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. Instrument measures cloud cover

    NASA Technical Reports Server (NTRS)

    Laue, E. G.

    1981-01-01

    Eight solar sensing cells comprise inexpensive monitoring instrument. Four cells always track Sun while other four face sky and clouds. On overcast day, cloud-irradiance sensors generate as much short-circuit current as Sun sensor cells. As clouds disappear, output of cloud sensors decreases. Ratio of two sensor type outputs determines fractional cloud cover.

  4. 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.

  5. 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.

  6. Comparison of Ground Techniques Used to Estimate Cloud Cover

    NASA Astrophysics Data System (ADS)

    Portugal, W.; Echer, M. P. D. S.; Martins, F. R.; Pinto, M. L. D. A.

    2015-12-01

    Clouds are the most important factor modulating the solar radiation incident on the earth's surface. Information on cloud cover state also play significant role for several applications, as weather forecast and climate knowledge. Several studies have been conducted to establish a methodology and experimental setup in order to acquire reliable cloud cover data from remote sense observations performed on the surface. This work comparing ground data acquired by different systems for the same atmospheric scenario regarding cloud cover. We used two ground sites located at Florianópolis, Brazil, where cloud cover and solar irradiance data were acquired. Solar radiation data and sky images were acquired at SONDA station (-27◦28', -48◦29', 15m asl) and cloud cover data collected at the international airport meteorological station (-27◦40', -48◦29'). This study compares these two datasets for sky scenarios presenting only stratocumulus cloud cover. The results show the complexity of the interaction process between solar irradiance and cloud cover and how it affects ground observations. It can be seen that even when sky is completely cloudy (8/8 or 100%) by a single type of cloud, the ratio between global and diffuse irradiance varied from 0.75 till 0.98.

  7. Cloud cover estimation using bispectral satellite measurements

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Childs, J.; Dorian, P.

    1986-01-01

    An algorithm has been developed for cloud cover estimation using bispectral satellite measurements. Based on the distribution of pixels in albedo-brightness temperature space, a number of threshold values are applied to identify those pixels which are most likely totally cloud filled. Mean cloudy-column albedo in a region much larger than a single pixel is then estimated and cloud cover computed. The algorithm has been applied to the International Satellite Cloud Climatology Project Geostationary Meteorological Satellite B2 data. Locations of tropical convective cells and the passage of fronts in higher latitudes are identified. Since these features represent the states of large-scale atmospheric circulations, it is concluded that the algorithm can yield consistent cloud data sets useful for climate studies.

  8. Multidecadal Changes in Near-Global Cloud Cover and Estimated Cloud Cover Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Norris, Joel

    2005-01-01

    The first paper was Multidecadal changes in near-global cloud cover and estimated cloud cover radiative forcing, by J. R. Norris (2005, J. Geophys. Res. - Atmos., 110, D08206, doi: lO.l029/2004JD005600). This study examined variability in zonal mean surface-observed upper-level (combined midlevel and high-level) and low-level cloud cover over land during 1971-1 996 and over ocean during 1952-1997. These data were averaged from individual synoptic reports in the Extended Edited Cloud Report Archive (EECRA). Although substantial interdecadal variability is present in the time series, long-term decreases in upper-level cloud cover occur over land and ocean at low and middle latitudes in both hemispheres. Near-global upper-level cloud cover declined by 1.5%-sky-cover over land between 1971 and 1996 and by 1.3%-sky-cover over ocean between 1952 and 1997. Consistency between EECRA upper-level cloud cover anomalies and those from the International Satellite Cloud Climatology Project (ISCCP) during 1984-1 997 suggests the surface-observed trends are real. The reduction in surface-observed upper-level cloud cover between the 1980s and 1990s is also consistent with the decadal increase in all-sky outgoing longwave radiation reported by the Earth Radiation Budget Satellite (EMS). Discrepancies occur between time series of EECRA and ISCCP low-level cloud cover due to identified and probable artifacts in satellite and surface cloud data. Radiative effects of surface-observed cloud cover anomalies, called "cloud cover radiative forcing (CCRF) anomalies," are estimated based on a linear relationship to climatological cloud radiative forcing per unit cloud cover. Zonal mean estimated longwave CCRF has decreased over most of the globe. Estimated shortwave CCRF has become slightly stronger over northern midlatitude oceans and slightly weaker over northern midlatitude land areas. A long-term decline in the magnitude of estimated shortwave CCRF occurs over low-latitude land and ocean

  9. 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.

  10. Sky cover from MFRSR observations: cumulus clouds

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J.; Berg, L. K.; Flynn, C.; Long, C. N.

    2011-01-01

    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 US 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.

  11. 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.

  12. 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.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    1993-05-01

    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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. COMPARISON VIEW OF MARS CLOUD COVER

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These color and black and white pictures of Mars were taken by NASA's Hubble Space Telescope just two weeks after Earth made its closest approach to the Red Planet during the 1997 opposition. When the Hubble pictures were taken Mars was at a distance of 62 million miles (100 million kilometers) and the resolution at the center of the disk is 13.5 miles/pixel (22 kilometers/pixel). Both images were made with the Wide Field and Planetary Camera 2. The color composite (left image) is constructed from three images taken in red (673 nanometers), green (502 nm) and blue (410 nm) light. The right image, in blue light only, brings out details in the cloud structure and is remarkably similar to weather satellite pictures taken of Earth. A planetary-scale wave curls around the north pole, similar in behavior to high latitude cold fronts which descend over North America and Europe during springtime. The picture was taken when Mars was near aphelion, its farthest point from the Sun. The faint sunlight results in cold atmospheric conditions which stimulate the formation of water ice clouds. The clouds themselves further reduce atmospheric temperatures. Atmospheric heating, resulting when sunlight is absorbed by the dust, is reduced when ice forms around the dust particles and causes the dust to gravitationally settle to the ground. These images of Mars are centered at approximately 94 degrees longitude and 23 degrees N latitude (oriented with north up). The four largest Tharsis Montes (massive extinct volcanoes) are visible as dark spots extending through the clouds. The vast canyon system, Valles Marineris, stretches across the eastern (lower right) half of the image; the Pathfinder landing site is near the eastern edge of the image. It is early summer in the northern hemisphere, and the North polar cap has retreated to about 80 degrees N latitude; the 'residual' summer cap, which is composed of water ice, is about one-third the size of the 'seasonal' winter cap, which

  2. Last updates on Titan's cloud cover monitoring with CASSINI

    NASA Astrophysics Data System (ADS)

    Rodriguez, Sebastien; Turtle, Elizabeth P.; Le Mouélic, Stephane; Rannou, Pascal; Sotin, Christophe; Barnes, Jason W.; Griffith, Caitlin A.; Brown, Robert H.; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Phil D.

    2016-04-01

    We report on the monitoring of cloud activity in Titan's atmosphere over a period spanning from early winter to mid-spring. Clouds on Titan have been observed by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft since its insertion into Saturn's orbit. A semi-automated method is used to detect cloud events in each VIMS cube acquired since July 2004 and statistics are drawn on the location of the clouds and their evolution. It is shown that the cloud activity has decreased at both pole approaching the equinox, while clouds at southern mid-latitudes were still very active. Close to the equinox, rare but intense cloud activity has also been detected in the equatorial area. After the equinox, the cloud activity has almost completely disappeared, except for rare and small cloud patches at northern high latitudes. Those long-term observations are compared with predictions of Global Circulation Models (GCMs) in order not only to better constrain the models, but also to better understand the processes which drive Titan's weather and how they interact with Titan's surface.

  3. 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).

  4. Developing a cloud mask climatology covering two Meteosat satellite generations

    NASA Astrophysics Data System (ADS)

    Posselt, Rebekka; Stöckli, Reto; Liniger, Mark A.

    2013-04-01

    Long term cloud cover observations from satellites are fundamental for climate model validation and climate monitoring. Further, they support ground-based observations in regions with sparse coverage. Additionally, information on cloud cover is needed to derive other physical parameters such as surface radiation fluxes or clear sky and cloudy atmospheric states and is of high relevance for the solar energy sector. Within the current project phase of the Satellite Application Facility on Climate Monitoring (CM SAF) an algorithm to calculate a climatological cloud mask (or cloud cover probability) from Meteosat satellites is developed. The algorithm shall be applicable for both Meteosat first generation (1983-2005) and Meteosat second generation (2004-present) which significantly differ in their spectral properties. The algorithm linearly aggregates a set of continuous scores instead of the commonly used decision tree approach. The scores are calculated for different channels as well as different spatial and temporal settings. Each score yields a probability for the pixel's cloud cover. The final result, the cloud cover probability, is obtained by combining all available scores taking into account the varying performance of the scores during day and night and over snow. The uncertainty of the final cloud cover estimate is an inherent part of the probability. The algorithm is calibrated using cloud cover measurements from SYNOP stations located on the Meteosat disc. The subsequent validation is done at an independent set of collocated SYNOP/ARSA (Automated Radiosonde Archive) stations. The presentation introduces the applied cloud mask algorithm and presents the results of the validation for both satellite generations. The comparison of the two satellite generations addresses the climatological homogeneity of the future cloud mask climate data record which will be distributed by CM SAF after 2016. Special attention is also drawn to issues like the day-night-bias of

  5. 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.

  6. Development of a sky imager for cloud cover assessment.

    PubMed

    Cazorla, A; Olmo, F J; Alados-Arboledas, L

    2008-01-01

    Based on a CCD camera, we have developed an in-house sky imager system for the purpose of cloud cover estimation and characterization. The system captures a multispectral image every 5 min, and the analysis is done with a method based on an optimized neural network classification procedure and a genetic algorithm. The method discriminates between clear sky and two cloud classes: opaque and thin clouds. It also divides the image into sectors and finds the percentage of clouds in those different regions. We have validated the classification algorithm on two levels: image level, using the cloud observations included in the METAR register performed at the closest meteorological station, and pixel level, determining whether the final classification is correct. PMID:18157209

  7. The Influence of Nonuniform Cloud Cover on Transit Transmission Spectra

    NASA Astrophysics Data System (ADS)

    Line, Michael R.; Parmentier, Vivien

    2016-03-01

    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.

  8. Orbital and cloud cover sampling analyses for space lidar missions

    NASA Technical Reports Server (NTRS)

    Lawrence, G. F.; Robbins, J. L.; Gibson, G. G.

    1985-01-01

    The sampling capabilities of an orbital lidar mission are evaluated. Spatial and temporal sampling data from a lidar spacecraft orbit simulation are combined with global, statistical cloud cover data to yield a quantification of lidar measurement opportunities for both partly cloudy and mostly overcast viewing conditions. The optimum launch time (month and local hour) is determined to maximize lidar measurement opportunities for specified cloud cover conditions. Results indicate that the time of year selected for the lidar mission is very important in maximizing acceptable data return, whereas the effect of launch time of day on mission optimization is generally not as strong as the seasonal effect.

  9. 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.

  10. Comparasion of Cloud Cover restituted by POLDER and MODIS

    NASA Astrophysics Data System (ADS)

    Zeng, S.; Parol, F.; Riedi, J.; Cornet, C.; Thieuxleux, F.

    2009-04-01

    PARASOL and AQUA are two sun-synchronous orbit satellites in the queue of A-Train satellites that observe our earth within a few minutes apart from each other. Aboard these two platforms, POLDER and MODIS provide coincident observations of the cloud cover with very different characteristics. These give us a good opportunity to study the clouds system and evaluate strengths and weaknesses of each dataset in order to provide an accurate representation of global cloud cover properties. This description is indeed of outermost importance to quantify and understand the effect of clouds on global radiation budget of the earth-atmosphere system and their influence on the climate changes. We have developed a joint dataset containing both POLDER and MODIS level 2 cloud products collocated and reprojected on a common sinusoidal grid in order to make the data comparison feasible and veracious. Our foremost work focuses on the comparison of both spatial distribution and temporal variation of the global cloud cover. This simple yet critical cloud parameter need to be clearly understood to allow further comparison of the other cloud parameters. From our study, we demonstrate that on average these two sensors both detect the clouds fairly well. They provide similar spatial distributions and temporal variations:both sensors see high values of cloud amount associated with deep convection in ITCZ, over Indonesia, and in west-central Pacific Ocean warm pool region; they also provide similar high cloud cover associated to mid-latitude storm tracks, to Indian monsoon or to the stratocumulus along the west coast of continents; on the other hand small cloud amounts that typically present over subtropical oceans and deserts in subsidence aeras are well identified by both POLDER and MODIS. Each sensor has its advantages and inconveniences for the detection of a particular cloud types. With higher spatial resolution, MODIS can better detect the fractional clouds thus explaining as one part

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. A method for remote sensing the emissivity, fractional cloud cover and cloud top temperature of high-level, thin clouds

    NASA Technical Reports Server (NTRS)

    Wu, Man-Li C.

    1987-01-01

    A methodology for retrieving the emissivity, cloud cover and cloud top temperature of high-level, thin clouds is developed and described. In the thermal infrared windows, the outgoing radiances from the earth's atmosphere contain information about cloud emissivity and cloud top temperature. This information is clearly demonstrated in the brightness temperature difference curves of two window channels. For the purpose of illustration, two window channels centered at 810 and 930 cm are chosen to construct the brightness temperature difference curves for a range of cloud top temperatures. These curves vary for different cloud top temperatures, and along each of these curves the emissivity changes. The brightness temperature difference method is used in a simulation study to demonstrate the feasibility of retrieving the cloud top temperature and emissivity by the utilization of measurements in two window channels. As expected, a perfect retrieval is found if perfect measurements and ideal atmospheric conditions are assumed. If a random error, which has a normal distribution with a mean of zero and standard deviation of + or - 0.5 C, is imposed to the measurements, a reasonable retrieval is found for emissivity greater than 0.3. The algorithm has been applied to a limited amount of HIRS2 data, which has 3.7, 3.98 and 11 micron channels. The cloud top temperature, emissivity and cloud cover are determined by using these channels.

  16. Cloud cover and horizontal plane eye damaging solar UV exposures.

    PubMed

    Parisi, A V; Downs, N

    2004-11-01

    The spectral UV and the cloud cover were measured at intervals of 5 min with an integrated cloud and spectral UV measurement system at a sub-tropical Southern Hemisphere site for a 6-month period and solar zenith angle (SZA) range of 4.7 degrees to approximately 80 degrees . The solar UV spectra were recorded between 280 nm and 400 nm in 0.5 nm increments and weighted with the action spectra for photokeratitis and cataracts in order to investigate the effect of cloud cover on the horizontal plane biologically damaging UV irradiances for cataracts (UVBE(cat)) and photokeratitis (UVBE(pker)). Eighty five percent of the recorded spectra produced a measured irradiance to a cloud free irradiance ratio of 0.6 and higher while 76% produced a ratio of 0.8 and higher. Empirical non-linear expressions as a function of SZA have been developed for all sky conditions to allow the evaluation of the biologically damaging UV irradiances for photokeratitis and cataracts from a knowledge of the unweighted UV irradiances. PMID:15257451

  17. Global patterns of solar influence on high cloud cover

    NASA Astrophysics Data System (ADS)

    Dima, Mihai; Voiculescu, Mirela

    2016-07-01

    One of the main sources of uncertainty in climate projections is represented by clouds, which have a profound influence on the Earth's radiation budget through the feedbacks in which they are involved. The improvement of clouds representation in General Circulation Models relies largely on constraints derived from observations and on correct identification of processes that influence cloud formation or lifetime. Here we identify solar forced high cloud cover (HCC) patterns in reanalysis and observed data extending over the 1871-2009 period, based on their associations with known fingerprints of the same forcing on surface air temperature, sea surface temperature (SST) and sea level pressure fields. The solar influence on HCC has maximum amplitudes over the Pacific basin, where HCC anomalies are distributed in bands of alternating polarities. The colocation of the HCC and SST anomalies bands indicates a thermal influence on high clouds through convection and an amplification of the HCC anomalies by a positive feedback of long-wave fluxes, which increases the solar signal. Consistent with numerical simulations, the solar forced HCC pattern appears to be generated through a constructive interference between the so-called "top-down" and "bottom-up" mechanisms of solar influence on climate and is amplified by ocean-atmosphere positive feedbacks.

  18. 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.

  19. General cloud cover modifier for clear sky solar radiation models

    NASA Astrophysics Data System (ADS)

    Myers, Daryl R.

    2007-09-01

    Worldwide lack of comprehensive measured solar radiation resource data for solar system design is well known. Several simple clear sky solar radiation models for computing hourly direct, diffuse and global hemispherical solar radiation have been developed over the past 25 years. The simple model of Richard Bird, Iqbal's parameterization C, and Gueymard's REST model are popular for estimating maximum hourly solar resources. We describe a simple polynomial in cloud cover (octa) modifier for these models that produces realistic time series of hourly solar radiation data representative of naturally occurring solar radiation conditions under all sky conditions. Surface cloud cover observations (Integrated Surface Hourly Data) from the National Climatic Data Center are the only additional (hourly) input data to model total hemispherical solar radiation under all sky conditions. Performance was evaluated using three years of hourly solar radiation data from 31 sites in the 1961-1990 National Solar Radiation Data Base. Mean bias errors range from - 10% to -20%, and are clear sky model dependant. Root mean square error of about 40%, are also dependent upon the particular model used and the uncertainty in the specific clear sky model inputs and lack of information on cloud type and spatial distributions.

  20. Three Key Processes Drive Marine Low-Cloud Cover Feedback

    NASA Astrophysics Data System (ADS)

    Qu, X.; Hall, A. D.; Klein, S. A.

    2014-12-01

    The tropical marine low-cloud cover (LCC) feedback is a key component of global cloud feedbacks. Differences in simulations of the feedback (ranging from a considerably negative to large, positive) are sources of significant spread in the temperature responses of climate models to anthropogenic forcing. Despite its importance, the underlying processes driving the feedback are not well-understood. Here we present evidence that in models it is mainly driven by three warming-induced changes---(1) strengthening tropical inversion, (2) increasing surface latent heat flux, and (3) an increasing moisture gradient in the lower-troposphere. The sensitivities of LCC to these changes, diagnosed through 20th-century climate variability, vary a great deal across models, contributing to the spread in the projected LCC changes over 21st-century. A methodology is devised to observationally constrain these sensitivities. We find that averaged over five main tropical low cloud regions, LCC decreases by 2% or more in models where the simulated sensitivities are consistent with the observed. This suggests that a positive LCC feedback is more consistent with observation than a negative one. Correcting biases in the simulated sensitivities will clearly be an important step towards a better simulation of cloud feedbacks in climate models.

  1. 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.

  2. 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

  3. Winter sky brightness and cloud cover at Dome A, Antarctica

    NASA Astrophysics Data System (ADS)

    Moore, Anna M.; Yang, Yi; Fu, Jianning; Ashley, Michael C. B.; Cui, Xiangqun; Feng, Long Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel M.; Riddle, Reed; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Tothill, Nicholas F. H.; Travouillon, Tony; Wang, Lifan; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

    2013-01-01

    At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical observatories. The Gattini Dome A 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 fisheye 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) and a long-pass red filter for the detection and monitoring of airglow emission. The system operated continuously throughout the 2009, and 2011 winter seasons and part-way through the 2010 season, recording long exposure images sequentially for each filter. We have in hand one complete winter-time dataset (2009) returned via a manned traverse. We present here the first measurements of sky brightness in the photometric V band, cloud cover statistics measured so far and an estimate of the extinction.

  4. 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.

  5. 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.

  6. Positive tropical marine low-cloud cover feedback inferred from cloud-controlling factors

    NASA Astrophysics Data System (ADS)

    Qu, Xin; Hall, Alex; Klein, Stephen A.; DeAngelis, Anthony M.

    2015-09-01

    Differences in simulations of tropical marine low-cloud cover (LCC) feedback are sources of significant spread in temperature responses of climate models to anthropogenic forcing. Here we show that in models the feedback is mainly driven by three large-scale changes—a strengthening tropical inversion, increasing surface latent heat flux, and an increasing vertical moisture gradient. Variations in the LCC response to these changes alone account for most of the spread in model-projected 21st century LCC changes. A methodology is devised to constrain the LCC response observationally using sea surface temperature (SST) as a surrogate for the latent heat flux and moisture gradient. In models where the current climate's LCC sensitivities to inversion strength and SST variations are consistent with observed, LCC decreases systematically, which would increase absorption of solar radiation. These results support a positive LCC feedback. Correcting biases in the sensitivities will be an important step toward more credible simulation of cloud feedbacks.

  7. Enhancement of Cloud Cover and Suppression of Nocturnal Drizzle in Stratocumulus Polluted by Haze

    NASA Technical Reports Server (NTRS)

    Ackerman, Andrew S.; Toon, O. B.; Stevens, D. E.; Coakley, J. A., Jr.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Recent satellite observations indicate a significant decrease of cloud water in ship tracks, in contrast to an ensemble of in situ ship-track measurements that show no average change in cloud water relative to the surrounding clouds. We find through large-eddy simulations of stratocumulus that the trend in the satellite data is likely an artifact of sampling only overcast clouds. The simulations instead show cloud cover increasing with droplet concentrations. Our simulations also show that increases in cloud water from drizzle suppression (by increasing droplet concentrations) are favored at night or at extremely low droplet concentrations.

  8. Cloud Cover Increase with Increasing Aerosol Absorptivity: A Counterexample to the Conventional Semidirect Aerosol Effect

    NASA Technical Reports Server (NTRS)

    Perlwitz, Jan; Miller, Ron L.

    2010-01-01

    We reexamine the aerosol semidirect effect using a general circulation model and four cases of the single-scattering albedo of dust aerosols. Contrary to the expected decrease in low cloud cover due to heating by tropospheric aerosols, we find a significant increase with increasing absorptivity of soil dust particles in regions with high dust load, except during Northern Hemisphere winter. The strongest sensitivity of cloud cover to dust absorption is found over land during Northern Hemisphere summer. Here even medium and high cloud cover increase where the dust load is highest. The cloud cover change is directly linked to the change in relative humidity in the troposphere as a result of contrasting changes in specific humidity and temperature. More absorption by aerosols leads to larger diabatic heating and increased warming of the column, decreasing relative humidity. However, a corresponding increase in the specific humidity exceeds the temperature effect on relative humidity. The net effect is more low cloud cover with increasing aerosol absorption. The higher specific humidity where cloud cover strongly increases is attributed to an enhanced convergence of moisture driven by dust radiative heating. Although in some areas our model exhibits a reduction of low cloud cover due to aerosol heating consistent with the conventional description of the semidirect effect, we conclude that the link between aerosols and clouds is more varied, depending also on changes in the atmospheric circulation and the specific humidity induced by the aerosols. Other absorbing aerosols such as black carbon are expected to have a similar effect.

  9. 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.

  10. 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.

  11. Relationships between nocturnal winter road slipperiness, cloud cover and surface temperature

    NASA Astrophysics Data System (ADS)

    Grimbacher, T.; Schmid, W.

    2003-04-01

    Ice and Snow are important risks for road traffic. In this study we show several events of slipperiness in Switzerland, mainly caused by rain or snow falling on a frozen surface. Other reasons for slippery conditions are frost or freezing dew in clear nights and nocturnal clearing after precipitation, which goes along with radiative cooling. The main parameters of road weather forecasts are precipitation, cloudiness and surface temperature. Precipitation is well predictable with weather radars and radar nowcasting algorithms. Temperatures are often taken from numerical weather prediction models, but because of changes in cloud cover these model values are inaccurate in terms of predicting the onset of freezing. Cloudiness, especially the advection, formation and dissipation of clouds and their interaction with surface temperatures, is one of the major unsolved problems of road weather forecasts. Cloud cover and the temperature difference between air and surface temperature are important parameters of the radiation balance. In this contribution, we show the relationship between them, proved at several stations all over Switzerland. We found a quadratic correlation coefficient of typically 60% and improved it considering other meteorological parameters like wind speed and surface water. The acquired relationship may vary from one station to another, but we conclude that temperature difference is a signature for nocturnal cloudiness. We investigated nocturnal cloudiness for two cases from winters 2002 and 2003 in the canton of Lucerne in central Switzerland. There, an ultra-dense combination of two networks with together 55 stations within 50x50 km^2 is operated, measuring air and surface temperature, wind and other road weather parameters. With the aid of our equations, temperature differences detected from this network were converted into cloud maps. A comparison between precipitation seen by radar, cloud maps and surface temperatures shows that there are similar

  12. 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.

  13. Characterizing Spatial Patterns of Cloud Cover And Fog Inundation in the California Channel Islands

    NASA Astrophysics Data System (ADS)

    Rastogi, B.; Fischer, D. T.; Williams, P.; Iacobellis, S.; McEachern, K.; Still, C. J.

    2013-12-01

    Coastal forests in Mediterranean climates are frequently covered by clouds or immersed in fog. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon and water budgets in these semi-arid environments. Both low level stratocumulus cloud cover and fog can enhance the water status of vegetation along the Californian coast and the Channel Islands by reducing insolation and raising relative humidity and thus reducing evapotranspiration, while also potentially supplying water directly to the landscape from fog-drip during otherwise warm and rainless summers. While cloud cover and fog can ameliorate summer drought stress and enhance soil water budgets, they often have different spatial and temporal patterns. The resulting shifts in relative ecological importance of fog and stratus are largely unknown. The overall objective of this project was 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. Daytime cloud cover maps were generated for the northern Channel Islands using GOES satellite imagery for the years 1996-2012. To discriminate fog from stratus the base of the cloud height was constrained by using airport cloud ceiling data and topographic information. In order to observe variation in fog frequency at scales relevant to species distributions on the Channel Islands the native GOES resolution was downscaled by using radiosonde and reanalysis data. Satellite derived estimates of cloud cover and fog were correlated with field measurements of insolation, fog drip and leaf wetness on Santa Rosa and Santa Cruz islands. This enabled spatial and temporal extrapolation to understand seasonal and inter-annual variations in cloud cover frequency and fog inundation and drip and will be important for future water balance modeling, studies of coastal vegetation distributions and for better

  14. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  16. Cloud cover retrieved from ground-base observation using Skyviewer : A validation with human observations

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Cloud cover is used in various fields of research in addition to weather forecasts; however, the ground observation of cloud cover is conducted by human observers, a method with low objectivity, temporal and spatial resolutions. Therefore, 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 of the Red Blue Ratio (RBR) determined from the frequency distributions 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 analysis on human observations of cloud cover obtained every hour from 0800 to 1700 LST for the entire year of 2012 at Gangwon Regional Meteorological Administration (GRMA), Korea. A daily case study compared the images of 1200 LST cases by season and pixel images of cloud cover calculated by the algorithm. The selected weekly cases yielded a high correlation of 0.93 with GRMA data. A monthly case study showed low RMSEs and high correlations 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 analysis showed that the bias of GRMA and Skyviewer for the year of 2012 was -0.36 tenth, with cloud cover of the GRMA data being greater, whilst RMSE was 2.12 tenths. Considering the spatial inconsistency of the data used in the analysis, GRMA and Skyviewer showed a high correlation (0.87) and 80% consistency for cases with a difference in cloud cover of within ±2 tenths.

  17. Possible external sources of terrestrial cloud cover variability: the solar wind

    NASA Astrophysics Data System (ADS)

    Voiculescu, Mirela; Usoskin, Ilya; Condurache-Bota, Simona

    2014-05-01

    Cloud cover plays an important role in the terrestrial radiation budget. The possible influence of the solar activity on cloud cover is still an open question with contradictory answers. An extraterrestrial factor potentially affecting the cloud cover is related to fields associated with solar wind. We focus here on a derived quantity, the interplanetary electric field (IEF), defined as the product between the solar wind speed and the meridional component, Bz, of the interplanetary magnetic field (IMF) in the Geocentric Solar Magnetospheric (GSM) system. We show that cloud cover at mid-high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Since the IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others. We also present results showing that the link between cloud cover and IMF varies depending on composition and altitude of clouds.

  18. Adaptive algorithm for cloud cover estimation from all-sky images over the sea

    NASA Astrophysics Data System (ADS)

    Krinitskiy, M. A.; Sinitsyn, A. V.

    2016-05-01

    A new algorithm for cloud cover estimation has been formulated and developed based on the synthetic control index, called the grayness rate index, and an additional algorithm step of adaptive filtering of the Mie scattering contribution. A setup for automated cloud cover estimation has been designed, assembled, and tested under field conditions. The results shows a significant advantage of the new algorithm over currently commonly used procedures.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  1. 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.

  2. High-resolution reconstruction of objects from cloud-covered infrared images

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Ralph, Jason F.; Goulermas, John Y.

    2009-05-01

    FLIR images are essential for the detection and recognition of ground targets. Small targets can be enhanced using super-resolution techniques to improve the effective resolution of the target area using a sequence of low-resolution images. However, when there is significant cloud cover, several problems can arise: clouds can obscure a target (partially or fully), they can affect the accuracy of image registration algorithms, and they can reduce the contrast of the object against the background. To reconstruct an image in the presence of cloud cover, image correlation metrics from optical flow and a robust super-resolution algorithm have been used to compile a 'best' frame.

  3. The Impact of Non-Uniform Cloud Cover on Transit Transmission Spectra

    NASA Astrophysics Data System (ADS)

    Line, Michael; Parmentier, Vivien

    2015-12-01

    Clouds play a substantial role in sculpting transit transmission spectra as they tend to mute or entirely mask spectral features. Many investigations have treated clouds as globally uniform with a single “1D” structure. However, we have learned from albedo phase curves (e.g., Kepler 7) that cloud coverage can be spatially inhomogeneous across the planetary disk. Non-uniform cloud coverage is also supported by brown dwarf variability observations which suggest the presence of “patchy clouds”. We also see non-uniform cloud coverage within our own solar system planets (e.g., belts and zones on Jupiter, ITCZ on earth etc.). Given the mounting evidence for spatially variable cloud coverage, it is prudent that we at least explore the role that non-uniform cloud coverage can have on transit transmission spectra. In this investigation we demonstrate how non-uniform cloud coverage on the terminator can influence transit transmission spectra and the potential biases incurred if non-uniform cloud coverage is not taken into account in spectral retrievals. For instance, a high altitude opaque cloud covering the entire morning terminator, along with a perfectly clear evening terminator can mimic a high mean molecular weight transmission spectrum in a hot Jupiter. Finally, we present the impact that non-uniform cloud coverage may have on transit light curves.

  4. Observations of fair-weather cumuli over land: Dynamical factors controlling cloud size and cover

    NASA Astrophysics Data System (ADS)

    Lamer, Katia; Kollias, Pavlos

    2015-10-01

    Comprehensive observations of shallow convection at the Atmospheric Radiation Measurement Southern Great Plains site are carefully analyzed to study the macrophysical and dynamical properties of active and forced cumuli separately and investigate their relationship to the subcloud layer turbulent structure. Clearly, active clouds possess stronger dynamics and greater horizontal extent than their forced counterpart. As previously reported, upper level stability and relative humidity do control the predominance of active clouds. While cloud cover remains difficult to associate to mixed-layer parameters (small correlation coefficients), mixed-layer top vertical velocity skewness, and coherent updraft fraction most significantly correlate to cumulus cloud cover and especially the portion attributed to active clouds; both of which are not currently considered in shallow cloudiness parameterizations. This study also points to several factors that continue to limit our ability to adequately sample shallow cumuli and suggests that forward models will be necessary to bridge observations and model outputs.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Trees Detection from Laser Point Clouds Acquired in Dense Urban Areas by a Mobile Mapping System

    NASA Astrophysics Data System (ADS)

    Monnier, F.; Vallet, B.; Soheilian, B.

    2012-07-01

    3D reconstruction of trees is of great interest in large-scale 3D city modelling. Laser scanners provide geometrically accurate 3D point clouds that are very useful for object recognition in complex urban scenes. Trees often cause important occlusions on building façades. Their recognition can lead to occlusion maps that are useful for many façade oriented applications such as visual based localisation and automatic image tagging. This paper proposes a pipeline to detect trees in point clouds acquired in dense urban areas with only laser informations (x,y, z coordinates and intensity). It is based on local geometric descriptors computed on each laser point using a determined neighbourhood. These descriptors describe the local shape of objects around every 3D laser point. A projection of these values on a 2D horizontal accumulation space followed by a combination of morphological filters provides individual tree clusters. The pipeline is evaluated and the results are presented on a set of one million laser points using a man made ground truth.

  10. 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.

  11. 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

  12. 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.

  13. Effect of cloud cover on UVB exposure under tree canopies: will climate change affect UVB exposure?

    PubMed

    Grant, Richard H; Heisler, Gordon M

    2006-01-01

    The effect of cloud cover on the amount of solar UV radiation that reaches pedestrians under tree cover was evaluated with a three-dimensional canopy radiation transport model. The spatial distribution of UVB irradiance at the base of a regular array of spherical tree crowns was modeled under the full range of sky conditions. The spatial mean relative irradiance (I(r)) and erythemal irradiance of the entire below-canopy domain and the spatial mean relative irradiance and erythemal irradiance in the shaded regions of the domain were determined for solar zenith angles from 15 degrees to 60 degrees. The erythemal UV irradiance under skies with 50% or less cloud cover was not remarkably different from that under clear skies. In the shade, the actual irradiance was greater under partly cloudy than under clear skies. The mean ultraviolet protection factor for tree canopies under skies with 50% or less cloud cover was nearly equivalent to that for clear sky days. Regression equations of spatially averaged I(r) as a function of cloud cover fraction, solar zenith angle and canopy cover were used to predict the variation in erythemal irradiance in different land uses across Baltimore, MD. PMID:16613503

  14. 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

    2016-01-01

    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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Teuling, Ryan; Melsen, Lieke; Vila-Guerau de Arellano, Jordi; van Heerwaarden, Chiel; Miralles, Diego; Taylor, Chris; Stegehuis, Annemiek; Fokke Meirink, Jan; Nabuurs, Gert-Jan

    2016-04-01

    The impact of temperate forests on their environment is still 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 attempts to study impacts of forest cover on atmospheric conditions through modeling. 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 strongly fragmented and often can be found on hilly terrain, making it impossible to attribute differences in for instance cloud cover or runoff directly to forest cover. Only few regions exist where forests can be found in absence of strong topography of a size large enough to result in near-equilibrium between the atmospheric boundary layer and local surface conditions. In this study, we analyse 10 years (2004-2013) of cloud cover observations from the Meteosat Second Generation satellite platform at a 15-minute temporal resolution. These observations come from a physically-based cloud product at the 6 km resolution [5], and a statistical cloud product based on the high-resolution visible imagery (1 km resolution). 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 pixel. We find that in particular in summer and late summer, clouds are much more likely to occur over forest than over the surrounding non-forest land (difference in the order of 0.2). An opposite signal, but of much weaker magnitude, is found during springtime, when clouds are less likely to develop over forest. Difference in cloud occurrence is consistent with MODIS-derived differences in EVI

  17. Climate coupling between temperature, humidity, precipitation, and cloud cover over the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Betts, Alan K.; Desjardins, Raymond; Worth, Devon; Beckage, Brian

    2014-12-01

    This analysis uses over 50 years of hourly observations of temperature, relative humidity, and opaque cloud cover and daily precipitation from 11 climate stations across the Canadian Prairies to analyze the monthly, seasonal, and long-term climate coupling in the warm season. On climate time scales, temperature depends on cloud forcing, while relative humidity depends on precipitation. The monthly climate depends on both opaque cloud cover for the current month and precipitation for both the present and past 2 months in summer. Multiple linear regression shows that anomalies of opaque cloud and precipitation explain 60-80% of the variance in the diurnal temperature range, afternoon relative humidity, and lifting condensation level on monthly time scales. We analyze the internal coupling of diurnal climate observables as a further guide to evaluating models. We couple the statistics to simplified energy and water budgets for the Prairies in the growing season. The opaque cloud observations have been calibrated against the incoming shortwave and longwave fluxes. We estimate that the drydown of total water storage on the landscape damps 56% of precipitation anomalies for the growing season on large spatial scales, although this drydown increases evapotranspiration. This couples the climatological surface fluxes to four key observables: cloud forcing, precipitation, temperature, and humidity. We estimate a climatological evaporative fraction of 0.61 for the Prairies. The observational relationships of the coupled Prairie climate system across time scale will be useful for evaluating these coupled processes in models for weather and seasonal forecasting and climate simulation.

  18. 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.

  19. 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.

  20. 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.

  1. A 350 Year Cloud Cover Reconstruction Deduced from Caribbean Coral Proxies

    NASA Astrophysics Data System (ADS)

    Winter, Amos; Sammarco, Paul; Mikolajewicz, Uwe; Jury, Mark; Zanchettin, Davide

    2015-04-01

    Clouds are a major factor contributing to climate change with respect to a variety of effects on the earth's climates, primarily radiative effects, amelioration of heating, and regional changes in precipitation patterns. There have been very few studies of decadal and longer term changes in cloud cover in the tropics and sub-tropics, both over land and the ocean. In the tropics, there is great uncertainty regarding how global warming will affect cloud cover. Observational satellite data is so short that it is difficult to discern any temporal trends. The skeletons of scleractinian corals are considered to contain among the best records of high-resolution (sub-annual) environmental variability in the tropical and sub-tropical oceans. Corals generally live in well-mixed coastal regions and can often record environmental conditions of large areas of the upper ocean. This is particularly the case at low latitudes. Scleractinian corals are sessile, epibenthic fauna, and the type of environmental information recorded at the location where the coral has been living is dependent upon the species of coral considered and proxy index of interest. Zooxanthellate hermatypic corals in tropical and sub-tropical seas precipitate CaCO3 skeletons as they grow. This growth is made possible through the manufacture of CaCO3 crystals, facilitated by the zooxanthellae. During the process of crystallization, the holobiont binds carbon of different isotopes into the crystals. Stable carbon isotope concentrations vary with a variety of environmental conditions. In the Caribbean, δ13C in corals of the species Montastraea faveolata can be used as a proxy for changes in cloud cover. In this contribution, we will demonstrate that the stable isotope 13C varies concomitantly with cloud cover and present a new reconstruction of cloud cover over the Caribbean Sea that extends back to the year 1760. We will show that there is good agreement between the main features of our coral proxy record of

  2. Road Signs Detection and Recognition Utilizing Images and 3d Point Cloud Acquired by Mobile Mapping System

    NASA Astrophysics Data System (ADS)

    Li, Y. H.; Shinohara, T.; Satoh, T.; Tachibana, K.

    2016-06-01

    High-definition and highly accurate road maps are necessary for the realization of automated driving, and road signs are among the most important element in the road map. Therefore, a technique is necessary which can acquire information about all kinds of road signs automatically and efficiently. Due to the continuous technical advancement of Mobile Mapping System (MMS), it has become possible to acquire large number of images and 3d point cloud efficiently with highly precise position information. In this paper, we present an automatic road sign detection and recognition approach utilizing both images and 3D point cloud acquired by MMS. The proposed approach consists of three stages: 1) detection of road signs from images based on their color and shape features using object based image analysis method, 2) filtering out of over detected candidates utilizing size and position information estimated from 3D point cloud, region of candidates and camera information, and 3) road sign recognition using template matching method after shape normalization. The effectiveness of proposed approach was evaluated by testing dataset, acquired from more than 180 km of different types of roads in Japan. The results show a very high success in detection and recognition of road signs, even under the challenging conditions such as discoloration, deformation and in spite of partial occlusions.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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%.

  9. Semi-Automated Cloud/shadow Removal and Land Cover Change Detection Using Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Sah, A. K.; Sah, B. P.; Honji, K.; Kubo, N.; Senthil, S.

    2012-08-01

    Multi-platform/sensor and multi-temporal satellite data facilitates analysis of successive change/monitoring over the longer period and there by forest biomass helping REDD mechanism. The historical archive satellite imagery, specifically Landsat, can play an important role for historical trend analysis of forest cover change at national level. Whereas the fresh high resolution satellite, such as ALOS, imagery can be used for detailed analysis of present forest cover status. ALOS satellite imagery is most suitable as it offers data with optical (AVNIR-2) as well as SAR (PALSAR) sensors. AVNIR-2 providing data in multispectral modes play due role in extracting forest information. In this study, a semi-automated approach has been devised for cloud/shadow and haze removal and land cover change detection. Cloud/shadow pixels are replaced by free pixels of same image with the help of PALSAR image. The tracking of pixel based land cover change for the 1995-2009 period in combination of Landsat and latest ALOS data from its AVNIR-2 for the tropical rain forest area has been carried out using Decision Tree Classifiers followed by un-supervised classification. As threshold for tree classifier, criteria of NDVI refined by reflectance value has been employed. The result shows all pixels have been successfully registered to the pre-defined 6 categories; in accordance with IPCC definition; of land cover types with an overall accuracy 80 percent.

  10. 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

  11. 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

  12. 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.

  13. Effects of Ozone and Cloud Cover on Surface Ultraviolet Radiation at High Southern Latitudes

    NASA Astrophysics Data System (ADS)

    Liao, Y.; Frederick, J. E.

    2002-12-01

    For over twenty years, the high latitude ozone depletion during austral springs and the increased surface ultraviolet (UV) radiation have caused concern due to the potential for negative biological and ecological effects. Since little long-term information on surface UV is available, the capability of assessing these effects has been limited. For a better understanding of the UV environment during springtime in the polar region, the National Science Foundation (NSF) Ultraviolet (UV) Monitoring Network was established in 1987 by the NSF Office of Polar Programs. Four out of the six sites, Ushuaia, Argentina (54°49'S, 68°19'W), Palmer Station, Antarctica (64°46'S, 64°03'W), McMurdo Station, Antarctica (77°51'S, 166°40'E), and South Pole Station, Antarctica (90°S), were at high southern latitudes. With the data at these four sites for over a decade (1990-2001), we were able to study the behavior of surface UV radiation in the south polar region, including the attenuation provided by total column ozone and cloud cover. To specify the effect of ozone on surface UV radiation, we used effective clear sky irradiances that were estimated from the actual measurements in a reference wavelength band from 342.5 to 347.5 nm throughout all years covered by the data. The effects of cloud cover can be obtained by taking ratios of measured UV irradiances to the corresponding effective clear sky values. We anticipate an upward trend in the surface UV irradiance in response to changes in total column ozone alone over the decadal time scale, and occasional abnormally large and small values due to the combined effects of variability in ozone and cloud cover. The latter case can be demonstrated by the fact that the monthly-integrated irradiance of UVB2 measured for October 1991 is actually 99.2% larger than the smallest value that was observed in October 1990.

  14. Object-Based Analysis of Aerial Photogrammetric Point Cloud and Spectral Data for Land Cover Mapping

    NASA Astrophysics Data System (ADS)

    Debella-Gilo, M.; Bjørkelo, K.; Breidenbach, J.; Rahlf, J.

    2013-04-01

    The acquisition of 3D point data with the use of both aerial laser scanning (ALS) and matching of aerial stereo images coupled with advances in image processing algorithms in the past years provide opportunities to map land cover types with better precision than before. The present study applies Object-Based Image Analysis (OBIA) to 3D point cloud data obtained from matching of stereo aerial images together with spectral data to map land cover types of the Nord-Trøndelag county of Norway. The multi-resolution segmentation algorithm of the Definiens eCognition™ software is used to segment the scenes into homogenous objects. The objects are then classified into different land cover types using rules created based on the definitions given for each land cover type by the Norwegian Forest and Landscape Institute. The quality of the land cover map was evaluated using data collected in the field as part of the Norwegian National Forest Inventory. The results show that the classification has an overall accuracy of about 80% and a kappa index of about 0.65. OBIA is found to be a suitable method for utilizing 3D remote sensing data for land cover mapping in an effort to replace manual delineation methods.

  15. 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.

  16. 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.

  17. An Assessment of Diurnal and Seasonal Cloud Cover Changes Over the Hawaiian Islands Using Terra and Aqua MODIS

    NASA Astrophysics Data System (ADS)

    Barnes, M.; Miura, T.; Giambelluca, T. W.; Chen, Q.

    2012-12-01

    To date, there has not yet been a spatial and temporal analysis of cloud cover over the Hawaiian Islands using high spatial resolution data. An understanding of patterns in cloud cover is essential to analyzing and understanding atmospheric and hydrologic processes, including evapotranspiration. The MODIS instruments aboard the Terra and Aqua satellites provide observations with the high spatial resolution necessary to determine patterns of cloud cover over the Hawaiian Islands. The objective of this study was to determine how spatial patterns of cloudiness change diurnally and seasonally over the Hawaiian Islands using high resolution cloud cover data generated from the Terra and Aqua MODIS satellite sensors. The MODIS cloud mask products (MOD35 and MYD35) were obtained for the entire MODIS time series over the major Hawaiian Islands. Monthly statistics including mean cloud cover probability at the daytime and nighttime overpasses for each instrument were generated from the daily MOD35 and MYD35 cloudiness time series. The derived monthly statistics for January and June (the wet and dry season, respectively) were analyzed for diurnal (morning vs. afternoon and late evening vs. early morning) changes in total amount and spatial patterns of cloudiness. They were also compared to analyze seasonal changes in cloudiness. Cloud probability generally increased with elevation until the elevation of the inversion layer. The lowest cloud cover probability was observed above the inversion layer on the islands of Maui and Hawaii. This elevational gradient varied in relation to the facings of slopes; cloud cover probability was higher on the windward (northeastern) sides than on the leeward (southwestern) sides of the mountains. Both morning and afternoon observations indicate that the Hawaiian Islands were cloudier in June than in January. This is the opposite of what we might expect as January is in the wet season and June is in the dry season. Both late evening and early

  18. 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.

  19. 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.

  20. Satellite remote sensing of particulate matter air quality: the cloud-cover problem.

    PubMed

    Christopher, Sundar A; Gupta, Pawan

    2010-05-01

    Satellite assessments of particulate matter (PM) air quality that use solar reflectance methods are dependent on availability of clear sky; in other words, mass concentrations of PM less than 2.5 microm in aerodynamic diameter (PM2.5) cannot be estimated from satellite observations under cloudy conditions or bright surfaces such as snow/ice. Whereas most ground monitors measure PM2.5 concentrations on an hourly basis regardless of cloud conditions, space-borne sensors can only estimate daytime PM2.5 in cloud-free conditions, therefore introducing a bias. In this study, an estimate of this clear-sky bias is provided from monthly to yearly time scales over the continental United States. One year of the Moderate Resolution Imaging Spectroradiometer (MODIS) 550-nm aerosol optical depth (AOD) retrievals from Terra and Aqua satellites, collocated with 371 U.S. Environmental Protection Agency (EPA) ground monitors, have been analyzed. The results indicate that the mean differences between PM2.5 reported by ground monitors and PM2.5 calculated from ground monitors during the satellite overpass times during cloud-free conditions are less than +/- 2.5 microg m(-3), although this value varies by season and location. The mean differences are not significant as calculated by t tests (alpha = 0.05). On the basis of this analysis, it is concluded that for the continental United States, cloud cover is not a major problem for inferring monthly to yearly PM2.5 from space-borne sensors. PMID:20480859

  1. Spatio-temporal MODIS EVI gap filling under cloud cover: An example in Scotland

    NASA Astrophysics Data System (ADS)

    Poggio, Laura; Gimona, Alessandro; Brown, Iain

    2012-08-01

    Time series of satellite data have an important role in the monitoring of regional and global ecosystem properties. Satellite images often present missing data due to atmospheric aerosol, clouds or other atmospheric conditions. Most methods proposed to minimise the effects of degradation and to restore signal values do not take into account the spatial and temporal correlation of the values in the pixels. The aim of this study was to propose and test a spatio-temporal interpolation method to reconstruct pixel values in MODIS data time series that are missing due to cloud cover or other image noise. The method presented and tested is an example of a hybrid Generalised Additive Model (GAM)-geostatistical space-time model, including the fitting of a smoother spatio-temporal trend and a spatial component to account for local details supported by information in covariates. The method is not limited by the type of noise or degradation of pixels values, latitude, vegetation dynamics and land uses. The application of cloud masks on the target image provided the data for a quantitative validation through the comparison between the modelled EVI values and those from the MODIS product. The method was able to restore data providing very good to adequate responses in series of simulations of missing data. The comparison of distributions showed good agreement and predictive capabilities. The spatio-temporal method always performed better and the use of kriged residuals was helpful for situations with high percentages of missing data. The spatial pattern and the local features were well preserved for cloud coverage ⩽20%. For higher percentages of missing data, the results were smoother with less local detail retained, but still showing the general spatial pattern of the variable. The method has proved to be flexible and able to provide reconstructed images reproducing spatial patterns and local features of the measured product, even with substantial amounts of missing pixels.

  2. Improved AIRS/AMSU Surface and Atmospheric Soundings Under Partial Cloud Cover Using an AIRS Only Cloud Clearing Approach

    NASA Technical Reports Server (NTRS)

    Susskind, Dr. Joel

    2007-01-01

    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. This paper describes the latest scientific advances made in the AIRS Science Team Version 5.0 retrieval algorithm. Starting in early 2007, the Goddard DAAC will use this algorithm to analyze near real time AIRS/AMSU observations. These products are then made available to the scientific community for research purposes. The products include twice daily measurements of the Earth's three dimensional global temperature, water vapor, and ozone distribution as well as cloud cover. In addition, accurate twice daily measurements of the earth's land and ocean temperatures are derived and reported. Scientists use this important set of observations for two major uses. They provide important information for climate studies of global and regional variability and trends of different aspects of the earth's atmosphere. They also provide information for researchers to improve the skill of weather forecasting. A very important new product of the AIRS Version 5 algorithm is accurate case-by-case error estimates of the retrieved products. This heightens their utility for use in both weather and climate applications. These error estimates are also used directly for quality control of the retrieved products.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Statistical dependence of albedo and cloud cover on sea surface temperature for two tropical marine stratocumulus regions

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Davies, Roger

    1993-01-01

    The relationship between sea surface temperature (SST) and albedo or cloud cover is examined for two tropical regions with high values of cloud radiative forcing and persistent marine stratocumulus (mSc)-one off the west coast of Peru, the other off the west coast of Angola. The data span five years, from December 1984 to November 1989. Albedos are from the Earth Radiation Budget Experiment (ERBE), cloud covers are from the International Satellite Cloud Climatology Project (ISCCP), and SSTS are from the Climate Analysis Center. Negative correlation coefficients between albedo and SST are found to be about -0.8 when the seasonal variation of the entire dataset is analyzed. The interannual variation and the spatial variation of individual months also yields correlation coefficients that are negative. The correlation between cloud cover and SST is found to be similar to but weaker than the correlation between albedo and SST, suggesting a decrease in cloud amount and a decrease in cloud albedo with increasing SST for these regions. The corresponding albedo sensitivity averages -0.018/K with local values reaching -0.04/K. These findings are valid from 19 C to 25 C for the Peru mSc and 22 C to 27 C for the Angola mSc. These temperatures approximately bound the domains over which mSc is the prevalent cloud type within each region. These results imply a potential positive feedback to global warming by marine stratocumulus that ranges from approximately 0.14 W/sq m/K to approximately 1 W/sq m/K, depending on whether or not our results apply to all marine stratocumulus. While these values are uncertain to at least +/- 50%, the sensitivity of albedo to sea surface temperature in the present climate may serve as a useful diagnostic tool in monitoring the performance of global climate models.

  9. 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.

  10. Monthly and Seasonal Cloud Cover Patterns at the Manila Observatory (14.64°N, 121.08°E)

    NASA Astrophysics Data System (ADS)

    Antioquia, C. T.; Lagrosas, N.; Caballa, K.

    2014-12-01

    A ground based sky imaging system was developed at the Manila Observatory in 2012 to measure cloud occurrence and to analyse seasonal variation of cloud cover over Metro Manila. Ground-based cloud occurrence measurements provide more reliable results compared to satellite observations. Also, cloud occurrence data aid in the analysis of radiation budget in the atmosphere. In this study, a GoPro Hero 2 with almost 180o field of view is employed to take pictures of the atmosphere. These pictures are taken continuously, having a temporal resolution of 1min. Atmospheric images from April 2012 to June 2013 (excluding the months of September, October, and November 2012) were processed to determine cloud cover. Cloud cover in an image is measured as the ratio of the number of pixels with clouds present in them to the total number of pixels. The cloud cover values were then averaged over each month to know its monthly and seasonal variation. In Metro Manila, the dry season occurs in the months of November to May of the next year, while the wet season occurs in the months of June to October of the same year. Fig 1 shows the measured monthly variation of cloud cover. No data was collected during the months of September (wherein the camera was used for the 7SEAS field campaign), October, and November 2012 (due to maintenance and repairs). Results show that there is high cloud cover during the wet season months (80% on average) while there is low cloud cover during the dry season months (62% on average). The lowest average cloud cover for a wet season month occurred in June 2012 (73%) while the highest average cloud cover for a wet season month occurred in June 2013 (86%). The variations in cloud cover average in this season is relatively smaller compared to that of the dry season wherein the lowest average cloud cover in a month was during April 2012 (38%) while the highest average cloud cover in a month was during January 2013 (77%); minimum and maximum averages being 39

  11. Cloud cover limits net CO2 uptake and growth of a rainforest tree during tropical rainy seasons

    PubMed Central

    Graham, Eric A.; Mulkey, Stephen S.; Kitajima, Kaoru; Phillips, Nathan G.; Wright, S. Joseph

    2003-01-01

    Recent global-scale analyses indicate that climate variability affects net carbon storage but regard temperature and precipitation to be the main contributors. Seasonal and interannual variation in light availability may also limit CO2 uptake. As an experimental test of light limitation by cloud cover during tropical rainy seasons and by the unusually heavy cloud cover associated with La Niña, we installed high-intensity lamps above the forest canopy to augment light for Luehea seemannii, a tropical canopy tree species, during cloudy periods of 1999–2000. Light augmentation only partially compensated for the reduction in photosynthetic photon flux density caused by clouds. Nonetheless, leaves acclimated to the augmented irradiance, and photosynthesis, vegetative growth, and reproduction increased significantly. Light, rather than water, temperature, or leaf nitrogen, was the primary factor limiting CO2 uptake during the rainy season. PMID:12518044

  12. 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.

  13. 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

  14. Atmospheric movies acquired at the Mars Science Laboratory landing site: Cloud morphology, frequency and significance to the Gale Crater water cycle and Phoenix mission results

    NASA Astrophysics Data System (ADS)

    Moores, John E.; Lemmon, Mark T.; Rafkin, Scot C. R.; Francis, Raymond; Pla-Garcia, Jorge; de la Torre Juárez, Manuel; Bean, Keri; Kass, David; Haberle, Robert; Newman, Claire; Mischna, Michael; Vasavada, Ashwin; Rennó, Nilton; Bell, Jim; Calef, Fred; Cantor, Bruce; Mcconnochie, Timothy H.; Harri, Ari-Matti; Genzer, Maria; Wong, Michael; Smith, Michael D.; Javier Martín-Torres, F.; Zorzano, María-Paz; Kemppinen, Osku; McCullough, Emily

    2015-05-01

    We report on the first 360 sols (LS 150° to 5°), representing just over half a Martian year, of atmospheric monitoring movies acquired using the NavCam imager from the Mars Science Laboratory (MSL) Rover Curiosity. Such movies reveal faint clouds that are difficult to discern in single images. The data set acquired was divided into two different classifications depending upon the orientation and intent of the observation. Up to sol 360, 73 Zenith movies and 79 Supra-Horizon movies have been acquired and time-variable features could be discerned in 25 of each. The data set from MSL is compared to similar observations made by the Surface Stereo Imager (SSI) onboard the Phoenix Lander and suggests a much drier environment at Gale Crater (4.6°S) during this season than was observed in Green Valley (68.2°N) as would be expected based on latitude and the global water cycle. The optical depth of the variable component of clouds seen in images with features are up to 0.047 ± 0.009 with a granularity to the features observed which averages 3.8°. MCS also observes clouds during the same period of comparable optical depth at 30 and 50 km that would suggest a cloud spacing of 2.0 to 3.3 km. Multiple motions visible in atmospheric movies support the presence of two distinct layers of clouds. At Gale Crater, these clouds are likely caused by atmospheric waves given the regular spacing of features observed in many Zenith movies and decreased spacing towards the horizon in sunset movies consistent with clouds forming at a constant elevation. Reanalysis of Phoenix data in the light of the NavCam equatorial dataset suggests that clouds may have been more frequent in the earlier portion of the Phoenix mission than was previously thought.

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Geographical correlation of earth cloud cover pictures obtained from unoriented satellites

    NASA Technical Reports Server (NTRS)

    Solovyev, V. I.

    1974-01-01

    Mathematical models have been developed for the determination of the geographic coordinates of cloud photographs taken from earth satellites. The proposed methods were realized on a Minsk-22 computer, and were used to process the earth cloud pictures obtained from the communications satellite Molyniya 1 and the automatic stations Zond 5 and 7. Experience using these methods showed that the accuracy of orientation angular element determination is on the order of 1 deg.

  1. Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries

    PubMed Central

    2015-01-01

    There are 52,380 cases of leukemia and 24,090 deaths from it in the US annually. Its causes are unknown and no preventive strategies have been implemented. We hypothesized that leukemia is due mainly to vitamin D deficiency, which is due mainly to low solar ultraviolet B (UVB) irradiance. To test this hypothesis, we estimated age-standardized cloud-cover-adjusted winter UVB irradiance using cloud cover data from the International Satellite Cloud Climatology Project, latitudes of population centroids, and standard astronomical calculations. Incidence rates for 172 countries, available from the International Agency for Cancer Research, were plotted according to cloud-adjusted UVB irradiance. We used multiple regression to account for national differences in elevation and average life expectancy. Leukemia incidence rates were inversely associated with cloud-adjusted UVB irradiance in males (p ≤ 0.01) and females (p ≤ 0.01) in both hemispheres. There were few departures from the trend line, which was parabolic when plotted with the equator at the center of the display, northern hemisphere countries on the right side and southern hemisphere countries on the left. The bivariate association displayed by the polynomial trend line indicated that populations at higher latitudes had at least two times the risk of leukemia compared to equatorial populations. The association persisted in males (p ≤ 0.05) and females (p ≤ 0.01) after controlling for elevation and life expectancy. Incidence rates of leukemia were inversely associated with solar UVB irradiance. It is plausible that the association is due to vitamin D deficiency. This would be consistent with laboratory studies and a previous epidemiological study. Consideration should be given to prudent use of vitamin D for prevention of leukemia. PMID:26637119

  2. Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries.

    PubMed

    Cuomo, Raphael E; Garland, Cedric F; Gorham, Edward D; Mohr, Sharif B

    2015-01-01

    There are 52,380 cases of leukemia and 24,090 deaths from it in the US annually. Its causes are unknown and no preventive strategies have been implemented. We hypothesized that leukemia is due mainly to vitamin D deficiency, which is due mainly to low solar ultraviolet B (UVB) irradiance. To test this hypothesis, we estimated age-standardized cloud-cover-adjusted winter UVB irradiance using cloud cover data from the International Satellite Cloud Climatology Project, latitudes of population centroids, and standard astronomical calculations. Incidence rates for 172 countries, available from the International Agency for Cancer Research, were plotted according to cloud-adjusted UVB irradiance. We used multiple regression to account for national differences in elevation and average life expectancy. Leukemia incidence rates were inversely associated with cloud-adjusted UVB irradiance in males (p ≤ 0.01) and females (p ≤ 0.01) in both hemispheres. There were few departures from the trend line, which was parabolic when plotted with the equator at the center of the display, northern hemisphere countries on the right side and southern hemisphere countries on the left. The bivariate association displayed by the polynomial trend line indicated that populations at higher latitudes had at least two times the risk of leukemia compared to equatorial populations. The association persisted in males (p ≤ 0.05) and females (p ≤ 0.01) after controlling for elevation and life expectancy. Incidence rates of leukemia were inversely associated with solar UVB irradiance. It is plausible that the association is due to vitamin D deficiency. This would be consistent with laboratory studies and a previous epidemiological study. Consideration should be given to prudent use of vitamin D for prevention of leukemia. PMID:26637119

  3. Characterizing Spatial Patterns of Cloud Cover and Fog Inundation in the Northern Channel Islands Using Satellite Datasets and Comparison to Ground Measurements

    NASA Astrophysics Data System (ADS)

    Rastogi, B.; Still, C. J.; Fischer, D. T.; Iacobellis, S. F.; Toomey, M. P.; Greer, B.; Baguskas, S. A.; Williams, P.; McEachern, K.

    2012-12-01

    Coastal forests in Mediterranean climates are frequently covered by clouds or immersed in fog. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon budgets in these semi-arid environments. Both low level stratocumulus cloud cover and fog can enhance the water status of vegetation along the Californian coast and the Channel Islands by reducing solar insolation, raising relative humidity and supplying water directly to the landscape during otherwise warm and rainless summers. While summertime fog and stratus cover in California's Channel Islands can ameliorate summer drought stress and enhance soil water budgets, they have different spatial patterns. These differing spatial patterns and the resulting shifts in relative ecological importance of fog and stratus are largely unknown. The overall objective of this project was to map spatial 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. Daytime cloud cover maps were generated for the Channel Islands using data from GOES satellite imagery. Cloud frequency maps were compared and found to be in agreement with solar insolation data collected at several sites on Santa Cruz and Santa Rosa islands for the summer of 2005. These cloud frequency maps were then combined with airport cloud height data and topographic data to map estimated weekly and monthly fog inundation. The fog inundation maps were then compared to fog drip data collected at several sites on the two islands. Correlation between fog inundation and fog drip accumulation enabled spatial and temporal extrapolation to understand seasonal and inter-annual variations in cloud cover frequency and fog inundation and drip. Future studies will use these cloud and fog distributions for water balance modeling and studies of plant geography and forest distributions.

  4. Evaluation of modeled surface ozone biases as a function of cloud cover fraction

    NASA Astrophysics Data System (ADS)

    Kim, H. C.; Lee, P.; Ngan, F.; Tang, Y.; Yoo, H. L.; Pan, L.

    2015-09-01

    A regional air-quality forecast system's model of surface ozone variability based on cloud coverage is evaluated using satellite-observed cloud fraction (CF) information and a surface air-quality monitoring system. We compared CF and daily maximum ozone from the National Oceanic and Atmospheric Administration's National Air Quality Forecast Capability (NOAA NAQFC) with CFs from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the US Environmental Protection Agency's AirNow surface ozone measurements during May to October 2014. We found that observed surface ozone shows a negative correlation with the MODIS CFs, showing around 1 ppb decrease for 10 % MODIS CF change over the contiguous United States, while the correlation of modeled surface ozone with the model CFs is much weaker, showing only -0.5 ppb per 10 % NAQFC CF change. Further, daytime CF differences between MODIS and NAQFC are correlated with modeled surface-ozone biases between AirNow and NAQFC, showing -1.05 ppb per 10 % CF change, implying that spatial and temporal misplacement of the modeled cloud field might have biased modeled surface ozone level. Current NAQFC cloud fields seem to have fewer CFs compared to MODIS cloud fields (mean NAQFC CF = 0.38 and mean MODIS CF = 0.55), contributing up to 35 % of surface-ozone bias in the current NAQFC system.

  5. Evaluation of modeled surface ozone biases as a function of cloud cover fraction

    NASA Astrophysics Data System (ADS)

    Kim, H. C.; Lee, P.; Ngan, F.; Tang, Y.; Yoo, H. L.; Pan, L.

    2015-04-01

    A regional air-quality forecast system's model of surface ozone variability based on cloud coverage is evaluated using satellite-observed cloud fraction (CF) information and a surface air-quality monitoring system. We compared CF and daily maximum ozone from the National Oceanic and Atmospheric Administration's National Air Quality Forecast Capability (NOAA NAQFC) with CFs from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the U.S. Environmental Protection Agency's AirNow surface ozone measurements during May to October 2014. We found that observed surface ozone shows a clear (negative) correlation with the MODIS CFs, showing around 1 ppb decrease for 10% MODIS CF change over the Contiguous United States, while the correlation of modeled surface ozone with the model CFs is much weaker, showing only -0.5 ppb per 10% NAQFC CF change. Further, daytime CF differences between MODIS and NAQFC are correlated with modeled surface-ozone biases between AirNow and NAQFC, showing -1.05 ppb per 10% CF change, implying that spatial- and temporal-misplacement of the modeled cloud field might have biased modeled surface ozone-level. Current NAQFC cloud fields seem to be too bright compared to MODIS cloud fields (mean NAQFC CF = 0.38 and mean MODIS CF = 0.55), contributing up to 35% of surface-ozone bias in the current NAQFC system.

  6. 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

  7. 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

  8. Comparing Arctic Surface Energy Fluxes and Cloud Cover in the ERA-40, SHEBA, and Other Data Sets

    NASA Astrophysics Data System (ADS)

    Wheeler, C.; Persson, O. P.; Shupe, M.

    2008-12-01

    Earth's climate has been changing rapidly in the past few decades. The effects of climate change have been shown to be most noticeable in the Arctic (IPCC 2001). However, the Arctic environment is poorly understood due to several unique factors: relatively high surface albedo, absence of solar radiation during the polar night, extremely cold and dry conditions, and presence of temperature and humidity inversions. In order to understand the response of the Arctic to a changing climate, studies of trends, processes, and feedbacks utilize models and model-observation hybrid data sets. Hence, the accuracy of the processes and feedbacks in these data sets are important. In this study, surface radiative and turbulent fluxes from the ECMWF reanalysis data set (ERA-40; Uppala 2005) are examined from November 1997 through October 1998 over the Arctic Ocean, spanning from 73°N to 76°N latitude and 26°W to 36°W longitude. The reanalysis product is compared to observations taken at the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment (Persson et al. 2002), Russian drifting stations (Lindsay 1998), and the 'Maud' expedition (Sverdrup 1933). In general, the radiative fluxes in ERA-40 agree well with the observations, but with some exceptions that lead to significant differences in the net radiative surface flux and thus in the total surface energy budget. The ERA-40 turbulent fluxes have a similar annual pattern to the observations, but differ in magnitude, again contributing to the error seen in the total surface energy budget. Since clouds have one of the largest impacts on feedback mechanisms, cloud cover from ERA-40 is validated against cloud radar data collected at SHEBA. Finally, the observed relationships between cloud cover and surface fluxes in the SHEBA data are used to validate those in the ERA-40 data.

  9. Development of a climatological data base to help forecast cloud cover conditions for shuttle landings at the Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Atchison, M. Kevin

    1993-01-01

    The Space Shuttle is an extremely weather sensitive vehicle with very restrictive constraints for both launches and landings. The most important difference between Shuttle and normal aircraft landings is that the Shuttle has no go-around capability once it begins its decent into the earth's atmosphere. The de-orbit burn decision is generally made approximately 90 minutes before landing requiring a forecast with little room for error. Because of the Shuttle's rapid re-entry to earth, the pilot must be able to see all runway and visual navigation aids from high altitude to land the Shuttle. In addition, the heat resistant tiles which are used to protect the Shuttle during its re-entry into the earth's atmosphere are extremely sensitive to any type of precipitation. Extensive damage to these tiles could occur if the Shuttle passes through any cloud that contains precipitation size particles. To help guard against changing weather conditions or any type of weather problems that might occur prior to landing, flight rules have been developed as guidelines for all landings. Although the rules vary depending on the location of the landing (Kennedy Space Center or Edwards AFB), length of mission, and weight of vehicle, most of the rules can be condensed into 4 major groupings. These are: (1) Cloud ceilings should not be less than 3048 m (10,000 feet), (2) Visibility should not be less than 13 km (7 nm), (3) Cross-wind no greater than 5-8 m/s (10-15 knots); and (4) No showers or thunderstorms at or within 56 km (30 nm) of the Shuttle Landing Facility. This study consisted of developing a climatological database of the Shuttle Landing Facility (SLF) surface observations and performing an analysis of observed conditions one and two hours subsequent to given conditions at the SLF to help analyze the 0.2 cloud cover rule. Particular emphasis was placed on Shuttle landing weather violations and the amounts of cloud cover below 3048 m (10,000 ft.). This analysis has helped to

  10. STS-44 Earth observation of a cloud-covered area of China and the Earth's limb

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-44 Earth observation taken aboard Atlantis, Orbiter Vehicle (OV) 104, is of China and the Earth's limb. OV-104 was flying over a point near Canton, China. View is to the west-northwest. It was taken near mid afternoon, local time. OV-104's vertical tail points to the Earth's surface below. The empty airborne support equipment (ASE) is visible in the aft payload bay (PLB). STS-44 crewmembers who had flown on Space Shuttle missions which were previous to the Mount Pinatubo eruption reported that the limb of the Earth showed a more bluish tint compared to the purple seen during this mission. The clouds in the foreground, according to NASA scientists studying STS-44 photography, are associated with a mid-latitude cyclone, and a pattern of jet-stream cirrus clouds also entends across the center of the image.

  11. 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

  12. 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

  13. A study of the cloud cover and cloud top pressure weekly cycle over the region of Eastern Mediterranean with the use of MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Dalampiras, Pashalis; Georgoulias, Aristeidis K.; Kourtidis, Konstantinos; Alexandri, Georgia; Meleti, Charoula

    2014-05-01

    In this work, the spatiotemporal variability of cloud cover (CC) and cloud top pressure (CTP) over the region of Eastern Mediterranean is presented. The analysis is based on level-2 data from MODIS TERRA and AQUA satellite sensors for the period 3/2000-12/2012 and 7/2002-12/2012, respectively. The data used here are from the 0.1-degree aerosol-cloud gridded dataset that was compiled within the framework of QUADIEEMS project for the investigation of the aerosol indirect effects. The Weekly Cycle Index (WCI) and the day of weekly maximum/minimum patterns are calculated on a seasonal basis and their possible connections with local aerosol sources and the regional aerosol patterns are investigated. To generalize our results, the day-of-the-week variability of CC and CTP for 9 sub-regions with different aerosol characteristics is examined. Among the most striking features is a summer CC midweek minimum over the Balkan Peninsula. Contrasting this, a weekend CC minimum appears over the Aegean and the Black Sea. In spring, we observe a statistically significant weekend CC maximum over the Balkan Peninsula and the sea regions around it. The synergistic use of various satellite, model and reanalysis products indicates that these regions are characterized by a strong presence of anthropogenic aerosols. The opposite behaviour is observed for CTP; however, the statistically significant weekly maxima and minima appear mostly over land. The QUADIEEMS project is co-financed by the European Social Fund (ESF) and national resources under the operational programme Education and Lifelong Learning (EdLL) within the framework of the Action "Supporting Postdoctoral Researchers".

  14. 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.

    2015-09-01

    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.

  15. 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.

  16. 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.

  17. 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.

  18. Red is the new black: how the colour of urban skyglow varies with cloud cover

    NASA Astrophysics Data System (ADS)

    Kyba, C. C. M.; Ruhtz, T.; Fischer, J.; Hölker, F.

    2012-09-01

    The development of street lamps based on solid-state lighting technology is likely to introduce a major change in the colour of urban skyglow (one form of light pollution). We demonstrate the need for long-term monitoring of this trend by reviewing the influences it is likely to have on disparate fields. We describe a prototype detector which is able to monitor these changes, and could be produced at a cost low enough to allow extremely widespread use. Using the detector, we observed the differences in skyglow radiance in red, green and blue channels. We find that clouds increase the radiance of red light by a factor of 17.6, which is much larger than that for blue (7.1). We also find that the gradual decrease in sky radiance observed on clear nights in Berlin appears to be most pronounced at longer wavelengths.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Trends in Upper-Level Cloud Cover and Surface Divergence Over the Tropical Indo-Pacific Ocean Between 1952 And 1997

    NASA Technical Reports Server (NTRS)

    Norris, Joel R.

    2005-01-01

    This study investigated the spatial pattern of linear trends in surface-observed upper-level (combined mid-level and High-level) cloud cover, precipitation, and surface divergence over the tropical Indo-Pacific Ocean during 1952-1957. Cloud values were obtained from the Extended Edited Cloud Report Archive (EECRA), precipitation values were obtained from the Hulme/Climate Research Unit Data Set, and surface divergence was alternatively calculated from wind reported Comprehensive Ocean-Atmosphere Data Set and from Smith and Reynolds Extended Reconstructed sea level pressure data.

  4. Protostellar collapse of rotating cloud cores. Covering the complete first accretion period of the stellar core

    NASA Astrophysics Data System (ADS)

    Schönke, J.; Tscharnuter, W. M.

    2011-02-01

    Aims: We investigate the influence of turbulent viscosity on the collapse of a rotating molecular cloud core with axial symmetry, in particular, on the first and second collapse phase, as well as the evolution of the second (protostellar) core during its first accretion period. By using extensive numerical calculations, we monitor the intricate interactions between the newly formed protostar and the surrounding accretion disk (the first core) in which the star is embedded. Methods: We use a grid-based radiation-hydrodynamics code with a spatial grid designed to meet the high resolution required to study the second core. The radiative transfer is treated in the flux-limited diffusion approximation. A slightly supercritical Bonnor-Ebert sphere of 1 Msun and uniform rotation according to a fixed centrifugal radius of 100 AU serves as the initial condition without exception. In a parameter study, we vary the β-viscosity driving the angular momentum transport. Results: Without viscosity (β=0), a highly flattened accretion disk forms that fragments into several "cold" rings. For β = 10-4, a single "warm" ring forms that undergoes collapse due to hydrogen dissociation. For β = 10-3, ring formation is suppressed completely. The second collapse proceeds on the local thermal timescale, which is in contrast to the current view of a generally dynamical second collapse. During the first accretion period of the second core, the first core heats up globally and, as a consequence, a nearly spherical outflow occurs, destroying the structure of the former accretion disk completely. Finally, for β = 10-2, we see the classical dynamical second collapse and a shorter but more rapid accretion phase. The impact on the surrounding accretion disk is even more pronounced. We follow the resulting massive outflow up to several kyr after the second collapse, where the central parts (R < 0.7 AU) are now cut out and replaced with an appropriate inner boundary condition. Matter is found to

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

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

    DOE PAGESBeta

    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 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

  11. 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.

  12. Cloud cover over the equatorial eastern Pacific derived from July 1983 International Satellite Cloud Climatology Project data using a hybrid bispectral threshold method

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Harrison, Edwin F.; Gibson, Gary G.

    1987-01-01

    A set of visible and IR data obtained with GOES from July 17-31, 1983 is analyzed using a modified version of the hybrid bispectral threshold method developed by Minnis and Harrison (1984). This methodology can be divided into a set of procedures or optional techniques to determine the proper contaminate clear-sky temperature or IR threshold. The various optional techniques are described; the options are: standard, low-temperature limit, high-reflectance limit, low-reflectance limit, coldest pixel and thermal adjustment limit, IR-only low-cloud temperature limit, IR clear-sky limit, and IR overcast limit. Variations in the cloud parameters and the characteristics and diurnal cycles of trade cumulus and stratocumulus clouds over the eastern equatorial Pacific are examined. It is noted that the new method produces substantial changes in about one third of the cloud amount retrieval; and low cloud retrievals are affected most by the new constraints.

  13. 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.

  14. 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.

  15. Aerosol effects on cloud cover as evidenced by ground-based and space-based observations at five rural sites in the United States

    NASA Astrophysics Data System (ADS)

    Ten Hoeve, John E.; Augustine, John A.

    2016-01-01

    Previous studies of the second aerosol indirect (lifetime) effect on cloud cover have estimated the strength of the effect without correcting for near-cloud contamination and other confounding factors. Here we combine satellite-based observations with a multiyear ground-based data set across five rural locations in the United States to more accurately constrain the second indirect aerosol effect and quantify aerosol effects on radiative forcing. Results show that near-cloud contamination accounts for approximately 40% of the satellite-derived aerosol-cloud relationship. When contamination is removed and the effect of meteorological covariation is minimized, a strong physical aerosol effect on cloud cover remains. Averaged over all stations and after correcting for contamination, the daytime solar and total (solar + IR) radiative forcing is -52 W/m2 and -19 W/m2, respectively, due to both direct and indirect aerosol effects for aerosol optical depths (τ) between 0 and 0.3. Averaged diurnally, the average total radiative forcing is +16 W/m2.

  16. Cloud cover sensor

    NASA Technical Reports Server (NTRS)

    Laue, E. G. (Inventor)

    1982-01-01

    An apparatus is described which provides a numerical indication of the cloudiness at a particular time of a day. The apparatus includes a frame holding several light sensors such as photovoltaic cells, with a direct sensor mounted to directly face the Sun and indirect sensors mounted to face different portions of the sky not containing the Sun. A light shield shields the direct sensor from most of the sky except a small portion containing the Sun, and also shields each of the indirect sensors from direct sunlight. The relative values of the outputs from the direct and indirect sensors, enables the generation of a numerical indication of the degree of cloudiness at a particular time of day.

  17. Cloud shadow speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2014-06-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system is presented that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term solar irradiance forecasts. The cloud shadow speed sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15° and 6% accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  18. Cloud speed sensor

    NASA Astrophysics Data System (ADS)

    Fung, V.; Bosch, J. L.; Roberts, S. W.; Kleissl, J.

    2013-10-01

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS) is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE), and a UC San Diego Sky Imager (USI). The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real) cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s-1 when compared to LCE results.

  19. Temporal variations in the cloud cover of Venus as detected from Venus Monitoring Camera Images on Venus Express Orbiter

    NASA Astrophysics Data System (ADS)

    Limaye, S. S.; Markiewicz, W. J.; Krauss, R. J.

    2014-12-01

    The Venus Monitoring Camera (VMC) on Venus Express [1] has been collecting images of the planet since orbit insertion in April 2006 through four narrow band pass (50 nm halfwidth) with center wavelengths of 365, 550, 950 and 1050 nm [2]. With varying range to the planet during the spacecraft's elliptical, near polar orbit, VMC obtains views of the day side southern hemisphere ( ~ 72,500 km) and the limb when it is furthest away from the planet, and can see a fraction of the planet's sun-lit limb northern latitudes when the spacecraft is closer to the planet ( >~ 25,000 km). We use these images to look at the temporal behavior of the normalized intensity and unit slant optical depth (location of the bright limb) at four wavelengths during April 2006 - March 2014. We detect correlated changes in the normalized brightness and the altitude of the unit optical depth over this period. Images were normalized using Minnaert function to account for the varying scattering geometry in order to detect changes in the reflectivity of the cloud cover at selected locations in local solar time. The unit optical depth was determined from the location of the planet's bright limb, taken to be where the brightness gradient is maximum along the bright limb azimuth. The changes observed appear to be quasi periodic. References [1] H. Svedhem,D.V. Titov, F.W. Taylor, O. Witasse, The Venus Express mission, Nature 450, 629-632, 2007. [2] Markiewicz, W. J. et al. Venus monitoring camera for Venus Express. Planet. Space Sci. 55, 1701-1711, 2007.

  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. 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

  3. 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

  4. Spatial and Temporal Inter-Relationships between Anomalies and Trends 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 by the AIRS Science Team include surface skin temperature and atmospheric temperature profiles; atmospheric humidity profiles, fractional cloud cover and cloud top pressure, and OLR. Products covering the period September 2002 through the present have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. In this paper, we will show results covering the time period September 2006 - November 2008. This time period is marked by a substantial warming trend of Northern Hemisphere Extratropical 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, will be shown, with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. Results will also be shown to validate the anomalies and trends of temperature profiles and OLR as determined from analysis of AIRS/AMSU data. Global and regional trends during the 6 1/3 year period are not necessarily indicative of what has happened in the past, or what may happen in the future. Nevertheless, the inter-relationships of spatial and temporal anomalies of atmospheric geophysical parameters with those of surface skin temperature are indicative of climate processes, and can be used to test the performance of climate models when driven by changes in surface temperatures.

  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. Spatial and Temporal Inter-Relationship between Anomalies and Trends of Temperature, Moisture, Cloud Cover and OLR as Observed by AIRS/AMSU on Aqua

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Molnar, Gyula

    2009-01-01

    AIRS/AMSU is the advanced IR/MW atmospheric sounding system launched on EOS Aqua in May 2002. Products derived from AIRS/AMSU by the AIRS Science Team include surface skin temperature and atmospheric temperature profiled; atmospheric humidity profiles, fractional cloud clover and cloud top pressure, and OLR. Products covering the period September 2002 through the present have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. In this paper, we will show results covering the time period September 2006 - November 2008. This time period is marked by a substantial warming trend of Northern Hemisphere Extra-tropical 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, will be shown with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. Results will also be shown to evaluate the anomalies and trends of temperature profiles and OLR as determined from analysis of AIRS/AMSU data. Global and regional trends during the 6 1/3 year time period are not necessarily indicative of what has happened in the past, or what may happen in the future. Nevertheless, the inter-relationships of spatial and temporal anomalies of atmospheric geophysical parameters with those of surface skin temperature are indicative of climate processes, and can be used to test the performance of climate models when driven by changes in surface temperatures.

  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. 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. PMID:22368479

  9. 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

  10. Cloud top remote sensing by airborne lidar

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Hansen, M. Z.; Caudill, L. O.

    1982-01-01

    Observations of cloud top height, backscattering, and signal depolarization have been obtained by a lidar system operating onboard a high-altitude research aircraft. The transmitter for the cloud lidar system is a doubled Nd:YAG laser operating at 5 Hz. The system functions as a fully automated sensor under microprocessor control and operates from a nominal 19-km altitude. Measurements have been acquired over a wide variety of cloud cover in conjunction with passive visible and infrared measurements. Initial observation results are reported

  11. Cloud top remote sensing by airborne lidar.

    PubMed

    Spinhirne, J D; Hansen, M Z; Caudill, L O

    1982-05-01

    Observations of cloud top height, backscattering, and signal depolarization have been obtained by a lidar system operating onboard a high-altitude research aircraft. The transmitter for the cloud lidar system is a doubled Nd:YAG laser operating at 5 Hz. The system functions as a fully automated sensor under microprocessor control and operates from a nominal 19-km altitude. Measurements have been acquired over a wide variety of cloud cover in conjunction with passive visible and infrared measurements. Initial observation results are reported. PMID:20389897

  12. Cloud shadow Speed Sensor (CSS)

    NASA Astrophysics Data System (ADS)

    Fung, Victor

    Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud shadow motion vectors to estimate power plant ramp rates and provide short-term forecasting is presented. The Cloud shadow Speed Sensor (CSS) is constructed using an array of luminance sensors and a high-speed data acquisition system to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud shadow motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground-measured irradiance (linear cloud edge, LCE), and a UC San Diego sky imager (USI). The CSS detected artificial shadow directions and speeds to within 15° and 6 % accuracy, respectively. The CSS detected (real) cloud shadow directions and speeds with average weighted root-mean-square difference of 22° and 1.9 m s-1 when compared to USI and 33° and 1.5 m s -1 when compared to LCE results.

  13. 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.

  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. 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 ... Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe ...

  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. Seasonal and Interannual Variations of Top-of-Atmosphere Irradiance and Cloud Cover over Polar Regions Derived from the CERES Data Set

    NASA Technical Reports Server (NTRS)

    Kato, Seiji; Loeb, Norman G.; Minnis, Patrick; Francis, Jennifer A.; Charlock, Thomas P.; Rutan, David A.; Clothiaux, Eugene E.; Sun-Mack, Szedung

    2006-01-01

    The semi-direct effects of dust aerosols are analyzed over eastern Asia using 2 years (June 2002 to June 2004) of data from the Clouds and the Earth s Radiant Energy System (CERES) scanning radiometer and MODerate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, and 18 years (1984 to 2001) of International Satellite Cloud Climatology Project (ISCCP) data. The results show that the water path of dust-contaminated clouds is considerably smaller than that of dust-free clouds. The mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are less than their dust-free counterparts by 23.7% and 49.8%, respectively. The long-term statistical relationship derived from ISCCP also confirms that there is significant negative correlation between dust storm index and ISCCP cloud water path. These results suggest that dust aerosols warm clouds, increase the evaporation of cloud droplets and further reduce cloud water path, the so-called semi-direct effect. The semi-direct effect may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation.

  19. 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.

  20. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... acquired person is the pre-acquisition ultimate parent entity of the entity. (ii) The value of an... directors of B. A is deemed to be acquiring all of the assets of B as a result. (g) Transfers of patent... transfer of patent rights covered by this paragraph constitutes an asset acquisition; and (3) Patent...

  1. 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

  2. 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

  3. Arsia Mons Spiral Cloud

    NASA Technical Reports Server (NTRS)

    2002-01-01

    One of the benefits of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. This picture of Arsia Mons was taken June 19, 2001; southern spring equinox occurred the same day. Arsia Mons is a volcano nearly large enough to cover the state of New Mexico. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 km (68 mi) diameter caldera--the summit crater--of the giant volcano. Because the cloud is bright both in the red and blue images acquired by the wide angle cameras, it probably consisted mostly of fine dust grains. The cloud's spin may have been induced by winds off the inner slopes of the volcano's caldera walls resulting from the temperature differences between the walls and the caldera floor, or by a vortex as winds blew up and over the caldera. Similar spiral clouds were seen inside the caldera for several days; we don't know if this was a single cloud that persisted throughout that time or one that regenerated each afternoon. Sunlight illuminates this scene from the left/upper left.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

    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.

  8. Smoke Above Clouds

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.

    2009-01-01

    Aerosols in the atmosphere alter the radiative balance of the Earth by reflecting or absorbing solar radiation. Spaceborne measurements of clouds and aerosols advected over the southeastern Atlantic Ocean indicate that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet.

  9. Clouds over Open Ocean

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The heavy concentration of these cirrocumulus and nimbostratus clouds over open ocean - location unknown, indicate that a heavy downpouring of rain is occuring on the Earth's surface below. Towering anvils, seen rising high above the base cloud cover and casting long shadows, also indicate high winds and possible tornado activity.

  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. 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.

  12. 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.

  13. 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

  14. Search Cloud

    MedlinePlus

    ... this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this page, ... Top 110 zoster vaccine Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  15. Search Cloud

    MedlinePlus

    ... www.nlm.nih.gov/medlineplus/cloud.html Search Cloud To use the sharing features on this page, please enable JavaScript. Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  16. 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.

  17. Io's sodium cloud

    NASA Astrophysics Data System (ADS)

    Goldberg, B. A.; Garneau, G. W.; Lavoie, S. K.

    1984-11-01

    The first two-dimensional images of the source region of Io's neutral sodium cloud have been acquired by ground-based observation. Observed asymmetries in its spatial brightness distribution provide new evidence that the cloud is supplied by sodium that is ejected nonisotropically from Io or its atmosphere. Complementary, high-time-resolution, calibrated image sequences that give the first comprehensive picture of the variations of the fainter regions of the cloud extending more than 100,000 kilometers from Io were also obtained. These data demonstrate that the cloud exhibits a persistent systematic behavior coupled with Io's orbital position, a distinct 'east-west orbital asymmetry', a variety of spatial morphologies, and true temporal changes. The geometric stability of the sodium source is also indicated. Isolation of the cloud's temporal changes constitutes an important milestone toward its utilization as a long-term probe of Io and the inner Jovian magnetosphere.

  18. 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

  19. Hospital-acquired pneumonia

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000146.htm Hospital-acquired pneumonia To use the sharing features on this page, please enable JavaScript. Hospital-acquired pneumonia is an infection of the lungs ...

  20. 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.

  1. Evolving land cover classification algorithms for multispectral and multitemporal imagery

    NASA Astrophysics Data System (ADS)

    Brumby, Steven P.; Theiler, James P.; Bloch, Jeffrey J.; Harvey, Neal R.; Perkins, Simon J.; Szymanski, John J.; Young, Aaron C.

    2002-01-01

    The Cerro Grande/Los Alamos forest fire devastated over 43,000 acres (17,500 ha) of forested land, and destroyed over 200 structures in the town of Los Alamos and the adjoining Los Alamos National Laboratory. The need to measure the continuing impact of the fire on the local environment has led to the application of a number of remote sensing technologies. During and after the fire, remote-sensing data was acquired from 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 to the automated classification of land cover using multi-spectral and multi-temporal imagery. We apply a hybrid genetic programming/supervised 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 from the Landsat 7 ETM+ instrument from before, during, and after the wildfire. Using an existing land cover classification based on a 1992 Landsat 5 TM scene for our training data, we evolve algorithms that distinguish a range of land cover categories, and an algorithm to mask out clouds and cloud shadows. We report preliminary results of combining individual classification results using a K-means clustering approach. The details of our evolved classification are compared to the manually produced land-cover classification.

  2. 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

  3. Radiative characteristics of clouds measured from satellites

    SciTech Connect

    Wylie, D.P.

    1994-12-22

    The significant findings reported in this paper are: (1) Cirrus clouds are very common and were found in 42% of the satellite data. There are seasonal changes in the locations of the most frequent cirrus which follow seasonal changes in convective clouds. However, very thin cirrus occurred at least 10% of the time in all areas. The diurnal cycle of cirrus was very small over the oceans. The diurnal cycle over land followed the diurnal cycle of convective clouds. (2) A large increase in cirrus and high cloud frequency was found in 1991. This cloud cover increase appeared with the strong El Nino - Southern Oscillation climate event. A volcanic eruption also occurred in 1991 which may have enhanced this cloud cover change. It should be noted that the total cloud cover of all cloud forms did not change during this period.

  4. 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.

  5. 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.

  6. Atmospheric science: Clouding the warming

    NASA Astrophysics Data System (ADS)

    Ortega, Pablo

    2016-08-01

    Summer temperatures in Europe varied markedly over the past millennium. Climate models and palaeoclimate records indicate that changes in cloud cover related to storm tracks contributed to the variations -- and may continue to do so in the future.

  7. Acquired reactive perforating collagenosis.

    PubMed

    Basak, P Y; Turkmen, C

    2001-01-01

    Acquired perforating disorder has been recognized as an uncommon distinct dermatosis in which altered collagen is eliminated through the epidermis. Several disorders accompanied by itching and scratching were reported to be associated with reactive perforating collagenosis. A 67-year-old white woman diagnosed as acquired reactive perforating collagenosis with poorly controlled diabetes mellitus and congestive cardiac failure is presented. PMID:11525959

  8. Covering Politics.

    ERIC Educational Resources Information Center

    Gruber, Ryan; Wind, Andrew; Trevidi, Neema

    2000-01-01

    Presents four articles considering: (1) the media's role in the coverage of politics; (2) the influence of photography particularly in terms of the president; (3) an event where an Iowa student had a chance to work with professionals while covering politics; and (4) considering scholastic reporters covering national candidates as they learn and…

  9. 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

  10. 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

  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. Acquired Cystic Kidney Disease

    MedlinePlus

    ... a kidney transplant or blood-filtering treatments called dialysis. The cysts are more likely to develop in people who are on kidney dialysis. The chance of developing acquired cystic kidney disease ...

  13. Hospital-acquired pneumonia

    MedlinePlus

    ... tends to be more serious than other lung infections because: People in the hospital are often very sick and cannot fight off ... prevent pneumonia. Most hospitals have programs to prevent hospital-acquired infections.

  14. 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.

  15. 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 ... formats available at JPL August 23, 2000 - Stratus clouds help modulate the arctic climate. project:  ...

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Cloud effects on ultraviolet photoclimatology

    NASA Technical Reports Server (NTRS)

    Green, A. E. S.; Spinhirne, J. D.

    1978-01-01

    The purpose of this study is to quantify for the needs of photobiology the influence of clouds upon the ultraviolet spectral irradiance reaching the ground. Towards this end, analytic formulas are developed which approximately characterize the influence of clouds upon total solar radiation. These may be used in conjunction with a solar pyranometer to assign an effective visual optical depth for the cloud cover. A formula is also developed which characterizes the influence of the optical depth of clouds upon the UV spectral irradiance in the 280-340 nm region. Thus total solar energy observations to assign cloud optical properties can be used to calculate the UV spectral irradiance at the ground in the presence of these clouds. As incidental by-products of this effort, convenient formulas are found for the direct and diffuse components of total solar energy.

  2. MODIS Views Variations in Cloud Types

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This MODIS image, centered over the Great Lakes region in North America, shows a variety of cloud types. The clouds at the top of the image, colored pink, are cold, high-level snow and ice clouds, while the neon green clouds are lower-level water clouds. Because different cloud types reflect and emit radiant energy differently, scientists can use MODIS' unique data set to measure the sizes of cloud particles and distinguish between water, snow, and ice clouds. This scene was acquired on Feb. 24, 2000, and is a red, green, blue composite of bands 1, 6, and 31 (0.66, 1.6, and 11.0 microns, respectively). Image by Liam Gumley, Space Science and Engineering Center, University of Wisconsin-Madison

  3. [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.

  4. 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.

  5. 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. PMID:26186969

  6. 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.

  7. 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.

  8. 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

  9. 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...

  10. Wall Covering

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The attractive wall covering shown below is one of 132 styles in the Mirror Magic II line offered by The General Tire & Rubber Company, Akron, Ohio. The material is metallized plastic fabric, a spinoff from space programs. Wall coverings are one of many consumer applications of aluminized plastic film technology developed for NASA by a firm later bought by King-Seeley Thermos Company, Winchester, Massachusetts, which now produces the material. The original NASA use was in the Echo 1 passive communications satellite, a "space baloon" made of aluminized mylar; the high reflectivity of the metallized coating enabled relay of communications signals from one Earth station to another by "bouncing" them off the satellite. The reflectivity feature also made the material an extremely efficient insulator and it was subsequently widely used in the Apollo program for such purposes as temperature control of spacecraft components and insulation of tanks for fuels that must be maintained at very low temperatures. I Used as a wall covering, the aluminized material offers extra insulation, reflects light and I resists cracking. In addition to General Tire, King-Seeley also supplies wall covering material to Columbus Coated Fabrics Division of Borden, Incorporated, Columbus, Ohio, among others.

  11. 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…

  12. Acquired von Willebrand disease.

    PubMed

    Petrini, P

    1999-05-01

    Acquired von Willebrand disease (AvWD) is a syndrome that has clinical and laboratory features similar to hereditary vWD. In contrast to the latter it occurs in patients without a family history of previous bleeding tendency. PMID:23401904

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. Atmospheric Corerection of Aviris Data of Monterey Bay Contaminated by Thin Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    van den Bosch, Jeannette; Davis, Curtiss O.; Mobley, Curtis D.; Rhea, W. Joseph

    1993-01-01

    Aviris scenes are often rejected when cloud cover exceeds 10 percent. However, if the cloud cover is determined to be primarily cirrus rather than cumulus, inwater optical properties may still be extracted over open ocean.

  20. Acquired von Willebrand disease.

    PubMed

    Kumar, Shaji; Pruthi, Rajiv K; Nichols, William L

    2002-02-01

    Acquired von Willebrand disease (AvWD) is a relatively rare acquired bleeding disorder that usually occurs in elderly patients, in whom its recognition may be delayed. Patients usually present predominantly with mucocutaneous bleeding, with no previous history of bleeding abnormalities and no clinically meaningful family history. Various underlying diseases have been associated with AvWD, most commonly hematoproliferative disorders, including monoclonal gammopathies, lymphoproliferative disorders, and myeloproliferative disorders. The pathogenesis of AvWD remains incompletely understood but includes autoantibodies directed against the von Willebrand factor (vWF), leading to a more rapid clearance from the circulation or interference with its function, adsorption of vWF by tumor cells, and nonimmunologic mechanisms of destruction. Laboratory evaluation usually reveals a pattern of prolonged bleeding time and decreased levels of vWF antigen, ristocetin cofactor activity, and factor VIII coagulant activity consistent with a diagnosis of vWD. Acquired vWD is distinguished from the congenital form by age at presentation, absence of a personal and family history of bleeding disorders, and, often, presence of a hematoproliferative or autoimmune disorder. The severity of the bleeding varies considerably among patients. Therapeutic options include desmopressin and certain factor VIII concentrates that also contain vWF. Successful treatment of the associated illness can reverse the clinical and laboratory manifestations. Intravenous immunoglobulins have also shown some efficacy in the management of AvWD, especially cases associated with monoclonal gammopathies. Awareness of AvWD is essential for diagnosis and appropriate management. PMID:11838652

  1. Climatology and first-order composition estimates of mesospheric clouds from Mars Climate Sounder limb spectra

    NASA Astrophysics Data System (ADS)

    Sefton-Nash, E.; Teanby, N. A.; Montabone, L.; Irwin, P. G. J.; Hurley, J.; Calcutt, S. B.

    2013-01-01

    Mesospheric clouds have been previously observed on Mars in a variety of datasets. However, because the clouds are optically thin and most missions have performed surface-focussed nadir sounding, geographic and seasonal coverage is sparse. We present new detections of mesospheric clouds using a limb spectra dataset with global coverage acquired by NASA's Mars Climate Sounder (MCS) aboard Mars Reconnaissance Orbiter. Mesospheric aerosol layers, which can be CO2 ice, water ice or dust clouds, cause high radiances in limb spectra, either by thermal emission or scattering of sunlight. We employ an object recognition and classification algorithm to identify and map aerosol layers in limb spectra acquired between December 2006 and April 2011, covering more than two Mars years. We use data from MCS band A4, to show thermal signatures of day and nightside features, and A6, which is sensitive to short wave IR and visible daytime features only. This large dataset provides several thousand detections of mesospheric clouds, more than an order of magnitude more than in previous studies. Our results show that aerosol layers tend to occur in two distinct regimes. They form in equatorial regions (30°S-30°N) during the aphelion season/northern hemisphere summer (Ls < 150°), which is in agreement with previous published observations of mesospheric clouds. During perihelion/dust storm season (Ls > 150°) a greater number of features are observed and are distributed in two mid-latitude bands, with a southern hemisphere bias. We observe temporal and longitudinal clustering of cloud occurrence, which we suggest is consistent with a formation mechanism dictated by interaction of broad temperature regimes imposed by global circulation and the propagation to the mesosphere of small-scale dynamics such as gravity waves and thermal tides. Using calculated frost point temperatures and a parameterization based on synthetic spectra we find that aphelion clouds are present in generally cooler

  2. 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

  3. 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.

  4. 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…

  5. 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…

  6. Effects of cloud types on cloud-radiation interaction over the Asian monsoon region

    NASA Astrophysics Data System (ADS)

    Shukla, Bipasha Paul; Sathiyamoorthy, V.; Pal, P. K.; Joshi, P. C.

    2009-08-01

    This paper quantifies the sensitivity of radiation budget quantities to different cloud types over the Asian monsoon region using the International Satellite Cloud Climatology Project. Multiple regression was used to estimate the radiative effects of individual cloud type. It was observed that the regression performed better when the solution was constrained with clear sky fluxes, which is evident by an improvement in R 2 statistics. The sensitivity coefficients calculated for the Asian monsoon region reveal that, while the LWCRCF and SWCRF will be most vulnerable to changes in cloud cover of deep convective clouds, NETCRF will be susceptible to changes in the nimbostratus clouds. Although the cloud radiative forcing of individual cloud types are found to be similar in sign to previous global findings, their magnitudes are found to vary. It is seen that cirrus clouds play an important role in governing the radiative behavior of this region.

  7. [Acquired von Willebrand syndrome].

    PubMed

    Franchini, Massimo

    2006-01-01

    Acquired von Willebrand syndrome (aVWS) is a rare, but probably underestimated, bleeding disorder that mimics the congenital form of von Willebrand disease (VWD) in terms of laboratory findings and clinical presentation. However, unlike congenital VWD, it arises in individuals with no personal or family history of bleeding. AVWS occurs in association with a variety of underlying disorders, including lymphoproliferative disorders, myeloproliferative disorders and cardiovascular diseases. The main pathogenic, clinical, laboratory and therapeutic aspects of this syndrome are concisely reported in this review. PMID:16913181

  8. 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.

  9. Evolutionary computation and post-wildfire land-cover mapping with multispectral imagery

    NASA Astrophysics Data System (ADS)

    Brumby, Steven P.; Koch, Steven; Hansen, Leslie A.

    2002-01-01

    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 from 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 to the automated classification of land cover using multispectral imagery. We apply a hybrid genetic programming/supervised 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 from the Landsat 7 ETM+ instrument from 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.

  10. 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.

  11. ASTER cloud coverage reassessment using MODIS cloud mask products

    NASA Astrophysics Data System (ADS)

    Tonooka, Hideyuki; Omagari, Kunjuro; Yamamoto, Hirokazu; Tachikawa, Tetsushi; Fujita, Masaru; Paitaer, Zaoreguli

    2010-10-01

    In the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) Project, two kinds of algorithms are used for cloud assessment in Level-1 processing. The first algorithm based on the LANDSAT-5 TM Automatic Cloud Cover Assessment (ACCA) algorithm is used for a part of daytime scenes observed with only VNIR bands and all nighttime scenes, and the second algorithm based on the LANDSAT-7 ETM+ ACCA algorithm is used for most of daytime scenes observed with all spectral bands. However, the first algorithm does not work well for lack of some spectral bands sensitive to cloud detection, and the two algorithms have been less accurate over snow/ice covered areas since April 2008 when the SWIR subsystem developed troubles. In addition, they perform less well for some combinations of surface type and sun elevation angle. We, therefore, have developed the ASTER cloud coverage reassessment system using MODIS cloud mask (MOD35) products, and have reassessed cloud coverage for all ASTER archived scenes (>1.7 million scenes). All of the new cloud coverage data are included in Image Management System (IMS) databases of the ASTER Ground Data System (GDS) and NASA's Land Process Data Active Archive Center (LP DAAC) and used for ASTER product search by users, and cloud mask images are distributed to users through Internet. Daily upcoming scenes (about 400 scenes per day) are reassessed and inserted into the IMS databases in 5 to 7 days after each scene observation date. Some validation studies for the new cloud coverage data and some mission-related analyses using those data are also demonstrated in the present paper.

  12. Cover Picture.

    PubMed

    Krömer; Rios-Carreras; Fuhrmann; Musch; Wunderlin; Debaerdemaeker; Mena-Osteritz; Bäuerle

    2000-10-01

    The cover picture shows the synthesis of novel conjugated macrocycles assembled from oligothiophenes bearing terminal acetylene groups. Under pseudo-high-dilution conditions the oxidative cyclooligomerization first gives the oligothiophenediynes, the precursors to the new class of alpha-cyclo[n]thiophenes. The detailed structure of macrocycles with up to 76 ring members and cavities of up to 3 nm could be investigated by means of X-ray structure analysis, scanning tunneling microscopy, and quantum chemical calculations (see the molecular model top right). The novel rings combine the excellent electronic properties of the corresponding linearly conjugated oligomers with the possibility of complexing large organic guest molecules or other objects (the tower of the Cathedral at Ulm represents a nanometer-sized, rodlike entity), which should have new fundamental properties and applications. The background shows the image obtained by scanning electron microscopy of a self-assembled and perfectly ordered monolayer of macrocycles on a graphite surface. More on these fascinating nanometer-sized rings can be found in the communication by P. Bäuerle et al. on p. 3481 ff. PMID:11091367

  13. 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

  14. Community-acquired pneumonia.

    PubMed

    Polverino, E; Torres Marti, A

    2011-02-01

    Despite the remarkable advances in antibiotic therapies, diagnostic tools, prevention campaigns and intensive care, community-acquired pneumonia (CAP) is still among the primary causes of death worldwide, and there have been no significant changes in mortality in the last decades. The clinical and economic burden of CAP makes it a major public health problem, particularly for children and the elderly. This issue provides a clinical overview of CAP, focusing on epidemiology, economic burden, diagnosis, risk stratification, treatment, clinical management, and prevention. Particular attention is given to some aspects related to the clinical management of CAP, such as the microbial etiology and the available tools to achieve it, the usefulness of new and old biomarkers, and antimicrobial and other non-antibiotic adjunctive therapies. Possible scenarios in which pneumonia does not respond to treatment are also analyzed to improve clinical outcomes of CAP. PMID:21242952

  15. Acquired Porphyria Cutanea Tarda

    PubMed Central

    Koval, Andrew; Danby, C. W. E.; Petermann, H.

    1965-01-01

    Currently, the porphyrias are classified in four main groups: congenital porphyria, acute intermittent porphyria, porphyria cutanea tarda hereditaria, and porphyria cutanea tarda symptomatica. The acquired form of porphyria (porphyria cutanea tarda symptomatica) occurs in older males and is nearly always associated with chronic alcoholism and hepatic cirrhosis. The main clinical changes are dermatological, with excessive skin fragility and photosensitivity resulting in erosions and bullae. Biochemically, high levels of uroporphyrin are found in the urine and stools. Treatment to date has been symptomatic and usually unsuccessful. A case of porphyria cutanea tarda symptomatica is presented showing dramatic improvement of both the skin lesions and porphyrin levels in urine and blood following repeated phlebotomy. Possible mechanisms of action of phlebotomy on porphyria cutanea tarda symptomatica are discussed. ImagesFig. 1Fig. 2 PMID:14341652

  16. [ICU acquired neuromyopathy].

    PubMed

    Gueret, G; Guillouet, M; Vermeersch, V; Guillard, E; Talarmin, H; Nguyen, B-V; Rannou, F; Giroux-Metges, M-A; Pennec, J-P; Ozier, Y

    2013-09-01

    ICU acquired neuromyopathy (IANM) is the most frequent neurological pathology observed in ICU. Nerve and muscle defects are merged with neuromuscular junction abnormalities. Its physiopathology is complex. The aim is probably the redistribution of nutriments and metabolism towards defense against sepsis. The main risk factors are sepsis, its severity and its duration of evolution. IANM is usually diagnosed in view of difficulties in weaning from mechanical ventilation, but electrophysiology may allow an earlier diagnosis. There is no curative therapy, but early treatment of sepsis, glycemic control as well as early physiotherapy may decrease its incidence. The outcomes of IANM are an increase in morbi-mortality and possibly long-lasting neuromuscular abnormalities as far as tetraplegia. PMID:23958176

  17. Infrared reflectance of high altitude clouds.

    PubMed

    Hovis, W A; Blaine, L R; Forman, M L

    1970-03-01

    The spectral reflectance characteristics of cirrostratus, cirrus clouds, and a jet contrail, in the 0.68-2.4-micro spectral interval, are of interest for remote sensing of cloud types from orbiting satellites. Measurements made with a down-looking spectrometer from a high altitude aircraft show differences between the signatures of naturally formed ice clouds, a fresh jet contrail, and a snow covered surface. PMID:20076243

  18. 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.

  19. Daytime Land Cloud Detection Enhancements For The VIIRS Cloud Mask

    NASA Astrophysics Data System (ADS)

    Frey, R. A.; Heidinger, A. K.; Hutchinson, K. D.; Iisager, B.

    2005-12-01

    The first in a new series of polar-orbiting satellites, National Polar-Orbiting Operational Satellite System (NPOESS), is scheduled to be launched in 2008. The Visible/Infrared Imager/Radiometer Suite (VIIRS) is a major component of the series and will replace the AVHRR instrument on operational polar orbiters. A crucial piece of the VIIRS data processing chain is the VIIRS Cloud Mask (VCM). A high quality cloud detection system is necessary as a first step for most if not all of the algorithms which produce the 18 EDRs (Environmental Data Records) from VIIRS. A cloud detection scheme similar to the one developed for MODIS data (MOD35) will be implemented for VIIRS, but several enhancements have been investigated for daytime land scenes. During daylight hours over vegetated surfaces and in the absence of snow cover, use of the high contrast between clouds and surface in visible wavelengths offers the most sensitive clear/cloud discrimination. However, visible surface reflectances vary from about 10% over tropical rain forests to as high as 50% in arid regions, making the use of a single cloud test threshold very difficult. A set of reflectance thresholds based on NDVI and scattering angle has been developed from historical AVHRR data. Clear-sky NDVIs were accumulated as a function of scattering angle over a multi-year period and from morning and afternoon satellites, from which cloud test thresholds were developed. The thresholds were then tested on several AVHRR scenes. For extremely arid scenes, where visible reflectances from clouds and surface are similar, a cloud test using 0.4 μm data has been devised. This poster describes the development of both new cloud tests and associated thresholds, from initial tests using MODIS data to the calculation and implementation of the thresholds.

  20. 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

  1. 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.

  2. Tropical cirrus cloud radiative forcing: Sensitivity studies

    SciTech Connect

    Jensen, E.J.; Kinne, S.; Toon, O.B.

    1994-09-01

    We have performed one dimensional radiative transfer calculations to evaluate the impact of cirrus clouds on the tropical radiation budget. We investigate the sensitivity of solar and infrared fluxes to cloud optical depth, particle size distributions, and cloud height. If the observed solar cloud forcing in excess of 100 W/sq m is to be attributed to cirrus anvils alone, then the optical depth of these anvils must be at least 5 (assuming 50% cloud cover and an ice crystal effective radius of 15 microns). The net radiative forcing of cirrus near the tropical tropopause is positive (heating) for cloud optical depths less than about 16 and negative (cooling) for larger optical depths. If cirrus clouds alone are responsible for the equal and opposite shortwave and longwave cloud forcing in excess of 100 W/sq m observed by Earth Radiation Budget Experiment (ERBE), then the cirrus must typically take the form of deep, optically thick clouds with relatively small particles (radii of 10-20 microns) and cloud-tops well below the tropopause. The maintenance of this balance on monthly time scales can be attributed to a variety of correlations: The cloud cover of optically thick cirrus or thin cirrus overlying low-level stratus clouds could vary; or cirrus anvil height cloud increase along with a decrease in the ice crystal effective radius and an increase in optical depth. It would be of great interest to determine observationally which of these correlations is responsible for the observed lack of variation in cloud forcing.

  3. Estimation of cloud optical thickness by processing SEVIRI images and implementing a semi analytical cloud property retrieval algorithm

    NASA Astrophysics Data System (ADS)

    Pandey, P.; De Ridder, K.; van Lipzig, N.

    2009-04-01

    Clouds play a very important role in the Earth's climate system, as they form an intermediate layer between Sun and the Earth. Satellite remote sensing systems are the only means to provide information about clouds on large scales. The geostationary satellite, Meteosat Second Generation (MSG) has onboard an imaging radiometer, the Spinning Enhanced Visible and Infrared Imager (SEVIRI). SEVIRI is a 12 channel imager, with 11 channels observing the earth's full disk with a temporal resolution of 15 min and spatial resolution of 3 km at nadir, and a high resolution visible (HRV) channel. The visible channels (0.6 µm and 0.81 µm) and near infrared channel (1.6µm) of SEVIRI are being used to retrieve the cloud optical thickness (COT). The study domain is over Europe covering the region between 35°N - 70°N and 10°W - 30°E. SEVIRI level 1.5 images over this domain are being acquired from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) archive. The processing of this imagery, involves a number of steps before estimating the COT. The steps involved in pre-processing are as follows. First, the digital count number is acquired from the imagery. Image geo-coding is performed in order to relate the pixel positions to the corresponding longitude and latitude. Solar zenith angle is determined as a function of latitude and time. The radiometric conversion is done using the values of offsets and slopes of each band. The values of radiance obtained are then used to calculate the reflectance for channels in the visible spectrum using the information of solar zenith angle. An attempt is made to estimate the COT from the observed radiances. A semi analytical algorithm [Kokhanovsky et al., 2003] is implemented for the estimation of cloud optical thickness from the visible spectrum of light intensity reflected from clouds. The asymptotical solution of the radiative transfer equation, for clouds with large optical thickness, is the basis of

  4. CLOUD CONDENSATION NUCLEI MEASUREMENTS WITHIN CLOUDS

    EPA Science Inventory

    Measurements of the spectra of cloud condensation nuclei (CCN) within and near the boundaries of clouds are presented. Some of the in-cloud measurements excluded the nuclei within cloud droplets (interstitial CCN) while others included all nuclei inside the cloud (total CCN). The...

  5. 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

  6. Acute Acquired Concomitant Esotropia

    PubMed Central

    Chen, Jingchang; Deng, Daming; Sun, Yuan; Shen, Tao; Cao, Guobin; Yan, Jianhua; Chen, Qiwen; Ye, Xuelian

    2015-01-01

    Abstract Acute acquired concomitant esotropia (AACE) is a rare, distinct subtype of esotropia. The purpose of this retrospective study was to describe the clinical characteristics and discuss the classification and etiology of AACE. Charts from 47 patients with AACE referred to our institute between October 2010 and November 2014 were reviewed. All participants underwent a complete medical history, ophthalmologic and orthoptic examinations, and brain and orbital imaging. Mean age at onset was 26.6 ± 12.2 years. Of the 18 cases with deviations ≤ 20 PD, 16 presented with diplopia at distance and fusion at near vision at the onset of deviation; differences between distance and near deviations were < 8 PD; all cases except one were treated with prism and diplopia resolved. Of the 29 cases with deviations > 20 PD, 5 were mild hypermetropic with age at onset between 5 and 19 years, 16 were myopic, and 8 were emmetropic with age at onset > 12 years; 24 were surgically treated and 5 cases remained under observation; all 24 cases achieved normal retinal correspondence or fusion or stereopsis on postoperative day 1 in synoptophore; in 23 cases diplopia or visual confusion resolved postoperatively. Of the 47 cases, brain and orbital imaging in 2 cases revealed a tumor in the cerebellopontine angle and 1 case involved spinocerebellar ataxia as revealed by genetic testing. AACE in this study was characterized by a sudden onset of concomitant nonaccommodative esotropia with diplopia or visual confusion at 5 years of age or older and the potential for normal binocular vision. We suggest that AACE can be divided into 2 subgroups consisting of patients with relatively small versus large angle deviations. Coexisting or underlying neurological diseases were infrequent in AACE. PMID:26705210

  7. Seasonal variation of land cover classification accuracy of Landsat 8 images in Burkina Faso

    NASA Astrophysics Data System (ADS)

    Liu, J.; Heiskanen, J.; Aynekulu, E.; Pellikka, P. K. E.

    2015-04-01

    In the seasonal tropics, vegetation shows large reflectance variation because of phenology, which complicates land cover change monitoring. Ideally, multi-temporal images for change monitoring should be from the same season, but availability of cloud-free images is limited in wet season in comparison to dry season. Our aim was to investigate how land cover classification accuracy depends on the season in southern Burkina Faso by analyzing 14 Landsat 8 OLI images from April 2013 to April 2014. Because all the images were acquired within one year, we assumed that most of the observed variation between the images was due to phenology. All the images were cloud masked and atmospherically corrected. Field data was collected from 160 field plots located within a 10 km x 10 km study area between December 2013 and February 2014. The plots were classified to closed forest, open forest and cropland, and used as training and validation data. Random forest classifier was employed for classifications. According to the results, there is a tendency for higher classification accuracy towards the dry season. The highest classification accuracy was provided by an image from December, which corresponds to the dry season and minimum NDVI period. In contrast, an image from October, which corresponds to the wet season and maximum NDVI period provided the lowest accuracy. Furthermore, the multi-temporal classification based on dry and wet season images had higher accuracy than single image classifications, but the improvement was small because seasonal changes affect similarly to the different land cover classes.

  8. 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.

  9. 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

  10. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... confer control of X and therefore will file as an acquiring person. Because A held the plant prior to the... within two persons, “A” and “B.” Under this section, if V is to acquire corporation X, both “A” and “B... person. Examples: 1. Assume that person “Q” will acquire voting securities of corporation X held by...

  11. 16 CFR 801.2 - Acquiring and acquired persons.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... confer control of X and therefore will file as an acquiring person. Because A held the plant prior to the... within two persons, “A” and “B.” Under this section, if V is to acquire corporation X, both “A” and “B... person. Examples: 1. Assume that person “Q” will acquire voting securities of corporation X held by...

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

    DOE PAGESBeta

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Menqistu; Brooks, Sarah D.; Cziczo, Dan; et al

    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

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... of this montage is a natural-color view of the Caribbean Sea east of the Yucatan Peninsula as seen by MISR's most steeply ... - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR category:  gallery ...

  19. 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

  20. 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.

  1. Clinicopathological correlation of acquired hypopigmentary disorders.

    PubMed

    Patel, Anisha B; Kubba, Raj; Kubba, Asha

    2013-01-01

    Acquired hypopigmentary disorders comprise a significant group of disorders that affect Indians and Asians. The pigment disturbance in darker skin individuals can be very distressing to the patient and the family. These disorders cover a wide array of pathologies including infections, autoimmune processes, lymphoproliferative disorders, and sclerosing diseases. Histological diagnosis is particularly important because treatments for these diseases are varied and specific. This review will focus on histopathological diagnosis based on clinicopathological correlation for commonly encountered disorders such as leprosy, vitiligo, lichen sclerosus, pityriasis alba (PA), and pityriasis versicolor (PV). Atypical or uncommon clinical presentation of classic diseases such as hypopigmented mycosis fungoides (HMF) and hypopigmented sarcoidosis are also included. PMID:23619442

  2. 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.

  3. Effects of Cloud-Processed CCN on Warm Clouds

    NASA Astrophysics Data System (ADS)

    Noble, S. R., Jr.; Hudson, J. G.

    2014-12-01

    Cloud condensation nuclei (CCN) distributions are transformed by in-cloud processing. This can be chemical: aqueous oxidation; or physical: Brownian scavenging, collision and coalescence. Droplet evaporation then leaves behind the cloud-processed CCN. Chemical processing increases CCN size (lower critical supersaturation; Sc) but does not change CCN concentration (NCCN) (Feingold and Kreidenweis, 2000). Physical processing leads to an increase in size (lower Sc) and decrease of NCCN. These processes are especially important in stratus clouds that cover large areas and persist for long periods. Modified CCN in turn modify cloud droplet spectra. Both chemical and physical processing were observed during the 2005 MArine Stratus/stratocumulus Experiment (MASE) field campaign. Higher concentrations of SO4 and NO3 anions with lower SO2 and O3 were associated with bimodal CCN spectra whereas monomodal spectra had lower SO4 and NO3 and higher SO2 and O3. These are consistent with chemical processing. Two nearby MASE CCN spectra, one bimodal and one monomodal were input to an adiabatic cloud droplet growth model. Model runs at various updrafts (W) show that the low Sc cloud processed mode of the bimodal CCN spectrum augmented droplet activation creating higher cloud droplet concentrations (Nc) for low W characteristic of stratus clouds (Fig. 1a, black). Higher NCCN at low Sc (black data) also increased condensation competition and thus reduced cloud effective S (Seff) (Fig.1b). This increases W importance for determining Nc (Hudson and Noble, 2014). These high NCCN at low Sc and lower Seff of the bimodal CCN spectrum reduce droplet mean diameter (MD; Fig. 1c) and broaden droplet distributions (sigma; Fig. 1d). Increased Nc and decreased MD of chemical processing seems to augment the indirect aerosol effect (IAE) whereas inherently decreased Nc and increased MD of coalescence processing reduces IAE. CCN cloud-processing alters cloud microphysics (Nc, Seff, MD, and sigma

  4. 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.

  5. 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.

  6. Children Acquire Emotion Categories Gradually

    ERIC Educational Resources Information Center

    Widen, Sherri C.; Russell, James A.

    2008-01-01

    Some accounts imply that basic-level emotion categories are acquired early and quickly, whereas others imply that they are acquired later and more gradually. Our study examined this question for fear, happiness, sadness, and anger in the context of children's categorization of emotional facial expressions. Children (N=168, 2-5 years) first labeled…

  7. MISR Stereo Imaging Distinguishes Smoke from Cloud

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These views of western Alaska were acquired by MISR on June 25, 2000 during Terra orbit 2775. The images cover an area of about 150 kilometers x 225 kilometers, and have been oriented with north to the left. The left image is from the vertical-viewing (nadir) camera, whereas the right image is a stereo 'anaglyph' that combines data from the forward-viewing 45-degree and 60-degree cameras. This image appears three-dimensional when viewed through red/blue glasses with the red filter over the left eye. It may help to darken the room lights when viewing the image on a computer screen.

    The Yukon River is seen wending its way from upper left to lower right. A forest fire in the Kaiyuh Mountains produced the long smoke plume that originates below and to the right of image center. In the nadir view, the high cirrus clouds at the top of the image and the smoke plume are similar in appearance, and the lack of vertical information makes them hard to differentiate. Viewing the righthand image with stereo glasses, on the other hand, demonstrates that the scene consists of several vertically-stratified layers, including the surface terrain, the smoke, some scattered cumulus clouds, and streaks of high, thin cirrus. This added dimensionality is one of the ways MISR data helps scientists identify and classify various components of terrestrial scenes.

    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.

  8. Variability of cloud optical depth and cloud droplet effective radius in layer clouds: Satellite based analysis

    NASA Astrophysics Data System (ADS)

    Szczodrak, Malgorzata Dorota

    1998-11-01

    Measurements made by the AVHRR (Advanced Very High Resolution Radiometer) on board of five NOAA polar orbiting satellites were used to retrieve cloud optical depth (/tau) and cloud droplet effective radius (reff) for marine boundary layer clouds over the Pacific Ocean west of California and over the Southern Ocean near Tasmania. Retrievals were obtained for 21 days of data acquired between 1987 and 1995 from which over 300 subscenes ~256 km x 256 km in size were extracted. On this spatial scale cloud fields were found to have mean τ between 8 and 32 and mean reff between 6 and 17 /mu m. The frequency distribution of τ is well approximated by a two parameter gamma distribution. The gamma distribution also provides a good fit to the observed reff distribution if the distribution is symmetric or positively skewed but fails for negatively skewed or bi-modal distributions of reff which were also observed. The retrievals show a relationship between τ and reff which is consistent with a simple 'reference' cloud model with reff~τ1/5. The proportionality constant depends on cloud droplet number concentration N and cloud subadiabaticity β through the parameter Nsat=N//sqrt[/beta]. Departures from the reference behaviour occur in scenes with spatially coherent Nsat regimes, separated by a sharp boundary. AVHRR imagery is able to separate two Nsat regimes if they differ by at least 30% in most cases. Satellite retrievals of τ and reff were compared with in situ aircraft measurement near Tasmania. The retrievals overestimated reff by 0.7 to 3.6 /mu m on different flights, in agreement with results from earlier comparison studies. The reff overestimation was found to be an offset independent of /tau. The reference cloud model and the Nsat retrieval were tested on aircraft data and yield results consistent with direct in situ measurements of N and /beta. Spectral and multifractal analyses of the spatial structure of cloud visible radiance, τ and reff fields in 34 satellite

  9. Sky cover from MFRSR observations

    NASA Astrophysics Data System (ADS)

    Kassianov, E.; Barnard, J. C.; Berg, L. K.; Flynn, C.; Long, C. N.

    2011-07-01

    The diffuse all-sky surface irradiances measured at two nearby wavelengths in the visible spectral range and their modeled clear-sky counterparts are the main components of a new method for estimating the fractional sky cover of different cloud types, including cumuli. The performance of this method is illustrated using 1-min resolution data from a ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR). The MFRSR data are collected at the US 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 cumuli. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Lake Effect Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The lake effect is particularly clear in this Sea-viewing Wide field-of-view Sensor (SeaWiFS) true-color image of the North American Great Lakes region, acquired December 5, 2000. Lakes Nipigon, Superior, and Michigan show striking contrasts between clear and cloudy air as the wind blows from the northwest across the lakes. As it flows across the relatively warm lakes, the cold dry air gathers heat and moisture from the surface. The warm moist air rises into the atmosphere and mixes vigorously with the cold dry air above. The layer of warm moist air deepens as it travels across the lake. Some of the evaporated water from the lake condenses into streamers of fog rising from the surface, while much of the moisture condenses to form a stratocumulus cloud in the upper half of the mixed layer. The cloud-forming water droplets may freeze into ice crystals and, due to accumulated water deposition over time, grow into snowflakes. This process can generate snowstorms that produce significant amounts of snowfall downwind. It is not uncommon for lake effect snowstorms to produce as much as two feet of snow within a 24-hour period in northwestern parts of New York and Pennsylvania. Image provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  19. Cosmic rays, clouds, and climate.

    PubMed

    Carslaw, K S; Harrison, R G; Kirkby, J

    2002-11-29

    It has been proposed that Earth's climate could be affected by changes in cloudiness caused by variations in the intensity of galactic cosmic rays in the atmosphere. This proposal stems from an observed correlation between cosmic ray intensity and Earth's average cloud cover over the course of one solar cycle. Some scientists question the reliability of the observations, whereas others, who accept them as reliable, suggest that the correlation may be caused by other physical phenomena with decadal periods or by a response to volcanic activity or El Niño. Nevertheless, the observation has raised the intriguing possibility that a cosmic ray-cloud interaction may help explain how a relatively small change in solar output can produce much larger changes in Earth's climate. Physical mechanisms have been proposed to explain how cosmic rays could affect clouds, but they need to be investigated further if the observation is to become more than just another correlation among geophysical variables. PMID:12459578

  20. Observational and model evidence for positive low-level cloud feedback.

    PubMed

    Clement, Amy C; Burgman, Robert; Norris, Joel R

    2009-07-24

    Feedbacks involving low-level clouds remain a primary cause of uncertainty in global climate model projections. This issue was addressed by examining changes in low-level clouds over the Northeast Pacific in observations and climate models. Decadal fluctuations were identified in multiple, independent cloud data sets, and changes in cloud cover appeared to be linked to changes in both local temperature structure and large-scale circulation. This observational analysis further indicated that clouds act as a positive feedback in this region on decadal time scales. The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current-generation climate models. The only model that passed this test simulated a reduction in cloud cover over much of the Pacific when greenhouse gases were increased, providing modeling evidence for a positive low-level cloud feedback. PMID:19628865

  1. 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.

  2. Analysis of Land Covers over Northern Peninsular Malaysia by Using ALOS-PALSAR Data Based on Frequency-Based Contextual and Neural Network Classification Technique

    NASA Astrophysics Data System (ADS)

    Lim, H. S.; MatJafri, M. Z.; Abdullah, K.; Saleh, N. Mohd.

    2008-11-01

    Optical and microwave remote sensing data have been widely used in land cover and land use classification. Optical satellite remote sensing methods are more appropriate but require cloud-free conditions for data to be useful especially at Equatorial region. In Equatorial region cloud free acquisitions can be rare reducing these sensors' applicability to such studies. ALOS-PALSAR data can be acquired day and night irrespective of weather conditions. This paper presents a comparison between frequency-based contextual and neural network classification technique by using ALOS-PALSAR data for land cover assessment in Northern Peninsular Malaysia. The ALOS-PALSAR data acquired on 10 November 2006 were converted to vegetation, urban, water and other land features. The PALSAR data of training areas were choose and selected based on the optical satellite imagery and were classified using supervised classification methods. Supervised classification techniques were used in the classification analysis. The best supervised classifier was chosen based on the highest overall accuracy and Kappa statistic. Based on the result produced by this study, it can be pointed out the utility of ALOS-PALSAR data as an alternative data source for land cover classification in the Peninsular Malaysia.

  3. 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.

  4. 26 CFR 31.3121(j)-1 - Covered transportation service.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 15 2012-04-01 2012-04-01 false Covered transportation service. 31.3121(j)-1... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in part... operation of a public transportation system constitutes covered transportation service if any part of...

  5. 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... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in part... operation of a public transportation system constitutes covered transportation service if any part of...

  6. 26 CFR 31.3121(j)-1 - Covered transportation service.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 15 2011-04-01 2011-04-01 false Covered transportation service. 31.3121(j)-1... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in part... operation of a public transportation system constitutes covered transportation service if any part of...

  7. 26 CFR 31.3121(j)-1 - Covered transportation service.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 15 2014-04-01 2014-04-01 false Covered transportation service. 31.3121(j)-1... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in part... operation of a public transportation system constitutes covered transportation service if any part of...

  8. 26 CFR 31.3121(j)-1 - Covered transportation service.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 15 2013-04-01 2013-04-01 false Covered transportation service. 31.3121(j)-1... § 31.3121(j)-1 Covered transportation service. (a) Transportation systems acquired in whole or in part... operation of a public transportation system constitutes covered transportation service if any part of...

  9. 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.

  10. The relationship between mesoscale circulation and cloud morphology at the upper cloud level of Venus from VMC/Venus Express

    NASA Astrophysics Data System (ADS)

    Patsaeva, M. V.; Khatuntsev, I. V.; Patsaev, D. V.; Titov, D. V.; Ignatiev, N. I.; Markiewicz, W. J.; Rodin, A. V.

    2015-08-01

    The Venus Monitoring Camera (VMC) acquired a set of ultraviolet (UV) images during the Venus Express mission unprecedented in its duration from May 2006 to September 2013. Here we present the results of digital tracking of the cloud features in the upper cloud layer at latitudes 25-75°S using images from 257 orbits with the best spatial coverage. The method relies on analysis of correlations between pairs of UV images separated in time. The bulk of data processed allows us to clarify the reasons why the mid-latitude jet is not always present in latitudinal wind profiles. Comparing VMC images with wind velocity fields we found a relationship between cloud morphology at middle latitudes and the circulation. The vector field in middle latitudes depends on the presence of a contrast global streak in the cloud morphology tilted with respect to latitude circles. The angle of the flow deflection (the angle between the wind velocity and latitudinal circles) and the difference of the zonal velocity on the opposite sides of the streak are in direct relationship to the angle between the streak and latitude circles. During such orbits the jet bulge does not appear in the latitudinal profile of the zonal wind component. Otherwise a zonal flow with small changes of the meridional velocity dominates in middle latitudes and manifests itself as a jet bulge. The relationship between the cloud cover morphology and circulation peculiarities can be attributed to the motion of global cloud features, like the Y-feature. We prepared plots of zonal and meridional velocities averaged with respect to the entire observation period. The average zonal velocity has a diurnal maximum at 15:00 local solar time and at 40°S. The meridional velocity reaches its maximum between 13:00 and 16:00 and at 50°S. The velocities obtained by the digital method are in good agreement with results of the visual method in the middle latitudes published earlier by Khatuntsev et al. (2013).

  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. 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.

  13. 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).

  14. Satellite SAR remote sensing of Great Lakes ice cover using RADARSAT data

    SciTech Connect

    Leshkevich, G.A.

    1997-06-01

    During winter months, cloud cover over the Laurentian Great Lakes impairs the use of satellite imagery from passive sensors operating in the visible, near infrared, and thermal infrared spectra for ice cover monitoring and analysis. The all-weather, day/night viewing capability of satellite Synthetic Aperture Radar (SAR) makes it a unique and valuable tool for Great Lakes ice identification and mapping providing that data analysis techniques and capability for using SAR data in an operational setting are developed. RADARSAT, an operational satellite carrying a SAR operating at 5.3 GHz (C-Band) with a horizontal polarization, was successfully launched in 1995. This study explores algorithms for Great Lakes ice cover classification and mapping using RADARSAT SAR data. Preliminary analysis of a ScanSAR Narrow scene of western Lake Superior using a supervised (level slicing) classification technique indicates that different ice types in the ice cover can be identified and mapped and that wind has a strong influence on the backscatter from open water. However, further research needs to be conducted on the repeatability and automation of classification and interpretation from scene to scene. During the 1997 winter season, an experiment is planned to acquire shipborne polarimetric backscatter data using the Jet Propulsion Laboratory (JPL) C-band scatterometer together with surface-based ice physical characterization measurements and environmental parameters coincident with RADARSAT overpass.

  15. 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.

  16. 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.

  17. GASP cloud encounter statistics - Implications for laminar flow control flight

    NASA Technical Reports Server (NTRS)

    Jasperson, W. H.; Nastrom, G. D.; Davis, R. E.; Holdeman, J. D.

    1984-01-01

    The cloud observation archive from the NASA Global Atmospheric Sampling Program (GASP) is analyzed in order to derive the probability of cloud encounter at altitudes normally flown by commercial airliners, for application to a determination of the feasability of Laminar Flow Control (LFC) on long-range routes. The probability of cloud encounter is found to vary significantly with season. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover. The cloud encounter data are shown to be consistent with the classical midlatitude cyclone model with more clouds encountered in highs than in lows. Aircraft measurements of route-averaged time-in-clouds fit a gamma probability distribution model which is applied to estimate the probability of extended cloud encounter, and the associated loss of LFC effectiveness along seven high-density routes. The probability is demonstrated to be low.

  18. 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

  19. 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.

  20. 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. PMID:27185925

  1. 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.

  2. 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.

  3. 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.

  4. Venus: uniformity of clouds, and photography.

    PubMed

    Keene, G T

    1968-01-19

    Photographs of Earth at a resolution of about 600 kilometers were compared to pictures of Venus taken from Earth at about the same resolution . Under these conditions Earth appear very heavily covered by clouds. Since details on the surface of Earth can be recorded from Earth orbit, it may be possible to phiotograph protions of the surface of Venus, through openings in the clouds, from an orbiting satellite. PMID:17799560

  5. 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

  6. 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. PMID:23894649

  7. 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

  8. Clouds in brown dwarfs and giant planets

    NASA Astrophysics Data System (ADS)

    Metchev, S.; Apai, D.; Radigan, J.; Artigau, É.; Heinze, A.; Helling, C.; Homeier, D.; Littlefair, S.; Morley, C.; Skemer, A.; Stark, C.

    2013-02-01

    A growing body of observational and theoretical evidence points toward the importance of clouds in the atmospheres of ultra-cool brown dwarfs and giant planets. Empirically, the presence of clouds is inferred from the red, likely dusty atmospheres of young substellar objects, and from detections of periodic variability in a fraction of brown dwarfs - as expected from rotation and a patchy cloud cover. Theoretical models have progressed alongside by including ever more comprehensive atomic and molecular opacity tables, incorporating the treatment of non-equilibrium chemistry and clouds through vertical mixing and grain size/sedimentation parameters, and employing 3-D hydrodynamical simulations. In this proceeding we summarize the key issues raised during the first gathering of observers and theorists to discuss clouds and atmospheric circulation in non-irradiated ultra-cool dwarfs and giant planets.

  9. 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.

  10. 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.

  11. Jupiter's Multi-level Clouds

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Clouds and hazes at various altitudes within the dynamic Jovian atmosphere are revealed by multi-color imaging taken by the Near-Infrared Mapping Spectrometer (NIMS) onboard the Galileo spacecraft. These images were taken during the second orbit (G2) on September 5, 1996 from an early-morning vantage point 2.1 million kilometers (1.3 million miles) above Jupiter. They show the planet's appearance as viewed at various near-infrared wavelengths, with distinct differences due primarily to variations in the altitudes and opacities of the cloud systems. The top left and right images, taken at 1.61 microns and 2.73 microns respectively, show relatively clear views of the deep atmosphere, with clouds down to a level about three times the atmospheric pressure at the Earth's surface.

    By contrast, the middle image in top row, taken at 2.17 microns, shows only the highest altitude clouds and hazes. This wavelength is severely affected by the absorption of light by hydrogen gas, the main constituent of Jupiter's atmosphere. Therefore, only the Great Red Spot, the highest equatorial clouds, a small feature at mid-northern latitudes, and thin, high photochemical polar hazes can be seen. In the lower left image, at 3.01 microns, deeper clouds can be seen dimly against gaseous ammonia and methane absorption. In the lower middle image, at 4.99 microns, the light observed is the planet's own indigenous heat from the deep, warm atmosphere.

    The false color image (lower right) succinctly shows various cloud and haze levels seen in the Jovian atmosphere. This image indicates the temperature and altitude at which the light being observed is produced. Thermally-rich red areas denote high temperatures from photons in the deep atmosphere leaking through minimal cloud cover; green denotes cool temperatures of the tropospheric clouds; blue denotes cold of the upper troposphere and lower stratosphere. The polar regions appear purplish, because small-particle hazes allow leakage and

  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. Cloud Infrastructure & Applications - CloudIA

    NASA Astrophysics Data System (ADS)

    Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

    The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure that leverages different virtualization technologies, by supporting Service-Level Agreements for various service offerings. This paper describes the CloudIA project in details and mentions our early experiences in building a private cloud using an existing infrastructure.

  14. 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.

  15. Detection of daily clouds on Titan.

    PubMed

    Griffith, C A; Hall, J L; Geballe, T R

    2000-10-20

    We have discovered frequent variations in the near-infrared spectrum of Titan, Saturn's largest moon, which are indicative of the daily presence of sparse clouds covering less than 1% of the area of the satellite. The thermodynamics of Titan's atmosphere and the clouds' altitudes suggest that convection governs their evolutions. Their short lives point to the presence of rain. We propose that Titan's atmosphere resembles Earth's, with clouds, rain, and an active weather cycle, driven by latent heat release from the primary condensible species. PMID:11039930

  16. Shocked clouds in the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Raymond, John C.

    1994-02-01

    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.

  17. 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

  18. Titan's atmosphere (clouds and composition): new results

    NASA Astrophysics Data System (ADS)

    Griffith, C. A.

    Titan's atmosphere potentially sports a cycle similar to the hydrologic one on Earth with clouds, rain and seas, but with methane playing the terrestrial role of water. Over the past ten years many independent efforts indicated no strong evidence for cloudiness until some unique spectra were analyzed in 1998 (Griffith et al.). These surprising observations displayed enhanced fluxes of 14-200 % on two nights at precisely the wavelengths (windows) that sense Titan's lower altitude where clouds might reside. The morphology of these enhancements in all 4 windows observed indicate that clouds covered ~6-9 % of Titan's surface and existed at ~15 km altitude. Here I discuss new observations recorded in 1999 aimed to further characterize Titan's clouds. While we find no evidence for a massive cloud system similar to the one observed previously, 1%-4% fluctuations in flux occur daily. These modulations, similar in wavelength and morphology to the more pronounced ones observed earlier, suggest the presence of clouds covering ≤1% of Titan's disk. The variations are too small to have been detected by most prior measurements. Repeated observations, spaced 30 minutes apart, indicate a temporal variability observable in the time scale of a couple of hours. The cloud heights hint that convection might govern their evolution. Their short lives point to the presence of rain.

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

    DOE PAGESBeta

    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

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

    DOE PAGESBeta

    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

  1. Climatology of POLDER/PARASOL cloud properties

    NASA Astrophysics Data System (ADS)

    Parol, F.; Riedi, J.; Vanbauce, C.; Cornet, C.; Zeng, S.; Thieuleux, F.; Henriot, N.

    2013-05-01

    Since December 2004 the CNES PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar) mission has been flying in the A-Train constellation. More than seven years of data have been routinely acquired and processed by the PARASOL/POLDER ground segment (CNES) and by ICARE Data Center in Lille, France. PARASOL's unique spectral, directional and polarization capabilities give powerful constraints to the cloud retrieval scheme. They allow derivation of classical cloud properties (amount, optical depth, altitude or pressure, albedo) with state of the art performance but also provide original information (thermodynamic phase, angular variability of properties, heterogeneity parameter, etc.). Climatology of cloud fraction and cloud optical thickness have been realized over the 2005-2011 period. Some results and comparisons to MODIS are shown for the year 2008.

  2. 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

  3. A Benchmark for Cloud Tracking Wind Measurements

    NASA Astrophysics Data System (ADS)

    Sayanagi, K. M.; Mitchell, J.; Ingersoll, A. P.; Ewald, S. P.; Marcus, P. S.; de Pater, I.; Wong, M. H.; Choi, D. S.; Sussman, M.; Ogohara, K.; Imamura, T.; Kouyama, T.; Takagi, M.; Satoh, N.; Del Genio, A. D.; Barbara, J.; Sanchez-Lavega, A.; Hueso, R.; García-Melendo, E.; Simon-Miller, A. A.

    2010-12-01

    Cloud tracking has been the primary method of measuring wind speeds in planetary atmospheres through Earth- and space- based remote sensing. Latest developments of automated feature tracking software are able to harvest thousands of wind vectors out of a sequence of high-resolution images acquired with an appropriate temporal separation. However, unlike satellite-based cloud-tracking measurements of Earth, these planetary measurements cannot easily be validated against in-situ data, which makes the interpretation difficult when different cloud-tracking schemes do not agree on their results. To address the issue of data validation, we run multiple automated cloud-tracking software independently developed at multiple institutions on synthetic wind data generated using a General Circulation Model. Our simulations calculate the advection of tracer distributions to represent cloud motions as done by Sayanagi and Showman (2007, Icarus 187, p520-539). The motions of tracers are measured using cloud-tracking software to derive wind vector fields, which will be compared against the model "truth." We test the performance of cloud-tracking software for different wind scenarios. Our first test wind field contains a simple zonal jet. The second test scenario is a large vortex like Jupiter’s Great Red Spot. The third test case has waves propagating alongside a zonal jet. We compare the results returned from different cloud-tracking schemes and discuss what approaches work better at measuring winds. In addition to verifying the wind vector field measurements, we also address the accuracy and validity of eddy momentum flux measurements by tracking clouds. The difficulties of such measurements are discussed by Salyk et al. (2006, Icarus 185, p430-442), and we re-examine the issue using our synthetic wind data. From our experiments, we aim to establish a standard benchmark of cloud tracking measurements for planetary mission applications.

  4. 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.

  5. 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.

  6. 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.

  7. Seasonal and global cloud variations deduced from polar orbiting satellite radiance measurements

    NASA Technical Reports Server (NTRS)

    Rossow, W. B.; Kinsella, E.; Garder, L.

    1983-01-01

    The utility of currently available satellite radiance data for determining cloud radiative effects is evaluated. Each location observed by satellite is classified as clear or cloudy by comparison of measured radiances with specified values. Clear scene radiances are functions of time and location which represent the actual variation of the surface and atmospheric properties that affect the measured radiances. Cloud properties are determined by comparison of model and observed radiance. The seasonal change in cloud properties is shown, displaying the difference between July and January monthly mean values of cloud cover fraction, cloud top temperature, cloud top altitude, and cloud optical thickness.

  8. Glory of clouds in the near infrared.

    PubMed

    Spinhirne, J D; Nakajima, T

    1994-07-20

    Spectrally resolved visible and infrared images of marine stratus clouds were acquired from the NASA ER-2 high-altitude aircraft during the 1987 First International Cloud Climatology Program Regional Experiment. The images were obtained by cross-track scanning radiometers. Data images at nearinfrared wavelengths show frequent and readily apparent brightness features that are due to glory single scattering. The observations and subsequent analysis by radiative transfer calculations show that the glory is a significant feature of near-infrared solar reflectance from water clouds. Glory observations and calculations based on in-cloud microphysics measurements agree well. The most dramatic difference from the visible glory is that the scattering angles are significantly larger in the near infrared. The glory is also apparently more distinct in the near infrared than in the visible, as scattering size parameters are in a range that effectively produces a glory feature, and also there is less obscuration bymultipe-scattering reflectance because of absorption of radiation by droplets in the near infrared. For both the visible and the near infrared, the principal factors that wash out the glory are dispersion and, to a lesser degree, the effective radius of the cloud droplet-size distribution. The obscuration by multiple scattering in optically thick clouds is secondary. Rather than being a novelty, glory observations would be an accurate and unambiguous technique to sense the droplet size of water clouds remotely. PMID:20935835

  9. Acquired Equivalence Changes Stimulus Representations

    ERIC Educational Resources Information Center

    Meeter, M.; Shohamy, D.; Myers, C. E.

    2009-01-01

    Acquired equivalence is a paradigm in which generalization is increased between two superficially dissimilar stimuli (or antecedents) that have previously been associated with similar outcomes (or consequents). Several possible mechanisms have been proposed, including changes in stimulus representations, either in the form of added associations or…

  10. Towards the objective analysis of clouds from satellite imagery data

    NASA Technical Reports Server (NTRS)

    Coakley, J. A., Jr.; Baldwin, D. G.

    1984-01-01

    It is suspected that clouds play a major role in climate dynamics. However, conclusive studies regarding the effects related to the cloud cover appear difficult because there is a lack of objective data. The present investigation is concerned with an objective scheme for deriving clouds and their properties from satellite imagery data for the oceans. The objective analysis makes use of the spatial coherence method for retrieving cloud cover from satellite imagery data. This method has advantages over other techniques often applied to imagery data. It is not necessary that clouds fill completely the observing instrument's field-of-view, and a priori or satellite derived knowledge of the cloud radiative properties is not needed.

  11. 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.

  12. 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.

  13. Quantification of accuracy of precipitation estimates from MSG data suing using CloudSat satellite observations in Europe and Africa

    NASA Astrophysics Data System (ADS)

    Amoni, E.; Su, Z.; Timmermans, J.

    2010-05-01

    Availability of fresh water supply is an essential important to humans and all forms of life. Precipitation, being the source of most of fresh water plays an important role in the socio-economic activities as human settlement is often found in regions abundant with this precious commodity in its various forms either sourced directly from rainfall or from rivers, lakes, springs, etc. A good estimate of the amount of precipitation in any place assists the population in better planning of their activities that may include agriculture, infrastructure development and maintenance, flood and forest fire monitoring, etc. Several remote sensing based rainfall monitoring schemes are currently in existence. One of the best known is the Meteosat Second Generation, MSG's Multi-sensor Precipitation Estimate (MPE). The MPE product relies mainly on the cloud top temperatures, a proxy for the cloud top-height, to estimate the rainfall intensity emanating from particular kinds of clouds with large vertical extent. The MSG has been useful in the estimation of rainfall intensity estimates especially for remote places over Africa and over the oceanic areas, however the accuracy of these products remains to be established using more quantitative . measurements, like the weather radar systems in Europe. On the other hand, as opposed to their counterparts in Western Europe, most of Africa is not covered by weather radar. This is attributed to affordability as these radars are costly. The weather radars which have been known to give more accurate rainfall intensity estimates than the MSG. , as opposed toThis approach is feasible in Europe which is endowed with a network of weather radars under the OPERA network. An advantage of the radar technology is that it penetrates into the cloud to examine the water and ice and considers them in estimation of rainfall intensities. On the other hand, as opposed to their counterparts in Western Europe, most of Africa is not covered by weather radar

  14. 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).

  15. Slicing The 2010 Saturn's Storm: Upper Clouds And Hazes

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sanz-Requena, J. F.; Sanchez-Lavega, A.; Hueso, R.

    2012-10-01

    At the end of 2010 a small storm erupted in Saturn's northern mid-latitudes. Starting from a localized perturbation, it grew up to be a global-scale disturbance and cover the whole latitude band by February, 2011 (Fletcher et al. 2011, Science 332; Sánchez-Lavega et al. 2011, Nature 475; Fischer et al. 2011, Nature 475). By June, 2011 the storm was facing its end and gradually disappeared (Sánchez-Lavega et al. 2012, Icarus 220). In this work we use the observations acquired by the Cassini ISS instrument during the whole process to investigate the vertical cloud and haze structure above the ammonia condensation level (roughly 1 bar). Cassini ISS observations cover visual wavelengths from the blue to the near-infrared including two methane absorption bands. Such observations have been modeled using a radiative transfer code which reproduces the atmospheric reflectivity as a function of observation/illumination geometry and wavelength together with a retrieval technique to find maximum likelihood atmospheric models. This allows to investigate some atmospheric parameters: cloud-top pressures, aerosol optical thickness and particle absorption, among others. We will focus on two aspects: (1) maximum likelihood models for the undisturbed reference atmosphere in the 15°N to 45°N band before and after the disturbance; (2) models for particular structures during the development of the global-scale phenomenon. Our results show a general increase of particle density and single-scattering albedo inside the storm. However, some discrete features showing anomalous structure and related to the storm peculiar dynamics will also be discussed. Acknowledgments: This work was supported by the Spanish MICIIN project AYA2009-10701 with FEDER funds, by Grupos Gobierno Vasco IT-464-07 and by Universidad País Vasco UPV/EHU through program UFI11/55.

  16. 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.

  17. 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

  18. 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

  19. Dominant roles of subgrid-scale cloud structures in model diversity of cloud radiative effects

    NASA Astrophysics Data System (ADS)

    Zhang, F.

    2013-12-01

    Today, large model discrepancies exist in estimated cloud radiative effects (CREs) and irradiances across 1-D radiative transfer schemes aimed for climate models. The primary purpose of this study is to understand physical causes of such model discrepancies, especially in CREs under partly cloudy sky. To achieve this goal, the unique Cloud-Aerosol-Radiation (CAR) ensemble modeling system was employed, offline driven by the ERA-Interim global data for July 2004 with no feedback considered. For evaluating each individual contribution from the existing scheme diversity of cloud horizontal inhomogeneity, cloud optical properties, cloud vertical overlap, and gas absorptions, several sets of numerical experiments were conducted. It is the first time to explicitly demonstrate that after removing most of the disagreement in cloud fields, model spreads of CREs among the CAR's seven major radiation schemes, as well as those of radiative fluxes, dramatically diminish. Taking global mean CREs for example, their current model ranges can decrease to <4Wm-2 from about 10Wm-2 for shortwave and also to <4Wm-2 from 5-8Wm-2 for longwave. Dominant roles of subgrid-scale cloud structures (including vertical overlap and horizontal variability) were proven in general, explaining about 40 -75% of the total model spreads. We have also found that model spreads of CREs are very sensitive to cloud cover fractions. Such nonlinear sensitivity can be largely reduced after removing the model difference in the treatments of cloud vertical overlap.

  20. Dominant roles of subgrid-scale cloud structures in model diversity of cloud radiative effects

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Liang, Xin-Zhong; Li, Jiangnan; Zeng, Qingcun

    2013-07-01

    Today, large model discrepancies exist in estimated cloud radiative effects (CREs) and irradiances across 1-D radiative transfer schemes aimed for climate models. The primary purpose of this study is to understand physical causes of such model discrepancies, especially in CREs under partly cloudy sky. To achieve this goal, the unique Cloud-Aerosol-Radiation (CAR) ensemble modeling system was employed, offline driven by the ERA-Interim global data for July 2004 with no feedback considered. For evaluating each individual contribution from the existing scheme diversity of cloud horizontal inhomogeneity, cloud optical properties, cloud vertical overlap, and gas absorptions, several sets of numerical experiments were conducted. It is the first time to explicitly demonstrate that after removing most of the disagreement in cloud fields, model spreads of CREs among the CAR's seven major radiation schemes, as well as those of radiative fluxes, dramatically diminish. Taking global mean CREs for example, their current model ranges can decrease to <4 W m-2 from about 10 W m-2 for shortwave and also to <4 W m-2 from 5-8 W m-2 for longwave. Dominant roles of subgrid-scale cloud structures (including vertical overlap and horizontal variability) were proven in general, explaining about 40-75% of the total model spreads. We have also found that model spreads of CREs are very sensitive to cloud cover fractions. Such nonlinear sensitivity can be largely reduced after removing the model difference in the treatments of cloud vertical overlap.

  1. 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.

  2. Sensitivity analysis of upwelling thermal radiance in presence of clouds

    NASA Technical Reports Server (NTRS)

    Subramanian, S. V.; Tiwari, S. N.; Suttles, J. T.

    1981-01-01

    Total upwelling radiance at the top of the atmosphere is evaluated theoretically in the presence of clouds. The influence of cloud heights, thicknesses and different cloud covers on the upwelling radiance is also investigated. The characteristics of the two cloud types considered in this study closely correspond to altocumulus and cirrus with the cloud emissivity as a function of its liquid water (or ice) content. For calculation of the integrated transmittance of atmospheric gases such as, H2O, CO2, O3, and N2O, the Quasi Random Band (QRB) model approach is adopted. Results are obtained in three different spectral ranges and are compared with the clearsky radiance results. It is found that the difference between the clearsky and cloudy radiance increases with increasing cloud height and liquid water content. This difference also decreases as the surface temperature approaches the value of the cloud top temperature.

  3. 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.

  4. 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.

  5. THE GALFA-H I COMPACT CLOUD CATALOG

    SciTech Connect

    Saul, Destry R.; Peek, J. E. G.; Grcevich, J.; Putman, M. E.; Brown, A. R. H.; Hamden, E. T.; Douglas, K. A.; Stanimirovic, S.; Lee, M.; Burkhart, B.; Pingel, N. M.; Heiles, C.; Gibson, S. J.; Begum, A.; Tonnesen, S.

    2012-10-10

    We present a catalog of 1964 isolated, compact neutral hydrogen clouds from the Galactic Arecibo L-Band Feed Array Survey Data Release One. The clouds were identified by a custom machine-vision algorithm utilizing the difference of Gaussian kernels to search for clouds smaller than 20'. The clouds have velocities typically between |V{sub LSR}| =20 and 400 km s{sup -1}, line widths of 2.5-35 km s{sup -1}, and column densities ranging from 1 to 35 Multiplication-Sign 10{sup 18} cm{sup -2}. The distances to the clouds in this catalog may cover several orders of magnitude, so the masses may range from less than a solar mass for clouds within the Galactic disk, to greater than 10{sup 4} M{sub Sun} for high-velocity clouds (HVCs) at the tip of the Magellanic Stream. To search for trends, we separate the catalog into five populations based on position, velocity, and line width: HVCs; galaxy candidates; cold low-velocity clouds (LVCs); warm, low positive-velocity clouds in the third Galactic quadrant; and the remaining warm LVCs. The observed HVCs are found to be associated with previously identified HVC complexes. We do not observe a large population of isolated clouds at high velocities as some models predict. We see evidence for distinct histories at low velocities in detecting populations of clouds corotating with the Galactic disk and a set of clouds that is not corotating.

  6. 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.

  7. Properties of marine stratocumulus obtained with partly cloudy pixel retrievals and found in the MODIS MOD06 cloud product

    NASA Astrophysics Data System (ADS)

    Boeke, Robyn C.; Allan, Andrea M.; Coakley, James A.

    2016-06-01

    Partly cloudy pixel retrievals (PCPRs) of cloud properties for marine stratocumulus were compared with those of the 1 km Moderate Resolution Imaging Spectroradiometer (MODIS) cloud product (MOD06). In addition, the fractional cloud cover obtained from the PCPRs applied to 1 km MODIS radiances was compared with that derived from the 250 m cloud mask (MOD35). The comparisons were made for pixels that were overcast and pixels that were only partially covered by clouds. Accounting for failed retrievals in both the MOD06 cloud properties and those obtained with the PCPRs leads to the suggestion that regional cloud cover be estimated in terms of lower and upper limits. The average could serve as the best estimate of the cloud cover, and the difference between the average and an extreme could serve as the uncertainty. The comparisons reveal that the overcast assumption used in the MODIS cloud property retrievals leads to cloud cover, droplet effective radii, and cloud top temperatures that are overestimated and, shortwave optical depths, liquid water paths that are underestimated. These biases persist when the properties are averaged to form spatial and temporal means. Owing to significant horizontal variations of cloud liquid water within the 1 km MODIS pixels, visible optical depths, droplet effective radii, and liquid water paths derived from the PCPRs show similar biases. The trends of the biases with pixel-scale and regional-scale cloud cover suggest that estimates of the aerosol indirect radiative forcing derived from satellites have been overestimated.

  8. Large-Scale Analysis of Cirrus Clouds from AVHRR Data: Assessment of Both a Microphysical Index and the Cloud-Top Temperature.

    NASA Astrophysics Data System (ADS)

    Giraud, V.; Buriez, J. C.; Fouquart, Y.; Parol, F.; Seze, G.

    1997-06-01

    An algorithm that allows an automatic analysis of cirrus properties from Advanced Very High Resolution Radiometer (AVHRR) observations is presented. Further investigations of the information content and physical meaning of the brightness temperature differences (BTD) between channels 4 (11 m) and 5 (12 m) of the radiometer have led to the development of an automatic procedure to provide global estimates both of the cirrus cloud temperature and of the ratio of the equivalent absorption coefficients in the two channels, accounting for scattering effects. The ratio is useful since its variations are related to differences in microphysical properties. Assuming that cirrus clouds are composed of ice spheres, the effective diameter of the particle size distribution can be deduced from this microphysical index.The automatic procedure includes first, a cloud classification and a selection of the pixels corresponding to the envelope of the BTD diagram observed at a scale of typically 100 × 100 pixels. The classification, which uses dynamic cluster analysis, takes into account spectral and spatial properties of the AVHRR pixels. The selection is made through a series of tests, which also guarantees that the BTD diagram contains the necessary information, such as the presence of both cirrus-free pixels and pixels totally covered by opaque cirrus in the same area. Finally, the cloud temperature and the equivalent absorption coefficient ratio are found by fitting the envelope of the BTD diagram with a theoretical curve. Note that the method leads to the retrieval of the maximum value of the equivalent absorption coefficient ratio in the scene under consideration. This, in turn, corresponds to the minimum value of the effective diameter of the size distribution of equivalent Mie particles.The automatic analysis has been applied to a series of 21 AVHRR images acquired during the International Cirrus Experiment (ICE'89). Although the dataset is obviously much too limited to draw

  9. Acquired causes of intestinal malabsorption.

    PubMed

    van der Heide, F

    2016-04-01

    This review focuses on the acquired causes, diagnosis, and treatment of intestinal malabsorption. Intestinal absorption is a complex process that depends on many variables, including the digestion of nutrients within the intestinal lumen, the absorptive surface of the small intestine, the membrane transport systems, and the epithelial absorptive enzymes. Acquired causes of malabsorption are classified by focussing on the three phases of digestion and absorption: 1) luminal/digestive phase, 2) mucosal/absorptive phase, and 3) transport phase. Most acquired diseases affect the luminal/digestive phase. These include short bowel syndrome, extensive small bowel inflammation, motility disorders, and deficiencies of digestive enzymes or bile salts. Diagnosis depends on symptoms, physical examination, and blood and stool tests. There is no gold standard for the diagnosis of malabsorption. Further testing should be based on the specific clinical context and the suspected underlying disease. Therapy is directed at nutritional support by enteral or parenteral feeding and screening for and supplementation of deficiencies in vitamins and minerals. Early enteral feeding is important for intestinal adaptation in short bowel syndrome. Medicinal treatment options for diarrhoea in malabsorption include loperamide, codeine, cholestyramine, or antibiotics. PMID:27086886

  10. 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.

  11. 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.

  12. Cover Your Cough

    MedlinePlus

    ... What's this? Submit Button Past Newsletters Cover Your Cough Language: English Español Recommend on Facebook Tweet ... Posters only available as PDF files. Cover Your Cough, Flyer for Health Care Settings English [324 KB] ...

  13. Macroscopic cloud properties in the WRF NWP model: An assessment using sky camera and ceilometer data

    NASA Astrophysics Data System (ADS)

    Arbizu-Barrena, Clara; Pozo-Vázquez, David; Ruiz-Arias, José A.; Tovar-Pescador, Joaquín.

    2015-10-01

    The ability of six microphysical parameterizations included in the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model to represent various macroscopic cloud characteristics at multiple spatial and temporal resolutions is investigated. In particular, the model prediction skills of cloud occurrence, cloud base height, and cloud cover are assessed. When it is possible, the results are provided separately for low-, middle-, and high-level clouds. The microphysical parameterizations assessed are WRF single-moment six-class, Thompson, Milbrandt-Yau, Morrison, Stony Brook University, and National Severe Storms Laboratory double moment. The evaluated macroscopic cloud properties are determined based on the model cloud fractions. Two cloud fraction approaches, namely, a binary cloud fraction and a continuous cloud fraction, are investigated. Model cloud cover is determined by overlapping the vertically distributed cloud fractions following three different strategies. The evaluation is conducted based on observations gathered with a ceilometer and a sky camera located in Jaén (southern Spain). The results prove that the reliability of the WRF model mostly depends on the considered cloud parameter, cloud level, and spatiotemporal resolution. In our test bed, it is found that WRF model tends to (i) overpredict the occurrence of high-level clouds irrespectively of the spatial resolution, (ii) underestimate the cloud base height, and (iii) overestimate the cloud cover. Overall, the best cloud estimates are found for finer spatial resolutions (1.3 and 4 km with slight differences between them) and coarser temporal resolutions. The roles of the parameterization choice of the microphysics scheme and the cloud overlapping strategy are, in general, less relevant.

  14. Structural characteristics and radiative properties of tropical cloud clusters

    SciTech Connect

    Machado, L.A.T.; Rossow, W.B.

    1993-12-01

    By identifying individual tropical cloud clusters in eight months of the International Satellite Cloud Climatology Project data, the size distribution, average cloud properties, and their variation with system size in tropical convective systems (CS) is examined. The geographic distribution of CS shows a concentration over land areas in the summer hemisphere with little seasonal variation except for the major shift of location into the summer hemisphere. When the tropics are considered as a whole or a region is considered over a whole season, CS of all sizes form a continuous size distribution where the area covered by the clouds in each size range is approximately the same. Land CS show a small excess of the smallest CS and a small deficit of the largest CS in comparison to ocean CS. Average CS cloud properties suggest two major cloud types: One with lower cloud-top pressures and much higher optical thicknesses, associated with deep convection, and one with higher cloud-top pressures and some evidence of a further division into optically thicker and thinner parts. The average properties of these clouds vary in a correlated fashion such that a larger horizontal extent of the convective system cloud is accompanied by a lower convective cloud-top pressure, larger anvil cloud size, and larger anvil cloud optical thickness. These structural properties and their diurnal variation also suggest that the smallest CS may represent a mixture of the formative and dissipative stages of CS, while the medium and large sizes are, principally, the mature stage. A radiative transfer model is used to evaluate the local radiative effects of CS with average cloud properties. The results imply that the mesoscale anvil cloud reinforces the diabatic heating of the atmosphere by the convection and may help sustain these systems at night. The radiative effects of the convective clouds may reinforce the diurnal variation of convection. 80 refs., 17 figs., 3 tabs.

  15. Cloud Statistics and Discrimination in the Polar Regions

    NASA Astrophysics Data System (ADS)

    Chan, M.; Comiso, J. C.

    2012-12-01

    Despite their important role in the climate system, cloud cover and their statistics are poorly known, especially in the polar regions, where clouds are difficult to discriminate from snow covered surfaces. The advent of the A-train, which included Aqua/MODIS, CALIPSO/CALIOP and CloudSat/CPR sensors has provided an opportunity to improve our ability to accurately characterize the cloud cover. MODIS provides global coverage at a relatively good temporal and spatial resolution while CALIOP and CPR provide limited nadir sampling but accurate characterization of the vertical structure and phase of the cloud cover. Over the polar regions, cloud detection from a passive sensors like MODIS is challenging because of the presence of cold and highly reflective surfaces such as snow, sea-ice, glaciers, and ice-sheet, which have surface signatures similar to those of clouds. On the other hand, active sensors such as CALIOP and CPR are not only very sensitive to the presence of clouds but can also provide information about its microphysical characteristics. However, these nadir-looking sensors have sparse spatial coverage and their global data can have data spatial gaps of up to 100 km. We developed a polar cloud detection system for MODIS that is trained using collocated data from CALIOP and CPR. In particular, we employ a machine learning system that reads the radiative profile observed by MODIS and determine whether the field of view is cloudy or clear. Results have shown that the improved cloud detection scheme performs better than typical cloud mask algorithms using a validation data set not used for training. A one-year data set was generated and results indicate that daytime cloud detection accuracies improved from 80.1% to 92.6% (over sea-ice) and 71.2% to 87.4% (over ice-sheet) with CALIOP data used as the baseline. Significant improvements are also observed during nighttime, where cloud detection accuracies increase by 19.8% (over sea-ice) and 11.6% (over ice

  16. Observing Ice in Clouds from Space

    NASA Technical Reports Server (NTRS)

    Ackerman, S.; Star, D. O'C.; Skofronick-Jackson, G.; Evans, F.; Wang, J. R.; Norris, P.; daSilva, A.; Soden, B.

    2006-01-01

    brightness temperatures to ice. The next step is a satellite mission designed to acquire global Earth radiance measurements in the submillimeter-wave region, thus bridging the measurement gap between microwave sounders and shorter-wavelength infrared and visible sensors. This presentation provides scientific justification and an approach to measuring ice water path and particle size from a satellite platform that spans a range encompassing both the hydrologically active and radiatively active components of cloud systems.

  17. Cloud CCN feedback

    SciTech Connect

    Hudson, J.G.

    1992-12-31

    Cloud microphysics affects cloud albedo precipitation efficiency and the extent of cloud feedback in response to global warming. Compared to other cloud parameters, microphysics is unique in its large range of variability and the fact that much of the variability is anthropogenic. Probably the most important determinant of cloud microphysics is the spectra of cloud condensation nuclei (CCN) which display considerable variability and have a large anthropogenic component. When analyzed in combination three field observation projects display the interrelationship between CCN and cloud microphysics. CCN were measured with the Desert Research Institute (DRI) instantaneous CCN spectrometer. Cloud microphysical measurements were obtained with the National Center for Atmospheric Research Lockheed Electra. Since CCN and cloud microphysics each affect the other a positive feedback mechanism can result.

  18. 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 ...

  19. Cover Crop Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential benefits of cover crops in vegetable production systems depend on the type of cover crop that is used and how it is managed from planting to termination date. This chapter focuses on management practices that are applicable to a broad range cover crops and vegetable production systems ...

  20. More clouds over large European forests

    NASA Astrophysics Data System (ADS)

    Teuling, Ryan; Fokke Meirink, Jan; Vila, Jordi; Stegehuis, Annemiek; Nabuurs, Gert-Jan; Miralles, Diego; Taylor, Chris

    2015-04-01

    The impact of temperate forests on their environment is still 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 attempts to study impacts of forest cover on atmospheric conditions through modeling. 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 strongly fragmented and often can be found on hilly terrain, making it impossible to attribute differences in for instance cloud cover or runoff directly to forest cover. Only few regions exist where forests can be found in absence of strong topography of a size large enough to result in near-equilibrium between the atmospheric boundary layer and local surface conditions. In this study, we analyse 10 years (2004-2013) of cloud cover observations 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 much more likely to occur over forest than over the surrounding non-forest land (difference in the order of 0.2). An opposite signal, but of much weaker magnitude, is found during springtime, 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

  1. 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

  2. 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

  3. 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.

  4. Scientific Data Storage for Cloud Computing

    NASA Astrophysics Data System (ADS)

    Readey, J.

    2014-12-01

    Traditionally data storage used for geophysical software systems has centered on file-based systems and libraries such as NetCDF and HDF5. In contrast cloud based infrastructure providers such as Amazon AWS, Microsoft Azure, and the Google Cloud Platform generally provide storage technologies based on an object based storage service (for large binary objects) complemented by a database service (for small objects that can be represented as key-value pairs). These systems have been shown to be highly scalable, reliable, and cost effective. We will discuss a proposed system that leverages these cloud-based storage technologies to provide an API-compatible library for traditional NetCDF and HDF5 applications. This system will enable cloud storage suitable for geophysical applications that can scale up to petabytes of data and thousands of users. We'll also cover other advantages of this system such as enhanced metadata search.

  5. 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.

  6. 3D Radiative Aspects of the Increased Aerosol Optical Depth Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Wen, Guoyong; Remer, Lorraine; Cahalan, Robert; Coakley, Jim

    2007-01-01

    To characterize aerosol-cloud interactions it is important to correctly retrieve aerosol optical depth in the vicinity of clouds. It is well reported in the literature that aerosol optical depth increases with cloud cover. Part of the increase comes from real physics as humidification; another part, however, comes from 3D cloud effects in the remote sensing retrievals. In many cases it is hard to say whether the retrieved increased values of aerosol optical depth are remote sensing artifacts or real. In the presentation, we will discuss how the 3D cloud affects can be mitigated. We will demonstrate a simple model that can assess the enhanced illumination of cloud-free columns in the vicinity of clouds. This model is based on the assumption that the enhancement in the cloud-free column radiance comes from the enhanced Rayleigh scattering due to presence of surrounding clouds. A stochastic cloud model of broken cloudiness is used to simulate the upward flux.

  7. Roughness Estimation from Point Clouds - A Comparison of Terrestrial Laser Scanning and Image Matching by Unmanned Aerial Vehicle Acquisitions

    NASA Astrophysics Data System (ADS)

    Rutzinger, Martin; Bremer, Magnus; Ragg, Hansjörg

    2013-04-01

    Recently, terrestrial laser scanning (TLS) and matching of images acquired by unmanned arial vehicles (UAV) are operationally used for 3D geodata acquisition in Geoscience applications. However, the two systems cover different application domains in terms of acquisition conditions and data properties i.e. accuracy and line of sight. In this study we investigate the major differences between the two platforms for terrain roughness estimation. Terrain roughness is an important input for various applications such as morphometry studies, geomorphologic mapping, and natural process modeling (e.g. rockfall, avalanche, and hydraulic modeling). Data has been collected simultaneously by TLS using an Optech ILRIS3D and a rotary UAV using an octocopter from twins.nrn for a 900 m² test site located in a riverbed in Tyrol, Austria (Judenbach, Mieming). The TLS point cloud has been acquired from three scan positions. These have been registered using iterative closest point algorithm and a target-based referencing approach. For registration geometric targets (spheres) with a diameter of 20 cm were used. These targets were measured with dGPS for absolute georeferencing. The TLS point cloud has an average point density of 19,000 pts/m², which represents a point spacing of about 5 mm. 15 images where acquired by UAV in a height of 20 m using a calibrated camera with focal length of 18.3 mm. A 3D point cloud containing RGB attributes was derived using APERO/MICMAC software, by a direct georeferencing approach based on the aircraft IMU data. The point cloud is finally co-registered with the TLS data to guarantee an optimal preparation in order to perform the analysis. The UAV point cloud has an average point density of 17,500 pts/m², which represents a point spacing of 7.5 mm. After registration and georeferencing the level of detail of roughness representation in both point clouds have been compared considering elevation differences, roughness and representation of different grain

  8. 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…

  9. 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.

  10. Tamper resistant choke cover

    SciTech Connect

    Kneipkamp, L.E.

    1981-12-29

    A carburetor improvement is described for inhibiting tampering with a thermostatic choke coil after carburetor manufacture. A cover (3) fits over a choke coil housing (H) to enclose a choke lever, the thermostatic coil being mounted inside the cover. The cover has a circumferential flange (5) which abuts the outer surface of the housing, the flange having a notch (9) formed therein and the cover being rotatable about the outer surface of the housing to position one end of the coil relative to the choke lever. A retainer (7) locks the cover in a fixed position once the one end of the coil is located with respect to the choke lever. The retainer has a tab (11) insertable in the notch to prevent further rotation of the cover. A screw (15) having a detachable head (17) unremovably secures the retainer to the carburetor whereby once the retainer is secured, further movement of the cover is prevented.

  11. 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.

  12. 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

  13. 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

  14. Influence of clouds on the earth's radiation budget determined from GOES data

    NASA Technical Reports Server (NTRS)

    Harrison, E. F.; Minnis, P.

    1983-01-01

    Estimates of the cloud radiative effects on the earth's regional and zonal radiation budgets derived from GOES data during November 1978 are presented. The diurnal cloud cover variability is shown to affect both the radiation-budget measurements and the estimation of the overall effect of clouds on the net flux. For this data set, the cloud cover causes a decrease in the net flux from the clear-sky value. Thus, the cloud albedo effect outweights the greenhouse effect of the clouds. It is found that the value of the change in the radiation balance is closely related to the amount of incident solar radiation and to the zonal distributions of low, middle, and high cloud cover.

  15. 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

  16. 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.

  17. 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

  18. Perioperatively acquired disorders of coagulation

    PubMed Central

    Grottke, Oliver; Fries, Dietmar; Nascimento, Bartolomeu

    2015-01-01

    Purpose of review To provide an overview of acquired coagulopathies that can occur in various perioperative clinical settings. Also described are coagulation disturbances linked to antithrombotic medications and currently available strategies to reverse their antithrombotic effects in situations of severe hemorrhage. Recent findings Recent studies highlight the link between low fibrinogen and decreased fibrin polymerization in the development of acquired coagulopathy. Particularly, fibrin(ogen) deficits are observable after cardiopulmonary bypass in cardiac surgery, on arrival at the emergency room in trauma patients, and with ongoing bleeding after child birth. Regarding antithrombotic therapy, although new oral anticoagulants offer the possibility of efficacy and relative safety compared with vitamin K antagonists, reversal of their anticoagulant effect with nonspecific agents, including prothrombin complex concentrate, has provided conflicting results. Specific antidotes, currently being developed, are not yet licensed for clinical use, but initial results are promising. Summary Targeted hemostatic therapy aims to correct coagulopathies in specific clinical settings, and reduce the need for allogeneic transfusions, thus preventing massive transfusion and its deleterious outcomes. Although there are specific guidelines for reversing anticoagulation in patients treated with antiplatelet agents or warfarin, there is currently little evidence to advocate comprehensive recommendations to treat drug-induced coagulopathy associated with new oral anticoagulants. PMID:25734869

  19. 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. PMID:24846635

  20. Aerosol - cloud - water vapor relations for cloud systems of different heights

    NASA Astrophysics Data System (ADS)

    Stathopoulos, Stavros; Kourtidis, Konstantinos; Georgoulias, Aristeidis

    2016-04-01

    Here we examine the annual and seasonal aerosol - cloud relations over three major urban clusters of China, for different cloud heights and atmospheric water vapor amounts, using a decade of Aerosol Optical Depth at 550nm (AOD), Cloud Cover (CC), Cloud Optical Depth (COD), Water Vapor (WV) and Cloud Top Pressure (CTP) data from the MODIS instrument. Over all regions (spanning from temperate to tropical monsoon climates) and for all seasons, CC is found to increase with AOD, WV and cloud height. Aerosols, at low WV environments and under constant cloud height, have less impact on CC than at high WV environments. In addition, AOD has a varying influence on COD depending on CTP. Finally, COD is found to increase with height for low and middle height clouds, and with increasing AOD, especially at low AOD, the latter being in line with the expected first indirect effect. This research has been financed under the FP7 Programme MarcoPolo (Grand Number 606953, Theme SPA.2013.3.2-01).

  1. A Thermal Infrared Cloud Mapper

    NASA Astrophysics Data System (ADS)

    Mallama, A.; Degnan, J. J.

    2001-12-01

    A thermal infrared imager for mapping the changing cloud cover over a ground based observing site has been developed. There are two main components to our instrument. One is a commercially made uncooled 10 micron thermal infrared detector that outputs a 120x120 pixel thermogram. The other is a convex electroplated reflector, which is situated beneath the detector and in its field of view. The resulting image covers the sky from zenith down to about 10 degrees elevation. The self-reflection of the camera and supporting vanes is removed by interpolation. Atmospheric transparency is distinguished by the difference between the sky temperature and the ambient air temperature. Clear sky is indicated by pixels having a difference of about 20 degrees C or more. The qualitative results 'clear, haze and cloud' have proven to be very reliable during two years of development and testing. Quantitative information, such as the extinction coefficient, is also available though it is not exact. The uncertainty is probably due to variability of the lapse rate under different atmospheric conditions. Software has been written for PC/DOS and VME/LynxOS (similar to Linux) systems in the C programming language. Functionality includes serial communication with the detector, analysis of the thermogram, mapping of cloud cover, data display, and file I/O. The main elements of cost in this system were for the thermal infrared detector and for the machining of an 18-inch diameter stainless steel mandrel. The latter is needed to produce an electroplated reflector. We have had good success with the gold and rhodium reflectors that have been generated. The reflectors themselves are relatively inexpensive now that the mandrel is available.

  2. 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. PMID:23599560

  3. 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...

  4. Closed Small Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Small Cell Clouds in the South Pacific     ... the Multi-angle Imaging SpectroRadiometer (MISR). Closed cell clouds are formed under conditions of widespread sinking of the air above. ...

  5. 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. PMID:26072748

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Cloud Scaling Properties and Cloud Parameterization

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Morcrette, J. J.

    1998-01-01

    Cloud liquid and cloud traction variability is studied as a function of horizontal scale in the ECMWF forecast model during several 10-day runs at the highest available model resolution, recently refined from approximately 60 km (T213) down to approximately 20 km (T639). At higher resolutions, model plane-parallel albedo biases are reduced, so that models may be tuned to have larger, more realistic, cloud liquid water amounts, However, the distribution of cloud liquid assumed -within- each gridbox, for radiative and thermodynamic computations, depends on ad hoc assumptions that are not necessarily consistent with observed scaling properties, or with scaling properties produced by the model at larger scales. To study the larger-scale cloud properties, ten locations on the Earth are chosen to coincide with locations having considerable surface data available for validation, and representing a variety of climatic regimes, scaling exponents are determined from a range or scales down to model resolution, and are re-computed every three hours, separately for low, medium and high clouds, as well as column-integrated cloudiness. Cloud variability fluctuates in time, due to diurnal, synoptic and other' processes, but scaling exponents are found to be relatively stable. various approaches are considered for applying computed cloud scaling to subgrid cloud distributions used for radiation, beyond simple random or maximal overlap now in common use. Considerably more work is needed to compare model cloud scaling with observations. This will be aided by increased availability of high-resolution surface, aircraft and satellite data, and by the increasing resolution of global models,

  12. 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…

  13. 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

  14. 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.

  15. Acquired immunodeficiency syndrome: neuroradiologic findings.

    PubMed

    Kelly, W M; Brant-Zawadzki, M

    1983-11-01

    Central nervous system complications depicted by CT in ten patients with acquired immunodeficiency syndrome are described. Three patients had multifocal intra-axial enhancing lesions representing atypical brain abscesses (two with toxoplasmosis, one with candidiasis). A fourth patient with multifocal "ring" lesions whose biopsy was interpreted as suggestive of toxoplasmosis responded poorly to treatment. Following his death three months later of Pneumocystis carinii pneumonia, autopsy revealed primary intracerebral immunoblastic lymphoma. One patient had Kaposi sarcoma involving the right frontal lobe (seen as an enhancing mass on the CT scan). CT findings in the remaining five patients revealed mild to moderate enlargement of cerebrospinal fluid spaces (including ventricles and basal cisternae) as a result of cryptococcal meningitis in three patients and "aseptic" meningitis in two. The two patients in whom early biopsy confirmed toxoplasmosis responded well to anti-infective therapy, resulting in dramatic clinical recoveries. PMID:6622693

  16. Bejel: acquirable only in childhood?

    PubMed

    Rothschild, Bruce M; Rothschild, Christine; Naples, Virginia; Billard, Michel; Panero, Barbara

    2006-10-01

    Bejel clearly has a long history in the Middle East and the Sudan, but was it transmitted to Europe? As the major manifestation of bejel is presence of periosteal reaction in 20-40% of afflicted populations, absence of significant population frequency of periosteal reaction in Europe would exclude that diagnosis. Examination of skeletal populations from continental Europe revealed no significant periosteal reaction at the time of and immediately subsequent to the Crusades. Thus, there is no evidence for bejel in Europe, in spite of clear contact (the mechanism of bejel transmission in children) between warring groups, at least during the Crusades. This supports the hypothesis that bejel is a childhood-acquired disease and apparently cannot be contracted in adulthood. PMID:17049474

  17. Lymphoma in acquired generalized lipodystrophy.

    PubMed

    Brown, Rebecca J; Chan, Jean L; Jaffe, Elaine S; Cochran, Elaine; DePaoli, Alex M; Gautier, Jean-Francois; Goujard, Cecile; Vigouroux, Corinne; Gorden, Phillip

    2016-01-01

    Acquired generalized lipodystrophy (AGL) is a rare disease thought to result from autoimmune destruction of adipose tissue. Peripheral T-cell lymphoma (PTCL) has been reported in two AGL patients. We report five additional cases of lymphoma in AGL, and analyze the role of underlying autoimmunity and recombinant human leptin (metreleptin) replacement in lymphoma development. Three patients developed lymphoma during metreleptin treatment (two PTCL and one ALK-positive anaplastic large cell lymphoma), and two developed lymphomas (mycosis fungoides and Burkitt lymphoma) without metreleptin. AGL is associated with high risk for lymphoma, especially PTCL. Autoimmunity likely contributes to this risk. Lymphoma developed with or without metreleptin, suggesting metreleptin does not directly cause lymphoma development; a theoretical role of metreleptin in lymphoma progression remains possible. For most patients with AGL and severe metabolic complications, the proven benefits of metreleptin on metabolic disease will likely outweigh theoretical risks of metreleptin in lymphoma development or progression. PMID:25864863

  18. Use of A-train satellite observations (CALIPSO-PARASOL) to evaluate tropical cloud properties in the LMDZ5 GCM

    NASA Astrophysics Data System (ADS)

    Konsta, D.; Dufresne, J.-L.; Chepfer, H.; Idelkadi, A.; Cesana, G.

    2016-08-01

    The evaluation of key cloud properties such as cloud cover, vertical profile and optical depth as well as the analysis of their intercorrelation lead to greater confidence in climate change projections. In addition, the comparison between observations and parameterizations of clouds in climate models is improved by using collocated and instantaneous data of cloud properties. Simultaneous and independent observations of the cloud cover and its three-dimensional structure at high spatial and temporal resolutions are made possible by the new space-borne multi-instruments observations collected with the A-train. The cloud cover and its vertical structure observed by CALIPSO and the visible directional reflectance (a surrogate for the cloud optical depth) observed by PARASOL, are used to evaluate the representation of cloudiness in two versions of the atmospheric component of the IPSL-CM5 climate model (LMDZ5). A model-to-satellite approach, applying the CFMIP Observation Simulation Package (COSP), is used to allow a quantitative comparison between model results and observations. The representation of clouds in the two model versions is first evaluated using monthly mean data. This classical approach reveals biases of different magnitudes in the two model versions. These biases consist of (1) an underestimation of cloud cover associated to an overestimation of cloud optical depth, (2) an underestimation of low- and mid-level tropical clouds and (3) an overestimation of high clouds. The difference in the magnitude of these biases between the two model versions clearly highlights the improvement of the amount of boundary layer clouds, the improvement of the properties of high-level clouds, and the improvement of the simulated mid-level clouds in the tropics in LMDZ5B compared to LMDZ5A, due to the new convective, boundary layer, and cloud parametrizations implemented in LMDZ5B. The correlation between instantaneous cloud properties allows for a process-oriented evaluation

  19. 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. PMID:24218569

  20. Corona Discharge in Clouds

    NASA Astrophysics Data System (ADS)

    Sin'kevich, A. A.; Dovgalyuk, Yu. A.

    2014-04-01

    We present a review of the results of theoretical studies and laboratory modeling of corona discharge initiation in clouds. The influence of corona discharges on the evolution of the cloud microstructure and electrification is analyzed. It is shown that corona discharges are initiated when large-size hydrometeors approach each other, whereas in some cases, corona discharges from crystals, ice pellets, and hailstones can appear. The corona discharges lead to significant air ionization, charging of cloud particles, and separation of charges in clouds and initiate streamers and lightnings. The influence of corona discharges on changes in the phase composition of clouds is analyzed.

  1. 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.

  2. 7 CFR 926.10 - Acquire.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.10 Acquire. Acquire means to obtain cranberries by any means whatsoever for the purpose of handling cranberries....

  3. 7 CFR 926.10 - Acquire.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.10 Acquire. Acquire means to obtain cranberries by any means whatsoever for the purpose of handling cranberries....

  4. 7 CFR 926.10 - Acquire.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.10 Acquire. Acquire means to obtain cranberries by any means whatsoever for the purpose of handling cranberries....

  5. 7 CFR 926.10 - Acquire.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.10 Acquire. Acquire means to obtain cranberries by any means whatsoever for the purpose of handling cranberries....

  6. 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 ...

  7. 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),...

  8. On the Cover

    ERIC Educational Resources Information Center

    Hays, Kate F.

    2006-01-01

    This is a discussion with Judith Warren regarding her painting on the cover of the present issue of American Psychologist. To Warren, the painting on the cover of this issue, Pentimento, speaks to the interplay of spontaneity and intentionality in psychotherapy.

  9. Cloud spatial structure during the FIRE MS IFO

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.

    1990-01-01

    The fractal properties of clouds observed during the FIRE Marine Stratocumulus Intensive Field Observations (MS IFO) and their effects on the large scale radiative properties of the atmosphere are examined. This involves three states: (1) analysis of LANDSAT Thematic Mapper (TM) cloud data to determine the scaling properties associated with various cloud types; (2) simulation of fractal clouds with realistic scaling properties; and (3) computation of mean radiative properties of fractal clouds as a function of their scaling properties. Thirty-three LANDSAT scenes were acquired as part of the FIRE Marine Stratocumulus IFO in July 1987. They exhibit a wide variety of stratocumulus structures. Analysis has so far focused upon the July 7 scene, in which the NASA ER-2, the BMO C130 and the NCAR Electra repeatedly gathered data across a stratocumulus-fair weather cumulus transition.

  10. Evaluating Voxel Enabled Scalable Intersection of Large Point Clouds

    NASA Astrophysics Data System (ADS)

    Wang, J.; Lindenbergh, R.; Menenti, M.

    2015-08-01

    Laser scanning has become a well established surveying solution for obtaining 3D geo-spatial information on objects and environment. Nowadays scanners acquire up to millions of points per second which makes point cloud huge. Laser scanning is widely applied from airborne, carborne and stable platforms, resulting in point clouds obtained at different attitudes and with different extents. Working with such different large point clouds makes the determination of their overlapping area necessary but often time consuming. In this paper, a scalable point cloud intersection determination method is presented based on voxels. The method takes two overlapping point clouds as input. It consecutively resamples the input point clouds according to a preset voxel cell size. For all non-empty cells the center of gravity of the points in contains is computed. Consecutively for those centers it is checked if they are in a voxel cell of the other point cloud. The same process is repeated after interchanging the role of the two point clouds. The quality of the results is evaluated by the distance to the pints from the other data set. Also computation time and quality of the results are compared for different voxel cell sizes. The results are demonstrated on determining he intersection between an airborne and carborne laser point clouds and show that the proposed method takes 0.10%, 0.15%, 1.26% and 14.35% of computation time compared the the classic method when using cell sizes of of 10, 8, 5 and 3 meters respectively.

  11. 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.

  12. Methane Clouds on Titan

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.

    Following the Voyager encounter with Titan in 1981 Saturn's largest moon was hypothesized sport a liquid cycle similar that on Earth with clouds rain and seas. On Titan methane is the condensible playing the role that water plays on Earth. Although the presence of seas is difficult to establish from ground methane clouds have been detected on Titan. Ground-based observations reveal that Titan's clouds differ remarkedly from their terrestrial counterparts. Titan's clouds are sparse reside primarily at particular altitude and concentrate presently in the south pole. That Titan's clouds are exotic is not surprising. Titan receives ~100 times less sunlight than Earth to drive weather. In addition Titan's radiative time constant is 180 years large compared to the 3 month terrestrial value. With little power and sluggish conditions it is not clear how clouds form on Titan. This talk will compare Titan to Earth to explore the nature of clouds under Titan's foreign conditions.

  13. Clouds Over Crater Rim

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Clouds above the rim of 'Endurance Crater' in this image from NASA's Mars Exploration Rover Opportunity can remind the viewer that Mars, our celestial neighbor, is subject to weather. On Earth, clouds like these would be referred to as 'cirrus' or the aptly nicknamed 'mares' tails.' These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover's 269th martian day (Oct. 26, 2004).

    The mission's atmospheric science team is studying cloud observations to deduce seasonal and time-of-day behavior of the clouds. This helps them gain a better understanding of processes that control cloud formation.

  14. Ammonium Hydrosulfide: Coloring Jupiter's Clouds

    NASA Astrophysics Data System (ADS)

    Loeffler, Mark J.; Hudson, Reggie L.; Chanover, Nancy J.; Simon, Amy A.

    2015-11-01

    The appearance and composition of Jupiter’s Great Red Spot (GRS) have been studied for over a century, yet there still is no consensus for what is causing the GRS’s color. As the GRS is believed to originate in tropospheric clouds, it seems likely that one or more cloud components may contribute to the GRS's color. Recently, we have begun to investigate whether either ammonium hydrosulfide (NH4SH), a predicted cloud component, or its radiation-chemical products can produce color and/or an ultraviolet-visible spectrum similar to what has been observed on Jupiter via remote sensing (e.g., Simon et al., 2015). Our initial experiments relied on infrared spectroscopy to quantify the radiolytic and thermal stability of NH4SH and to identify the new chemical products formed during MeV ion irradiation (Loeffler et al., 2015). This DPS presentation will cover some of our most recent results detailing the ultraviolet-visible spectral and color changes observed during irradiation and post-irradiation warming of NH4SH ices. This work is funded by NASA’s Outer Planets and Planetary Atmospheres programs.

  15. 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.

  16. Impact of microbiological samples in the hospital management of community-acquired, nursing home-acquired and hospital-acquired pneumonia in older patients.

    PubMed

    Putot, A; Tetu, J; Perrin, S; Bailly, H; Piroth, L; Besancenot, J-F; Bonnotte, B; Chavanet, P; d'Athis, P; Charles, P-E; Sordet-Guépet, H; Manckoundia, P

    2016-03-01

    We investigated the positivity rate, the detection rates for non-covered pathogens and the therapeutic impact of microbiological samples (MS) in community-acquired pneumonia (CAP), nursing home-acquired pneumonia (NHAP) and hospital-acquired pneumonia (HAP) in elderly hospitalised patients. Patients aged 75 years and over with pneumonia and hospitalised between 1/1/2013 and 30/6/2013 in the departments of medicine (5) and intensive care (1) of our university hospital were included. Microbiological findings, intra-hospital mortality and one-year mortality were recorded. Among the 217 patients included, there were 138 CAP, 56 NHAP and 23 HAP. MS were performed in 89.9, 91.1 and 95.6 % of CAP, NHAP and HAP, respectively. Microbiological diagnosis was made for 29, 11.8 and 27.3 % of patients for CAP, NHAP and HAP, respectively (p = 0.05). Non-covered pathogens were detected for 8 % of CAP, 2 % of NHAP and 13.6 % of HAP (p = 0.1). The antimicrobial spectrum was significantly more frequently reduced when the MS were positive (46.7 % vs. 10.8 % when MS were negative, p = 10(-7)). The MS positivity rate was significantly lower in NHAP than in CAP and HAP. MS revealed non-covered pathogens in only 2 % of NHAP. These results show the poor efficiency and weak clinical impact of MS in the management of pneumonia in hospitalised older patients and suggest that their use should be rationalised. PMID:26753994

  17. Observation of cloud sytems during the African monsoon with METEOSAT

    NASA Astrophysics Data System (ADS)

    Sèze, G.; Szantai, A.; Desalmand, F.

    2003-04-01

    In the frame of the AMMA (African Monsoon Multidisciplinary Analyses) project and the related field experiments planned for 2005, satellite data are of prime importance to provide a good description of cloud systems. The simultaneous observations of low clouds associated with the monsoon flow and of cloud sytems associated with deep convection could bring useful information on the relation between these two processes. Using geostationnary satellite data, we have developed an approach allowing to classify clouds in cloud types, to study their evolution and their displacement. It is applied to METEOSAT-7 data during the JET2000 experiment ; it combines the cloud classification obtained from the LMD Dynamic Cluster Method developed by Sèze and Desbois (Sèze and Desbois, 1987; Sèze and Pawlowska, 2001), with the LMD cloud tracking method (Desalmand et al., 1999; Szantai et al., 2002). An analysis of the low cloud cover in the monsoon flow during the 10 day period of the experiment, is presented and the advantage of this combined study (cloud classification plus cloud tracking) is demonstrated. The improvements that the higher image frequency provided by the MSG (METEOSAT Second Generation) satellite will bring are illustrated with results obtained with the same kind of processing on METEOSAT-6 Rapid Scan data available over West Africa on 28 July 1999.

  18. 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

  19. Acquired immune deficiency syndrome (AIDS).

    PubMed

    1987-02-01

    The International Planned Parenthood Medical Advisory Panel has developed recommendations to assist family planning associations in playing a more active role in the prevention and control of acquired immunodeficiency syndrome (AIDS). Of primary importance is an effective program of information and education aimed at communicating the following facts: AIDS is a fatal disease for which there is no cure; AIDS is spread by sexual intercourse, contaminated blood, and contaminated needles; an infected woman can transmit AIDS to her fetus during pregnancy; a monogamous sexual relationship is the surest way to avoid AIDS infection; condom use is good protection; an infected person can look and feel well, yet still be able to transmit the AIDS virus; and AIDS is not spread by ordinary contact with an infected person. Family planning associations should include information on AIDS in all existing IEC projects, as well as develop new materials. Among the target audiences for IEC activities are family planning workers, family planning clients, and the general public including youth, teachers, parents, employers, and national leaders. Special attention should be given to high-risk groups such as homosexual and bisexual men, hemophiliacs, male and female prostitutes, clients of sexually transmitted disease clinics, people with many sexual partners, illegal users of intravenous drugs, and the sexual partners of those in any of these groups. Wide promotion of condom use is a priority activity for family planning organizations. PMID:12340977

  20. Infections Acquired in the Garden.

    PubMed

    Cunha, Cheston B; Cunha, Burke A

    2015-10-01

    Gardening is a wonderful pastime, and the garden is a very peaceful place to enjoy one's vacation. However, the garden may be a treacherous place for very young or compromised hosts when one takes into account the infectious potential residing in the soil, as well as the insect vectors on plants and animals. Even normal hosts may acquire a variety of infections from the soil, animals, or animal-related insect bites. The location of the garden, its natural animal and insect inhabitants, and the characteristics of the soil play a part in determining its infectious potential. The most important factor making the garden an infectious and dangerous place is the number and interaction of animals, whether they are pets or wild, that temporarily use the garden for part of their daily activities. The clinician should always ask about garden exposure, which will help in eliminating the diagnostic possibilities for the patient. The diagnostic approach is to use epidemiological principles in concert with clinical clues, which together should suggest a reasonable list of diagnostic possibilities. Organ involvement and specific laboratory tests help further narrow the differential diagnosis and determine the specific tests necessary to make a definitive diagnosis. PMID:26542044

  1. Associative Learning Through Acquired Salience

    PubMed Central

    Treviño, Mario

    2016-01-01

    Most associative learning studies describe the salience of stimuli as a fixed learning-rate parameter. Presumptive saliency signals, however, have also been linked to motivational and attentional processes. An interesting possibility, therefore, is that discriminative stimuli could also acquire salience as they become powerful predictors of outcomes. To explore this idea, we first characterized and extracted the learning curves from mice trained with discriminative images offering varying degrees of structural similarity. Next, we fitted a linear model of associative learning coupled to a series of mathematical representations for stimulus salience. We found that the best prediction, from the set of tested models, was one in which the visual salience depended on stimulus similarity and a non-linear function of the associative strength. Therefore, these analytic results support the idea that the net salience of a stimulus depends both on the items' effective salience and the motivational state of the subject that learns about it. Moreover, this dual salience model can explain why learning about a stimulus not only depends on the effective salience during acquisition but also on the specific learning trajectory that was used to reach this state. Our mathematical description could be instrumental for understanding aberrant salience acquisition under stressful situations and in neuropsychiatric disorders like schizophrenia, obsessive-compulsive disorder, and addiction. PMID:26793078

  2. Associative Learning Through Acquired Salience.

    PubMed

    Treviño, Mario

    2015-01-01

    Most associative learning studies describe the salience of stimuli as a fixed learning-rate parameter. Presumptive saliency signals, however, have also been linked to motivational and attentional processes. An interesting possibility, therefore, is that discriminative stimuli could also acquire salience as they become powerful predictors of outcomes. To explore this idea, we first characterized and extracted the learning curves from mice trained with discriminative images offering varying degrees of structural similarity. Next, we fitted a linear model of associative learning coupled to a series of mathematical representations for stimulus salience. We found that the best prediction, from the set of tested models, was one in which the visual salience depended on stimulus similarity and a non-linear function of the associative strength. Therefore, these analytic results support the idea that the net salience of a stimulus depends both on the items' effective salience and the motivational state of the subject that learns about it. Moreover, this dual salience model can explain why learning about a stimulus not only depends on the effective salience during acquisition but also on the specific learning trajectory that was used to reach this state. Our mathematical description could be instrumental for understanding aberrant salience acquisition under stressful situations and in neuropsychiatric disorders like schizophrenia, obsessive-compulsive disorder, and addiction. PMID:26793078

  3. The analysis of global cloud and radiation data for the study of cloud-climate interactions

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN

    1993-01-01

    During the past year, ISCCP C1 data has been analyzed for two regions, the stratocumulus area off California and the tropical Atlantic. The first part of the study dealing with stratocumulus clouds is complete and the results form the technical portion of this report. A manuscript that has recently been prepared covering this subject is attached as an Appendix. The abstract describes the key finding that cloudy mean liquid water path (LWP) is invariant with cloud fraction for cloud cover between 20% - 80%. Similar conclusions are reached with ISCCP and LANDSAT data. This has important implications for General Circulation Models. A possible application is described in the Discussion section of the Appendix. An idea that has been proposed for dealing with GCM hydrology can be used.

  4. 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.

  5. 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

  6. Land cover estimation using multiple satellite platforms during CLASIC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a part of the Department of Energy Cloud and Land Surface Interaction Campaign (CLASIC) in June 2007, the land cover/land use was characteristized over the Atmospheric Radiation Measurement Southern Great Plains Testbed in Oklahoma throughout the month long field campaign. Excessive and persiste...

  7. 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.

  8. European ISCCP sector surface and satellite retrieved cloud comparison

    NASA Astrophysics Data System (ADS)

    Drake, F.; Sèze, G.; Desbois, M.; Henderson-Sellers, A.

    A comparison between surface-observed total, low and high cloud amount and retrievals from METEOSAT radiance data made using the cluster technique of Desbois et al. has been undertaken. Observations for 12.00 GMT for the 20 day period 22nd July to 10th August 1983 were compared with retrievals made from METEOSAT radiances measured at 11.30 GMT. The comparisons for total and low cloud amount were made for 204 stations covering France, southern Britain and West Germany although high cloud amount comparisons were not possible for France, so only 114 stations were used. The location and time period were selected to coincide with one of the regions designated for the validation phase of the International Satellite Cloud Climatology Project, ISCCP. The results are generally good: for total cloud amount 30% of retrievals were fully in agreement and 64% of the differences were within +/-1 okta. As anticipated, the surface observations offered additional information oin low cloud cover in multi-layer situations. Surface observers were also found to identify thin cirrus which was not detected by the satellite retrieval and to detect small gaps in cloud decks and small clouds missed by the satellite retrieval.

  9. A diagnostic statistical cloud scheme for data assimilation purposes

    NASA Astrophysics Data System (ADS)

    Tompkins, A. M.; Janiskova, M.

    2003-04-01

    The task of assimilating cloud and rainfall information is steadily increasing in importance with a new generation of observing platforms. The inherent non-linearity of many cloud related processes exacerbates the archetypical assimilation dilemma. Overly simplistic schemes may not represent the physical cloud processes adequately for assimilation purposes. At the other extreme, many current cloud schemes used in forecast or climate models are simply too complex for the tangent linear and adjoint codes to be constructed. Even if the latter is achievable, the full schemes in forecast models often contain discrete switches and non linear processes to maximize forecast performance, but render the linear approximation invalid for perturbations of the magnitude of typical analysis increments. This may cause convergence problems over typical assimilation windows (currently 12 hours) in 4D variational assimilation (4DVAR). The existing ECMWF cloud scheme used in the assimilating model is deficient since there is no connection between diagnosed cloud cover, water/ice and precipitation generation. We thus present a new non-linear diagnostic cloud scheme for which the tangent linear and adjoint codes have been constructed. The scheme is based on prognostic humidity and temperature variables and a diagnostic assumption concerning subgrid variability is used to derive cloud water, ice and cover characteristics. Results using the new scheme are shown.

  10. 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.

  11. 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

  12. Clinicopathological associations of acquired erythroblastopenia

    PubMed Central

    Gunes, Gursel; Malkan, Umit Yavuz; Yasar, Hatime Arzu; Eliacik, Eylem; Haznedaroglu, Ibrahim Celalettin; Demiroglu, Haluk; Sayinalp, Nilgun; Aksu, Salih; Etgul, Sezgin; Aslan, Tuncay; Goker, Hakan; Ozcebe, Osman Ilhami; Buyukasik, Yahya

    2015-01-01

    Introduction: Acquired erythroblastopenia (AE) is a rare clinical situation. It is characterized by the reduction of erythroid precursors in the bone marrow together with the low reticulocyte counts in the peripheral blood. Background: Main secondary causes of AE are drugs, Parvovirus B19 and other infectious reasons, lymphoid and myeloid neoplasia, autoimmune diseases, thymoma and pregnancy. The aim of this study is to assess the frequencies and clinical associations of AE via analyzing 12340 bone marrow samples in a retrospective manner. Material and method: Bone marrow aspirations which were obtained from patients who applied to Hacettepe University Hematology Clinic between 2002 and 2013, were analyzed retrospectively. Results: Thirty four erythroblastopenia cases were found. Patients ranged in age from 16 to 80 years with a median of 38 years. Fifteen patients were men (44%) and nineteen were women (56%). In these patients, detected causes of erythroblastopenia were MDS, idiopathic pure red cell aplasia (PRCA), parvovirus infection, post chemotherapy aplasia, plasma proliferative diseases, copper deficiency due to secondary amyloidosis, fever of unknown origin, hemophagocytic syndrome, enteric fever and legionella pneumonia. We found that between those reasons the most common causes of erythroblastopenia are MDS (17.7%) and idiopathic PRCA (17.7%). Discussion: As a result, erythroblastopenia in the bone marrow may be an early sign of MDS. In those AE cases possibility of being MDS must be kept in mind as it can be mistaken for PRCA. Conclusion: To conclude, in adults MDS without excess blast is one of the most common causes of erythroblastopenia in clinical practice and in case of erythroblastopenia the presence of MDS should be investigated. PMID:26885236

  13. Surface Sampler Arm Acquiring Sample

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Operation of the surface sampler in obtaining Martian soil for Viking 2's molecular analysis experiment last Saturday (September 25) was closely monitored by one of the Lander cameras because of the precision required in trenching the small area--8 by 9 inches-surrounded by rocks. Dubbed 'Bonneville Salt Flats,' the exposure of thin crust appeared unique in contrast with surrounding materials and became a prime target for organic analysis in spite of potential hazards. Large rock in foreground is 8 inches high. At left, the sampler scoop has touched the surface, missing the rock at upper left by a comfortable 6 inches, and the backhoe has penetrated the surface about one-half inch. The scoop was then pulled back to sample the desired point and (second photo) the backhoe furrowed the surface pulling a piece of thin crust toward the spacecraft. The initial touchdown and retraction sequence was used to avoid a collision between a rock in the shadow of the arm and a plate joining the arm and scoop. The rock was cleared by 2 to 3 inches. The third picture was taken 8 minutes after the scoop touched the surface and shows that the collector head has acquired a quantity of soil. With surface sampler withdrawn (right), the foot-long trench is seen between the rocks. The trench is three inches wide and about 1 1/2 to 2 inches deep. The scoop reached to within 3 inches of the rock at far end of trench. Penetration appears to have left a cavernous opening roofed by the crust and only about one inch of undisturbed crust separates the deformed surface and the rock.

  14. Land Cover Characterization Program

    USGS Publications Warehouse

    U.S. Geological Survey

    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.

  15. 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)

  16. 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.

  17. 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

  18. Stratus Cloud Supersaturations

    NASA Astrophysics Data System (ADS)

    Noble, S.; Hudson, J. G.; Jha, V.

    2009-12-01

    Extensive aircraft measurements of cloud microphysics and complete CCN spectra from 15 flights in central California stratus clouds are presented. Cloud droplet and CCN concentrations varied over an order of magnitude in this July-August, 2008 POST project. Correlation coefficients (R) between CCN and average total cloud droplet concentrations within parcels with specific minimal liquid water contents (LWC) are shown in the table. For most LWC thresholds R is greatest for CCN concentrations at rather high supersaturations (S); i.e., 1%. The highest R for the 0.1 gm-3 are for the 300’ altitude CCN measurements but the number of cases is very small. The 0.5 g-3 R values are higher at lower S but the number of cases is also very small. The high cloud S implied by most R values goes against conventional wisdom that low stratus cloud updraft velocities limit cloud S to < 0.3%. On the other hand average droplet concentrations for most LWC thresholds match best the CCN concentrations at 0.2-0.3% S, which is more in keeping with conventional wisdom. However, these average droplet concentrations were probably reduced from adiabatic values by entrainment, which would suggest higher initial cloud S. Yum and Hudson (2002, Tellus) did report S > 1% in some maritime clouds. Further research is ongoing with this data set to substantiate stratus cloud S values. If stratus cloud S is determined to be higher than previous estimates this would imply that a much larger subset of particles (even smaller sizes) influence cloud microphysics and this would have important climate implications. As has recently been reported for small cumulus clouds (Hudson et al. 2009 JGR and Hudson and Noble 2009 GRL) negative R values were found for CCN with larger cloud droplets and drizzle drop concentrations. Correlation coefficients (R) between average droplet and CCN concentrations. 1st row (1 min)is for CCN measurements in ascents or descents closest to cloud base. 2nd row is for CCN averaged in

  19. 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

  20. Energy Aware Clouds

    NASA Astrophysics Data System (ADS)

    Orgerie, Anne-Cécile; de Assunção, Marcos Dias; Lefèvre, Laurent

    Cloud infrastructures are increasingly becoming essential components for providing Internet services. By benefiting from economies of scale, Clouds can efficiently manage and offer a virtually unlimited number of resources and can minimize the costs incurred by organizations when providing Internet services. However, as Cloud providers often rely on large data centres to sustain their business and offer the resources that users need, the energy consumed by Cloud infrastructures has become a key environmental and economical concern. This chapter presents an overview of techniques that can improve the energy efficiency of Cloud infrastructures. We propose a framework termed as Green Open Cloud, which uses energy efficient solutions for virtualized environments; the framework is validated on a reference scenario.

  1. 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

  2. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 2 2011-04-01 2011-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND... Statements of Smaller Reporting Companies § 210.8-06 Real estate operations acquired or to be acquired....

  3. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 2 2013-04-01 2013-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND...-06 Real estate operations acquired or to be acquired. If, during the period for which...

  4. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 3 2014-04-01 2014-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND...-06 Real estate operations acquired or to be acquired. If, during the period for which...

  5. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 2 2012-04-01 2012-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND...-06 Real estate operations acquired or to be acquired. If, during the period for which...

  6. 17 CFR 210.8-06 - Real estate operations acquired or to be acquired.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Real estate operations acquired or to be acquired. 210.8-06 Section 210.8-06 Commodity and Securities Exchanges SECURITIES AND... Statements of Smaller Reporting Companies § 210.8-06 Real estate operations acquired or to be acquired....

  7. 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.

  8. Clouds blown by the solar wind

    NASA Astrophysics Data System (ADS)

    Voiculescu, M.; Usoskin, I.; Condurache-Bota, S.

    2013-12-01

    In this letter we investigate possible relationships between the cloud cover (CC) and the interplanetary electric field (IEF), which is modulated by the solar wind speed and the interplanetary magnetic field. We show that CC at mid-high latitudes systematically correlates with positive IEF, which has a clear energetic input into the atmosphere, but not with negative IEF, in general agreement with predictions of the global electric circuit (GEC)-related mechanism. Thus, our results suggest that mid-high latitude clouds might be affected by the solar wind via the GEC. Since IEF responds differently to solar activity than, for instance, cosmic ray flux or solar irradiance, we also show that such a study allows distinguishing one solar-driven mechanism of cloud evolution, via the GEC, from others.

  9. High velocity clouds in nearby disk galaxies

    NASA Technical Reports Server (NTRS)

    Schulman, Eric; Bregman, Joel N.; Roberts, Morton S.; Brinks, Elias

    1993-01-01

    Clouds of neutral hydrogen in our galaxy with the absolute value of v greater than 100 km/s cover approximately 10 percent of the sky to a limiting column density of 1 x 10(exp 18) cm(exp -2). These high velocity clouds (HVCs) may dominate the kinetic energy of neutral hydrogen in non-circular motion, and are an important though poorly understood component of galactic gas. It has been suggested that the HVCs can be reproduced by a combination of three phenomena: a galactic fountain driven by disk supernovae which would account for most of the HVCs, material tidally torn from the Magellanic Clouds, and an outer arm complex which is associated with the large scale structure of the warped galactic disk. We sought to detect HVCs in external galaxies in order to test the galactic fountain model.

  10. 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.

  11. EFFECTS OF CLOUDS ON UV-B RADIATION

    EPA Science Inventory

    Data acquired in Research Triangle Park, North Carolina from a Yankee Environmental Systems UVB-1 pyranometer, an Eppley Laboratory Precession Spectral Pyranometer, and a SCI-TEC Brewer Spectrophotometer were used in conjunction with hourly cloud observations from the National We...

  12. Cloud Ozone Dust Imager (CODI)

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Dusenbery, Paul; Wolff, Michael; James, Phil; Allen, Mark; Goguen, Jay; Kahn, Ralph; Gladstone, Rany; Murphy, Jim

    1995-01-01

    pixel arrays, as partitioned on two 1024 x 1024 CCD's operated in frame transfer mode. The center of the CODI field-of-view is canted 40 deg from the zenith direction to obtain sky brightness measurements and a 20 deg surface field-of-view. Daily image observations will be conducted when the Sun is greater than or equal to 5 deg outside the edge of the CODI field-of-view, and twilight and nighttime imaging will obtained on a weekly basis. The 673 nm channel includes a polarizer wheel to obtain sky/surface polarimetry. A dust cover protects the entire lens assemblies of all four CODI channels. This opaque dust cover, which is normally opened for CODI imaging, includes a small fixed mirror and transparent window positioned above the 673 nm lens, to redirect the 673 nm field-of-view to the surface for descent imaging. Fixed pointing, internal data buffering, low operating power (2-4 W for less than or equal to 30 seconds), selective data transmission, and simple operational characteristics of the CODI experiment place minimum resource and operational demands on the Mars Surveyor 1998 lander. The CODI science goals are optimized for, but not restricted to, a low-latitude landing site (20 deg S-30 deg N). The primary CODI measurement objectives are the opacities, wave forms, particle properties (size, shape, and alignment), and heights of clouds; the opacities, particle properties, and vertical distribution of dust; and the opacity and vertical distribution of ozone. The variability of cloud, ozone, and dust opacities will be determined on diurnal, daily, and seasonal timescales. Wind velocities will be determined from cloud motions and wave characteristics; and the temporal variability of atmospheric water vapor, with limited altitude information, will be inferred from the CODI ozone observations. Secondary measurement objectives include limited descent imaging capability, surface uv-visible photometry and polarimetry, photochemistry, and meteorite infall rates.

  13. Revising a statistical cloud scheme for general circulation models

    NASA Astrophysics Data System (ADS)

    Schemann, Vera; Stevens, Bjorn; Grützun, Verena; Quaas, Johannes

    2013-04-01

    Cloud cover is an important factor for global climate simulations (e.g. for radiation). But in a global climate model with a typical resolution around 100 km clouds can not be resolved. The parameterization of cloud cover still is a major reason for uncertainties in climate change simulations. The aim of this study is to revise a statistical cloud scheme with special focus on the representation of low level clouds in the trade wind region. The development is based on the assumed PDF (probability density function) scheme of Tompkins 2002, which is part of the global climate model ECHAM6. The assumed PDF approach is based on the assumption of a certain PDF family and the determination of a certain member by further assumptions or constraints. For the scheme used in this study a beta distribution is assumed and two prognostic equations are added. Besides the original prognostic equations for a shape parameter and the distribution width, adjusted equations for the higher moments variance and skewness are introduced. This change leads to an easier physical interpretation. The source and sink terms due to the physical processes of convection, turbulence and microphysics play an important role in describing the total water PDF and with this the cloud fraction in one grid box. A better understanding of these terms and their effect on the cloud fraction and their vertical distribution is essential for the evaluation and development of the statistical cloud scheme. One known problem of the scheme is the underestimation of subgrid-scale variance of total water (Quaas 2012, Weber 2011). The aim of this study is to improve the representation of subgrid-scale variability by introducing and evaluating different source terms. For this several runs with the ECHAM6 model and modified cloud schemes are performed and analyzed. The focus is placed on the trade wind region to get a better understanding of the important processes for an improved representation of shallow cumuli

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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. PMID:26438280

  20. Chemistry and physics of a winter stratus cloud layer: A case study

    SciTech Connect

    Daum, P.H.; Kelly, T.J.; Strapp, J.W.; Leaitch, W.R.; Joe, P.; Schemenauer, R.S.; Isaac, G.A.; Anlauf, K.G.; Wiebe, H.A.

    1987-07-20

    The chemical and physical properties of a supercooled stratus cloud layer and surrounding clear air covering southern Ontario on February 20, 1984, were studied with the objectives of identifying the processes responsible for the cloud water chemical composition. The cloud layer, which extended from circa 650 to 1050 m mean sea level, was bounded by a strong temperature inversion just at cloud top. The air below this inversion was well mixed vertically, as indicated by the near independence of concentrations of various trace gas species with altitude and by conservation of number concentration of particles from the surface to cloud top, with below-cloud aerosol number concentrations (0.2cloud droplet (2cloud water, determined by comparison of interstitial and cloud water sulfate concentrations, was in the range of 85--90%, similar to the result inferred from comparison of interstitial aerosol and cloud droplet number concentrations. Gas phase equivalent concentrations of cloud water species in the below-cloud air. These results suggest that the dominant processes determining cloud water composition in this cloud layer were nucleation scavenging of sulfate aerosol and scavenging of gaseous HNO3, with no significant contribution from reactive scavenging processes. copyright American Geophysical Union 1987

  1. Evaluation of clouds and radiative fluxes in the EC-Earth general circulation model

    NASA Astrophysics Data System (ADS)

    Lacagnina, Carlo; Selten, Frank

    2014-11-01

    Observations, mostly from the International Satellite Cloud Climatology (ISCCP), are used to assess clouds and radiative fluxes in the EC-Earth general circulation model, when forced by prescribed observed sea surface temperatures. An ISCCP instrument simulator is employed to consistently compare model outputs with satellite observations. The use of a satellite simulator is shown to be imperative for model evaluation. EC-Earth exhibits the largest cloud biases in the tropics. It generally underestimates the total cloud cover but overestimates the optically thick clouds, with the net result that clouds exert an overly strong cooling effect in the model. Every cloud type has its own source of bias. The magnitude of the cooling due to the shortwave cloud radiative effect () is underestimated for the stratiform low-clouds, because the model simulates too few of them. In contrast, is overestimated for trade wind cumulus clouds, because in the model these are too thick. The clouds in the deep convection regions also lead to overestimate the . These clouds are generally too thick and there are too few mid and high thin clouds. These biases are consistent with the positive precipitation bias and the overly strong mass flux for deep convective plumes. Potential sources for the various cloud biases in the model are discussed.

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  4. 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

  5. A Global Cloud Detection Approach for Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Trepte, Q.; Minnis, P.; Palikonda, R.; Ayers, J. K.; Shan, B.; Yost, C. R.

    2014-12-01

    Geostationary satellites provide continuous cloud and meteorological observations over a fixed portion of the Earth's surface, allowing them to monitor and track the development and movement of severe storm systems in real time. For climate studies, geostationary observations provide valuable insight of cloud formation and evolution and how they influence the Earth's radiation budget. Five well-positioned geostationary satellites can cover most of the globe and their products can be merged into a uniform data set. Presently the constellation of these geostationary satellites consists of the NOAA GOES-West (135° W) and East (75° W), the EUMETSAT Meteosat-9 (9.5° E), the Chinese Feng-Yun (105° E), and the Japanese MTSAT-2 (140° E) platforms. Stitching together observations from these imagers requires an understanding of their different spectral characteristics and calibrations. This paper presents the cloud detection algorithms developed using the imager data on the five geostationary satellites. The algorithms are used operationally in NASA's Cloud and Earth's Radiant Energy System (CERES) Time and Space Averaging (TISA) gridded cloud products and for near-real-time retrievals used for weather and nowcasting applications. Examples of cloud mask results for different surface background (ocean, land, desert) and their diurnal changes will be described. Additionally, merged global cloud fractions and zonal cloud distributions are compared with CERES-MODIS, CALIPSO, and NASA LaRC AVHRR cloud fractions. Potential future improvements are discussed.

  6. 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.

  7. Effects of sensor spatial resolution on cloud properties retrieved from imagery data

    NASA Technical Reports Server (NTRS)

    Coakley, J. A., Jr.

    1986-01-01

    Techniques being applied to test the sensitivity of the physical characteristics of clouds, as determined by remote sensing, to the spatial resolution of the scans are described. The sensitivity is being evaluated with an error assessment of data from the AVHRR instrument on Nimbus-7. A spatial coherence analysis is being applied to AVHRR data for a 250 sq km region in the Pacific off the Mexican coast. Errors in the derived cloud cover and radiances from which cloud-free regions and cloud-covered regions are being estimated on the basis of radiance values in pixel-sized areas.

  8. Impact of deforestation in the Amazon basin on cloud climatology

    PubMed Central

    Wang, Jingfeng; Chagnon, Frédéric J. F.; Williams, Earle R.; Betts, Alan K.; Renno, Nilton O.; Machado, Luiz A. T.; Bisht, Gautam; Knox, Ryan; Bras, Rafael L.

    2009-01-01

    Shallow clouds are prone to appear over deforested surfaces whereas deep clouds, much less frequent than shallow clouds, favor forested surfaces. Simultaneous atmospheric soundings at forest and pasture sites during the Rondonian Boundary Layer Experiment (RBLE-3) elucidate the physical mechanisms responsible for the observed correlation between clouds and land cover. We demonstrate that the atmospheric boundary layer over the forested areas is more unstable and characterized by larger values of the convective available potential energy (CAPE) due to greater humidity than that which is found over the deforested area. The shallow convection over the deforested areas is relatively more active than the deep convection over the forested areas. This greater activity results from a stronger lifting mechanism caused by mesoscale circulations driven by deforestation-induced heterogeneities in land cover. PMID:19237571

  9. Acquired tracheoesophageal fistula in infancy and childhood.

    PubMed

    Szold, A; Udassin, R; Seror, D; Mogle, P; Godfrey, S

    1991-06-01

    Acquired tracheoesophageal fistula (TEF) is a rare entity in the pediatric age group. We report two pediatric patie