST and WVT11P combined to form the AMPHM can achieve a relative high accuracy of phase discrimination compared to the surface-based retrievals. Since it only uses MODIS WV and IR channels, the AMPHM is robust in the sense that it can be applied to daytime, twilight, and nighttime scenes with no discontinuities in the output phase.

  10. Noctilucent Cloud Sightings

    NASA Video Gallery

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

  11. Cloud Computing for radiologists.

    PubMed

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

    2012-07-01

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

  12. Ice Nuclei Production in Volcanic Clouds

    NASA Astrophysics Data System (ADS)

    Few, A. A.

    2012-12-01

    The paper [Durant et al., 2008] includes a review of research on ice nucleation in explosive volcanic clouds in addition to reporting their own research on laboratory measurements focused on single-particle ice nucleation. Their research as well as the research they reviewed were concerned with the freezing of supercooled water drops (250 to 260 K) by volcanic ash particles acting as ice freezing nuclei. Among their conclusions are: Fine volcanic ash particles are very efficient ice freezing nuclei. Volcanic clouds likely contain fine ash concentrations 104 to 105 times greater than found in meteorological clouds. This overabundance of ice nuclei will produce a cloud with many small ice crystals that will not grow larger as they do in meteorological clouds because the cloud water content is widely distributed among the numerous small ice crystals. The small ice crystals have a small fall velocity, thus volcanic clouds are very stable. The small ice crystals are easily lofted into the stratosphere transporting water and adsorbed trace gasses. In this paper we examine the mechanism for the production of the small ice nuclei and develop a simple model for calculating the size of the ice nuclei based upon the distribution of magma around imbedded bubbles. We also have acquired a volcanic bomb that exhibits bubble remnants on its entire surface. The naturally occurring fragments from the volcanic bomb reveal a size distribution consistent with that predicted by the simple model. Durant, A. J., R. A. Shaw, W. I. Rose, Y. Mi, and G. G. J. Ernst (2008), Ice nucleation and overseeding of ice in volcanic clouds, J. Geophys. Res., 113, D09206, doi:10.1029/2007JD009064.

  13. Airborne Cloud Computing Environment (ACCE)

    NASA Technical Reports Server (NTRS)

    Hardman, Sean; Freeborn, Dana; Crichton, Dan; Law, Emily; Kay-Im, Liz

    2011-01-01

    Airborne Cloud Computing Environment (ACCE) is JPL's internal investment to improve the return on airborne missions. Improve development performance of the data system. Improve return on the captured science data. The investment is to develop a common science data system capability for airborne instruments that encompasses the end-to-end lifecycle covering planning, provisioning of data system capabilities, and support for scientific analysis in order to improve the quality, cost effectiveness, and capabilities to enable new scientific discovery and research in earth observation.

  14. Computer animation of clouds

    SciTech Connect

    Max, N.

    1994-01-28

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

  15. Comparing Point Clouds

    DTIC Science & Technology

    2004-04-01

    Point clouds are one of the most primitive and fundamental surface representations. A popular source of point clouds are three dimensional shape...acquisition devices such as laser range scanners. Another important field where point clouds are found is in the representation of high-dimensional...framework for comparing manifolds given by point clouds is presented in this paper. The underlying theory is based on Gromov-Hausdorff distances, leading

  16. Automated detection of cloud and cloud-shadow in single-date Landsat imagery using neural networks and spatial post-processing

    SciTech Connect

    Hughes, Michael J.; Hayes, Daniel J

    2014-01-01

    Use of Landsat data to answer ecological questions is contingent on the effective removal of cloud and cloud shadow from satellite images. We develop a novel algorithm to identify and classify clouds and cloud shadow, \\textsc{sparcs}: Spacial Procedures for Automated Removal of Cloud and Shadow. The method uses neural networks to determine cloud, cloud-shadow, water, snow/ice, and clear-sky membership of each pixel in a Landsat scene, and then applies a set of procedures to enforce spatial rules. In a comparison to FMask, a high-quality cloud and cloud-shadow classification algorithm currently available, \\textsc{sparcs} performs favorably, with similar omission errors for clouds (0.8% and 0.9%, respectively), substantially lower omission error for cloud-shadow (8.3% and 1.1%), and fewer errors of commission (7.8% and 5.0%). Additionally, textsc{sparcs} provides a measure of uncertainty in its classification that can be exploited by other processes that use the cloud and cloud-shadow detection. To illustrate this, we present an application that constructs obstruction-free composites of images acquired on different dates in support of algorithms detecting vegetation change.

  17. Musicality: instinct or acquired skill?

    PubMed

    Marcus, Gary F

    2012-10-01

    Is the human tendency toward musicality better thought of as the product of a specific, evolved instinct or an acquired skill? Developmental and evolutionary arguments are considered, along with issues of domain-specificity. The article also considers the question of why humans might be consistently and intensely drawn to music if musicality is not in fact the product of a specifically evolved instinct.

  18. Duplicated Information Acquired by Libraries.

    ERIC Educational Resources Information Center

    White, Carl M.

    The object of this study is to make a start toward determining the extent of duplicated information that is being acquired in spite of customary precautions to avoid it. Referring to a specific case, the percentages in Table II show the frequency of appearance in five other works of 19 items in Mitchell's "Encyclopedia of American Politics." While…

  19. Acquired aplastic anemia in children.

    PubMed

    Hartung, Helge D; Olson, Timothy S; Bessler, Monica

    2013-12-01

    This article provides a practice-based and concise review of the etiology, diagnosis, and management of acquired aplastic anemia in children. Bone marrow transplantation, immunosuppressive therapy, and supportive care are discussed in detail. The aim is to provide the clinician with a better understanding of the disease and to offer guidelines for the management of children with this uncommon yet serious disorder.

  20. Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds.

    PubMed

    Fan, Jiwen; Leung, L Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-26

    Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol's thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ~27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3-5 W m(-2)) and a surface cooling (-5 to -8 W m(-2)). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments.

  1. Convective cloud top vertical velocity estimated from geostationary satellite rapid-scan measurements

    NASA Astrophysics Data System (ADS)

    Hamada, Atsushi; Takayabu, Yukari N.

    2016-05-01

    We demonstrate that the rate of development of cumulus clouds, as inferred from the so-called geostationary satellite "rapid-scan" measurements, is a good proxy for convective cloud top vertical velocity related to deep convective clouds. Convective cloud top vertical velocity is estimated from the decreasing rate of infrared brightness temperature observed by the Multi-functional Transport SATellite-1R (MTSAT-1R) over the ocean south of Japan during boreal summer. The frequency distribution of the estimated convective cloud top vertical velocity at each height is shown to distribute lognormally, and it is consistent with the statistical characteristics of direct measurements acquired in previous studies.

  2. Silostop Bunker Covers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The quality of the seal provided by the plastic cover is a key issue for minimizing losses in bunker and pile silos. Most bunker covers are 6 to 8 mil polyethylene sheets held in place by tires or tire sidewalls. Frequently there are problems with spoilage at the shoulders (i.e., against the walls),...

  3. ENGINEERING BULLETIN: LANDFILL COVERS

    EPA Science Inventory

    Landfill covers are used at Superfund sites to minimize surface water infiltration and control gas migration. In many cases covers are used in conjunction with other waste treatment technologies, such as slurry walls, ground water pump-and-treat systems, and gas collection. This ...

  4. Cloud Computing Explained

    ERIC Educational Resources Information Center

    Metz, Rosalyn

    2010-01-01

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

  5. Clouds in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    West, R.

    1999-01-01

    In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

  6. Security in the cloud.

    PubMed

    Degaspari, John

    2011-08-01

    As more provider organizations look to the cloud computing model, they face a host of security-related questions. What are the appropriate applications for the cloud, what is the best cloud model, and what do they need to know to choose the best vendor? Hospital CIOs and security experts weigh in.

  7. Land Cover Trends Project

    USGS Publications Warehouse

    Acevedo, William

    2006-01-01

    The Land Cover Trends Project is designed to document the types, rates, causes, and consequences of land cover change from 1973 to 2000 within each of the 84 U.S. Environmental Protection Agency (EPA) Level III ecoregions that span the conterminous United States. The project's objectives are to: * Develop a comprehensive methodology using probability sampling and change analysis techniques and Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), and Enhanced Thematic Mapper (ETM) data for estimating regional land cover change. * Characterize the spatial and temporal characteristics of conterminous U.S. land cover change for five periods from 1973 to 2000 (nominally 1973, 1980, 1986, 1992, and 2000). * Document the regional driving forces and consequences of change. * Prepare a national synthesis of land cover change.

  8. A blending snow cover data base on MODIS and AMSR-E snow cover in Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Xiaohua, H.; Wang, J.; Che, T.; Dai, L. Y.

    2012-04-01

    The algorithms of MODIS Terra and MODIS Aqua versions of the snow products have been developed by the NASA National Snow and Ice Data Center (NSIDC). The MODIS global snow-cover products have been available through the NSIDC Distributed Active Archive Center (DAAC) since February 24, 2000 to Terra and July 4, 2002 to Aqua. The MODIS snow-cover maps represent a potential improvement relative to hemispheric-scale snow maps that are available today mainly because of the improved spatial resolution and snow/cloud discrimination capabilities of MODIS, and the frequent global coverage. In China, the snow distribution is different to other regions. Their accuracy on Qinghai-Tibet Plateau (QTP), however, has not yet been established. There are some drawbacks about NSIDC global snow cover products on QTP: 1. The characteristics of snow depth distribution on QTP: Thin, discontinuous. Our research indicated the MODIS snow-cover products underestimated the snow cover area in QTP. 2. The daily snow cover product from MODIS-Terra and Aqua can include the data gaps. 3. The snow products can separate snow from most obscuring clouds. However, there are still many cloud pixels in daily snow cover products. The study developed a new blending daily snow cover algorithm through improving the NSIDC snow algorithms and combining MODIS and AMSR-E data in QTP. The new snow cover products will provide daily snow cover at 500-m resolution in QTP. The new snow cover algorithm employs a grouped-criteria technique using the Normalized Difference Snow Index (NDSI) and other spectral threshold tests and image fusion technology to identify and classify snow on a pixel-by-pixel basis. The usefulness of the NDSI is based on the fact that snow and ice are considerably more reflective in the visible than in the shortwave IR part of the spectrum, and the reflectance of most clouds remains high in the short-wave IR, while the reflectance of snow is low. We propose a set of three steps, based on a

  9. Integrating Cloud-Computing-Specific Model into Aircraft Design

    NASA Astrophysics Data System (ADS)

    Zhimin, Tian; Qi, Lin; Guangwen, Yang

    Cloud Computing is becoming increasingly relevant, as it will enable companies involved in spreading this technology to open the door to Web 3.0. In the paper, the new categories of services introduced will slowly replace many types of computational resources currently used. In this perspective, grid computing, the basic element for the large scale supply of cloud services, will play a fundamental role in defining how those services will be provided. The paper tries to integrate cloud computing specific model into aircraft design. This work has acquired good results in sharing licenses of large scale and expensive software, such as CFD (Computational Fluid Dynamics), UG, CATIA, and so on.

  10. Potential reciprocal effect between land use / land cover change and climate change

    NASA Astrophysics Data System (ADS)

    Daham, Afrah; Han, Dawei; Rico-Ramirez, Miguel

    2016-04-01

    Land use/land cover (LULC) activity influences climate change and one way to explore climate change is to analyse the change in LULC patterns. Modelling the Spatio-temporal pattern of LULC change requires the use of satellite remote sensing data and aerial photographs with different pre-processing steps. The aim of this research is to analyse the reciprocal effects of LUCC (Land Use and Cover Change) and the climate change on each other in the study area which covers part of Bristol, South Gloucestershire, Bath and Somerset in England for the period (1975-2015). LUCC is assessed using remote sensing data. Three sets of remotely sensed data, LanSAT-1 Multispectral Scanner (MSS) data obtained in (1975 and 1976), LanSAT-5 Thematic Mapper (TM) data obtained in (1984 and 1997), and LandSAT-7 Enhanced Thematic Mapper Plus (ETM+) acquired in (2003 and 2015), with a time span of forty years were used in the study. One of the most common problems in the satellite images is the presence of cloud covers. In this study, the cloud cover problem is handled using a novel algorithm, which is capable of reducing the cloud coverage in the classified images significantly. This study also examines a suite of possible photogrammetry techniques applicable to detect the change in LULC. At the moment photogrammertic techniques are used to derive the ground truth for supervised classification from the high resolution aerial photos which were provided by Ordnance Survey (contract number: 240215) and global mapper for the years in (2001 and 2014). After obtaining the classified images almost free of clouds, accuracy assessment is implemented with the derived classified images using confusion matrix at some ground truth points. Eight classes (Improved grassland, Built up areas and gardens, Arable and horticulture, Broad-leaved / mixed woodland, Coniferous woodland, Oceanic seas, Standing open water and reservoir, and Mountain; heath; bog) have been classified in the chosen study area. Also

  11. Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    SciTech Connect

    Thompson, David R.; McCubbin, Ian; Gao, Bo Cai; Green, Robert O.; Matthews, Alyssa A.; Mei, Fan; Meyer, Kerry G.; Platnick, Steven; Schmid, Beat; Tomlinson, Jason; Wilcox, Eric

    2016-08-12

    Shortwave Infrared imaging spectroscopy enables accurate remote mapping of cloud thermodynamic phase at high spatial resolution. We describe a measurement strategy to exploit signatures of liquid and ice absorption in cloud top apparent reflectance spectra from 1.4 to 1.8 μm. This signal is generally insensitive to confounding factors such as solar angles, view angles, and surface albedo. We first evaluate the approach in simulation and then apply it to airborne data acquired in the Calwater-2/ACAPEX campaign of Winter 2015. Here NASA’s “Classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) remotely observed diverse cloud formations while the U.S. Department of Energy ARM Aerial Facility G-1 aircraft measured cloud integral and microphysical properties in situ. Finally, the coincident measurements demonstrate good separation of the thermodynamic phases for relatively homogeneous clouds.

  12. Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, David R.; McCubbin, Ian; Gao, Bo Cai; Green, Robert O.; Matthews, Alyssa A.; Mei, Fan; Meyer, Kerry G.; Platnick, Steven; Schmid, Beat; Tomlinson, Jason; Wilcox, Eric

    2016-08-01

    Shortwave Infrared imaging spectroscopy enables accurate remote mapping of cloud thermodynamic phase at high spatial resolution. We describe a measurement strategy to exploit signatures of liquid and ice absorption in cloud top apparent reflectance spectra from 1.4 to 1.8 μm. This signal is generally insensitive to confounding factors such as solar angles, view angles, and surface albedo. We first evaluate the approach in simulation and then apply it to airborne data acquired in the Calwater-2/ACAPEX campaign of Winter 2015. Here NASA's "Classic" Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) remotely observed diverse cloud formations while the U.S. Department of Energy ARM Aerial Facility G-1 aircraft measured cloud integral and microphysical properties in situ. The coincident measurements demonstrate good separation of the thermodynamic phases for relatively homogeneous clouds.

  13. Use of cloud observations and mesoscale meteorology models to evaluate and improve cloud parameterizations. Technical progress report, 1 October 1993--30 December 1994

    SciTech Connect

    Walcek, C.J.

    1994-12-28

    The main goal of this research effort is to improve methods for calculating cloud cover within climate models. Until now, cloud cover and heights have been diagnosed from the US Air Force RTNEPH and 3DNEPH archive, and recently, CART measurements are available for analysis. Improved cloud cover formulations have been compared with existing climate model algorithms. The authors earlier conclusions were that relative humidity and convective potential were the strongest factors influencing cloud cover on regional scales. Therefore, they are refining and validating an innovative Single Column Model (SCM) cumulus parameterization for calculating heating and moistening tendencies, and precipitation rates attributable to subgrid-scale convection not resolved by climate models. This SCM will be tested and evaluated using tropical convective measurements (GATE) and they will also be applied to the incoming measurements from the Oklahoma ARM site. Further development and testing of this SCM will improve their ability to predict convective effects and cloud cover in climate models. They will quantify the influence of convection on cloud cover using convective measures derived from this SCM. The output of this research will be a family of validated algorithms for assessing cloud cover under a variety of stable, unstable, continental or oceanic conditions, and an improved cumulus parameterization scheme.

  14. Use of cloud observations and mesoscale meteorology models to evaluate and improve cloud parameterizations. Final technical progress report, December 1, 1991--September 30, 1996

    SciTech Connect

    Walcek, C.J.

    1996-12-28

    The main goal of this research effort is to improve methods for calculating cloud cover within climate models. Cloud cover observations are being used with standard meteorological observations to improve the ability to diagnose cloud cover in climate models. Until now, cloud cover and heights have been diagnosed from the US Air force RTNEPH and 3DNEPH archive, although recent CART measurements are also being analyzed. Improved cloud cover formulations have been compared with existing climate model algorithms. Recently, the authors are also refining and validating an innovative Single Column Model (SCM) cumulus parameterization for calculating heating and moistening tendencies, and precipitation rates attributable to subgrid-scale convection not resolved by climate models. This SCM will be tested and evaluated using tropical convective measurements (GATE) and the author will also use incoming measurements from the Oklahoma ARM site. Further development and testing of this SCM could improve the ability to predict convective effects in climate models. The author will quantify the influence of convection on cloud cover using convective measures derived from this SCM. The output of this research will be a family of validated algorithms for assessing cloud cover under a variety of stable, unstable, continental or oceanic conditions, and an improved cumulus parameterization scheme.

  15. Cloud microstructure studies

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  16. Variations inf Ninbus-7 cloud estimates. Part II: Regional changes

    SciTech Connect

    Weare, B.C. )

    1992-12-01

    Regional estimates of low, middle, high and total cloud amounts derived from bispectral measurements from Nimbus-7 have been analyzed for the six-year period April 1979 through March 1985. Fractional cloud cover for the three height categories was used to calculate a proxy mean cloud-top height. Intra- and interannual standard deviations of total cloud amount and mean cloud height show realistic patterns throughout most of the globe except at very high latitudes. Over much of the earth, intra-annual and interannual variations in total cloud amount are strongly positively correlated with variations in cloud height. Furthermore, both total cloud amount and cloud height variations are moderately correlated with sea surface temperature variations. The strongest correlations are positive in the tropics for both intra-annual and interannual variations. In middle latitudes, moderate negative correlations are associated with intra-annual variations, whereas moderate positive correlations occur on interannual time frames. In the tropics 1[degrees]C changes in temperature are statistically related to a change of total cloudiness of a least 2% and a change in cloud height of more than 0.5 km. 15 refs., 9 figs.

  17. Impact of decadal cloud variations on the Earth's energy budget

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Zelinka, Mark D.; Klein, Stephen A.

    2016-12-01

    Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth's energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and offer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low.

  18. A satellite observation test bed for cloud parameterization development

    NASA Astrophysics Data System (ADS)

    Lebsock, M. D.; Suselj, K.

    2015-12-01

    We present an observational test-bed of cloud and precipitation properties derived from CloudSat, CALIPSO, and the the A-Train. The focus of the test-bed is on marine boundary layer clouds including stratocumulus and cumulus and the transition between these cloud regimes. Test-bed properties include the cloud cover and three dimensional cloud fraction along with the cloud water path and precipitation water content, and associated radiative fluxes. We also include the subgrid scale distribution of cloud and precipitation, and radiaitive quantities, which must be diagnosed by a model parameterization. The test-bed further includes meterological variables from the Modern Era Retrospective-analysis for Research and Applications (MERRA). MERRA variables provide the initialization and forcing datasets to run a parameterization in Single Column Model (SCM) mode. We show comparisons of an Eddy-Diffusivity/Mass-FLux (EDMF) parameterization coupled to micorphsycis and macrophysics packages run in SCM mode with observed clouds. Comparsions are performed regionally in areas of climatological subsidence as well stratified by dynamical and thermodynamical variables. Comparisons demonstrate the ability of the EDMF model to capture the observed transitions between subtropical stratocumulus and cumulus cloud regimes.

  19. Star Clusters in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Gallagher, J. S., III

    2014-09-01

    The Magellanic Clouds (MC) are prime locations for studies of star clusters covering a full range in age and mass. This contribution briefly reviews selected properties of Magellanic star clusters, by focusing first on young systems that show evidence for hierarchical star formation. The structures and chemical abundance patterns of older intermediate age star clusters in the Small Magellanic Cloud (SMC) are a second topic. These suggest a complex history has affected the chemical enrichment in the SMC and that low tidal stresses in the SMC foster star cluster survival.

  20. Formation of Bidisperse Particle Clouds

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  1. Aerosol-Cloud-Drizzle-Turbulence Interactions in Boundary Layer Clouds

    DTIC Science & Technology

    2012-09-30

    and cloud observations in trade wind cumulus clouds using the CIRPAS aircraft with the cloud radar was designed and carried out. The observational...gradients in cloud properties off the coast. Further from the South Florida area of fair-weather cumulus clouds (Jan. 2008) where clouds with both...marine and continental characteristics were observed. This was followed by a set of observations made in 2010 of cumulus clouds in off of Barbados

  2. Evapotranspiration (ET) covers.

    PubMed

    Rock, Steve; Myers, Bill; Fiedler, Linda

    2012-01-01

    Evapotranspiration (ET) cover systems are increasingly being used at municipal solid waste (MSW) landfills, hazardous waste landfills, at industrial monofills, and at mine sites. Conventional cover systems use materials with low hydraulic permeability (barrier layers) to minimize the downward migration of water from the surface to the waste (percolation), ET cover systems use water balance components to minimize percolation. These cover systems rely on soil to capture and store precipitation until it is either transpired through vegetation or evaporated from the soil surface. Compared to conventional membrane or compacted clay cover systems, ET cover systems are expected to cost less to construct. They are often aesthetic because they employ naturalized vegetation, require less maintenance once the vegetative system is established, including eliminating mowing, and may require fewer repairs than a barrier system. All cover systems should consider the goals of the cover in terms of protectiveness, including the pathways of risk from contained material, the lifecycle of the containment system. The containment system needs to be protective of direct contact of people and animals with the waste, prevent surface and groundwater water pollution, and minimize release of airborne contaminants. While most containment strategies have been based on the dry tomb strategy of keeping waste dry, there are some sites where adding or allowing moisture to help decompose organic waste is the current plan. ET covers may work well in places where complete exclusion of precipitation is not needed. The U.S. EPA Alternative Cover Assessment Program (ACAP), USDOE, the Nuclear Regulatory Commission, and others have researched ET cover design and efficacy, including the history of their use, general considerations in their design, performance, monitoring, cost, current status, limitations on their use, and project specific examples. An on-line database has been developed with information

  3. Nursing home-acquired pneumonia.

    PubMed

    El Solh, Ali A

    2009-02-01

    Nursing home-acquired pneumonia (NHAP) was first described in 1978. Since then there has been much written regarding NHAP and its management despite the lack of well-designed studies in this patient population. The most characteristic features of patients with NHAP are the atypical presentation, which may lead to delay in diagnosis and therapy. The microbial etiology of pneumonia encompasses a wide spectrum that spans microbes recovered from patients with community-acquired pneumonia to organisms considered specific only to nosocomial settings. Decision to transfer a nursing home patient to an acute care facility depends on a host of factors, which include the level of staffing available at the nursing home, patients' advance directives, and complexity of treatment. The presence of risk factors for multidrug-resistant pathogens dictates approach to therapy. Prevention remains the cornerstone of reducing the incidence of disease. Despite the advance in medical services, mortality from NHAP remains high.

  4. Occupationally Acquired American Cutaneous Leishmaniasis

    PubMed Central

    Felinto de Brito, Maria Edileuza; Andrade, Maria Sandra; de Almeida, Éricka Lima; Medeiros, Ângela Cristina Rapela; Werkhäuser, Roberto Pereira; de Araújo, Ana Isabele Freitas; Brandão-Filho, Sinval Pinto; Paiva de Almeida, Alzira Maria; Gomes Rodrigues, Eduardo Henrique

    2012-01-01

    We report two occupationally acquired cases of American cutaneous leishmaniasis (ACL): one accidental laboratory autoinoculation by contaminated needlestick while handling an ACL lesion sample, and one acquired during field studies on bird biology. Polymerase chain reaction (PCR) assays of patient lesions were positive for Leishmania, subgenus Viannia. One isolate was obtained by culture (from patient 2 biopsy samples) and characterized as Leishmania (Viannia) naiffi through an indirect immunofluorescence assay (IFA) with species-specific monoclonal antibodies (mAbs) and by multilocus enzyme electrophoresis (MLEE). Patients were successfully treated with N-methyl-glucamine. These two cases highlight the potential risks of laboratory and field work and the need to comply with strict biosafety procedures in daily routines. The swab collection method, coupled with PCR detection, has greatly improved ACL laboratory diagnosis. PMID:23227369

  5. Distributed modeling of snow cover mass and energy balance in the Rheraya watershed (High Atlas, Morocco)

    NASA Astrophysics Data System (ADS)

    Marchane, Ahmed; Gascoin, Simon; Jarlan, Lionel; Hanich, Lahoucine

    2016-04-01

    The mountains of the High Moroccan Atlas represent an important source of water for the neighboring arid plains. Despite the importance of snow in the regional water balance, few studies were devoted to the modeling of the snow cover at the watershed scale. This type of modeling is necessary to characterize the contribution of snowmelt to water balance and understanding its sensitivity to natural and human-induced climate fluctuations. In this study, we applied a spatially-distributed model of the snowpack evolution (SnowModel, Liston & Elder 2006) on the Rheraya watershed (225 km²) in the High Atlas in order to simulate the mass and energy balance of the snow cover and the evolution of snow depth over a full season (2008-2009). The model was forced by 6 meteorological stations. The model was evaluated locally at the Oukaimeden meteorological station (3230 m asl) where snow depth is recorded continuously. To evaluate the model at the watershed scale we used the daily MODIS snow cover products and a series of 15 cloud-free optical images acquired by the FORMOSAT-2 satellite at 8-m resolution from February to June 2009. The results showed that the model is able to simulate the snow depth in the Oukaimeden station for the 2008-2009 season, and also to simulate the spatial and temporal variation of of the snow cover area in the watershed Rheraya. Based on the model output we examine the importance of the snow sublimation on the water balance at the watershed scale.

  6. [Acquired disorders of color vision].

    PubMed

    Lascu, Lidia; Balaş, Mihaela

    2002-01-01

    This article is a general view of acquired disorders of color vision. The revision of the best known methods and of the etiopathogenic classification is not very important in ophthalmology but on the other hand, the detection of the blue defect advertise and associated ocular pathology. There is a major interest in serious diseases as multiple sclerosis, AIDS, diabetes melitus, when the first ocular sign can be a defect in the color vision.

  7. Smart Point Cloud: Definition and Remaining Challenges

    NASA Astrophysics Data System (ADS)

    Poux, F.; Hallot, P.; Neuville, R.; Billen, R.

    2016-10-01

    Dealing with coloured point cloud acquired from terrestrial laser scanner, this paper identifies remaining challenges for a new data structure: the smart point cloud. This concept arises with the statement that massive and discretized spatial information from active remote sensing technology is often underused due to data mining limitations. The generalisation of point cloud data associated with the heterogeneity and temporality of such datasets is the main issue regarding structure, segmentation, classification, and interaction for an immediate understanding. We propose to use both point cloud properties and human knowledge through machine learning to rapidly extract pertinent information, using user-centered information (smart data) rather than raw data. A review of feature detection, machine learning frameworks and database systems indexed both for mining queries and data visualisation is studied. Based on existing approaches, we propose a new 3-block flexible framework around device expertise, analytic expertise and domain base reflexion. This contribution serves as the first step for the realisation of a comprehensive smart point cloud data structure.

  8. Cloud observations in Switzerland using hemispherical sky cameras

    NASA Astrophysics Data System (ADS)

    Wacker, Stefan; Gröbner, Julian; Zysset, Christoph; Diener, Laurin; Tzoumanikas, Panagiotis; Kazantzidis, Andreas; Vuilleumier, Laurent; Stöckli, Reto; Nyeki, Stephan; Kämpfer, Niklaus

    2015-01-01

    We present observations of total cloud cover and cloud type classification results from a sky camera network comprising four stations in Switzerland. In a comprehensive intercomparison study, records of total cloud cover from the sky camera, long-wave radiation observations, Meteosat, ceilometer, and visual observations were compared. Total cloud cover from the sky camera was in 65-85% of cases within ±1 okta with respect to the other methods. The sky camera overestimates cloudiness with respect to the other automatic techniques on average by up to 1.1 ± 2.8 oktas but underestimates it by 0.8 ± 1.9 oktas compared to the human observer. However, the bias depends on the cloudiness and therefore needs to be considered when records from various observational techniques are being homogenized. Cloud type classification was conducted using the k-Nearest Neighbor classifier in combination with a set of color and textural features. In addition, a radiative feature was introduced which improved the discrimination by up to 10%. The performance of the algorithm mainly depends on the atmospheric conditions, site-specific characteristics, the randomness of the selected images, and possible visual misclassifications: The mean success rate was 80-90% when the image only contained a single cloud class but dropped to 50-70% if the test images were completely randomly selected and multiple cloud classes occurred in the images.

  9. Covering the State Legislature

    ERIC Educational Resources Information Center

    Hook, Stephen C.

    1975-01-01

    Describes how journalism majors at Ball State University are required to cover the annual sessions of the Indiana legislature, and discusses some of the experiences and problems that were encountered. (RB)

  10. Global, seasonal cloud variations from satellite radiance measurements. II - Cloud properties and radiative effects

    NASA Technical Reports Server (NTRS)

    Rossow, William B.; Lacis, Andrew A.

    1990-01-01

    Cloud and surface radiative properties and their effects on the earth and surface radiation budgets are obtained based on global daily visible and IR radiance measurements. The magnitude of cloud property variations and their effects on radiation increase strongly with decreasing space/time scales. Cloud properties are systematically different between land and ocean, with ocean having larger cloud cover with somewhat larger optical thicknesses and lower cloud top altitudes. Although cloud variations appear to be the primary cause of regional radiation budget variability at 5-30 daytime scales, the effects of their seasonal variations at larger spatial scales are less important than the changes associated with changes in solar declination and atmospheric/surface temperatures. The largest seasonal variations in radiation occur in the 30-60 deg latitude band in each hemisphere. Although clouds have a net cooling effect on the global, annual mean radiation balance at both the top of the atmosphere and the surface, their net effect on regional, seasonal balances is much more varied.

  11. Land Cover Characterization Program

    USGS Publications Warehouse

    ,

    1997-01-01

    (2) identify sources, develop procedures, and organize partners to deliver data and information to meet user requirements. The LCCP builds on the heritage and success of previous USGS land use and land cover programs and projects. It will be compatible with current concepts of government operations, the changing needs of the land use and land cover data users, and the technological tools with which the data are applied.

  12. WATER COOLED RETORT COVER

    DOEpatents

    Ash, W.J.; Pozzi, J.F.

    1962-05-01

    A retort cover is designed for use in the production of magnesium metal by the condensation of vaporized metal on a collecting surface. The cover includes a condensing surface, insulating means adjacent to the condensing surface, ind a water-cooled means for the insulating means. The irrangement of insulation and the cooling means permits the magnesium to be condensed at a high temperature and in massive nonpyrophoric form. (AEC)

  13. Remote sensing of Arctic boundary layer clouds above snow surfaces

    NASA Astrophysics Data System (ADS)

    Ehrlich, André; Bierwirth, Eike; Wendisch, Manfred

    2015-04-01

    In the Arctic remote sensing of clouds using reflected solar radiation is mostly related to high uncertainties as the contrast between the bright sea ice and snow surface and the clouds is low. Additionally, uncertainties result from variation of the snow grain size which changes the absorption of solar radiation similarly to the size of cloud particles. This is a major issue for understanding the response of Arctic clouds to climate warming as the quantification of cloud properties in this remote region mostly relies on satellite observations. We used spectral radiation measurements of the Spectral Modular Airborne Radiation measurement sysTem (SMART-Albedometer) to improve common used cloud remote sensing algorithms in case of snow surfaces. The measurements were collected during the airborne research campaign Vertical distribution of ice in Arctic mixed-phase clouds (VERDI, April/May 2012) above the Canadian Beaufort where both sea ice covered and ice free ocean areas were present during the observation period. Based on the spectral absorption characteristics of snow and clouds (assuming to be dominated by the liquid fraction) a combination of wavelengths was found which allows to separate the impact of clouds and snow surface on the reflected radiation measured above the clouds. While snow grain size dominates the absorption at a wavelength of 1.0 μm, information on cloud optical thickness and cloud particle effective radius can be extracted at wavelengths of 1.7 μm and 2.1 μm, respectively. Based on radiative transfer simulations lookup tables for the retrieval algorithm were calculated and used to estimate the theoretical uncertainties of the retrieval. It was found that using ratios instead of absolute radiances reduces the uncertainties significantly. The new algorithm was applied to a specific case observed during the VERDI campaign where a stratocumulus clouds was located above an ice edge. It could be shown that the method works also over water

  14. Cloud forcing in Arctic polynyas: Climatology, parameterization, and modeling

    NASA Astrophysics Data System (ADS)

    Key, Erica

    Cloud and radiation data gathered in four polynyas across the Western Arctic span a decade of extreme environmental variability that culminated in the furthest retreat of sea ice cover on satellite record. These polynyas, oases of open water within the pack ice, are areas of intense surface exchange and serve as small-scale natural models of all active polar processes. Each of the studied polynyas is uniquely forced and maintained, resulting in an ensemble which representatively samples pan-Arctic variability. Cloud amount in each polynya, as analyzed to WMO standards by a meteorologist from time-lapse imagery collected using a hemispheric mirror, exceeded previous observational estimates of 80%. Calculations of surface cloud radiative forcing point to Arctic clouds' tendency toward scattering incoming shortwave radiation over re-emission of radiation in the longwave from cloud base. Sensitivity of this cloud forcing to variations in albedo, aerosol loading, and cloud microphysics, calculated with a polar-optimized radiative transfer model, indicate that small changes in snow and ice cover elicit stronger responses than heavy aerosol loading, changing particle effective radius, or liquid water content, especially at small solar zenith angles. Results obtained locally within polynyas are given regional relevance through the use of CASPR (Cloud and Surface Parameter Retrieval) algorithms and AVHRR Polar Pathfinder data.

  15. Separating Real and Apparent Effects of Cloud, Humidity, and Dynamics on Aerosol Optical Thickness near Cloud Edges

    NASA Technical Reports Server (NTRS)

    Jeong, Myeong-Jae; Li, Zhanqing

    2010-01-01

    Aerosol optical thickness (AOT) is one of aerosol parameters that can be measured on a routine basis with reasonable accuracy from Sun-photometric observations at the surface. However, AOT-derived near clouds is fraught with various real effects and artifacts, posing a big challenge for studying aerosol and cloud interactions. Recently, several studies have reported correlations between AOT and cloud cover, pointing to potential cloud contamination and the aerosol humidification effect; however, not many quantitative assessments have been made. In this study, various potential causes of apparent correlations are investigated in order to separate the real effects from the artifacts, using well-maintained observations from the Aerosol Robotic Network, Total Sky Imager, airborne nephelometer, etc., over the Southern Great Plains site operated by the U.S. Department of Energy's Atmospheric Radiation Measurement Program. It was found that aerosol humidification effects can explain about one fourth of the correlation between the cloud cover and AOT. New particle genesis, cloud-processed particles, atmospheric dynamics, and aerosol indirect effects are likely to be contributing to as much as the remaining three fourth of the relationship between cloud cover and AOT.

  16. Aerosol-cloud interactions studied with the chemistry-climate model EMAC

    NASA Astrophysics Data System (ADS)

    Chang, D. Y.; Tost, H.; Steil, B.; Lelieveld, J.

    2014-08-01

    This study uses the EMAC atmospheric chemistry-climate model to simulate cloud properties and estimate cloud radiative effects induced by aerosols. We have tested two prognostic cloud droplet nucleation parameterizations, i.e., the standard STN (osmotic coefficient model) and hybrid (HYB, replacing the osmotic coefficient by the κ hygroscopicity parameter) schemes to calculate aerosol hygroscopicity and critical supersaturation, and consider aerosol-cloud feedbacks with a focus on warm clouds. Both prognostic schemes (STN and HYB) account for aerosol number, size and composition effects on droplet nucleation, and are tested in combination with two different cloud cover parameterizations, i.e., a relative humidity threshold and a statistical cloud cover scheme (RH-CLC and ST-CLC). The use of either STN and HYB leads to very different cloud radiative effects, particularly over the continents. The STN scheme predicts highly effective CCN activation in warm clouds and hazes/fogs near the surface. The enhanced CCN activity increases the cloud albedo effect of aerosols and cools the Earth's surface. The cooler surface enhances the hydrostatic stability of the lower continental troposphere and thereby reduces convection and convective precipitation. In contrast, the HYB simulations calculate lower, more realistic CCN activation and consequent cloud albedo effect, leading to relatively stronger convection and high cloud formation. The enhanced high clouds increase greenhouse warming and moderate the cooling effect of the low clouds. With respect to the cloud radiative effects, the statistical ST-CLC scheme shows much higher sensitivity to aerosol-cloud coupling for all continental regions than the RH-CLC threshold scheme, most pronounced for low clouds but also for high clouds. Simulations of the short wave cloud radiative effect at the top of the atmosphere in ST-CLC are a factor of 2-8 more sensitive to aerosol coupling than the RH-CLC configurations. The long wave

  17. How Does the Global-Scale Atmosphere Circulation Produce Clouds?

    NASA Technical Reports Server (NTRS)

    Rossow, William B.

    1999-01-01

    Although clouds are produced by "micro-scale" processes, these processes operate as a response to global-scale atmospheric motions to produce the complex geographic distribution of clouds on Earth. One way to attack this larger-scale problem is to combine global-scale satellite observations of cloud property variations with global-scale determinations of the atmospheric circulation. Such a global data analysis can be used to describe the mean characteristics of clouds and their variations for comparison with global circulation models, to identify systematic relations among observed cloud properties and atmospheric motions, or to estimate, directly, the derivative relations of the processes at work using statistical life-cycle-composites of cloud system evolution. Another approach is to find what characteristics of the global atmospheric circulation are revealed in observed global-scale cloud variations. For the first time this type of analysis is possible with the advent of global, satellite-based cloud (ISCCP), precipitation (microwave-based), and water vapor (merged infrared and microwave) datasets, together with global wind datasets (ECMWF and NCEP re-analyses), all of which resolve features at least down to the upper end of the mesoscale and cover more than a decade. We report on some preliminary attempts to identify quantitative relationships between atmospheric motions and cloud properties that are relevant to cloud processes. Three examples are given: (1) cloud variations at the smallest scales and what they reveal about the nature of small-scale turbulence in the atmospheric boundary layer, (2) cloud variations at "moderate" weather-scales and what they reveal about meteorological storm systems, and (3) cloud variations at the largest scales and what they indicate about interannual variations of climate.

  18. How cloud radiative forcing could allow Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Abbot, D. S.

    2014-12-01

    Neoproterozoic, and possibly Paleoproterozoic, glaciations represent the most extreme climate events in post-Hadean Earth, and may link closely with the evolution of the atmosphere and life. According to the Snowball Earth hypothesis, the entire ocean was covered with ice during these events for a few million years, during which time volcanic CO2 increased enough to cause deglaciation. Geochemical proxy data and geochemical model calculations suggest that the maximum CO2 was 0.01-0.1 by volume, but early climate modeling suggested that the Snowball was not even close to deglaciation at CO2=0.2. Unless resolved, this discrepancy would be problematic for the Snowball Earth hypothesis. First, I will present results from six GCMs suggesting that positive cloud radiative forcing would likely have warmed a Snowball Earth enough to reduce the CO2 required for deglaciation by a factor of 10-100. Next, I will present results from a cloud resolving model run on a small domain that are consistent with the GCM results and allow us to understand the GCM behavior better. The cloud resolving model produces convection that extends vertically to a similar temperature as modern tropical convection. This convection produces clouds that resemble stratocumulus clouds under an inversion on modern Earth, which slowly dissipate by sedimentation of cloud ice. There is enough cloud ice for the clouds to be optically thick in the longwave, and the resulting cloud radiative forcing is similar to that produced in GCMs run in Snowball conditions. This result is robust to large changes in the cloud microphysics scheme because the cloud longwave forcing, which dominates the total forcing, is relatively insensitive to cloud amount and particle size. Taken together, these results from a hierarchy of models suggest that positive cloud radiative forcing would warm a Snowball Earth enough to allow deglaciation at a CO2 consistent with geochemical data.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. THE CALIFORNIA MOLECULAR CLOUD

    SciTech Connect

    Lada, Charles J.; Lombardi, Marco; Alves, Joao F. E-mail: mlombard@eso.or

    2009-09-20

    We present an analysis of wide-field infrared extinction maps of a region in Perseus just north of the Taurus-Auriga dark cloud complex. From this analysis we have identified a massive, nearby, but previously unrecognized, giant molecular cloud (GMC). Both a uniform foreground star density and measurements of the cloud's velocity field from CO observations indicate that this cloud is likely a coherent structure at a single distance. From comparison of foreground star counts with Galactic models, we derive a distance of 450 +- 23 pc to the cloud. At this distance the cloud extends over roughly 80 pc and has a mass of {approx} 10{sup 5} M{sub sun}, rivaling the Orion (A) molecular cloud as the largest and most massive GMC in the solar neighborhood. Although surprisingly similar in mass and size to the more famous Orion molecular cloud (OMC) the newly recognized cloud displays significantly less star formation activity with more than an order of magnitude fewer young stellar objects than found in the OMC, suggesting that both the level of star formation and perhaps the star formation rate in this cloud are an order of magnitude or more lower than in the OMC. Analysis of extinction maps of both clouds shows that the new cloud contains only 10% the amount of high extinction (A{sub K} > 1.0 mag) material as is found in the OMC. This, in turn, suggests that the level of star formation activity and perhaps the star formation rate in these two clouds may be directly proportional to the total amount of high extinction material and presumably high density gas within them and that there might be a density threshold for star formation on the order of n(H{sub 2}) {approx} a few x 10{sup 4} cm{sup -3}.

  1. OMMYDCLD: a New A-train Cloud Product that Co-locates OMI and MODIS Cloud and Radiance Parameters onto the OMI Footprint

    NASA Technical Reports Server (NTRS)

    Fisher, Brad; Joiner, Joanna; Vasilkov, Alexander; Veefkind, Pepijn; Platnick, Steven; Wind, Galina

    2014-01-01

    Clouds cover approximately 60% of the earth's surface. When obscuring the satellite's field of view (FOV), clouds complicate the retrieval of ozone, trace gases and aerosols from data collected by earth observing satellites. Cloud properties associated with optical thickness, cloud pressure, water phase, drop size distribution (DSD), cloud fraction, vertical and areal extent can also change significantly over short spatio-temporal scales. The radiative transfer models used to retrieve column estimates of atmospheric constituents typically do not account for all these properties and their variations. The OMI science team is preparing to release a new data product, OMMYDCLD, which combines the cloud information from sensors on board two earth observing satellites in the NASA A-Train: Aura/OMI and Aqua/MODIS. OMMYDCLD co-locates high resolution cloud and radiance information from MODIS onto the much larger OMI pixel and combines it with parameters derived from the two other OMI cloud products: OMCLDRR and OMCLDO2. The product includes histograms for MODIS scientific data sets (SDS) provided at 1 km resolution. The statistics of key data fields - such as effective particle radius, cloud optical thickness and cloud water path - are further separated into liquid and ice categories using the optical and IR phase information. OMMYDCLD offers users of OMI data cloud information that will be useful for carrying out OMI calibration work, multi-year studies of cloud vertical structure and in the identification and classification of multi-layer clouds.

  2. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II; Cloud Fraction and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Dong, Xiquan; Xi, Baike; Minnis, Patrick

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility are analyzed for determining the variability of cloud fraction and radiative forcing at several temporal scales between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layer low (0-3 km), middle (3-6 km), and high clouds (greater than 6 km) using ARM SGP ground-based paired lidar-radar measurements. Shortwave (SW), longwave (LW), and net cloud radiative forcings (CRF) are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements. The annual averages of total, and single-layer, nonoverlapped low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Total and low cloud amounts were greatest from December through March and least during July and August. The monthly variation of high cloud amount is relatively small with a broad maximum from May to August. During winter, total cloud cover varies diurnally with a small amplitude, mid-morning maximum and early evening minimum, and during summer it changes by more than 0.14 over the daily cycle with a pronounced early evening minimum. The diurnal variations of mean single-layer cloud cover change with season and cloud height. Annual averages of all-sky, total, and single-layer high, middle, and low LW CRFs are 21.4, 40.2, 16.7, 27.2, and 55.0 Wm(sup -2), respectively; and their SW CRFs are -41.5, -77.2, -37.0, -47.0, and -90.5 Wm(sup -2). Their net CRFs range from -20 to -37 Wm(sup -2). For all-sky, total, and low clouds, the maximum negative net CRFs of -40.1, -70, and -69.5 Wm(sup -2), occur during April; while the respective minimum values of -3.9, -5.7, and -4.6 Wm(sup -2), are found during December. July is the month having maximum negative net CRF of -46.2 Wm(sup -2) for middle clouds, and May has the maximum value of -45.9 Wm(sup -2) for high clouds. An

  3. Direct atmosphere opacity observations from CALIPSO provide new constraints on cloud-radiation interactions

    NASA Astrophysics Data System (ADS)

    Guzman, R.; Chepfer, H.; Noel, V.; Vaillant de Guélis, T.; Kay, J. E.; Raberanto, P.; Cesana, G.; Vaughan, M. A.; Winker, D. M.

    2017-01-01

    The spaceborne lidar CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) directly measures atmospheric opacity. In 8 years of CALIPSO observations, we find that 69% of vertical profiles penetrate through the complete atmosphere. The remaining 31% do not reach the surface, due to opaque clouds. The global mean altitude of full attenuation of the lidar beam (z_opaque) is 3.2 km, but there are large regional variations in this altitude. Of relevance to cloud-climate studies, the annual zonal mean longwave cloud radiative effect and annual zonal mean z_opaque weighted by opaque cloud cover are highly correlated (0.94). The annual zonal mean shortwave cloud radiative effect and annual zonal mean opaque cloud cover are also correlated (-0.95). The new diagnostics introduced here are implemented within a simulator framework to enable scale-aware and definition-aware evaluation of the LMDZ5B global climate model. The evaluation shows that the model overestimates opaque cloud cover (31% obs. versus 38% model) and z_opaque (3.2 km obs. versus 5.1 km model). In contrast, the model underestimates thin cloud cover (35% obs. versus 14% model). Further assessment shows that reasonable agreement between modeled and observed longwave cloud radiative effects results from compensating errors between insufficient warming by thin clouds and excessive warming due to overestimating both z_opaque and opaque cloud cover. This work shows the power of spaceborne lidar observations to directly constrain cloud-radiation interactions in both observations and models.

  4. Silicon photonics cloud (SiCloud)

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  5. Mapping folds and fractures in basement and cover rocks using UAV photogrammetry, Cape Liptrap and Cape Paterson, Victoria, Australia

    NASA Astrophysics Data System (ADS)

    Vollgger, Stefan A.; Cruden, Alexander R.

    2016-04-01

    Brittle and ductile deformation of alternating layers of Devonian sandstone and mudstone at Cape Liptrap, Victoria, Australia, resulted in upright folds with associated fold accommodation faults and multiple fracture sets. Structures were mapped at the Fold Stack locality at Cape Liptrap using high-resolution aerial photographs acquired by a digital camera mounted on an unmanned aerial vehicle (UAV). Subsequent photogrammetric modelling resulted in georeferenced spatial datasets (point cloud, digital elevation model and orthophotograph) with sub-cm resolution and cm accuracy, which were used to extract brittle and ductile structure orientation data. An extensive dataset of bedding measurements derived from the dense point cloud was used to compute a 3D implicit structural trend model to visualise along-strike changes of Devonian (Tabberabberan) folds at the Fold Stack locality and to estimate bulk shortening strain. This model and newly collected data indicate that first generation shallowly south-southwest plunging upright folds were gently refolded about a steeply plunging/subvertical fold axis during a Devonian low-strain north-south shortening event. This also led to the local tightening of first generation folds and possibly strike-slip movement along regional scale faults. In order to distinguish fractures associated with Devonian compression from those that formed during Cretaceous extension and later inversion, we compared the five fracture sets defined at Cape Liptrap to previously mapped joints and faults within the overlying sedimentary cover rocks of the Cretaceous Strzelecki Group (Gippsland Basin), which crop out nearby. An east-southeast trending fracture set that is not evident in the Strzelecki Group can be linked to the formation of Devonian folds. Additionally, hinge line traces extracted from the Fold Stack dataset are aligned parallel to a dominant fracture set within the overlying cover sediments. This suggests that basement structures (folds

  6. Equatorial cloud level convection on Venus

    NASA Astrophysics Data System (ADS)

    Lee, Yeon Joo; Imamura, Takeshi; Sugiyama, Koichiro; Sato, Takao M.; Maejima, Yasumitsu

    2016-10-01

    In the equatorial region on Venus, a clear cloud top morphology difference depending on solar local time has been observed through UV images. Laminar flow shaped clouds are shown on the morning side, and convective-like cells on the afternoon side (Titov et al. 2012). Baker et al. (1998) suggested that deep convective motions in the low-to-middle cloud layers at the 40-60 km range can explain cellular shapes. Imamura et al. (2014), however argued that this cannot be a reason, as convection in the low-to-middle cloud layers can be suppressed near sub solar regions due to a stabilizing effect by strong solar heating. We suggest that the observed feature may be related to strong solar heating at local noon time (Lee et al. 2015). Horizontal uneven distribution of an unknown UV absorber and/or cloud top structure may trigger horizontal convection (Toigo et al. 1994). In order to examine these possibilities, we processed 1-D radiative transfer model calculations from surface to 100 km altitude (SHDOM, Evans 1998), which includes clouds at 48-71 km altitudes (Crisp et al. 1986). The results on the equatorial thermal cooling and solar heating profiles were employed in a 2D fluid dynamic model calculation (CReSS, Tsuboki and Sakakibara 2007). The calculation covered an altitude range of 40-80 km and a 100-km horizontal distance. We compared three conditions; an 'effective' global circulation condition that cancels out unbalanced net radiative energy at equator, a condition without such global circulation effect, and the last condition assumed horizontally inhomogeneous unknown UV absorber distribution. Our results show that the local time dependence of lower level cloud convection is consistent with Imamura et al.'s result, and suggest a possible cloud top level convection caused by locally unbalanced net energy and/or horizontally uneven solar heating. This may be related to the observed cloud morphology in UV images. The effective global circulation condition, however

  7. Molecular Clouds in the Magellanic System

    NASA Astrophysics Data System (ADS)

    Chin, Y.

    Temperature, density, metallicity, and radiation field are important parameters that characterize the physical and chemical state of molecular clouds. In order to understand physics and chemistry, it is therefore necessary to observe and analyse molecular clouds in a variety of ennvironments and to combine observational data with results from model calculations. Observationally, it is possible to vary the first two parameters (temperature and density) within our Milky Way by observing clouds in different locations. The metallicity, however, does not change drastically in the plane of the Milky Way. As two of the closest galaxies, the Magellanic Clouds provide metallicities which are factors of 3 and 10 lower (Westerlund 1991). If we treat our Galaxy as a "chemically" evolved system, the Magellanic System are without doubt still in an early stage of "chemical" evolution, with elemental abundances that may resemble those that characterize larger galaxies at high redshifts. In addition, the radiation field is stronger than in the solar neighborhood. As a consequence of low metallicities and strong UV radiation field, the Magellanic Clouds are characterized by low dust-to-gas mass ratios. They are thus a "laboratory" where we can study molecular clouds with exotic boundary conditions and it is easy to foresee that detailed observations will have a great impact on our general knowledge of astrochemistry and astrophysice of interstellar clouds. To date, it is possible to carry out a detailed molecular study of Magellanic Cloud cores located at distances of 50 - 60 kpc. Two prominent molecular clouds -- one in the LMC and one in the SMC -- have been observed. Preliminary results are presented. On the other hand, searches for a variety of molecules in the LMC & SMC have been made (e.g. Johansson et al. 1994; Chin et al. 1997, 1998) so far mostly towards molecular cores associated with prominent HII regions. This does not cover, however, the entire range of physical and

  8. What is a Cloud?

    NASA Astrophysics Data System (ADS)

    Long, C. N.; Wu, W.

    2013-12-01

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

  9. Acquired Upper Extremity Growth Arrest.

    PubMed

    Gauger, Erich M; Casnovsky, Lauren L; Gauger, Erica J; Bohn, Deborah C; Van Heest, Ann E

    2016-09-29

    This study reviewed the clinical history and management of acquired growth arrest in the upper extremity in pediatric patients. The records of all patients presenting from 1996 to 2012 with radiographically proven acquired growth arrest were reviewed. Records were examined to determine the etiology and site of growth arrest, management, and complications. Patients with tumors or hereditary etiology were excluded. A total of 44 patients (24 boys and 20 girls) with 51 physeal arrests who presented at a mean age of 10.6 years (range, 0.8-18.2 years) were included in the study. The distal radius was the most common site (n=24), followed by the distal humerus (n=8), metacarpal (n=6), distal ulna (n=5), proximal humerus (n=4), radial head (n=3), and olecranon (n=1). Growth arrest was secondary to trauma (n=22), infection (n=11), idiopathy (n=6), inflammation (n=2), compartment syndrome (n=2), and avascular necrosis (n=1). Twenty-six patients (59%) underwent surgical intervention to address deformity caused by the physeal arrest. Operative procedures included ipsilateral unaffected bone epiphysiodesis (n=21), shortening osteotomy (n=10), lengthening osteotomy (n=8), excision of physeal bar or bone fragment (n=2), angular correction osteotomy (n=1), and creation of single bone forearm (n=1). Four complications occurred; 3 of these required additional procedures. Acquired upper extremity growth arrest usually is caused by trauma or infection, and the most frequent site is the distal radius. Growth disturbances due to premature arrest can be treated effectively with epiphysiodesis or osteotomy. In this series, the specific site of anatomic growth arrest was the primary factor in determining treatment. [Orthopedics. 201x; xx(x):xx-xx.].

  10. SERM Forest Cover Data of Saskatchewan in Vector Format

    NASA Technical Reports Server (NTRS)

    Nickeson, Jaime; Hall, Forrest G. (Editor); Gruszka, Fern

    2000-01-01

    This data set was acquired as a general provincial scale vegetation cover map and an alternative to the very detailed vector forest cover data available for the BOREAS SSA. The data set was prepared by SERM-FBIU, and is a condensed forest cover type map of Saskatchewan at a scale of 1:1,000,000. The date of the maps from which this data set was generated is unknown; it is estimated that the forest cover maps were made in the mid-1980s.

  11. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN; Wielicki, Bruce A.; Ginger, Kathryn M.

    1994-01-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  12. The interpretation of remotely sensed cloud properties from a model paramterization perspective

    SciTech Connect

    Harshvardhan; Wielicki, B.A.; Ginger, K.M. |

    1994-12-01

    A study has been made of the relationship between mean cloud radiative properties and cloud fraction in stratocumulus cloud systems. The analysis is of several Land Resources Satellite System (LANDSAT) images and three hourly International Satellite Cloud Climatology Project (ISCCP) C-1 data during daylight hours for two grid boxes covering an area typical of a general circulation model (GCM) grid increment. Cloud properties were inferred from the LANDSAT images using two thresholds and several pixel resolutions ranging from roughly 0.0625 km to 8 km. At the finest resolution, the analysis shows that mean cloud optical depth (or liquid water path) increases somewhat with increasing cloud fraction up to 20% cloud coverage. More striking, however, is the lack of correlation between the two quantities for cloud fractions between roughly 0.2 and 0.8. When the scene is essentially overcast, the mean cloud optical tends to be higher. Coarse resolution LANDSAT analysis and the ISCCP 8-km data show lack of correlation between mean cloud optical depth and cloud fraction for coverage less than about 90%. This study shows that there is perhaps a local mean liquid water path (LWP) associated with partly cloudy areas of stratocumulus clouds. A method has been suggested to use this property to construct the cloud fraction paramterization in a GCM when the model computes a grid-box-mean LWP.

  13. Cloud retrievals from satellite data using optimal estimation: evaluation and application to ATSR

    NASA Astrophysics Data System (ADS)

    Poulsen, C. A.; Watts, P. D.; Thomas, G. E.; Sayer, A. M.; Siddans, R.; Grainger, R. G.; Lawrence, B. N.; Campmany, E.; Dean, S. M.; Arnold, C.

    2011-04-01

    Clouds play an important role in balancing the Earth's radiation budget. Clouds reflect sunlight which cools the Earth, and also trap infrared radiation in the same manner as greenhouse gases. Changes in cloud cover and cloud properties over time can have important consequences for climate. The Intergovernmental Panel for Climate Change (IPCC) has identified current gaps in the understanding of clouds and related climate feedback processes as a leading cause of uncertainty in forecasting climate change. In this paper we present an algorithm that uses optimal estimation to retrieve cloud parameters from satellite multi-spectral imager data, in particular the Along-Track Scanning Radiometers ATSR-2 and AATSR. The cloud parameters retrieved are the cloud top pressure, cloud optical depth, cloud effective radius, cloud fraction and cloud phase. Importantly, the technique also provides estimated errors along with the retrieved values and quantifies the consistency between retrieval representation of cloud and satellite radiances. This should enable the effective use of the products for comparison with climate models or for exploitation via data assimilation. The technique is evaluated by performing retrieval simulations for a variety of simulated single layer and multi-layer conditions. Examples of applying the algorithm to ATSR-2 flight data are presented and the sensitivity of the retrievals assessed. This algorithm has been applied to both ATSR-2 and AATSR visible and infrared measurements in the context of the GRAPE (Global Retrieval and cloud Product Evaluation) project to produce a 14 year consistent record for climate research (Sayer et al., 2010).

  14. Insights into low-latitude cloud feedbacks from high-resolution models.

    PubMed

    Bretherton, Christopher S

    2015-11-13

    Cloud feedbacks are a leading source of uncertainty in the climate sensitivity simulated by global climate models (GCMs). Low-latitude boundary-layer and cumulus cloud regimes are particularly problematic, because they are sustained by tight interactions between clouds and unresolved turbulent circulations. Turbulence-resolving models better simulate such cloud regimes and support the GCM consensus that they contribute to positive global cloud feedbacks. Large-eddy simulations using sub-100 m grid spacings over small computational domains elucidate marine boundary-layer cloud response to greenhouse warming. Four observationally supported mechanisms contribute: 'thermodynamic' cloudiness reduction from warming of the atmosphere-ocean column, 'radiative' cloudiness reduction from CO2- and H2O-induced increase in atmospheric emissivity aloft, 'stability-induced' cloud increase from increased lower tropospheric stratification, and 'dynamical' cloudiness increase from reduced subsidence. The cloudiness reduction mechanisms typically dominate, giving positive shortwave cloud feedback. Cloud-resolving models with horizontal grid spacings of a few kilometres illuminate how cumulonimbus cloud systems affect climate feedbacks. Limited-area simulations and superparameterized GCMs show upward shift and slight reduction of cloud cover in a warmer climate, implying positive cloud feedbacks. A global cloud-resolving model suggests tropical cirrus increases in a warmer climate, producing positive longwave cloud feedback, but results are sensitive to subgrid turbulence and ice microphysics schemes.

  15. The inhibition of acquired fear.

    PubMed

    Izquierdo, Iván; Cammarota, Martín; Vianna, Mónica M R; Bevilaqua, Lía R M

    2004-01-01

    A conditioned stimulus (CS) associated with a fearsome unconditioned stimulus (US) generates learned fear. Acquired fear is at the root of a variety of mental disorders, among which phobias, generalized anxiety, the posttraumatic stress disorder (PTSD) and some forms of depression. The simplest way to inhibit learned fear is to extinguish it, which is usually done by repeatedly presenting the CS alone, so that a new association, CS-"no US", will eventually overcome the previously acquired CS-US association. Extinction was first described by Pavlov as a form of "internal inhibition" and was recommended by Freud and Ferenczi in the 1920s (who called it "habituation") as the treatment of choice for phobic disorders. It is used with success till this day, often in association with anxiolytic drugs. Extinction has since then been applied, also successfully and also often in association with anxiolytics, to the treatment of panic, generalized anxiety disorders and, more recently, PTSD. Extinction of learned fear involves gene expression, protein synthesis, N-methyl-D-aspartate (NMDA) receptors and signaling pathways in the hippocampus and the amygdala at the time of the first CS-no US association. It can be enhanced by increasing the exposure to the "no US" component at the time of behavioral testing, to the point of causing the complete uninstallment of the original fear response. Some theorists have recently proposed that reiteration of the CS alone may induce a reconsolidation of the learned behavior instead of its extinction. Reconsolidation would preserve the original memory from the labilization induced by its retrieval. If true, this would of course be disastrous for the psychotherapy of fear-motivated disorders. Here we show that neither the CS nor retrieval cause anything remotely like reconsolidation, but just extinction. In fact, our findings indicate that the reconsolidation hypothesis is essentially incorrect, at least for the form of contextual fear most

  16. Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites

    NASA Technical Reports Server (NTRS)

    King, Michael D.; Platnick, Steven; Menzel, W. Paul; Ackerman, Steven A.; Hubanks, Paul A.

    2012-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched aboard the Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. A comprehensive set of remote sensing algorithms for the retrieval of cloud physical and optical properties have enabled over twelve years of continuous observations of cloud properties from Terra and over nine years from Aqua. The archived products from these algorithms include 1 km pixel-level (Level-2) and global gridded Level-3 products. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. Results include the latitudinal distribution of cloud optical and radiative properties for both liquid water and ice clouds, as well as latitudinal distributions of cloud top pressure and cloud top temperature. MODIS finds the cloud fraction, as derived by the cloud mask, is nearly identical during the day and night, with only modest diurnal variation. Globally, the cloud fraction derived by the MODIS cloud mask is approx.67%, with somewhat more clouds over land during the afternoon and less clouds over ocean in the afternoon, with very little difference in global cloud cover between Terra and Aqua. Overall, cloud fraction over land is approx.55%, with a distinctive seasonal cycle, whereas the ocean cloudiness is much higher, around 72%, with much reduced seasonal variation. Cloud top pressure and temperature have distinct spatial and temporal patterns, and clearly reflect our understanding of the global cloud distribution. High clouds are especially prevalent over the northern hemisphere continents between 30 and 50 . Aqua and Terra have comparable zonal cloud top pressures, with Aqua having somewhat higher clouds (cloud top pressures lower by 100 hPa) over land due to

  17. Sensitivity of PARASOL multi-angle photopolarimetric aerosol retrievals to cloud contamination

    NASA Astrophysics Data System (ADS)

    Stap, F. A.; Hasekamp, O. P.; Röckmann, T.

    2015-03-01

    An important problem in satellite remote sensing of aerosols is related to the need to perform an adequate cloud screening. If a cloud screening is applied that is not strict enough, the ground scene has the probability of residual cloud cover which causes large errors on the retrieved aerosol parameters. On the other hand, if the cloud-screening procedure is too strict, too many clear sky cases, especially near-cloud scenes, will falsely be flagged cloudy. The detrimental effects of cloud contamination as well as the importance of aerosol cloud interactions that can be studied in these near-cloud scenes call for new approaches to cloud screening. Multi-angle multi-wavelength photopolarimetric measurements have a unique capability to distinguish between scattering by (liquid) cloud droplets and aerosol particles. In this paper the sensitivity of aerosol retrievals from multi-angle photopolarimetric measurements to cloud contamination is investigated and the ability to intrinsically filter the cloud-contaminated scenes based on a goodness-of-fit criteria is evaluated. Hereto, an aerosol retrieval algorithm is applied to a partially clouded over-ocean synthetic data set as well as non-cloud-screened over-ocean POLDER-3/PARASOL observations. It is found that a goodness-of-fit filter, together with a filter on the coarse mode refractive index (mrcoarse > 1.335) and a cirrus screening, adequately rejects the cloud-contaminated scenes. No bias or larger SD are found in the retrieved parameters for this intrinsic cloud filter compared to the parameters retrieved in a priori cloud-screened data set (using MODIS/AQUA cloud masks) of PARASOL observations. Moreover, less high-aerosol load scenes are misinterpreted as cloud contaminated. The retrieved aerosol optical thickness, single scattering albedo and Ångström exponent show good agreement with AERONET observations. Furthermore, the synthetic retrievals give confidence in the ability of the algorithm to correctly

  18. Measurement of the effect of Amazon smoke on inhibition of cloud formation.

    PubMed

    Koren, Ilan; Kaufman, Yoram J; Remer, Lorraine A; Martins, Jose V

    2004-02-27

    Urban air pollution and smoke from fires have been modeled to reduce cloud formation by absorbing sunlight, thereby cooling the surface and heating the atmosphere. Satellite data over the Amazon region during the biomass burning season showed that scattered cumulus cloud cover was reduced from 38%in clean conditions to 0%for heavy smoke (optical depth of 1.3). This response to the smoke radiative effect reverses the regional smoke instantaneous forcing of climate from -28 watts per square meter in cloud-free conditions to +8 watts per square meter once the reduction of cloud cover is accounted for.

  19. Intercomparison of independent estimates of cloud properties from simultaneous satellite observations

    NASA Technical Reports Server (NTRS)

    Coakley, J. A., Jr.; Chahine, M. T.; Susskind, J.

    1986-01-01

    Preliminary results are reported from comparisons between two techniques for determining the cloud cover fraction within a satellite remote sensing scene. One method (PRM) quantifies cloud-free and cloud-filled areas on the bases of physical relationships between temperature, humidity, cloud optical properties and emitted radiation. The other approach (RSSM) derives the fractional cover from the spatial structure of radiances detected by the sensor. The HIRS (PRM) and the AVHRR (RSSM) instruments, tuned to IR wavelengths, on the TIROS-N polar-orbiting satellite furnished the trial data. Sample results are provided from scans at 15 and 11 microns over the Pacific Ocean.

  20. Assessment of aerosol-cloud interactions during southern African biomass burning activity, employing cloud parameterizations

    NASA Astrophysics Data System (ADS)

    Wiston, Modise; McFiggans, Gordon; Schultz, David

    2015-04-01

    In this study, we perform a simulation of the spatial distributions of particle and gas concentrations from a significantly large source of pollution event during a dry season in southern Africa and their interactions with cloud processes. Specific focus is on the extent to which cloud-aerosol interactions are affected by various inputs (i.e. emissions) and parameterizations and feedback mechanisms in a coupled mesoscale chemistry-meteorology model -herein Weather Research and Forecasting model with chemistry (WRF-Chem). The southern African dry season (May-Sep) is characterised by biomass burning (BB) type of pollution. During this period, BB particles are frequently observed over the subcontinent, at the same time a persistent deck of stratocumulus covers the south West African coast, favouring long-range transport over the Atlantic Ocean of aerosols above clouds. While anthropogenic pollutants tend to spread more over the entire domain, biomass pollutants are concentrated around the burning areas, especially the savannah and tropical rainforest of the Congo Basin. BB is linked to agricultural practice at latitudes south of 10° N. During an intense burning event, there is a clear signal of strong interactions of aerosols and cloud microphysics. These species interfere with the radiative budget, and directly affect the amount of solar radiation reflected and scattered back to space and partly absorbed by the atmosphere. Aerosols also affect cloud microphysics by acting as cloud condensation nuclei (CCN), modifying precipitation pattern and the cloud albedo. Key area is to understand the role of pollution on convective cloud processes and its impacts on cloud dynamics. The hypothesis is that an environment of potentially high pollution enables the probability of interactions between co-located aerosols and cloud layers. To investigate this hypothesis, we outline an approach to integrate three elements: i) focusing on regime(s) where there are strong indications of

  1. Total and partial cloud amount detection during summer 2005 at Westerland (Sylt, Germany)

    NASA Astrophysics Data System (ADS)

    Schade, N. H.; Macke, A.; Sandmann, H.; Stick, C.

    2009-02-01

    The detection of cloudiness is investigated by means of partial and total cloud amount estimations from pyrgeometer radiation measurements and visible all-sky imager observations. The measurements have been performed in Westerland, a seaside resort on the North Sea island of Sylt, Germany, during summer 2005. An improvement to previous studies on this subject resulting in the first time partial cloud amounts (PCAs), defined as cloud amounts without high clouds calculated from longwave downward radiation (LDR) according to the APCADA algorithm (Dürr and Philipona, 2004), are validated against both human observations from the National Meteorological Servive DWD at the nearby airport of Sylt and digital all-sky imaging. The aim is to establish the APCADA scheme at a coastal midlatitude site for longterm observations of cloud cover and to quantify errors resulting from the different methods of detecting cloudiness. Differences between the resulting total cloud amounts (TCAs), defined as cloud amount for all-cloud situations, derived from the camera images and from human observations are within ±1 octa in 72% and within ±2 octa in 85% of the cases. Compared to human observations, PCA measurements, according to APCADA, underestimate the observed cloud cover in 47% of all cases and the differences are within ±1 octa in 60% and ±2 octa in 74% of all cases. Since high cirrus clouds can not be derived from LDR, separate comparisons for all cases without high clouds have been performed showing an agreement within ±1(2) octa in 73(90)% for PCA and also for camera-derived TCA. For this coastal mid-latitude site under investigation, we find similar though slightly smaller agreements to human observations as reported by Dürr and Philipona (2004). Though limited to daytime, the cloud cover retrievals from the sky imager are not really affected by cirrus clouds and provide a more reliable cloud climatology for all-cloud conditions than APCADA.

  2. Cloud Forensics Issues

    DTIC Science & Technology

    2014-07-01

    I N S T I T U T E F O R D E F E N S E A N A L Y S E S Cloud Forensics Issues William R. Simpson Coimbatore Chandersekaran 1 July 2014 IDA...252.227-7013 (a)(16) [Sep 2011]. Cloud Forensics Issues William R Simpson and Coimbatore Chandersekaran Abstract— Forensics is...offerings of cloud capabilities have not provided security, monitoring or attribution that would allow an effective forensics investigation. The high

  3. Cryptographic Cloud Storage

    NASA Astrophysics Data System (ADS)

    Kamara, Seny; Lauter, Kristin

    We consider the problem of building a secure cloud storage service on top of a public cloud infrastructure where the service provider is not completely trusted by the customer. We describe, at a high level, several architectures that combine recent and non-standard cryptographic primitives in order to achieve our goal. We survey the benefits such an architecture would provide to both customers and service providers and give an overview of recent advances in cryptography motivated specifically by cloud storage.

  4. Ammonia Clouds on Jupiter

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

  5. The ESA Cloud_cci project: generation of multi-decadal, consistent, global data sets of cloud properties with uncertainty information

    NASA Astrophysics Data System (ADS)

    Stapelberg, Stefan; Finkensieper, Stephan; Stengel, Martin; Schlundt, Cornelia; Sus, Oliver; Hollmann, Rainer; Poulsen, Caroline; ESA Cloud cci Team

    2016-04-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  6. The ESA Cloud_cci Project: Generation of Multi-Decadal, Consistent, Global Data Sets of Cloud Properties with Uncertainty Information

    NASA Astrophysics Data System (ADS)

    Stapelberg, S.; Stengel, M.; Schlundt, C.; Sus, O.; Hollmann, R.; Poulsen, C. A.

    2015-12-01

    In 2010 the ESA Climate Change Initiative (CCI) Cloud project was started along with 12 other CCI projects covering atmospheric, oceanic and terrestrial "essential climate variables (ECV)". The main goal is the generation of satellite-based climate data records that meet the challenging requirements of the Global Climate Observing System. The objective target within the ESA Cloud_cci project is the generation of long-term coherent cloud property datasets covering 33 years that also provide mathematically consistent uncertainty information following the optimal estimation (OE) retrieval theory. The cloud properties considered are cloud mask, cloud top level estimates, cloud thermodynamic phase, cloud optical thickness, cloud effective radius and post processed parameters such as cloud liquid and ice water path. In this presentation we will discuss the benefit of using an optimal estimation retrieval framework, which provides consistence among the retrieved cloud variables and pixel-based uncertainty estimates based on different passive instruments such as AVHRR, MODIS and AATSR. We will summarize the results of the project so far along with ongoing further developments that currently take place. Our results will be compared with other well-established satellite data records, surface observations and cloud climatologies (e.g., PATMOS-X, ISCCP, CLARA-A2, MODIS collection 6, SYNOP). These inter-comparison results will indicate the strengths and weaknesses of the Cloud_cci datasets. Finally, we will present long-term time series of the retrieved cloud variables for AVHRR (1982-2014) that enable global, multi-decadal analyses of clouds.

  7. A CERES-like Cloud Property Climatology Using AVHRR Data

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Bedka, K. M.; Yost, C. R.; Trepte, Q.; Bedka, S. T.; Sun-Mack, S.; Doelling, D.

    2015-12-01

    Clouds affect the climate system by modulating the radiation budget and distributing precipitation. Variations in cloud patterns and properties are expected to accompany changes in climate. The NASA Clouds and the Earth's Radiant Energy System (CERES) Project developed an end-to-end analysis system to measure broadband radiances from a radiometer and retrieve cloud properties from collocated high-resolution MODerate-resolution Imaging Spectroradiometer (MODIS) data to generate a long-term climate data record of clouds and clear-sky properties and top-of-atmosphere radiation budget. The first MODIS was not launched until 2000, so the current CERES record is only 15 years long at this point. The core of the algorithms used to retrieve the cloud properties from MODIS is based on the spectral complement of the Advanced Very High Resolution Radiometer (AVHRR), which has been aboard a string of satellites since 1978. The CERES cloud algorithms were adapted for application to AVHRR data and have been used to produce an ongoing CERES-like cloud property and surface temperature product that includes an initial narrowband-based radiation budget. This presentation will summarize this new product, which covers nearly 37 years, and its comparability with cloud parameters from CERES, CALIPSO, and other satellites. Examples of some applications of this dataset are given and the potential for generating a long-term radiation budget CDR is also discussed.

  8. Reusable pipe flange covers

    DOEpatents

    Holden, James Elliott; Perez, Julieta

    2001-01-01

    A molded, flexible pipe flange cover for temporarily covering a pipe flange and a pipe opening includes a substantially round center portion having a peripheral skirt portion depending from the center portion, the center portion adapted to engage a front side of the pipe flange and to seal the pipe opening. The peripheral skirt portion is formed to include a plurality of circumferentially spaced tabs, wherein free ends of the flexible tabs are formed with respective through passages adapted to receive a drawstring for pulling the tabs together on a back side of the pipe flange.

  9. SparkClouds: visualizing trends in tag clouds.

    PubMed

    Lee, Bongshin; Riche, Nathalie Henry; Karlson, Amy K; Carpendale, Sheelash

    2010-01-01

    Tag clouds have proliferated over the web over the last decade. They provide a visual summary of a collection of texts by visually depicting the tag frequency by font size. In use, tag clouds can evolve as the associated data source changes over time. Interesting discussions around tag clouds often include a series of tag clouds and consider how they evolve over time. However, since tag clouds do not explicitly represent trends or support comparisons, the cognitive demands placed on the person for perceiving trends in multiple tag clouds are high. In this paper, we introduce SparkClouds, which integrate sparklines into a tag cloud to convey trends between multiple tag clouds. We present results from a controlled study that compares SparkClouds with two traditional trend visualizations—multiple line graphs and stacked bar charts—as well as Parallel Tag Clouds. Results show that SparkClouds ability to show trends compares favourably to the alternative visualizations.

  10. Foodborne listeriosis acquired in hospitals.

    PubMed

    Silk, Benjamin J; McCoy, Morgan H; Iwamoto, Martha; Griffin, Patricia M

    2014-08-15

    Listeriosis is characterized by bacteremia or meningitis. We searched for listeriosis case series and outbreak investigations published in English by 2013, and assessed the strength of evidence for foodborne acquisition among patients who ate hospital food. We identified 30 reports from 13 countries. Among the case series, the median proportion of cases considered to be hospital-acquired was 25% (range, 9%-67%). The median number of outbreak-related illnesses considered to be hospital-acquired was 4.0 (range, 2-16). All patients were immunosuppressed in 18 of 24 (75%) reports with available data. Eight outbreak reports with strong evidence for foodborne acquisition in a hospital implicated sandwiches (3 reports), butter, precut celery, Camembert cheese, sausage, and tuna salad (1 report each). Foodborne acquisition of listeriosis among hospitalized patients is well documented internationally. The number of listeriosis cases could be reduced substantially by establishing hospital policies for safe food preparation for immunocompromised patients and by not serving them higher-risk foods.

  11. Cloud Computing: An Overview

    NASA Astrophysics Data System (ADS)

    Qian, Ling; Luo, Zhiguo; Du, Yujian; Guo, Leitao

    In order to support the maximum number of user and elastic service with the minimum resource, the Internet service provider invented the cloud computing. within a few years, emerging cloud computing has became the hottest technology. From the publication of core papers by Google since 2003 to the commercialization of Amazon EC2 in 2006, and to the service offering of AT&T Synaptic Hosting, the cloud computing has been evolved from internal IT system to public service, from cost-saving tools to revenue generator, and from ISP to telecom. This paper introduces the concept, history, pros and cons of cloud computing as well as the value chain and standardization effort.

  12. Building a 15-Year Cloud Climatology using Lidar in Space Observations: CALIOP and CloudSat now, EarthCARE next.

    NASA Astrophysics Data System (ADS)

    Reverdy, M.; Chepfer, H.; Donovan, D. P.; Noel, V.; Marchand, R.; Cesana, G.; Hoareau, C.; Chiriaco, M.; Bastin, S.

    2014-12-01

    Today, the CALIOP lidar and CloudSat radar have collected more than seven years of observations, and willhopefully still operate in 2016, after the EarthCARE-ATLID/CPR launch. Lidars and Radars in space providecutting edge information on the detailed vertical structure of clouds: a key element for both the evaluation ofthe description of clouds in climate models, and the survey of the clouds inter-annual evolution in variousclimatic conditions (El Nino, variation of North Atlantic Oscillations, polar regions, etc). For this purpose,the observations collected by CALIOP and by ATLID as well as CloudSat and EarthCARE CPR need to bemerged into a long-term (15 years) cloud climatology. Here, we examine the possibility of building such a climatology, with the aim of defining its accuracy andrelevance for cloud inter-annual studies. We examine the differences between the instruments (wavelengths,satellite's altitudes, telescope fields of view, multiple scattering processes, spatial resolutions) and theirability to detect the same clouds consistently. Then, we define a set of cloud detection thresholds for ATLID,CALIOP, CloudSat and EarthCARE-CPR and test against synthetic cloud scenes (cirrus and shallowcumulus) over small areas (about 200km) produced by a lidar and radar instrument simulator (ECSIM)running on Large Eddy Simulations. Doing so, we verify that the fourth instruments will be able to detect thesame clouds despite their differences (e.g. their sensitivities to noise). Finally, we use the COSP lidar andradar simulator to predict the global scale cloud cover that ATLID, CALIOP, CloudSat and EarthCARE CPRwould observe if they were overflying the same atmosphere predicted by a GCM. Our results suggest that amerged CALIOP/ATLID and CloudSat/CPR cloud climatology could be to be useful for clouds inter-annualstudies, if the post-launch sensitivity of EarthCARE instruments is in line with what is predicted today.

  13. Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.

    1992-01-01

    Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

  14. Seasonal and interannual variations in snow cover thickness, glacier mass balance, and gravity-induced dynamics in a high Arctic valley glacier watershed.

    NASA Astrophysics Data System (ADS)

    Prokop, Alexander; Tolle, Florian; Bernard, Eric; Friedt, Jean-Michel; Griselin, Madeleine

    2015-04-01

    For 3 consecutive years, terrestrial laser scanning surveys have been conducted in the glacier basin of Austre Lovénbreen (Svalbard, 79°N). Each year, high density point clouds were acquired on the glacier surface and on the surrounding slopes. Two yearly scanning sessions were required in order to spatialize and quantify snow cover. The first session was done late April at the expected annual snow maximum. The second session was done in August near the end of the melting season. On the glacier itself, laser scans were produced on the glacier snout, in the area close to the equilibrium line, and in the upper reaches of the glacier. Manual snow drilling measurements and glacier mass balance data were subsequently used to validate snow cover results. In the steep slopes surrounding the glacier, scans were acquired on slopes at various altitudes and orientations in order to get a representative view of different snow cover settings. Particular attention was granted to snowdrift and avalanche processes, and their consequences on remaining packed snow stored in perennial snow accumulation at the bottom of slopes. A good knowledge of the dynamics of the snow cover is of particular interest in a glacier undergoing a clear retreat. Snow is protecting the ice from melting for part of the season, and snow is also providing what will constitute future glacier ice in the upper reaches of the basin. Snow on slopes is also of importance as avalanches reaching on the glacier can contribute to the overall mass balance. Snow cover, by keeping the slopes permafrost from thawing early in the season, or by providing liquid water affecting it later in the season, is also playing a key role in the glacier basin morphology and its interactions with the glacier body.

  15. Seasonal and interannual variations in snow cover thickness, water equivalent, and gravity-induced dynamics in a high Arctic valley glacier watershed.

    NASA Astrophysics Data System (ADS)

    Tolle, F.; Prokop, A.; Bernard, É.; Friedt, J. M.; Griselin, M.

    2014-12-01

    For 3 consecutive years, terrestrial laser scanning surveys have been conducted in the glacier basin of Austre Lovénbreen (Svalbard, 79°N). Each year, high density point clouds were acquired on the glacier surface and on the surrounding slopes. Two yearly scanning sessions were required in order to spatialize and quantify snow cover. The first session was done late April at the expected annual snow maximum. The second session was done in August near the end of the melting season and before the first potential significant snow falls. On the glacier itself, laser scans were produced on the glacier snout, in the area close to the equilibrium line, and in the upper reaches of the glacier. Manual snow drilling measurements and glacier mass balance data were subsequently used to validate snow cover results. In the steep slopes surrounding the glacier, scans were acquired on slopes at various altitudes and orientations in order to get a representative view of different snow cover settings. Particular attention was granted to snowdrift and avalanche processes, and their consequences on remaining packed snow stored in perennial snow accumulation at the bottom of slopes. A good knowledge of the dynamics of the snow cover is of particular interest in a glacier undergoing a clear retreat. Snow is slowing the melting of the ice for part of the season, and snow is also providing what will constitute future glacier ice in the upper reaches of the basin. Snow on slopes is also of importance as avalanches reaching on the glacier can contribute to the overall mass balance. Snow cover, by keeping the slopes permafrost from thawing early in the season, or by providing liquid water affecting it later in the season, is also playing a key role in the glacier basin morphology and its interactions with the glacier body.

  16. HI clouds in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kim, S.

    We present HI and Halpha surveys of the Large Magellanic Cloud (LMC) with the Australia Telescope Compact Array, the Parkes multibeam receiver, and the 16 inch optical telescope at the Siding Spring Observatory (SSO). Using a Fourier-plane technique, we have merged both ATCA and Parkes observations, providing an accurate set of images of the LMC sensitive to structure on scales of 9 pc upward. The spatial dynamic range (2.8 orders of magnitude), velocity resolution (1.649 km/sec per channel) allow for studies of phenomena ranging from the galaxy-wide interaction of the LMC with its close neighbors to the small-scale injection of energy from supernovae and stellar associations into the ISM of the LMC. On the large scale, the HI disk appears to be remarkably symmetric and to have a well-organized and orderly, if somewhat complex, rotational field. The bulk of the HI resides in a disk of 7.3 kpc in diameter. The mass of disk component of the LMC is 2.5 x10^9 M[sun ]and the mass within a radius of 4 kpc is about 3.5 x 10^9 M[sun ]. The structure of the neutral atomic ISM in the LMC is dominated by HI filaments combined with numerous shell, holes, and HI clouds. 23 HI supergiant shells and 103 giant shells are catalogued. Supergiant shells are defined as those regions whose extent is much larger than the HI scale height. The size distribution of HI shells follows a crude power law, N(log R) =AR^-1.5 . The HI clouds have been identified by defining a cloud to be an object composed of all pixels in right ascension, declination, and velocity that are connected and that lie above the threshold brightness temperature. The size spectrum of HI clouds is similar to the typical size spectrum of holes and shells in the HI distribution. The relationship between the size and the velocity dispersion of HI cloud is found to have the power law relationship so called as Larson's scaling law. A slope of the power law varies from 1.2 to 1.6. The virial masses of HI clouds range from 10

  17. Smith's Cloud (HVC) in 21 cm HI emission

    NASA Astrophysics Data System (ADS)

    Heroux, A. J.

    2006-12-01

    In studying the continuing formation of the Milky Way, we have used the Green Bank Telescope (GBT) of the NRAO to measure the 21 cm HI emission from a specific high velocity cloud known as “Smith’s Cloud”. This cloud is likely within the bounds of the galaxy and appears to be actively plunging into the disk. Our map covers an area about 10x14 degrees, with data taken every 3’ over this range. Most of the emission is concentrated into a single large structure with an unusual cometary morphology, which displays signs of interaction between the cloud and the Galactic halo. We will present an analysis of the cloud, along with information on possible FIR emission with information gained from the IRAS data, kinematics and likely orbits and paths for the origin and future of the cloud. This research was funded through an NSF REU Grant.

  18. Pattern recognition analysis of polar clouds during summer and winter

    NASA Technical Reports Server (NTRS)

    Ebert, Elizabeth E.

    1992-01-01

    A pattern recognition algorithm is demonstrated which classifies eighteen surface and cloud types in high-latitude AVHRR imagery based on several spectral and textural features, then estimates the cloud properties (fractional coverage, albedo, and brightness temperature) using a hybrid histogram and spatial coherence technique. The summertime version of the algorithm uses both visible and infrared data (AVHRR channels 1-4), while the wintertime version uses only infrared data (AVHRR channels 3-5). Three days of low-resolution AVHRR imagery from the Arctic and Antarctic during January and July 1984 were analyzed for cloud type and fractional coverage. The analysis showed significant amounts of high cloudiness in the Arctic during one day in winter. The Antarctic summer scene was characterized by heavy cloud cover in the southern ocean and relatively clear conditions in the continental interior. A large region of extremely low brightness temperatures in East Antarctica during winter suggests the presence of polar stratospheric cloud.

  19. Covering All Options

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2011-01-01

    The day a school opens its doors for the first time, the flooring will be new and untarnished. When the flooring is in such pristine condition, many flooring materials--carpeting, vinyl, terrazzo, wood or some other surface--will look good. But school and university planners who decide what kind of material covers the floors of their facilities…

  20. Coronary covered stents.

    PubMed

    Kilic, Ismail Dogu; Fabris, Enrico; Serdoz, Roberta; Caiazzo, Gianluca; Foin, Nicolas; Abou-Sherif, Sara; Di Mario, Carlo

    2016-11-20

    Covered stents offer an effective bail-out strategy in vessel perforations, are an alternative to surgery for the exclusion of coronary aneurysms, and have a potential role in the treatment of friable embolisation-prone plaques. The aim of this manuscript is to offer an overview of currently available platforms and to report results obtained in prior studies.

  1. Cloud vertical distribution from radiosonde, remote sensing, and model simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Jinqiang; Li, Zhanqing; Chen, Hongbin; Yoo, Hyelim; Cribb, Maureen

    2014-08-01

    Knowledge of cloud vertical structure is important for meteorological and climate studies due to the impact of clouds on both the Earth's radiation budget and atmospheric adiabatic heating. Yet it is among the most difficult quantities to observe. In this study, we develop a long-term (10 years) radiosonde-based cloud profile product over the Southern Great Plains and along with ground-based and space-borne remote sensing products, use it to evaluate cloud layer distributions simulated by the National Centers for Environmental Prediction global forecast system (GFS) model. The primary objective of this study is to identify advantages and limitations associated with different cloud layer detection methods and model simulations. Cloud occurrence frequencies are evaluated on monthly, annual, and seasonal scales. Cloud vertical distributions from all datasets are bimodal with a lower peak located in the boundary layer and an upper peak located in the high troposphere. In general, radiosonde low-level cloud retrievals bear close resemblance to the ground-based remote sensing product in terms of their variability and gross spatial patterns. The ground-based remote sensing approach tends to underestimate high clouds relative to the radiosonde-based estimation and satellite products which tend to underestimate low clouds. As such, caution must be exercised to use any single product. Overall, the GFS model simulates less low-level and more high-level clouds than observations. In terms of total cloud cover, GFS model simulations agree fairly well with the ground-based remote sensing product. A large wet bias is revealed in GFS-simulated relative humidity fields at high levels in the atmosphere.

  2. Variability of Clouds Over a Solar Cycle

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    2002-01-01

    One of the most controversial aspects of climate studies is the debate over the natural and anthropogenic causes of climate change. Historical data strongly suggest that the Little Ice Age (from 1550 to 1850 AD when the mean temperature was colder by about 1 C) was most likely caused by variability of the sun and not greenhouse molecules (e.g., CO2). However, the known variability in solar irradiance and modulation of cosmic rays provides too little energy, by many orders of magnitude, to lead to climate changes in the troposphere. The conjecture is that there is a 'trigger mechanism'. This idea may now be subjected to a quantitative test using recen