Science.gov

Sample records for clouds

  1. Search Cloud

    MedlinePlus

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

  2. 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.

  3. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... their delicate appearance, thin, feathery clouds of ice crystals called cirrus may contribute to global warming. Some scientists ... July 9, 2002 - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR ...

  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 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…

  6. Cloud Modeling

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  7. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

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

  8. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

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

  9. Complex Clouds

    Atmospheric Science Data Center

    2013-04-16

    ... title:  Multi-layer Clouds Over the South Indian Ocean     View Larger Image ... a noticeable cyclonic circulation over the Southern Indian Ocean, to the north of Enderbyland, East Antarctica. The image at left was ...

  10. Noctilucent clouds

    NASA Astrophysics Data System (ADS)

    Gadsden, M.

    An assessment of spacecraft, sounding rocket and ground level observational data on the noctilucent clouds which appear during summertime, at high latitudes, near the top of the mesosphere shows that these data are not sufficiently unambiguous and clear to permit conclusions as to the nature of the clouds. Although they seem to be ice particles nucleated at very low temperatures and pressures by either meteoric smoke or atmospheric ions, the very existence of the clouds poses the problem of how so much water vapor could be present at such a great height. An attempt is made to predict the microscopic behavior of the cloud particles through consideration of the relative importance of radiometer effects, radiation balance, Brownian movement, electric polarization, and the influence of Coulomb attraction on the growth of large clustered ions.

  11. 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

  12. 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.

  13. Gathering clouds.

    PubMed

    Conde, Crystal

    2012-01-01

    Many physicians are finding their heads in a "cloud" as they ponder adopting or upgrading an electronic health record (EHR). That doesn't mean they're not in touch with reality. It means they now can choose new web-based systems, also known as cloud-based EHRs, that allow them to pay a monthly subscription fee to access an EHR rather than purchase it. They don't have to buy an expensive server with its associated hardware and software; a computer with an Internet connection will do. PMID:22714732

  14. Gathering clouds.

    PubMed

    Conde, Crystal

    2012-01-01

    Many physicians are finding their heads in a "cloud" as they ponder adopting or upgrading an electronic health record (EHR). That doesn't mean they're not in touch with reality. It means they now can choose new web-based systems, also known as cloud-based EHRs, that allow them to pay a monthly subscription fee to access an EHR rather than purchase it. They don't have to buy an expensive server with its associated hardware and software; a computer with an Internet connection will do.

  15. 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...

  16. 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.

  17. Cloud Arcs

    Atmospheric Science Data Center

    2013-04-19

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

  18. 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.

  19. 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.)

  20. 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

  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. 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.

  3. 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.

  4. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Variations in the bimodality/monomodality of CCN spectra (Hudson et al. 2015) exert opposite effects on cloud microphysics in two aircraft field projects. The figure shows two examples, droplet concentration, Nc, and drizzle liquid water content, Ld, against classification of CCN spectral modality. Low ratings go to balanced separated bimodal spectra, high ratings go to single mode spectra, strictly monomodal 8. Intermediate ratings go merged modes, e.g., one mode a shoulder of another. Bimodality is caused by mass or hygroscopicity increases that go only to CCN that made activated cloud droplets. In the Ice in Clouds Experiment-Tropical (ICE-T) small cumuli with lower Nc, greater droplet mean diameters, MD, effective radii, re, spectral widths, σ, cloud liquid water contents, Lc, and Ld were closer to more bimodal (lower modal ratings) below cloud CCN spectra whereas clouds with higher Nc, smaller MD, re, σ, and Ld were closer to more monomodal CCN (higher modal ratings). In polluted stratus clouds of the MArine Stratus/Stratocumulus Experiment (MASE) clouds that had greater Nc, and smaller MD, re, σ, Lc, and Ld were closer to more bimodal CCN spectra whereas clouds with lower Nc, and greater MD, re, σ, Lc, and Ld were closer to more monomodal CCN. These relationships are opposite because the dominant ICE-T cloud processing was coalescence whereas chemical transformations (e.g., SO2 to SO4) were dominant in MASE. Coalescence reduces Nc and thus also CCN concentrations (NCCN) when droplets evaporate. In subsequent clouds the reduced competition increases MD and σ, which further enhance coalescence and drizzle. Chemical transformations do not change Nc but added sulfate enhances droplet and CCN solubility. Thus, lower critical supersaturation (S) CCN can produce more cloud droplets in subsequent cloud cycles, especially for the low W and effective S of stratus. The increased competition reduces MD, re, and σ, which inhibit coalescence and thus reduce drizzle

  5. 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...

  6. 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.

  7. 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.

  8. 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,

  9. New MISR Cloud Data

    Atmospheric Science Data Center

    2013-08-06

    ... are provided for 70% of clouds observed by MISR with vector RMS difference from atmospheric motion vectors from other sources ranging from ... m/s. Cloud top heights are provided for 80% of clouds with RMS differences of less than 1 km (the same as for the existing Level 2 Stereo ...

  10. Clouds in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    West, R.

    1999-01-01

    In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

  11. 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…

  12. Security in the cloud.

    PubMed

    Degaspari, John

    2011-08-01

    As more provider organizations look to the cloud computing model, they face a host of security-related questions. What are the appropriate applications for the cloud, what is the best cloud model, and what do they need to know to choose the best vendor? Hospital CIOs and security experts weigh in.

  13. 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.

  14. 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.

  15. THE CALIFORNIA MOLECULAR CLOUD

    SciTech Connect

    Lada, Charles J.; Lombardi, Marco; Alves, Joao F. E-mail: mlombard@eso.or

    2009-09-20

    We present an analysis of wide-field infrared extinction maps of a region in Perseus just north of the Taurus-Auriga dark cloud complex. From this analysis we have identified a massive, nearby, but previously unrecognized, giant molecular cloud (GMC). Both a uniform foreground star density and measurements of the cloud's velocity field from CO observations indicate that this cloud is likely a coherent structure at a single distance. From comparison of foreground star counts with Galactic models, we derive a distance of 450 +- 23 pc to the cloud. At this distance the cloud extends over roughly 80 pc and has a mass of {approx} 10{sup 5} M{sub sun}, rivaling the Orion (A) molecular cloud as the largest and most massive GMC in the solar neighborhood. Although surprisingly similar in mass and size to the more famous Orion molecular cloud (OMC) the newly recognized cloud displays significantly less star formation activity with more than an order of magnitude fewer young stellar objects than found in the OMC, suggesting that both the level of star formation and perhaps the star formation rate in this cloud are an order of magnitude or more lower than in the OMC. Analysis of extinction maps of both clouds shows that the new cloud contains only 10% the amount of high extinction (A{sub K} > 1.0 mag) material as is found in the OMC. This, in turn, suggests that the level of star formation activity and perhaps the star formation rate in these two clouds may be directly proportional to the total amount of high extinction material and presumably high density gas within them and that there might be a density threshold for star formation on the order of n(H{sub 2}) {approx} a few x 10{sup 4} cm{sup -3}.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Clouds and hazes

    NASA Astrophysics Data System (ADS)

    Knollenberg, R. G.

    1982-03-01

    Characteristics of the planetary-scale cloud and haze system on Venus are discussed. The clouds have been found to be rather tenuous, with an average visibility of about 1 km, and the main cloud deck is at an altitude of 45-70 km. Haze layers, with optical depths from about 0.1 to 1 in., overlie and underlie the main cloud deck. A multi-modal cloud particle size distribution has been obtained, corresponding to populations of aerosols varying in composition with altitude, H2SO4 droplets, and larger particles including H2SO4 droplets and possibly crystals of unknown composition. The entire cloud system has an optical depth of 20-35 at visible wavelengths, a radiometric albedo increasing from 0.77 to 0.82 from equator to pole, single scattering albedoes from 0.995 in the upper cloud region to 0.999 in the lower clouds, and striking UV absorption contrasts. Although embedded in the zonal circulation at altitudes of greatest wind velocity and vertical shear, cloud particle growth is most strongly influenced by radiative exchanges.

  1. JINR cloud infrastructure evolution

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  2. Cloud Computing: An Overview

    NASA Astrophysics Data System (ADS)

    Qian, Ling; Luo, Zhiguo; Du, Yujian; Guo, Leitao

    In order to support the maximum number of user and elastic service with the minimum resource, the Internet service provider invented the cloud computing. within a few years, emerging cloud computing has became the hottest technology. From the publication of core papers by Google since 2003 to the commercialization of Amazon EC2 in 2006, and to the service offering of AT&T Synaptic Hosting, the cloud computing has been evolved from internal IT system to public service, from cost-saving tools to revenue generator, and from ISP to telecom. This paper introduces the concept, history, pros and cons of cloud computing as well as the value chain and standardization effort.

  3. SparkClouds: visualizing trends in tag clouds.

    PubMed

    Lee, Bongshin; Riche, Nathalie Henry; Karlson, Amy K; Carpendale, Sheelash

    2010-01-01

    Tag clouds have proliferated over the web over the last decade. They provide a visual summary of a collection of texts by visually depicting the tag frequency by font size. In use, tag clouds can evolve as the associated data source changes over time. Interesting discussions around tag clouds often include a series of tag clouds and consider how they evolve over time. However, since tag clouds do not explicitly represent trends or support comparisons, the cognitive demands placed on the person for perceiving trends in multiple tag clouds are high. In this paper, we introduce SparkClouds, which integrate sparklines into a tag cloud to convey trends between multiple tag clouds. We present results from a controlled study that compares SparkClouds with two traditional trend visualizations—multiple line graphs and stacked bar charts—as well as Parallel Tag Clouds. Results show that SparkClouds ability to show trends compares favourably to the alternative visualizations.

  4. HI clouds in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kim, S.

    We present HI and Halpha surveys of the Large Magellanic Cloud (LMC) with the Australia Telescope Compact Array, the Parkes multibeam receiver, and the 16 inch optical telescope at the Siding Spring Observatory (SSO). Using a Fourier-plane technique, we have merged both ATCA and Parkes observations, providing an accurate set of images of the LMC sensitive to structure on scales of 9 pc upward. The spatial dynamic range (2.8 orders of magnitude), velocity resolution (1.649 km/sec per channel) allow for studies of phenomena ranging from the galaxy-wide interaction of the LMC with its close neighbors to the small-scale injection of energy from supernovae and stellar associations into the ISM of the LMC. On the large scale, the HI disk appears to be remarkably symmetric and to have a well-organized and orderly, if somewhat complex, rotational field. The bulk of the HI resides in a disk of 7.3 kpc in diameter. The mass of disk component of the LMC is 2.5 x10^9 M[sun ]and the mass within a radius of 4 kpc is about 3.5 x 10^9 M[sun ]. The structure of the neutral atomic ISM in the LMC is dominated by HI filaments combined with numerous shell, holes, and HI clouds. 23 HI supergiant shells and 103 giant shells are catalogued. Supergiant shells are defined as those regions whose extent is much larger than the HI scale height. The size distribution of HI shells follows a crude power law, N(log R) =AR^-1.5 . The HI clouds have been identified by defining a cloud to be an object composed of all pixels in right ascension, declination, and velocity that are connected and that lie above the threshold brightness temperature. The size spectrum of HI clouds is similar to the typical size spectrum of holes and shells in the HI distribution. The relationship between the size and the velocity dispersion of HI cloud is found to have the power law relationship so called as Larson's scaling law. A slope of the power law varies from 1.2 to 1.6. The virial masses of HI clouds range from 10

  5. Lost in Cloud

    NASA Technical Reports Server (NTRS)

    Maluf, David A.; Shetye, Sandeep D.; Chilukuri, Sri; Sturken, Ian

    2012-01-01

    Cloud computing can reduce cost significantly because businesses can share computing resources. In recent years Small and Medium Businesses (SMB) have used Cloud effectively for cost saving and for sharing IT expenses. With the success of SMBs, many perceive that the larger enterprises ought to move into Cloud environment as well. Government agency s stove-piped environments are being considered as candidates for potential use of Cloud either as an enterprise entity or pockets of small communities. Cloud Computing is the delivery of computing as a service rather than as a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network. Underneath the offered services, there exists a modern infrastructure cost of which is often spread across its services or its investors. As NASA is considered as an Enterprise class organization, like other enterprises, a shift has been occurring in perceiving its IT services as candidates for Cloud services. This paper discusses market trends in cloud computing from an enterprise angle and then addresses the topic of Cloud Computing for NASA in two possible forms. First, in the form of a public Cloud to support it as an enterprise, as well as to share it with the commercial and public at large. Second, as a private Cloud wherein the infrastructure is operated solely for NASA, whether managed internally or by a third-party and hosted internally or externally. The paper addresses the strengths and weaknesses of both paradigms of public and private Clouds, in both internally and externally operated settings. The content of the paper is from a NASA perspective but is applicable to any large enterprise with thousands of employees and contractors.

  6. 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.

  7. 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, rising above the base cloud cover, also indicate high winds and possible tornado activity.

  8. On Cloud Nine

    ERIC Educational Resources Information Center

    McCrea, Bridget; Weil, Marty

    2011-01-01

    Across the U.S., innovative collaboration practices are happening in the cloud: Sixth-graders participate in literary salons. Fourth-graders mentor kindergarteners. And teachers use virtual Post-it notes to advise students as they create their own television shows. In other words, cloud computing is no longer just used to manage administrative…

  9. Cloud Resolving Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

    One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with cloud-resolving models (CRMs). CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (with sizes ranging from about 2-200 km). CRMs also allow for explicit interaction between clouds, outgoing longwave (cooling) and incoming solar (heating) radiation, and ocean and land surface processes. Observations are required to initialize CRMs and to validate their results. This paper provides a brief discussion and review of the main characteristics of CRMs as well as some of their major applications. These include the use of CRMs to improve our understanding of: (1) convective organization, (2) cloud temperature and water vapor budgets, and convective momentum transport, (3) diurnal variation of precipitation processes, (4) radiative-convective quasi-equilibrium states, (5) cloud-chemistry interaction, (6) aerosol-precipitation interaction, and (7) improving moist processes in large-scale models. In addition, current and future developments and applications of CRMs will be presented.

  10. Weather Fundamentals: Clouds. [Videotape].

    ERIC Educational Resources Information Center

    1998

    The videos in this educational series, for grades 4-7, help students understand the science behind weather phenomena through dramatic live-action footage, vivid animated graphics, detailed weather maps, and hands-on experiments. This episode (23 minutes) discusses how clouds form, the different types of clouds, and the important role they play in…

  11. Learning in the Clouds?

    ERIC Educational Resources Information Center

    Butin, Dan W.

    2013-01-01

    Engaged learning--the type that happens outside textbooks and beyond the four walls of the classroom--moves beyond right and wrong answers to grappling with the uncertainties and contradictions of a complex world. iPhones back up to the "cloud." GoogleDocs is all about "cloud computing." Facebook is as ubiquitous as the sky.…

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

    SciTech Connect

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

    2011-07-21

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

  13. Cloud computing security.

    SciTech Connect

    Shin, Dongwan; Claycomb, William R.; Urias, Vincent E.

    2010-10-01

    Cloud computing is a paradigm rapidly being embraced by government and industry as a solution for cost-savings, scalability, and collaboration. While a multitude of applications and services are available commercially for cloud-based solutions, research in this area has yet to fully embrace the full spectrum of potential challenges facing cloud computing. This tutorial aims to provide researchers with a fundamental understanding of cloud computing, with the goals of identifying a broad range of potential research topics, and inspiring a new surge in research to address current issues. We will also discuss real implementations of research-oriented cloud computing systems for both academia and government, including configuration options, hardware issues, challenges, and solutions.

  14. Identifying Nearby Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Rathborne, J. M.; Shah, R. Y., Jackson, J. M.; Bania, T. M.; Clemens, D. P.; Johnson, A. M.; Flynn, E.; Bonaventura, N.; Simon, R.; Meyer, M. H.

    2004-12-01

    Recent molecular surveys, such as the BU-FCRAO Galactic Ring Survey, are revealing the complex structure and dynamics of clouds within the Galactic plane. Yet, difficulties often remain in separating molecular clouds along a line of sight. Identification of nearby clouds is facilitated through the combination of molecular datasets and extinction maps. Star counts at optical and infrared (IR) wavelengths indirectly trace extinction, and when morphologically similar to molecular emission, unambiguously reveal nearby clouds. Here we present the methodology and data used to separate and determine the relative distance to two molecular clouds along the same line of sight (GRSMC 45.60+0.30 and GRSMC 45.46+0.05). We use a combination of optical and near-IR star count maps (derived from the US Naval Observatory and 2MASS catalogs, respectively) and molecular data from the BU-FCRAO Galactic Ring Survey.

  15. Polarization of clouds

    NASA Astrophysics Data System (ADS)

    Goloub, Philippe; Herman, Maurice; Parol, Frederic

    1995-12-01

    This paper reports the main results concerning polarization by clouds derived from POLDER (polarization and directionality of earth's reflectances) airborne version. These results tend to confirm the high information content in the polarization (phase, altimetry). The preliminary results of EUCREX'94 (European Cloud Radiation Experiment) evidenced the drastically different polarized signatures for ice crystals and water droplets. Here we report systematic and statistically significative observations over the whole EUCREX data set. The results show that the cirrus exhibit their own signature. Preliminary observations performed during CLEOPATRA'91 (Cloud Experiment Ober Pfaffenhofen And Transport) and EUCREX'94 campaigns have shown the feasibility of cloud altimetry using spectral information (443 nm and 865 nm) of the polarized light over liquid water droplets clouds. Altimetry technique has been generalized on ASTEX-SOFIA'92 and EUCREX'94 data sets. All these results are presented and discussed in this paper.

  16. Cloud model bat algorithm.

    PubMed

    Zhou, Yongquan; Xie, Jian; Li, Liangliang; Ma, Mingzhi

    2014-01-01

    Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformation theory of cloud model to depict the qualitative concept: "bats approach their prey." Furthermore, Lévy flight mode and population information communication mechanism of bats are introduced to balance the advantage between exploration and exploitation. The simulation results show that the cloud model bat algorithm has good performance on functions optimization. PMID:24967425

  17. SMILES ice cloud products

    NASA Astrophysics Data System (ADS)

    MilláN, L.; Read, W.; Kasai, Y.; Lambert, A.; Livesey, N.; Mendrok, J.; Sagawa, H.; Sano, T.; Shiotani, M.; Wu, D. L.

    2013-06-01

    Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

  18. Prebiotic chemistry in clouds

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Marshall, John; Shen, Thomas

    1991-01-01

    The chemical evolution hypothesis of Woese (1979), according to which prebiotic reactions occurred rapidly in droplets in giant atmospheric reflux columns was criticized by Scherer (1985). This paper proposes a mechanism for prebiotic chemistry in clouds that answers Scherer's concerns and supports Woese's hypothesis. According to this mechanism, rapid prebiotic chemical evolution was facilitated on the primordial earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of meteorites, comets, and interplanetary dust, would have been scavenged by cloud drops containing clay condensation nuclei and would be polymerized within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops.

  19. Cirrus cloud retrieval using infrared sounding data: Multilevel cloud errors

    NASA Technical Reports Server (NTRS)

    Baum, Bryan A.; Wielicki, Bruce A.

    1994-01-01

    In this study we perform an error analysis for cloud-top pressure retrieval using the High-Resolution Infrared Radiometric Sounder (HIRS/2) 15-microns CO2 channels for the two-layer case of transmissive cirrus overlying an overcast, opaque stratiform cloud. This analysis includes standard deviation and bias error due to instrument noise and the presence of two cloud layers, the lower of which is opaque. Instantaneous cloud pressure retrieval errors are determined for a range of cloud amounts (0.1-1.0) and cloud-top pressures (850-250 mb). Large cloud-top pressure retrieval errors are found to occur when a lower opaque layer is present underneath an upper transmissive cloud layer in the satellite field of view (FOV). Errors tend to increase with decreasing upper-cloud effective cloud amount and with decreasing cloud height (increasing pressure). Errors in retrieved upper-cloud pressure result in corresponding errors in derived effective cloud amount. For the case in which a HIRS FOV has two distinct cloud layers, the difference between the retrieved and actual cloud-top pressure is positive in all cases, meaning that the retrieved upper-cloud height is lower than the actual upper-cloud height. In addition, errors in retrieved cloud pressure are found to depend upon the lapse rate between the low-level cloud top and the surface. We examined which sounder channel combinations would minimize the total errors in derived cirrus cloud height caused by instrument noise and by the presence of a lower-level cloud. We find that while the sounding channels that peak between 700 and 1000 mb minimize random errors, the sounding channels that peak at 300-500 mb minimize bias errors. For a cloud climatology, the bias errors are most critical.

  20. Interstellar molecular clouds

    NASA Astrophysics Data System (ADS)

    Bally, J.

    1986-04-01

    The physical properties of the molecular phase of the interstellar medium are studied with regard to star formation and the structure of the Galaxy. Most observations of molecular clouds are made with single-dish, high-surface precision radio telescopes, with the best resolution attainable at 0.2 to 1 arcmin; the smallest structures that can be resolved are of order 10 to the 17th cm in diameter. It is now believed that: (1) most of the mass of the Galaxy is in the form of giant molecular clouds; (2) the largest clouds and those responsible for most massive star formation are concentrated in spiral arms; (3) the molecular clouds are the sites of perpetual star formation, and are significant in the chemical evolution of the Galaxy; (4) giant molecular clouds determine the evolution of the kinematic properties of galactic disk stars; (5) the total gas content is diminishing with time; and (6) most clouds have supersonic internal motions and do not form stars on a free-fall time scale. It is concluded that though progress has been made, more advanced instruments are needed to inspect the processes operating within stellar nurseries and to study the distribution of the molecular clouds in more distant galaxies. Instruments presently under construction which are designed to meet these ends are presented.

  1. Community Cloud Computing

    NASA Astrophysics Data System (ADS)

    Marinos, Alexandros; Briscoe, Gerard

    Cloud Computing is rising fast, with its data centres growing at an unprecedented rate. However, this has come with concerns over privacy, efficiency at the expense of resilience, and environmental sustainability, because of the dependence on Cloud vendors such as Google, Amazon and Microsoft. Our response is an alternative model for the Cloud conceptualisation, providing a paradigm for Clouds in the community, utilising networked personal computers for liberation from the centralised vendor model. Community Cloud Computing (C3) offers an alternative architecture, created by combing the Cloud with paradigms from Grid Computing, principles from Digital Ecosystems, and sustainability from Green Computing, while remaining true to the original vision of the Internet. It is more technically challenging than Cloud Computing, having to deal with distributed computing issues, including heterogeneous nodes, varying quality of service, and additional security constraints. However, these are not insurmountable challenges, and with the need to retain control over our digital lives and the potential environmental consequences, it is a challenge we must pursue.

  2. Clouds in GEOS-5

    NASA Technical Reports Server (NTRS)

    Bacmeister, Julio; Rienecker, Michele; Suarez, Max; Norris, Peter

    2007-01-01

    The GEOS-5 atmospheric model is being developed as a weather-and-climate capable model. It must perform well in assimilation mode as well as in weather and climate simulations and forecasts and in coupled chemistry-climate simulations. In developing GEOS-5, attention has focused on the representation of moist processes. The moist physics package uses a single phase prognostic condensate and a prognostic cloud fraction. Two separate cloud types are distinguished by their source: "anvil" cloud originates in detraining convection, and large-scale cloud originates in a PDF-based condensation calculation. Ice and liquid phases for each cloud type are considered. Once created, condensate and fraction from the anvil and statistical cloud types experience the same loss processes: evaporation of condensate and fraction, auto-conversion of liquid or mixed phase condensate, sedimentation of frozen condensate, and accretion of condensate by falling precipitation. The convective parameterization scheme is the Relaxed Arakawa-Schubert, or RAS, scheme. Satellite data are used to evaluate the performance of the moist physics packages and help in their tuning. In addition, analysis of and comparisons to cloud-resolving models such as the Goddard Cumulus Ensemble model are used to help improve the PDFs used in the moist physics. The presentation will show some of our evaluations including precipitation diagnostics.

  3. Diagnosing AIRS Sampling with CloudSat Cloud Classes

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric; Yue, Qing; Guillaume, Alexandre; Kahn, Brian

    2011-01-01

    AIRS yield and sampling vary with cloud state. Careful utilization of collocated multiple satellite sensors is necessary. Profile differences between AIRS and ECMWF model analyses indicate that AIRS has high sampling and excellent accuracy for certain meteorological conditions. Cloud-dependent sampling biases may have large impact on AIRS L2 and L3 data in climate research. MBL clouds / lower tropospheric stability relationship is one example. AIRS and CloudSat reveal a reasonable climatology in the MBL cloud regime despite limited sampling in stratocumulus. Thermodynamic parameters such as EIS derived from AIRS data map these cloud conditions successfully. We are working on characterizing AIRS scenes with mixed cloud types.

  4. Cloud computing basics for librarians.

    PubMed

    Hoy, Matthew B

    2012-01-01

    "Cloud computing" is the name for the recent trend of moving software and computing resources to an online, shared-service model. This article briefly defines cloud computing, discusses different models, explores the advantages and disadvantages, and describes some of the ways cloud computing can be used in libraries. Examples of cloud services are included at the end of the article.

  5. Cloud computing basics for librarians.

    PubMed

    Hoy, Matthew B

    2012-01-01

    "Cloud computing" is the name for the recent trend of moving software and computing resources to an online, shared-service model. This article briefly defines cloud computing, discusses different models, explores the advantages and disadvantages, and describes some of the ways cloud computing can be used in libraries. Examples of cloud services are included at the end of the article. PMID:22289098

  6. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

    The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

  7. My NASA Data Clouds

    NASA Video Gallery

    This lesson has two activities that help students develop a basic understanding of the relationship between cloud type and the form of precipitation and the relationship between the amount of water...

  8. Turbulence in molecular clouds

    NASA Astrophysics Data System (ADS)

    Dickman, R. L.

    The basic aim of this paper is to offer a primer of basic concepts and methods of analysis for observationally-oriented individuals who wish to work in the rapidly developing area of molecular cloud turbulence. First the difficulties which beset early attempts to determine the nature of gas motions within molecular clouds are reviewed. Some aspects of turbulence as a hydrodynamic phenomenon are considered next along with an introduction to the statistical vocabulary of the subject which is required to understand the methods for analyzing observational data. A simple and useful approximation for estimating the velocity correlation length of a molecular cloud is also described. The paper concludes with a final perspective, which considers the extent to which size-velocity dispersion correlations can serve as a probe of chaotic velocity fields in molecular clouds.

  9. Methanol in dark clouds

    NASA Technical Reports Server (NTRS)

    Friberg, P.; Hjalmarson, A.; Madden, S. C.; Irvine, W. M.

    1988-01-01

    The first observation of methanol in cold dark clouds TMC 1, L 134 N, and B 335 is reported. In all three clouds, the relative abundance of methanol was found to be in the range of 10 to the -9th (i.e., almost an order of magnitude more abundant than acetaldehyde), with no observable variation between the clouds. Methanol emission showed a complex velocity structure; in TMC 1, clear indications of non-LTE were observed. Dimethyl ether was searched for in L 134 N; the upper limit of the column density of dimethyl ether in L 134 N was estimated to be 4 x 10 to the 12th/sq cm, assuming 5 K rotation temperature and LTE. This limit makes the abundance ratio (CH3)2O/CH3OH not higher than 1/5, indicating that dimethyl ether is not overabundant in this dark cloud.

  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. Closed Large Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Large Cell Clouds in the South Pacific     ... unperturbed by cyclonic or frontal activity. When the cell centers are cloudy and the main sinking motion is concentrated at cell ...

  12. Noctilucent Clouds in Motion

    NASA Video Gallery

    Swedish photographer Peter Rosén took this close-up, time-lapse movieof Noctilucent Clouds (NLCs) over Stockholm, Sweden on the evening ofJuly 16, 2012. "What looked like a serene view from a di...

  13. Marine cloud brightening.

    PubMed

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

    2012-09-13

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

  14. Magellanic Clouds: Stellar Populations

    NASA Astrophysics Data System (ADS)

    Mould, J.; Murdin, P.

    2000-11-01

    The Magellanic Clouds (figure 1) have long been seen as the prototypical young STELLAR POPULATION. The presence of young GLOBULAR CLUSTERS in the Clouds spoke to southern hemisphere observers of the opportunity to study close up processes which have not occurred in the Milky Way for a long time. Young globulars are also seen in other gas-rich, highly disturbed environments, such as merging galaxi...

  15. Light tunneling in clouds.

    PubMed

    Nussenzveig, H Moyses

    2003-03-20

    Solar radiation, traveling outside cloud water droplets, excites sharp resonances and surface waves by tunneling into the droplets. This effect contributes substantially to the total absorption (typically, of the order of 20%) and yields the major contribution to backscattering, producing the meteorological glory. Usual computational practices in atmospheric science misrepresent resonance contributions and cannot be relied on in the assessment of possible anomalies in cloud absorption.

  16. Mesospheric cloud formations

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1980-01-01

    Formation of mesospheric clouds as a result of deposition of large amounts of H2O by the heavy lift launch vehicle (HLLV) of the solar power satellite system is discussed. The conditions which must be met in order to form and maintain clouds near the mesopause are described. The frequency and magnitude of H2O injections from the HLLV rocket exhaust are considered.

  17. Cloud Inhomogeneity from MODIS

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cahalan, Robert F.

    2004-01-01

    Two full months (July 2003 and January 2004) of MODIS Atmosphere Level-3 data from the Terra and Aqua satellites are analyzed in order to characterize the horizontal variability of cloud optical thickness and water path at global scales. Various options to derive cloud variability parameters are discussed. The climatology of cloud inhomogeneity is built by first calculating daily parameter values at spatial scales of l degree x 1 degree, and then at zonal and global scales, followed by averaging over monthly time scales. Geographical, diurnal, and seasonal changes of inhomogeneity parameters are examined separately for the two cloud phases, and separately over land and ocean. We find that cloud inhomogeneity is weaker in summer than in winter, weaker over land than ocean for liquid clouds, weaker for local morning than local afternoon, about the same for liquid and ice clouds on a global scale, but with wider probability distribution functions (PDFs) and larger latitudinal variations for ice, and relatively insensitive to whether water path or optical thickness products are used. Typical mean values at hemispheric and global scales of the inhomogeneity parameter nu (roughly the mean over the standard deviation of water path or optical thickness), range from approximately 2.5 to 3, while for the inhomogeneity parameter chi (the ratio of the logarithmic to linear mean) from approximately 0.7 to 0.8. Values of chi for zonal averages can occasionally fall below 0.6 and for individual gridpoints below 0.5. Our results demonstrate that MODIS is capable of revealing significant fluctuations in cloud horizontal inhomogenity and stress the need to model their global radiative effect in future studies.

  18. 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.

  19. FIRE Arctic Clouds Experiment

    NASA Technical Reports Server (NTRS)

    Curry, J. A.; Hobbs, P. V.; King, M. D.; Randall, D. A.; Minnis, P.; Issac, G. A.; Pinto, J. O.; Uttal, T.; Bucholtz, A.; Cripe, D. G.; Gerber, H.; Fairall, C. W.; Garrett, T. J.; Hudson, J.; Intrieri, J. M.; Jakob, C.; Jensen, T.; Lawson, P.; Marcotte, D.; Nguyen, L.

    1998-01-01

    An overview is given of the First ISCCP Regional Experiment (FIRE) Arctic Clouds Experiment that was conducted in the Arctic during April through July, 1998. The principal goal of the field experiment was to gather the data needed to examine the impact of arctic clouds on the radiation exchange between the surface, atmosphere, and space, and to study how the surface influences the evolution of boundary layer clouds. The observations will be used to evaluate and improve climate model parameterizations of cloud and radiation processes, satellite remote sensing of cloud and surface characteristics, and understanding of cloud-radiation feedbacks in the Arctic. The experiment utilized four research aircraft that flew over surface-based observational sites in the Arctic Ocean and Barrow, Alaska. In this paper we describe the programmatic and science objectives of the project, the experimental design (including research platforms and instrumentation), conditions that were encountered during the field experiment, and some highlights of preliminary observations, modelling, and satellite remote sensing studies.

  20. FORMATION OF MASSIVE MOLECULAR CLOUD CORES BY CLOUD-CLOUD COLLISION

    SciTech Connect

    Inoue, Tsuyoshi; Fukui, Yasuo

    2013-09-10

    Recent observations of molecular clouds around rich massive star clusters including NGC 3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by cloud-cloud collision. We find that the massive molecular cloud cores have large effective Jeans mass owing to the enhancement of the magnetic field strength by shock compression and turbulence in the compressed layer. Our results predict that massive molecular cloud cores formed by the cloud-cloud collision are filamentary and threaded by magnetic fields perpendicular to the filament.

  1. First observations of tracking clouds using scanning ARM cloud radars

    SciTech Connect

    Borque, Paloma; Giangrande, Scott; Kollias, Pavlos

    2014-12-01

    Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (‘‘first echo’’). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud field and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.

  2. Bayesian Exploration of Cloud Microphysical Sensitivities in Mesoscale Cloud Systems

    NASA Astrophysics Data System (ADS)

    Posselt, D. J.

    2015-12-01

    It is well known that changes in cloud microphysical processes can have a significant effect on the structure and evolution of cloud systems. In particular, changes in water phase and the associated energy sources and sinks have a direct influence on cloud mass and precipitation, and an indirect effect on cloud system thermodynamic properties and dynamics. The details of cloud particle nucleation and growth, as well as the interactions among vapor, liquid, and ice phases, occur on scales too small to be explicitly simulated in the vast majority of numerical models. These processes are represented by approximations that introduce uncertainty into the simulation of cloud mass and spatial distribution and by extension the simulation of the cloud system itself. This presentation demonstrates how Bayesian methodologies can be used to explore the relationships between cloud microphysics and cloud content, precipitation, dynamics, and radiative transfer. Specifically, a Markov chain Monte Carlo algorithm is used to compute the probability distribution of cloud microphysical parameters consistent with particular mesoscale environments. Two different physical systems are considered. The first example explores the multivariate functional relationships between precipitation, cloud microphysics, and the environment in a deep convective cloud system. The second examines how changes in cloud microphysical parameters may affect orographic cloud structure, precipitation, and dynamics. In each case, the Bayesian framework can be shown to provide unique information on the inter-dependencies present in the physical system.

  3. Stratocumulus cloud evolution

    SciTech Connect

    Yang, X.; Rogers, D.P.; Norris, P.M.; Johnson, D.W.; Martin, G.M.

    1994-12-31

    The structure and evolution of the extra-tropical marine atmospheric boundary layer (MABL) depends largely on the variability of stratus and stratocumulus clouds. The typical boundary-layer is capped by a temperature inversion that limits exchange with the free atmosphere. Cloud-top is usually coincident with the base of the inversion. Stratus clouds are generally associated with a well-mixed MABL, whereas daytime observations of stratocumulus-topped boundary-layers indicate that the cloud and subcloud layers are often decoupled due to shortwave radiative heating of the cloud layer. In this case the surface-based mixed layer is separated from the base of the stratocumulus (Sc) by a layer that is stable to dry turbulent mixing. This is sometimes referred to as the transition layer. Often cumulus clouds (Cu) develop in the transition layer. The cumulus tops may remain below the Sc base or they may penetrate into the Sc layer and occasionally through the capping temperature inversion. While this cloud structure is characteristic of the daytime MABL, it may persist at night also. The Cu play an important role in connecting the mixed layer to the Sc layer. If the Cu are active they transport water vapor from the sea surface that maintains the Sc against the dissipating effects of shortwave heating. The Cu, however, are very sensitive to small changes in the heat and moisture in the boundary-layer and are transient features. Here the authors discuss the effect of these small Cu on the turbulent structure of the MABL.

  4. 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

  5. Microphysics of Pyrocumulonimbus Clouds

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Ackerman, Andrew S.; Fridlind, Ann

    2004-01-01

    The intense heat from forest fires can generate explosive deep convective cloud systems that inject pollutants to high altitudes. Both satellite and high-altitude aircraft measurements have documented cases in which these pyrocumulonimbus clouds inject large amounts of smoke well into the stratosphere (Fromm and Servranckx 2003; Jost et al. 2004). This smoke can remain in the stratosphere, be transported large distances, and affect lower stratospheric chemistry. In addition recent in situ measurements in pyrocumulus updrafts have shown that the high concentrations of smoke particles have significant impacts on cloud microphysical properties. Very high droplet number densities result in delayed precipitation and may enhance lightning (Andrew et al. 2004). Presumably, the smoke particles will also lead to changes in the properties of anvil cirrus produces by the deep convection, with resulting influences on cloud radiative forcing. In situ sampling near the tops of mature pyrocumulonimbus is difficult due to the high altitude and violence of the storms. In this study, we use large eddy simulations (LES) with size-resolved microphysics to elucidate physical processes in pyrocumulonimbus clouds.

  6. Orbiter cloud photopolarimeter investigation.

    PubMed

    Travis, L D; Coffeen, D L; Hansen, J E; Kawabata, K; Lacis, A A; Lane, W A; Limaye, S S; Stone, P H

    1979-02-23

    The first polarization measurements of the orbiter cloud photopolarimeter have detected a planet-wide layer of submicrometer aerosols of substantial visible optical thickness, of the order of 0.05 to 0.1, in the lower stratosphere well above the main visible sulfuric acid cloud layer. Early images show a number of features observed by Mariner 10 in 1974, including planetary scale markings that propagate around the planet in the retrograde sense at roughly 100 meters per second and bright- and dark-rimmed cells suggesting convective activity at low latitudes. The polar regions are covered by bright clouds down to latitudes aproximately 50 degrees, with both caps significantly brighter (relative to low latitudes) than the south polar cloud observed by Mariner 10. The cellular features, often organized into clusters with large horizontal scale, exist also at mid-latitudes, and include at least one case in which a cell cuts across the edge of the bright polar cloud of the northern hemisphere.

  7. Cloud condensation nucleus-sulfate mass relationship and cloud albedo

    NASA Technical Reports Server (NTRS)

    Hegg, Dean A.

    1994-01-01

    Analysis of previously published, simultaneous measurements of cloud condensation nucleus number concentration and sulfate mass concentration suggest a nonlinear relationship between the two variables. This nonlinearity reduces the sensitivity of cloud albedo to changes in the sulfur cycle.

  8. Cloud top entrainment instability and cloud top distributions

    NASA Technical Reports Server (NTRS)

    Boers, Reinout; Spinhirne, James D.

    1990-01-01

    Classical cloud-top entrainment instability condition formulation is discussed. A saturation point diagram is used to investigate the details of mixing in cases where the cloud-top entrainment instability criterion is satisfied.

  9. HNCO in molecular clouds

    SciTech Connect

    Jackson, J.M.; Armstrong, J.T.; Barrett, A.H.

    1984-05-15

    In a survey of 18 molecular clouds, HNCO J/sub K/-1K1..-->..J'/sub K/'-1K'1 = 5/sub 05/..-->..4/sub 05/ and 4/sub 04/..-->..3/sub 03/ emission was etected in seven clouds, and possibly in one other. Emission in these transitions originates in high-density regions (n> or approx. =10/sup 6/ cm/sup -3/). The molecule's excitation requirements allow us to derive limits to excitation temperatures an optical depths. We discuss the possibility of clumping with respect to the beam and compare our results with data from other molecular species. The HNCO emission from Sgr A is an ordder of magnitude larger than the other detected sources as is the ratio ..delta..T +- /sub A/(HNCO 5/sub 05/..-->..4/sub 04/)/..delta..T +- /sub A/(C/sup 18/O 1..-->..0). HNCO is probably a constituent of most molecular clouds.

  10. Winter Clouds Over Mie

    NASA Technical Reports Server (NTRS)

    2004-01-01

    12 March 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows late winter clouds over the 104 km (65 mi) diameter crater, Mie. Cellular clouds occur in the lower martian atmosphere, surrounding Mie Crater. Their cloudtops are at an altitude that is below the crater rim. Higher than the crater rim occurs a series of lee wave clouds, indicating air circulation moving from west/northwest (left) toward the east/southeast (right). Mie Crater is located in Utopia Planitia, not too far from the Viking 2 landing site, near 48.5 N, 220.4 W. Sunlight illuminates this January 2004 scene from the lower left.

  11. Ash cloud aviation advisories

    SciTech Connect

    Sullivan, T.J.; Ellis, J.S.; Schalk, W.W.; Nasstrom, J.S.

    1992-06-25

    During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet and every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast Asia, India and beyond. The low-level eruptions (< 7 km) and quasi-steady-state venting produced a plume which generally dispersed to the north and east throughout the support period. Modeling the sequence of eruptions presented a unique challenge. Although the initial approach proved viable, further refinement is necessary and possible. A distinct need exists to quantify eruptions consistently such that ``relative`` ash concentrations relate to specific aviation hazard categories.

  12. The Oort cloud

    NASA Technical Reports Server (NTRS)

    Wessman, Paul R.

    1990-01-01

    Although the outermost planet, Pluto, is 6 x 10 to the 9th km from the sun, the sun's gravitational sphere of influence extends much further, out to about 2 x 10 to the 13th km. This space is occupied by the Oort cloud, comprising 10 to the 12th-10 to the 13th cometary nuclei, formed in the primordial solar nebula. Observations and computer modeling have contributed to a detailed understanding of the structure and dynamics of the cloud, which is thought to be the source of the long-period comets and possibly comet showers.

  13. Infrared cloud radiance.

    PubMed

    Kattawar, G W; Plass, G N

    1969-06-01

    The radiance of clouds is calculated at nine wavelengths in the ir. The single scattering function is obtained by Mie theory from the measured values of the complex index of refraction and with two different drop size distributions. Multiple scattering is taken into account by a Monte Carlo technique which computes the exact three-dimensional paths of the photons. The upward and downward radiance is obtained as a function of optical thickness, angle of observation, drop size distribution, and incident solar angle. The mean optical path of the photon, the cloud albedo, and the flux at the lower and upper boundaries are also given.

  14. Opaque cloud detection

    DOEpatents

    Roskovensky, John K.

    2009-01-20

    A method of detecting clouds in a digital image comprising, for an area of the digital image, determining a reflectance value in at least three discrete electromagnetic spectrum bands, computing a first ratio of one reflectance value minus another reflectance value and the same two values added together, computing a second ratio of one reflectance value and another reflectance value, choosing one of the reflectance values, and concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.

  15. Dust clouds of Sagittarius

    NASA Astrophysics Data System (ADS)

    Malin, D. F.

    1982-03-01

    The development of knowledge of the exact nature of the dust clouds in the southern Milky Way galaxy is traced. First observation of the clouds were made by Herschel in 1784, and identification came with Barnard in 1916. The region around Barnard 86 is reviewed, noting the presence of the cluster NGC 6520 and NGC 6523, which is an area of a wide and dark dust lane backed by a blue nebulosity. Further attention is given to the blue objects NGC 6589, and NGC 6590, the Trifid nebula M20, the H II region NGC 6559 and IC 1274-5, and the six hot stars in the Sagittarius constellation.

  16. Cloud and Precipitation Radar

    NASA Astrophysics Data System (ADS)

    Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

    Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

  17. Cloud Based Applications and Platforms (Presentation)

    SciTech Connect

    Brodt-Giles, D.

    2014-05-15

    Presentation to the Cloud Computing East 2014 Conference, where we are highlighting our cloud computing strategy, describing the platforms on the cloud (including Smartgrid.gov), and defining our process for implementing cloud based applications.

  18. Real World: Global Cloud Observation Day

    NASA Video Gallery

    Learn about precipitation and how clouds are formed. Find out why scientists study clouds and how you can help NASA collect cloud observation data as part of the Students' Cloud Observation OnLine,...

  19. Relationships among cloud occurrence frequency, overlap, and effective thickness derived from CALIPSO and CloudSat merged cloud vertical profiles

    NASA Astrophysics Data System (ADS)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2010-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profiles derived from the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and cloud profiling radar. The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical profiles can be related by a cloud overlap matrix when the correlation length of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches random overlap with increasing distance separating cloud layers and that the probability of deviating from random overlap decreases exponentially with distance. One month of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat data (July 2006) support these assumptions, although the correlation length sometimes increases with separation distance when the cloud top height is large. The data also show that the correlation length depends on cloud top hight and the maximum occurs when the cloud top height is 8 to 10 km. The cloud correlation length is equivalent to the decorrelation distance introduced by Hogan and Illingworth (2000) when cloud fractions of both layers in a two-cloud layer system are the same. The simple relationships derived in this study can be used to estimate the top-of-atmosphere irradiance difference caused by cloud fraction, uppermost cloud top, and cloud thickness vertical profile differences.

  20. Active Imaging through Cirrus Clouds.

    PubMed

    Landesman, B; Kindilien, P; Pierson, R; Matson, C; Mosley, D

    1997-11-24

    The presence of clouds of ice particles in the uplink and downlink path of an illumination beam can severely impede the performance of an active imaging system. Depending on the optical depth of the cloud, i.e., its density and depth, the beam can be completely scattered and extinguished, or the beam can pass through the cloud with some fraction attenuated, scattered, and depolarized. In particular, subvisual cirrus clouds, i.e., high, thin cirrus clouds that cannot be observed from the ground, can affect the properties and alignment of both uplink and downlink beams. This paper discusses the potential for active imaging in the presence of cirrus clouds. We document field data results from an active imaging experiment conducted several years ago, which the authors believe to show the effects of cirrus clouds on an active imaging system. To verify these conclusions, we include the results of a simulation of the interaction of a coherent illumination scheme with a cirrus cloud.

  1. Cloud structure from infrared imagery.

    PubMed

    Blau, H H

    1968-10-01

    Infrared images of clouds recorded in reflected sunlight at wavelengths at which water and ice absorb will show greater structural detail than visible images, and, in principle, can provide information on cloud phase and particle size distributions.

  2. Clouding behaviour in surfactant systems.

    PubMed

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources.

  3. Clouding behaviour in surfactant systems.

    PubMed

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources. PMID:21296314

  4. Animated View of Noctilucent Cloud

    NASA Video Gallery

    Polar mesospheric clouds, as they are known to those who study them from satellite observations, are also often called "noctilucent," or night shining, clouds as seen by ground-based observers. Bec...

  5. G2 Gas Cloud Simulation

    NASA Video Gallery

    This simulation shows the future behavior of the G2 gas cloud now approaching Sgr A*, the supermassive black hole at the center of the Milky Way. X-ray emission from the cloud's tidal interaction w...

  6. Stratocumulus Clouds, eastern Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This sheet of closed-cell stratocumulus clouds was sighted in the eastern Pacific Ocean (13.5N, 141.0W) southeast of the Hawaiian Islands. This cloud sheet has a distinctive fracture zone that separates an older cloud layer (right side of scene) from a newly formed layer (left). Stratocumulus cloud sheets originate over the cold waters of the California current and migrate westward over the Pacific Ocean.

  7. Utilizing clouds for Belle II

    NASA Astrophysics Data System (ADS)

    Sobie, R. J.

    2015-12-01

    This paper describes the use of cloud computing resources for the Belle II experiment. A number of different methods are used to exploit the private and opportunistic clouds. Clouds are making significant contributions to the generation of Belle II MC data samples and it is expected that their impact will continue to grow over the coming years.

  8. A View from the Clouds

    ERIC Educational Resources Information Center

    Chudnov, Daniel

    2010-01-01

    Cloud computing is definitely a thing now, but it's not new and it's not even novel. Back when people were first learning about the Internet in the 1990s, every diagram that one saw showing how the Internet worked had a big cloud in the middle. That cloud represented the diverse links, routers, gateways, and protocols that passed traffic around in…

  9. Wind measurements in noctilucent clouds.

    PubMed

    Theon, J S; Smith, W S; McGovern, W E

    1969-05-01

    The results of eight soundings conducted from sites at high latitude during the summers of 1963 through 1965 suggest that a relation exists between the winds at the mesopause and the occurrence of noctilucent clouds. These measurements indicate that situations in which noctilucent clouds are present are associated with lower wind speeds than is the case where there are no clouds.

  10. The Basics of Cloud Computing

    ERIC Educational Resources Information Center

    Kaestner, Rich

    2012-01-01

    Most school business officials have heard the term "cloud computing" bandied about and may have some idea of what the term means. In fact, they likely already leverage a cloud-computing solution somewhere within their district. But what does cloud computing really mean? This brief article puts a bit of definition behind the term and helps one…

  11. AceCloud: Molecular Dynamics Simulations in the Cloud.

    PubMed

    Harvey, M J; De Fabritiis, G

    2015-05-26

    We present AceCloud, an on-demand service for molecular dynamics simulations. AceCloud is designed to facilitate the secure execution of large ensembles of simulations on an external cloud computing service (currently Amazon Web Services). The AceCloud client, integrated into the ACEMD molecular dynamics package, provides an easy-to-use interface that abstracts all aspects of interaction with the cloud services. This gives the user the experience that all simulations are running on their local machine, minimizing the learning curve typically associated with the transition to using high performance computing services.

  12. Training in the Clouds

    ERIC Educational Resources Information Center

    Pretlow, Cassi; Jayroe, Tina

    2010-01-01

    In this article, the authors share how cloud-based applications, such as Google Calendar, Wikidot, Google Docs, Google Sites, YouTube, and Craigslist, played a big part in the success of their plan of implementing a technology training program for customers and employees. A few years ago the Denver Public Library, where the authors work, developed…

  13. 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

  14. Invisible Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Moderate-resolution Imaging Spectroradiometer's (MODIS') cloud detection capability is so sensitive that it can detect clouds that would be indistinguishable to the human eye. This pair of images highlights MODIS' ability to detect what scientists call 'sub-visible cirrus.' The image on top shows the scene using data collected in the visible part of the electromagnetic spectrum-the part our eyes can see. Clouds are apparent in the center and lower right of the image, while the rest of the image appears to be relatively clear. However, data collected at 1.38um (lower image) show that a thick layer of previously undetected cirrus clouds obscures the entire scene. These kinds of cirrus are called 'sub-visible' because they can't be detected using only visible light. MODIS' 1.38um channel detects electromagnetic radiation in the infrared region of the spectrum. These images were made from data collected on April 4, 2000. Image courtesy Mark Gray, MODIS Atmosphere Team

  15. Clouds over Open Ocean

    NASA Technical Reports Server (NTRS)

    1981-01-01

    These cirrocumulus clouds photographed over open ocean - location unknown, seem to be in a state of agitation as in the early stages of storm development. The window frame at the top of this scene obscures almost half of the image and the panel seen in the middle of the scene is a corner of one of the payload bay closure doors.

  16. Data Products on Cloud

    NASA Technical Reports Server (NTRS)

    Ly, Vuong T.; Mandl, Daniel J.

    2014-01-01

    This presentation lays out the data processing products that exist and are planned for the Matsu cloud for Earth Observing 1. The presentation focuses on a new feature called co-registration of Earth Observing 1 with Landsat Global Land Survey chips.

  17. Methanol in dark clouds.

    PubMed

    Friberg, P; Madden, S C; Hjalmarson, A; Irvine, W M

    1988-01-01

    We report observations, for the first time, of the 2(0) - 1(0)A+ and E, 2(-1) - 1(-1) E, and 1(0) - 0(0)A+ lines of methanol (CH3OH) in three dark cold clouds, TMC1, L134N, and B335. The CH3OH emission is extended in these clouds and shows a complex velocity structure. Clear indications of non LTE excitation are observed in TMC 1. Estimated column densities are a few 10(13) cm-2. Although less abundant than formaldehyde (H2CO), methanol is almost an order of magnitude more abundant than acetaldehyde (CH3CHO), in these clouds. Dimethyl ether was searched for in L134N, to an upper limit of 4 10(12) cm-2 (3 sigma). Implications for dark cloud excitation and chemistry are discussed. A new, more accurate, rest frequency 96741.39(0.01) MHz is determined for the 2(0) - 1(0) A+ E line of methanol.

  18. Interstellar molecular clouds.

    PubMed

    Bally, J

    1986-04-11

    The interstellar medium in our galaxy contains matter in a variety of states ranging from hot plasma to cold and dusty molecular gas. The molecular phase consists of giant clouds, which are the largest gravitationally bound objects in the galaxy, the primary reservoir of material for the ongoing birth of new stars, and the medium regulating the evolution of galactic disks.

  19. Seeding the Cloud

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2013-01-01

    For any institution looking to shift enterprise resource planning (ERP) systems to the cloud, big savings can be achieved--but only if the school has properly prepped "before" negotiations begin. These three steps can help: (1) Mop up the mess first; (2) Understand the true costs for services; and (3) Calculate the cost of transition.

  20. Living under a Cloud.

    ERIC Educational Resources Information Center

    Gursky, Daniel

    1991-01-01

    This article examines the efforts of three high school teachers at Richland High School in Richland (Washington) to change the school logo from a mushroom cloud, the symbol for a nuclear explosion. Opposition to these teachers' efforts has come from school administrators and fellow teachers, students, alumnae, and community residents. (IAH)

  1. Data in the Cloud

    ERIC Educational Resources Information Center

    Bull, Glen; Garofalo, Joe

    2010-01-01

    The ability to move from one representation of data to another is one of the key characteristics of expert mathematicians and scientists. Cloud computing will offer more opportunities to create and display multiple representations of data, making this skill even more important in the future. The advent of the Internet led to widespread…

  2. Computing in the Clouds

    ERIC Educational Resources Information Center

    Johnson, Doug

    2010-01-01

    Web-based applications offer teachers, students, and school districts a convenient way to accomplish a wide range of tasks, from accounting to word processing, for free. Cloud computing has the potential to offer staff and students better services at a lower cost than the technology deployment models they're using now. Saving money and improving…

  3. Ice clouds over Fairbanks, Alaska

    NASA Astrophysics Data System (ADS)

    Kayetha, Vinay Kumar

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

  4. Prebiotic chemistry in clouds.

    PubMed

    Oberbeck, V R; Marshall, J; Shen, T

    1991-01-01

    In the traditional concept for the origin of life as proposed by Oparin and Haldane in the 1920s, prebiotic reactants became slowly concentrated in the primordial oceans and life evolved slowly from a series of highly protracted chemical reactions during the first billion years of Earth's history. However, chemical evolution may not have occurred continuously because planetesimals and asteroids impacted the Earth many times during the first billion years, may have sterilized the Earth, and required the process to start over. A rapid process of chemical evolution may have been required in order that life appeared at or before 3.5 billion years ago. Thus, a setting favoring rapid chemical evolution may be required. A chemical evolution hypothesis set forth by Woese in 1979 accomplished prebiotic reactions rapidly in droplets in giant atmospheric reflux columns. However, in 1985 Scherer raised a number of objections to Woese's hypothesis and concluded that it was not valid. We propose a mechanism for prebiotic chemistry in clouds that satisfies Scherer's concerns regarding the Woese hypothesis and includes advantageous droplet chemistry. Prebiotic reactants were supplied to the atmosphere by comets, meteorites, and interplanetary dust or synthesized in the atmosphere from simple compounds using energy sources such as ultraviolet light, corona discharge, or lightning. These prebiotic monomers would have first encountered moisture in cloud drops and precipitation. We propose that rapid prebiotic chemical evolution was facilitated on the primordial Earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by , or synthesized during entry of, meteorites, comets, and interplanetary dust would have been scavenged by cloud drops containing clay condensation nuclei. Polymerization would have occurred within cloud systems during cycles of condensation, freezing, melting, and

  5. 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.

  6. First observations of tracking clouds using scanning ARM cloud radars

    DOE PAGES

    Borque, Paloma; Giangrande, Scott; Kollias, Pavlos

    2014-12-01

    Tracking clouds using scanning cloud radars can help to document the temporal evolution of cloud properties well before large drop formation (‘‘first echo’’). These measurements complement cloud and precipitation tracking using geostationary satellites and weather radars. Here, two-dimensional (2-D) Along-Wind Range Height Indicator (AW-RHI) observations of a population of shallow cumuli (with and without precipitation) from the 35-GHz scanning ARM cloud radar (SACR) at the DOE Atmospheric Radiation Measurements (ARM) program Southern Great Plains (SGP) site are presented. Observations from the ARM SGP network of scanning precipitation radars are used to provide the larger scale context of the cloud fieldmore » and to highlight the advantages of the SACR to detect the numerous, small, non-precipitating cloud elements. A new Cloud Identification and Tracking Algorithm (CITA) is developed to track cloud elements. In CITA, a cloud element is identified as a region having a contiguous set of pixels exceeding a preset reflectivity and size threshold. The high temporal resolution of the SACR 2-D observations (30 sec) allows for an area superposition criteria algorithm to match cloud elements at consecutive times. Following CITA, the temporal evolution of cloud element properties (number, size, and maximum reflectivity) is presented. The vast majority of the designated elements during this cumulus event were short-lived non-precipitating clouds having an apparent life cycle shorter than 15 minutes. The advantages and disadvantages of cloud tracking using an SACR are discussed.« less

  7. Overlap Properties of Clouds Generated by a Cloud Resolving Model

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Khairoutdinov, M.

    2002-01-01

    In order for General Circulation Models (GCMs), one of our most important tools to predict future climate, to correctly describe the propagation of solar and thermal radiation through the cloudy atmosphere a realistic description of the vertical distribution of cloud amount is needed. Actually, one needs not only the cloud amounts at different levels of the atmosphere, but also how these cloud amounts are related, in other words, how they overlap. Currently GCMs make some idealized assumptions about cloud overlap, for example that contiguous cloud layers overlap maximally and non-contiguous cloud layers overlap in a random fashion. Since there are difficulties in obtaining the vertical profile of cloud amount from observations, the realism of the overlap assumptions made in GCMs has not been yet rigorously investigated. Recently however, cloud observations from a relatively new type of ground radar have been used to examine the vertical distribution of cloudiness. These observations suggest that the GCM overlap assumptions are dubious. Our study uses cloud fields from sophisticated models dedicated to simulate cloud formation, maintenance, and dissipation called Cloud Resolving Models . These models are generally considered capable of producing realistic three-dimensional representation of cloudiness. Using numerous cloud fields produced by such a CRM we show that the degree of overlap between cloud layers is a function of their separation distance, and is in general described by a combination of the maximum and random overlap assumption, with random overlap dominating as separation distances increase. We show that it is possible to parameterize this behavior in a way that can eventually be incorporated in GCMs. Our results seem to have a significant resemblance to the results from the radar observations despite the completely different nature of the datasets. This consistency is encouraging and will promote development of new radiative transfer codes that will

  8. Formation of giant molecular clouds in global spiral structures: The role of orbital dynamics and cloud-cloud collisions

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.; Stewart, G. R.

    1987-01-01

    The different roles played by orbital dynamics and dissipative cloud-cloud collisions in the formation of giant molecular clouds (GMCs) in a global spiral structure are investigated. The interstellar medium (ISM) is simulated by a system of particles, representing clouds, which orbit in a spiral-perturbed, galactic gravitational field. The overall magnitude and width of the global cloud density distribution in spiral arms is very similar in the collisional and collisionless simulations. The results suggest that the assumed number density and size distribution of clouds and the details of individual cloud-cloud collisions have relatively little effect on these features. Dissipative cloud-cloud collisions play an important steadying role for the cloud system's global spiral structure. Dissipative cloud-cloud collisions also damp the relative velocity dispersion of clouds in massive associations and thereby aid in the effective assembling of GMC-like complexes.

  9. Alpine cloud climatology: regional effects

    NASA Astrophysics Data System (ADS)

    Kaestner, Martina; Kriebel, Karl T.

    1996-12-01

    The present understanding of moist atmospheric processes and the role of clouds in the hydrologic cycle shows severe gaps of knowledge. Water vapor plays an essential part in atmospheric dynamics. For example, the release of large amounts of latent heat, due to the condensation in convective clouds, plays an important role in the general circulation. Knowledge of the distribution of clouds and its transport is essential to understand atmospheric dynamics. Clouds can have a positive as well as a negative contribution to the greenhouse effect. A cloud cover climatology in a 15 km grid resolution has been retrieved by means of the APOLLO algorithm using the 5 calibrated AVHRR channels. The monthly means of total cloud cover are about 15 percent too high compared to conventional data, the standard deviation is +/- 12 percent. The high resolution cloud cover maps show topometeorological features like 'Fohn' on single days but not in monthly means, because these events are too rare. But increased cloud cover in the luff regions are detected in monthly means as well as some cloud sparse regions like Lake Garda, Ticino or the Swiss Rhone valley. The different annual cycles of cloud cover show the different climatic regions, which are temperate, Alpine, and Mediterranean climate. This is indicated, for example, by the remarkably smaller cloud cover in the Alpine region in winter as compared to the northern and southern forelands.

  10. Fractal statistics of cloud fields

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Joseph, Joachim H.

    1989-01-01

    Landsat Multispectral Scanner (MSS) and Thematic Mapper (TM) data, with 80 and 30 m spatial resolution, respectively, have been employed to study the spatial structure of boundary-layer and intertropical convergence zone (ITCZ) clouds. The probability distributions of cloud areas and cloud perimeters are found to approximately follow a power-law, with a different power (i.e., fractal dimension) for each cloud type. They are better approximated by a double power-law behavior, indicating a change in the fractal dimension at a characteristic size which depends upon cloud type. The fractal dimension also changes with threshold. The more intense cloud areas are found to have a higher perimeter fractal dimension, perhaps indicative of the increased turbulence at cloud top. A detailed picture of the inhomogeneous spatial structure of various cloud types will contribute to a better understanding of basic cloud processes, and also has implications for the remote sensing of clouds, for their effects on remote sensing of other parameters, and for the parameterization of clouds in general circulation models, all of which rely upon plane-parallel radiative transfer algorithms.

  11. Scientific Workflows in the Cloud

    NASA Astrophysics Data System (ADS)

    Juve, Gideon; Deelman, Ewa

    The development of cloud computing has generated significant interest in the scientific computing community. In this chapter we consider the impact of cloud computing on scientific workflow applications. We examine the benefits and drawbacks of cloud computing for workflows, and argue that the primary benefit of cloud computing is not the economic model it promotes, but rather the technologies it employs and how they enable new features for workflow applications. We describe how clouds can be configured to execute workflow tasks and present a case study that examines the performance and cost of three typical workflow applications on Amazon EC2. Finally, we identify several areas in which existing clouds can be improved and discuss the future of workflows in the cloud.

  12. Aircraft measurements of wave clouds

    NASA Astrophysics Data System (ADS)

    Cui, Z.; Blyth, A. M.; Bower, K. N.; Crosier, J.; Choularton, T.

    2012-10-01

    In this paper, aircraft measurements are presented of liquid phase (ice-free) wave clouds made at temperatures greater than -5°C that formed over Scotland, UK. The horizontal variations of the vertical velocity across wave clouds display a distinct pattern. The maximum updraughts occur at the upshear flanks of the clouds and the strong downdraughts at the downshear flanks. The cloud droplet concentrations were a couple of hundreds per cubic centimetres, and the drops generally had a mean diameter between 15-45 μm. A small proportion of the drops were drizzle. The measurements presented here and in previous recent studies suggest a different interaction of dynamics and microphysics in wave clouds from the accepted model. The results in this paper provide a case for future numerical simulation of wave cloud and the interaction between wave and cloud.

  13. Aircraft measurements of wave cloud

    NASA Astrophysics Data System (ADS)

    Cui, Z.; Blyth, A. M.; Bower, K. N.; Crosier, J.; Choularton, T.

    2012-05-01

    In this paper, aircraft measurements are presented of liquid phase (ice-free) wave clouds made at temperatures greater than -5 °C that formed over Scotland, UK. The horizontal variations of the vertical velocity across wave clouds display a distinct pattern. The maximum updraughts occur at the upshear flanks of the clouds and the strong downdraughts at the downshear flanks. The cloud droplet concentrations were a couple of hundreds per cubic centimetres, and the drops generally had a mean diameter between 15-45 μm. A small proportion of the drops were drizzle. A new definition of a mountain-wave cloud is given, based on the measurements presented here and previous studies. The results in this paper provide a case for future numerical simulation of wave cloud and the interaction between wave and clouds.

  14. 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

  15. Cloud optical parameters as derived from the multispectral cloud radiometer

    NASA Technical Reports Server (NTRS)

    Nakajima, Teruyuki; King, Michael D.

    1990-01-01

    Simultaneous measurements of the liquid water content and particle size have assumed an important role in cloud physics as they help elucidate the mechanism of cloud particle formation and the mechanism of air mass-mixing in stratus clouds. Such measurements can reveal the modification of cloud air masses by anthropogenic aerosol particles (Coakley et al. 1987, Durkee 1989). Studies of the climatic impact of these modification processes on cloud microphysics seems to be urgent for understanding mechanisms of climate change. General Circulation Model (GCM) simulations can be improved by introducing a parameterization of cloud optical properties in terms of integrated liquid water content (liquid water path) and particle size (Slingo 1989). Motivated by the above mentioned circumstances, remote sensing techniques were developed for simultaneously retrieving the cloud optical thickness and effective particle radius, from which the liquid water path can be inferred. Statistical features of the cloud optical thickness (or liquid water path) and effective particle size for marine stratocumulus clouds are presented. These results were obtained during 4 days (7, 10, 13, and 16 July 1987) of observations with the Multispectral Cloud Radiometer (ER-2) and the Thematic Mapper (LANDSAT-5) during the First ISCCP Regional Experiment (FIRE).

  16. Cloud and Cloud Shadow Masking Using Multi-Temporal Cloud Masking Algorithm in Tropical Environmental

    NASA Astrophysics Data System (ADS)

    Candra, D. S.; Phinn, S.; Scarth, P.

    2016-06-01

    A cloud masking approach based on multi-temporal satellite images is proposed. The basic idea of this approach is to detect cloud and cloud shadow by using the difference reflectance values between clear pixels and cloud and cloud shadow contaminated pixels. Several bands of satellite image which have big difference values are selected for developing Multi-temporal Cloud Masking (MCM) algorithm. Some experimental analyses are conducted by using Landsat-8 images. Band 3 and band 4 are selected because they can distinguish between cloud and non cloud. Afterwards, band 5 and band 6 are used to distinguish between cloud shadow and clear. The results show that the MCM algorithm can detect cloud and cloud shadow appropriately. Moreover, qualitative and quantitative assessments are conducted using visual inspections and confusion matrix, respectively, to evaluate the reliability of this algorithm. Comparison between this algorithm and QA band are conducted to prove the reliability of the approach. The results show that MCM better than QA band and the accuracy of the results are very high.

  17. Cloud-Vegetation Interaction: Use of Normalized Difference Cloud Index for Estimation of Cloud Optical Thickness

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Knyazikhint, Y.; Davis, A.; Wiscombe, W.; Pilewskie, P.

    1999-01-01

    A new technique to retrieve cloud optical depth for broken clouds above green vegetation using ground-based zenith radiance measurements is developed. By analogy with the Normalized Difference Vegetation Index NDVI), the Normalized Difference Cloud Index (NDCI) is defined as a ratio between the difference and the sum of two zenith radiances measured for two narrow spectral bands in the visible and near-IR regions. The very different spectral behavior of cloud liquid water drops and green vegetation is the key physics behind the NDCI. It provides extra tools to remove the radiative effects of the 3D cloud structure. Numerical calculations based on fractal clouds and real measurements of NDCI and cloud liquid water path confirm the improvements.

  18. IBM Cloud Computing Powering a Smarter Planet

    NASA Astrophysics Data System (ADS)

    Zhu, Jinzy; Fang, Xing; Guo, Zhe; Niu, Meng Hua; Cao, Fan; Yue, Shuang; Liu, Qin Yu

    With increasing need for intelligent systems supporting the world's businesses, Cloud Computing has emerged as a dominant trend to provide a dynamic infrastructure to make such intelligence possible. The article introduced how to build a smarter planet with cloud computing technology. First, it introduced why we need cloud, and the evolution of cloud technology. Secondly, it analyzed the value of cloud computing and how to apply cloud technology. Finally, it predicted the future of cloud in the smarter planet.

  19. Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The smaller of two nearby companions of the Milky Way Galaxy that can be seen with the naked eye in the southern hemisphere sky and which are named after the Portuguese navigator, Ferdinand Magellan. Located in the constellation of Tucana, at a distance of about 190 000 light-years, the Small Magellanic Cloud (SMC) has an angular diameter of about three degrees, about half the apparent diameter o...

  20. Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The larger of two nearby companions of the Milky Way Galaxy that can be seen with the naked eye in the southern hemisphere sky and which are named after the Portuguese navigator, Ferdinand Magellan, who observed them in 1519 during his circumnavigation of the world. Located in the constellation of Dorado, at a distance of about 170 000 light-years, the Large Magellanic Cloud (LMC) has an overall ...

  1. Positron clouds within thunderstorms

    NASA Astrophysics Data System (ADS)

    Dwyer, Joseph R.; Smith, David M.; Hazelton, Bryna J.; Grefenstette, Brian W.; Kelley, Nicole A.; Lowell, Alexander W.; Schaal, Meagan M.; Rassoul, Hamid K.

    2015-08-01

    We report the observation of two isolated clouds of positrons inside an active thunderstorm. These observations were made by the Airborne Detector for Energetic Lightning Emissions (ADELE), an array of six gamma-ray detectors, which flew on a Gulfstream V jet aircraft through the top of an active thunderstorm in August 2009. ADELE recorded two 511 keV gamma-ray count rate enhancements, 35 s apart, each lasting approximately 0.2 s. The enhancements, which were approximately a factor of 12 above background, were both accompanied by electrical activity as measured by a flat-plate antenna on the underside of the aircraft. The energy spectra were consistent with a source mostly composed of positron annihilation gamma rays, with a prominent 511 keV line clearly visible in the data. Model fits to the data suggest that the aircraft was briefly immersed in clouds of positrons, more than a kilometre across. It is not clear how the positron clouds were created within the thunderstorm, but it is possible they were caused by the presence of the aircraft in the electrified environment.

  2. Chemistry and microphysics of polar stratospheric clouds and cirrus clouds.

    PubMed

    Zondlo, M A; Hudson, P K; Prenni, A J; Tolbert, M A

    2000-01-01

    Ice particles found within polar stratospheric clouds (PSCs) and upper tropospheric cirrus clouds can dramatically impact the chemistry and climate of the Earth's atmosphere. The formation of PSCs and the subsequent chemical reactions that occur on their surfaces are key components of the massive ozone hole observed each spring over Antarctica. Cirrus clouds also provide surfaces for heterogeneous reactions and significantly modify the Earth's climate by changing the visible and infrared radiation fluxes. Although the role of ice particles in climate and chemistry is well recognized, the exact mechanisms of cloud formation are still unknown, and thus it is difficult to predict how anthropogenic activities will change cloud abundances in the future. This article focuses on the nucleation, chemistry, and microphysical properties of ice particles composing PSCs and cirrus clouds. A general overview of the current state of research is presented along with some unresolved issues facing scientists in the future.

  3. cloud supersaturations and CCN spectra

    NASA Astrophysics Data System (ADS)

    Hudson, James; Noble, Stephen

    2014-05-01

    Multiple regression analysis predictions of low altitude cloud droplet concentrations based on measured CCN spectra compared much better with measured low altitude droplet concentrations than various CCN concentrations at single supersaturations (S) in two aircraft cumulus cloud projects, RICO and ICE-T. The addition of vertical velocity (W) to the single and multiple regressions showed small improvements. For RICO the multiple regression correlations were also superior to previous adiabatic model predictions of droplet concentrations also based on CCN spectra and mean W. More adiabatic cloud parcels showed only slightly better correlations than flight-averaged droplet concentrations. Results show the value of more extensive CCN spectra and the relative unimportance of W variations for determining droplet concentrations in these Caribbean cumuli. The fact that flight-averaged droplet concentrations of all low cloud data was almost as well correlated with CCN spectra as were droplet concentrations of more adiabatic cloud parcels indicates that entrainment did not significantly perturb CCN-droplet concentration relationships. As should be expected higher cloud S were determined for the cumulus clouds than for stratus clouds. Suppression of cloud S by higher CCN concentrations that had previously been observed in stratus was observed in ICE-T but not in RICO where the CCN range may have been too low for cloud S suppression. But ICE-T and a stratus project, POST, even showed this S suppression over the same limited maritime CCN range as RICO.

  4. ATLAS Cloud R&D

    NASA Astrophysics Data System (ADS)

    Panitkin, Sergey; Barreiro Megino, Fernando; Caballero Bejar, Jose; Benjamin, Doug; Di Girolamo, Alessandro; Gable, Ian; Hendrix, Val; Hover, John; Kucharczyk, Katarzyna; Medrano Llamas, Ramon; Love, Peter; Ohman, Henrik; Paterson, Michael; Sobie, Randall; Taylor, Ryan; Walker, Rodney; Zaytsev, Alexander; Atlas Collaboration

    2014-06-01

    The computing model of the ATLAS experiment was designed around the concept of grid computing and, since the start of data taking, this model has proven very successful. However, new cloud computing technologies bring attractive features to improve the operations and elasticity of scientific distributed computing. ATLAS sees grid and cloud computing as complementary technologies that will coexist at different levels of resource abstraction, and two years ago created an R&D working group to investigate the different integration scenarios. The ATLAS Cloud Computing R&D has been able to demonstrate the feasibility of offloading work from grid to cloud sites and, as of today, is able to integrate transparently various cloud resources into the PanDA workload management system. The ATLAS Cloud Computing R&D is operating various PanDA queues on private and public resources and has provided several hundred thousand CPU days to the experiment. As a result, the ATLAS Cloud Computing R&D group has gained a significant insight into the cloud computing landscape and has identified points that still need to be addressed in order to fully utilize this technology. This contribution will explain the cloud integration models that are being evaluated and will discuss ATLAS' learning during the collaboration with leading commercial and academic cloud providers.

  5. The cloud albedo-cloud droplet effective radius relationship for clean and polluted clouds from RACE and FIRE.ACE

    NASA Astrophysics Data System (ADS)

    Peng, Yiran; Lohmann, Ulrike; Leaitch, Richard; Banic, Catharine; Couture, Mark

    2002-06-01

    Twenty-eight liquid water cloud cases selected from two field studies (the Canadian Radiation, Aerosol and Cloud Experiment (RACE) and the First ISCCP Regional Experiment-Arctic Cloud Experiment (FIRE.ACE)) are analyzed with respect to the first and second indirect aerosol effects and the relationship between cloud droplet effective radius and cloud albedo for clean and polluted clouds. For the same liquid water path the polluted clouds have more and smaller cloud droplets and thus a higher cloud albedo and less drizzle size drops. The effective radius is positively correlated with cloud albedo for polluted clouds caused by the absence of drizzle size drops. Conversely effective radius is negatively correlated with cloud albedo for clean clouds.

  6. Military clouds: utilization of cloud computing systems at the battlefield

    NASA Astrophysics Data System (ADS)

    Süleyman, Sarıkürk; Volkan, Karaca; İbrahim, Kocaman; Ahmet, Şirzai

    2012-05-01

    Cloud computing is known as a novel information technology (IT) concept, which involves facilitated and rapid access to networks, servers, data saving media, applications and services via Internet with minimum hardware requirements. Use of information systems and technologies at the battlefield is not new. Information superiority is a force multiplier and is crucial to mission success. Recent advances in information systems and technologies provide new means to decision makers and users in order to gain information superiority. These developments in information technologies lead to a new term, which is known as network centric capability. Similar to network centric capable systems, cloud computing systems are operational today. In the near future extensive use of military clouds at the battlefield is predicted. Integrating cloud computing logic to network centric applications will increase the flexibility, cost-effectiveness, efficiency and accessibility of network-centric capabilities. In this paper, cloud computing and network centric capability concepts are defined. Some commercial cloud computing products and applications are mentioned. Network centric capable applications are covered. Cloud computing supported battlefield applications are analyzed. The effects of cloud computing systems on network centric capability and on the information domain in future warfare are discussed. Battlefield opportunities and novelties which might be introduced to network centric capability by cloud computing systems are researched. The role of military clouds in future warfare is proposed in this paper. It was concluded that military clouds will be indispensible components of the future battlefield. Military clouds have the potential of improving network centric capabilities, increasing situational awareness at the battlefield and facilitating the settlement of information superiority.

  7. CLOUD PARAMETERIZATIONS, CLOUD PHYSICS, AND THEIR CONNECTIONS: AN OVERVIEW.

    SciTech Connect

    LIU,Y.; DAUM,P.H.; CHAI,S.K.; LIU,F.

    2002-02-12

    This paper consists of three parts. The first part is concerned with the parameterization of cloud microphysics in climate models. We demonstrate the crucial importance of spectral dispersion of the cloud droplet size distribution in determining radiative properties of clouds (e.g., effective radius), and underline the necessity of specifying spectral dispersion in the parameterization of cloud microphysics. It is argued that the inclusion of spectral dispersion makes the issue of cloud parameterization essentially equivalent to that of the droplet size distribution function, bringing cloud parameterization to the forefront of cloud physics. The second part is concerned with theoretical investigations into the spectral shape of droplet size distributions in cloud physics. After briefly reviewing the mainstream theories (including entrainment and mixing theories, and stochastic theories), we discuss their deficiencies and the need for a paradigm shift from reductionist approaches to systems approaches. A systems theory that has recently been formulated by utilizing ideas from statistical physics and information theory is discussed, along with the major results derived from it. It is shown that the systems formalism not only easily explains many puzzles that have been frustrating the mainstream theories, but also reveals such new phenomena as scale-dependence of cloud droplet size distributions. The third part is concerned with the potential applications of the systems theory to the specification of spectral dispersion in terms of predictable variables and scale-dependence under different fluctuating environments.

  8. TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

    SciTech Connect

    Gao, Yang; Law, Chung K.; Xu, Haitao

    2015-02-01

    The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the turbulence, such as in molecular clouds, the turbulence decays with an energy dissipation time comparable to the dynamic timescale of clouds, which could change the size limits obtained from Jean's criterion by assuming constant turbulence intensities. Here we adopt scaling relations of physical variables in decaying turbulence to analyze its specific effects on the formation of stars. We find that the decay of turbulence provides an additional approach for Jeans' criterion to be achieved, after which gravitational infall governs the motion of the cloud core. This epoch of turbulence decay is defined as cloud core relaxation. The existence of cloud core relaxation provides a more complete understanding of the effect of the competition between turbulence and gravity on the dynamics of molecular cloud cores and star formation.

  9. Exoplanet Clouds in the Laboratory

    NASA Astrophysics Data System (ADS)

    Johnson, Alexandria; Cziczo, Daniel J.; Seager, Sara; Charbonneau, David; Bauer, Amy J. R.

    2015-12-01

    The lack of strong spectral features of some exoplanet atmospheres may suggest the presence of a cloud layer and poses great challenges for atmospheric characterization. We aim to address these observations and the challenges by leveraging lab-based terrestrial cloud particle instrumentation as a means of investigating how particles representative of those in exoplanet atmospheres interact with incoming radiation. In the end we hope to achieve two goals - First, to better understand the observable properties of cloud particles in exoplanet atmospheres. Second, to determine how these clouds might directly limit our ability to observe and characterize the atmosphere below.In this presentation I will discuss the cloud chamber used for this work, how we leverage terrestrial based cloud knowledge, our initial investigation of the light scattered by ammonium nitrate (NH4NO3) across temperature and relative humidity dependent phase changes, and future work with suspected exoplanet atmospheric condensates under various atmospheric compositions, pressures, and temperatures.

  10. Study of Cloud Droplet Radius and Cloud Optical Thickness in "Warm" Clouds Using Satellite Data

    NASA Astrophysics Data System (ADS)

    Grigoras, Cristinel; Stefan, Sabina

    2014-05-01

    The present study is focused on the analysis of the cloud microphysical properties using two very important parameters which characterize the liquid water clouds: the cloud droplet radius and the cloud optical thickness. It is known that the knowledge of the variations of these parameters can provide valuable information on most microphysical processes in clouds. Therefore, the correlation between these parameters has been carefully considered. Satellite data from the MODIS 06 system has been analyzed first, for four years time span (2008-2011) and then for the summer's months of the years 2010 and 2011. The data collected from three stations was used to analyze the dependence between the two parameters: a continental station (in Magurele, Ilfov, lat 44.34, lon 26.03), a coastal station (Eforie Nord, Constanta, lat 44.07,lon 28.63) and a maritime station (Gloria, lat 44.6, lon 29.36), all from Romania. The relationship between the cloud droplet radii and the cloud optical thicknesses obtained processing satellite data for the four years between 2008 and 2011 shows a good correlation (correlation coefficient 0.54). The ensuing relationship between the two parameters could be used for cloud microphysics studies. The analysis of dependence between cloud droplet radii and cloud optical thickness from satellite data during summer confirms the presence of their positive correlation. But contrary of the expectations, the analysis shows very small differences between the results found out for the three different locations.

  11. Evaluation of Passive Multilayer Cloud Detection Using Preliminary CloudSat and CALIPSO Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.

    2006-12-01

    During the last few years, several algorithms have been developed to detect and retrieve multilayered clouds using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as cloud radars and lidars that can "see" through different layers of clouds. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and CloudSat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated cloud radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The Clouds and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping cloud systems and to retrieve the cloud liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES cloud retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing cloud retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice clouds. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary CloudSat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water clouds in overlapped conditions.

  12. Biogeography, Cloud Base Heights and Cloud Immersion in Tropical Montane Cloud Forests

    NASA Astrophysics Data System (ADS)

    Welch, R. M.; Asefi, S.; Zeng, J.; Nair, U. S.; Lawton, R. O.; Ray, D. K.; Han, Q.; Manoharan, V. S.

    2007-05-01

    Tropical Montane Cloud Forests (TMCFs) are ecosystems characterized by frequent and prolonged immersion within orographic clouds. TMCFs often lie at the core of the biological hotspots, areas of high biodiversity, whose conservation is necessary to ensure the preservation of a significant amount of the plant and animal species in the world. TMCFs support islands of endemism dependent on cloud water interception that are extremely susceptible to environmental and climatic changes at regional or global scales. Due to the ecological and hydrological importance of TMCFs it is important to understand the biogeographical distribution of these ecosystems. The best current list of TMCFs is a global atlas compiled by the United Nations Environmental Program (UNEP). However, this list is incomplete, and it does not provide information on cloud immersion, which is the defining characteristic of TMCFs and sorely needed for ecological and hydrological studies. The present study utilizes MODIS satellite data both to determine orographic cloud base heights and then to quantify cloud immersion statistics over TMCFs. Results are validated from surface measurements over Northern Costa Rica for the month of March 2003. Cloud base heights are retrieved with approximately 80m accuracy, as determined at Monteverde, Costa Rica. Cloud immersion derived from MODIS data is also compared to an independent cloud immersion dataset created using a combination of GOES satellite data and RAMS model simulations. Comparison against known locations of cloud forests in Northern Costa Rica shows that the MODIS-derived cloud immersion maps successfully identify these cloud forest locations, including those not included in the UNEP data set. Results also will be shown for cloud immersion in Hawaii. The procedure appears to be ready for global mapping.

  13. Evaluation of Passive Multilayer Cloud Detection Using Preliminary CloudSat and CALIPSO Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Minnis, P.; Sun-Mack, S.; Chang, F.; Huang, J.; Nguyen, L.; Ayers, J. K.; Spangenberg, D. A.; Yi, Y.; Trepte, C. R.

    2005-05-01

    During the last few years, several algorithms have been developed to detect and retrieve multilayered clouds using passive satellite data. Assessing these techniques has been difficult due to the need for active sensors such as cloud radars and lidars that can "see" through different layers of clouds. Such sensors have been available only at a few surface sites and on aircraft during field programs. With the launch of the CALIPSO and CloudSat satellites on April 28, 2006, it is now possible to observe multilayered systems all over the globe using collocated cloud radar and lidar data. As part of the A- Train, these new active sensors are also matched in time ad space with passive measurements from the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer - EOS (AMSR-E). The Clouds and the Earth's Radiant Energy System (CERES) has been developing and testing algorithms to detect ice-over-water overlapping cloud systems and to retrieve the cloud liquid path (LWP) and ice water path (IWP) for those systems. One technique uses a combination of the CERES cloud retrieval algorithm applied to MODIS data and a microwave retrieval method applied to AMSR-E data. The combination of a CO2-slicing cloud retireval technique with the CERES algorithms applied to MODIS data (Chang et al., 2005) is used to detect and analyze such overlapped systems that contain thin ice clouds. A third technique uses brightness temperature differences and the CERES algorithms to detect similar overlapped methods. This paper uses preliminary CloudSat and CALIPSO data to begin a global scale assessment of these different methods. The long-term goals are to assess and refine the algorithms to aid the development of an optimal combination of the techniques to better monitor ice 9and liquid water clouds in overlapped conditions.

  14. Particle cloud mixing in microgravity

    NASA Technical Reports Server (NTRS)

    Ross, H.; Facca, L.; Tangirala, V.; Berlad, A. L.

    1989-01-01

    Quasi-steady flame propagation through clouds of combustible particles requires quasi-steady transport properties and quasi-steady particle number density. Microgravity conditions may be employed to help achieve the conditions of quiescent, uniform clouds needed for such combustion studies. Joint experimental and theoretical NASA-UCSD studies were concerned with the use of acoustic, electrostatic, and other methods of dispersion of fuel particulates. Results of these studies are presented for particle clouds in long cylindrical tubes.

  15. Shape of fair weather clouds.

    PubMed

    Wang, Yong; Zocchi, Giovanni

    2010-03-19

    We introduce a model which accounts for the shape of cumulus clouds exclusively in terms of thermal plumes or thermals. The plumes are explicitly represented by a simple potential flow generated by singularities (sources and sinks) and are thus laminar, but with their motion create a field which supports the cloud. We compare this model with actual clouds by means of various shape descriptors including the fractal dimension, and find agreement.

  16. Jupiter's Clouds: Structure and Composition.

    PubMed

    Lewis, J S; Prinn, R G

    1970-07-31

    Recent infrared radiometric observations of Jupiter have disclosed local temperatures in the North Equatorial Belt far in excess of those at the level of the solid ammonia clouds, and visual observations reveal an orange-brown coloration within this belt. We suggest that, in a multilayer cloud model, solar ultraviolet photolysis of hydrogen sulfide in regions where ammonia clouds are sparse or absent should lead to the production of substantial quantities of inorganic chromophores.

  17. Cloud droplet size distributions in low-level stratiform clouds

    SciTech Connect

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

    2000-01-15

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

  18. Cloud supersaturations and Hoppel minima

    NASA Astrophysics Data System (ADS)

    Noble, Stephen; Hudson, James G.

    2013-05-01

    CCN spectral measurements in four aircraft research projects often showed bimodal distributions of which the Hoppel minima can be used to infer cloud supersaturations (S)—effective S (Seff). These direct critical S (Sc) measurements are superior to differential mobility analyzer (DMA) Seff estimates because they do not need composition information and have more channel resolution. These Seff are higher than Seff obtained by matching CCN spectra with droplet concentrations (Nc). These differences can help determine whether the easier evaporation of polluted cloud droplets can increase cloud turbulence and thus reduce cloud thickness, extent, and liquid water content and thus essentially mitigate the indirect aerosol effect (IAE).

  19. Empirical data from Oort's cloud

    NASA Technical Reports Server (NTRS)

    Desemme, A. H.

    1985-01-01

    Empirical evidence on the size and origin of the Oort cloud of comets is compared with theories on the origin of the Oort cloud. Data on the binding energy of the very long period comets indicate that the Oort cloud is five times smaller than previously thought and that the mean velocity perturbation introduced by stellar passages is smaller than Oort believed. The bimodal brightness distribution of 'new' comets indicates that their formation mechanism is straightforward accretion without later fragmentation. Data on retrograde versus prograde orbits and their relevance to the rotation of the Oort cloud are examined. Models of the solar nebula are discussed in the light of the foregoing evidence.

  20. On the surface of clouds

    SciTech Connect

    Malinowski, S.P.; Zawadzki, I. )

    1993-01-01

    The cloud-environment mixing process is considered in terms of fractal properties of the cloud-clear air interface. The fractal dimension of the cloud surface is estimated from high-resolution airborne data. The value obtained is D = 2.55 in a range of scales from at least 10 m to over 1,000 m with the possibility of even greater extension. This differs significantly from values obtained in shear-generated, well-developed, and homogeneous turbulence. This distribution of filament sizes of cloudy and clear air and estimates of the cloud surface and characteristic time of mixing process are given. 22 refs., 5 figs., 2 tabs.

  1. 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.

  2. Using cloud computing infrastructure with CloudBioLinux, CloudMan, and Galaxy.

    PubMed

    Afgan, Enis; Chapman, Brad; Jadan, Margita; Franke, Vedran; Taylor, James

    2012-06-01

    Cloud computing has revolutionized availability and access to computing and storage resources, making it possible to provision a large computational infrastructure with only a few clicks in a Web browser. However, those resources are typically provided in the form of low-level infrastructure components that need to be procured and configured before use. In this unit, we demonstrate how to utilize cloud computing resources to perform open-ended bioinformatic analyses, with fully automated management of the underlying cloud infrastructure. By combining three projects, CloudBioLinux, CloudMan, and Galaxy, into a cohesive unit, we have enabled researchers to gain access to more than 100 preconfigured bioinformatics tools and gigabytes of reference genomes on top of the flexible cloud computing infrastructure. The protocol demonstrates how to set up the available infrastructure and how to use the tools via a graphical desktop interface, a parallel command-line interface, and the Web-based Galaxy interface.

  3. 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.

  4. Alterations of Cloud Microphysics Due to Cloud Processed CCN

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    High-resolution CCN spectra have revealed bimodality (Hudson et al. 2015) similar to aerosol size spectra (e.g., Hoppel et al. 1985). Bimodality is caused by chemical and physical cloud processes that increase mass or hygroscopicity of only CCN that produced activated cloud droplets. Bimodality is categorized by relative CCN concentrations (NCCN) within the two modes, Nu-Np; i.e., NCCN within the higher critical supersaturation, Sc, mode that did not undergo cloud processing minus NCCN within the lower Sc mode that was cloud processed. Lower, especially negative, Nu-Np designates greater processing. The table shows regressions between Nu-Np and characteristics of clouds nearest the CCN measurements. ICE-T MASE parameter R SL R SL Nc 0.17 93.24 -0.26 98.65 MD -0.31 99.69 0.33 99.78 σ -0.27 99.04 0.48 100.00 Ld -0.31 99.61 0.38 99.96 Table. Correlation coefficients, R, and one-tailed significance levels in percent, SL, for Nu-Np with microphysics of the clouds closest to each CCN measurement, 75 ICE-T and 74 MASE cases. Nc is cloud droplet concentration, MD is cloud droplet mean diameter, σ is standard deviation of cloud droplet spectra, Ldis drizzle drop LWC. Two aircraft field campaigns, Ice in Clouds Experiment-Tropical (ICE-T) and Marine Stratus/Stratocumulus Experiment (MASE) show opposite R signs because coalescence dominated cloud processing in low altitude ICE-T cumuli whereas chemical transformations predominated in MASE low altitude polluted stratus. Coalescence reduces Nc and NCCN, which thus increases MD, and σ, which promote Ld. Chemical transformations, e.g., SO2 to SO4, increase CCN hygroscopicity, thus reducing Sc, but not affecting Nc or NCCN. Lower Sc CCN are capable of producing greater Nc in subsequent cloud cycles, which leads to lower MD and σ which reduce Ld (figure). These observations are consistent with cloud droplet growth models for the higher vertical wind (W) of cumuli and lower W of stratus. Coalescence thus reduces the indirect

  5. CloudSat View of Flossie

    NASA Video Gallery

    CloudSat passed directly over Tropical Storm Flossie on July 29 and showed cumulus and stratocumulus clouds in northern Hawaii and cumulonimbus clouds over the southern part. Large amounts of liqui...

  6. MISR Level 3 Albedo and Cloud Versioning

    Atmospheric Science Data Center

    2016-09-07

    ... MIL3YALN MISR_AM1_CGAL Stage 2:  CLOUD - Wind Vectors, Height Histogram Stage 1:  ALBEDO - Expansive, ... Stage 2 CLOUD - Height Histogram Stage 1 CLOUD - Wind Vectors Stage 1 ALBEDO - Expansive and Restrictive Albedos ...

  7. Chemical evolution of molecular clouds

    NASA Technical Reports Server (NTRS)

    Prasad, Sheo S.; Tarafdar, Sankar P.; Villere, Karen R.; Huntress, Wesley T., Jr.

    1987-01-01

    The principles behind the coupled chemical-dynamical evolution of molecular clouds are described. Particular attention is given to current problems involving the simplest species (i.e., C. CO, O2, and H2) in quiescent clouds. The results of a comparison made between the molecular abundances in the Orion ridge and the hot core (Blake, 1986) are presented.

  8. Venus clouds: structure and composition.

    PubMed

    Young, A T

    1974-02-01

    The clouds of Venus consist of a fine sulfuric acid aerosol similar to that found in the earth's stratosphere. The acid aerosol on Venus appears to be uniformly mixed with the gas, at least in the visible layers, and possibly down to the cloud base.

  9. Temperature measurements in noctilucent clouds.

    PubMed

    Theon, J S; Nordberg, W; Smith, W S

    1967-07-28

    Results of ten rocket soundings conducted from Kronogard, Sweden, and Barrow, Alaska, during the summers of 1963 through 1965 indicate that a temperature of 150 degrees K or less is a necessary but not sufficient condition for the existence of noctilucent clouds. Water vapor appears to be a critical ingredient in the occurrence of these clouds.

  10. Venus clouds: test for hydrocarbons.

    PubMed

    Plummer, W T

    1969-03-14

    Infrared reflection spectra of hydrocarbon clouds and frosts now give a critical test of Velikovsky's prediction that Venus is surrounded by a dense envelope of hydrocarbon clouds and dusts. Venus does not exhibit an absorption feature near 2.4 microns, although such a feature is prominent in every hydrocarbon spectrum observed.

  11. Time lapse photography of clouds.

    PubMed

    Schaefer, V J

    1970-08-01

    The equipment and procedures used in preparing more than 15,240 m of 16-mm time lapse movies of atmospheric clouds is described. Such photographic records are of great value in establishing a dynamic cloud census of a specific area. Operational techniques, the support diagrams, and the optimum time intervals in use for different types of records are presented.

  12. A Tale of Two Clouds

    ERIC Educational Resources Information Center

    Gray, Terry

    2010-01-01

    The University of Washington (UW) adopted a dual-provider cloud-computing strategy, focusing initially on software as a service. The original project--to replace an obsolete alumni e-mail system--resulted in a cloud solution that soon grew to encompass the entire campus community. The policies and contract terms UW developed, focusing on…

  13. Climate Effects of Cloud Modified CCN-Cloud Interactions

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Cloud condensation nuclei (CCN) play an important role in the climate system through the indirect aerosol effect (IAE). IAE is one of the least understood aspects of the climate system as many cloud processes are complicated. Many studies of aerosol-cloud interaction involve CCN interaction with cloud droplet concentrations (Nc), cloud microphysics, and radiative properties. However, fewer studies investigate how cloud processes modify CCN. Upon evaporation from non-precipitating clouds, CCN distributions develop bimodal shaped distributions (Hoppel et al. 1986). Activated CCN participate in cloud processing that is either chemical: aqueous oxidation; or physical: Brownian scavenging, collision and coalescence. Chemical processing does not change CCN concentration (NCCN) but reduces critical supersaturations (Sc; larger size) (Feingold and Kreidenweis, 2000) while physical processing reduces NCCN and Sc. These processes create the minima in the bimodal CCN distributions (Hudson et al., 2015). Updraft velocity (W) and NCCN are major factors on how these modified CCN distributions affect clouds. Panel a shows two nearby CCN distributions in the MArine Stratus/stratocumulus Experiment (MASE), which have similar concentrations, but the bimodal one (red) has been modified by cloud processing. In a simplified cloud droplet model, the modified CCN then produces higher Nc (panel b) and smaller droplet mean diameters (MD; panel c) when compared to the unmodified CCN (black) for W lower than 50 cm/s. The better CCN (lower Sc) increase competition among droplets reducing MD and droplet distribution spread (σ) which acts to reduce drizzle. Competition is created by limited available condensate due to lower S created by the low W (<50 cm/s) typical of stratus. The increased Nc of the modified CCN in stratus then increases IAE in the climate system. At higher W (>50 cm/s) typical of cumuli, Ncis reduced and MD is increased from the modified CCN distribution (panels b & c). Here

  14. The latitudinal distribution of clouds on Titan.

    PubMed

    Rannou, P; Montmessin, F; Hourdin, F; Lebonnois, S

    2006-01-13

    Clouds have been observed recently on Titan, through the thick haze, using near-infrared spectroscopy and images near the south pole and in temperate regions near 40 degrees S. Recent telescope and Cassini orbiter observations are now providing an insight into cloud climatology. To study clouds, we have developed a general circulation model of Titan that includes cloud microphysics. We identify and explain the formation of several types of ethane and methane clouds, including south polar clouds and sporadic clouds in temperate regions and especially at 40 degrees in the summer hemisphere. The locations, frequencies, and composition of these cloud types are essentially explained by the large-scale circulation.

  15. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David OC.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric; Khvorostyanov, Vitaly; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction (Browning et al, 1994). The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  16. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction. The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  17. Physical conditions in molecular clouds

    NASA Technical Reports Server (NTRS)

    Evans, Neal J., II

    1989-01-01

    Recent developments have complicated the picture of the physical conditions in molecular clouds. The discoveries of widespread emission from high-J lines of CD and 12-micron IRAS emission have revealed the presence of considerably hotter gas and dust near the surfaces of molecular clouds. These components can complicate interpretation of the bulk of the cloud gas. Commonly assumed relations between column density or mean density and cloud size are called into question by conflicting results and by consideration of selection effects. Analysis of density and density structure through molecular excitation has shown that very high densities exist in star formation regions, but unresolved structure and possible chemical effects complicate the interpretation. High resolution far-IR and submillimeter observations offer a complementary approach and are beginning to test theoretical predictions of density gradients in clouds.

  18. Cloud regimes as phase transitions

    NASA Astrophysics Data System (ADS)

    Stechmann, Samuel N.; Hottovy, Scott

    2016-06-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.

  19. Trusted computing strengthens cloud authentication.

    PubMed

    Ghazizadeh, Eghbal; Zamani, Mazdak; Ab Manan, Jamalul-lail; Alizadeh, Mojtaba

    2014-01-01

    Cloud computing is a new generation of technology which is designed to provide the commercial necessities, solve the IT management issues, and run the appropriate applications. Another entry on the list of cloud functions which has been handled internally is Identity Access Management (IAM). Companies encounter IAM as security challenges while adopting more technologies became apparent. Trust Multi-tenancy and trusted computing based on a Trusted Platform Module (TPM) are great technologies for solving the trust and security concerns in the cloud identity environment. Single sign-on (SSO) and OpenID have been released to solve security and privacy problems for cloud identity. This paper proposes the use of trusted computing, Federated Identity Management, and OpenID Web SSO to solve identity theft in the cloud. Besides, this proposed model has been simulated in .Net environment. Security analyzing, simulation, and BLP confidential model are three ways to evaluate and analyze our proposed model. PMID:24701149

  20. Trusted Computing Strengthens Cloud Authentication

    PubMed Central

    2014-01-01

    Cloud computing is a new generation of technology which is designed to provide the commercial necessities, solve the IT management issues, and run the appropriate applications. Another entry on the list of cloud functions which has been handled internally is Identity Access Management (IAM). Companies encounter IAM as security challenges while adopting more technologies became apparent. Trust Multi-tenancy and trusted computing based on a Trusted Platform Module (TPM) are great technologies for solving the trust and security concerns in the cloud identity environment. Single sign-on (SSO) and OpenID have been released to solve security and privacy problems for cloud identity. This paper proposes the use of trusted computing, Federated Identity Management, and OpenID Web SSO to solve identity theft in the cloud. Besides, this proposed model has been simulated in .Net environment. Security analyzing, simulation, and BLP confidential model are three ways to evaluate and analyze our proposed model. PMID:24701149

  1. Trusted computing strengthens cloud authentication.

    PubMed

    Ghazizadeh, Eghbal; Zamani, Mazdak; Ab Manan, Jamalul-lail; Alizadeh, Mojtaba

    2014-01-01

    Cloud computing is a new generation of technology which is designed to provide the commercial necessities, solve the IT management issues, and run the appropriate applications. Another entry on the list of cloud functions which has been handled internally is Identity Access Management (IAM). Companies encounter IAM as security challenges while adopting more technologies became apparent. Trust Multi-tenancy and trusted computing based on a Trusted Platform Module (TPM) are great technologies for solving the trust and security concerns in the cloud identity environment. Single sign-on (SSO) and OpenID have been released to solve security and privacy problems for cloud identity. This paper proposes the use of trusted computing, Federated Identity Management, and OpenID Web SSO to solve identity theft in the cloud. Besides, this proposed model has been simulated in .Net environment. Security analyzing, simulation, and BLP confidential model are three ways to evaluate and analyze our proposed model.

  2. Analysis of cloud polarization measurements

    NASA Technical Reports Server (NTRS)

    Hansen, J. E.; Coffeen, D. L.

    1975-01-01

    The polarization of sunlight reflected by various cloud types was measured in the near-infrared with a polarimeter flown aboard the NASA Convair 990. The data reduction has been completed and detailed comparisons have been made between the observations and theoretical computations. The analysis presented shows that the polarization in the near-infrared can be used on a routine basis to reliably yield the cloud particle phase (water or ice) and the average particle size in the top part of water clouds (usually within + or - 25%). In some cases the polarization also yields the cloud optical thickness (or a lower limit) and a measure of the width of the particle size distribution in the top of the water clouds.

  3. Tropical deep convective cloud morphology

    NASA Astrophysics Data System (ADS)

    Igel, Matthew R.

    A cloud-object partitioning algorithm is developed. It takes contiguous CloudSat cloudy regions and identifies various length scales of deep convective clouds from a tropical, oceanic subset of data. The methodology identifies a level above which anvil characteristics become important by analyzing the cloud object shape. Below this level in what is termed the pedestal region, convective cores are identified based on reflectivity maxima. Identifying these regions allows for the assessment of length scales of the anvil and pedestal of the deep convective clouds. Cloud objects are also appended with certain environmental quantities from the ECMWF reanalysis. Simple geospatial and temporal assessments show that the cloud object technique agrees with standard observations of local frequency of deep-convective cloudiness. Additionally, the nature of cloud volume scale populations is investigated. Deep convection is seen to exhibit power-law scaling. It is suggested that this scaling has implications for the continuous, scale invariant, and random nature of the physics controlling tropical deep convection and therefore on the potentially unphysical nature of contemporary convective parameterizations. Deep-convective clouds over tropical oceans play important roles in Earth's climate system. The response of tropical, deep convective clouds to sea surface temperatures (SSTs) is investigated using this new data set. Several previously proposed feedbacks are examined: the FAT hypothesis, the Iris hypothesis, and the Thermostat hypothesis. When the data are analyzed per cloud object, each hypothesis is broadly found to correctly predict cloud behavior in nature, although it appears that the FAT hypothesis needs a slight modification to allow for cooling cloud top temperatures with increasing SSTs. A new response that shows that the base temperature of deep convective anvils remains approximately constant with increasing SSTs is introduced. These cloud-climate feedbacks are

  4. EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

    NASA Astrophysics Data System (ADS)

    Falkovich, Gregory; Malinowski, Szymon P.

    2008-07-01

    Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping

  5. Cloud microphysical background for the Israel-4 cloud seeding experiment

    NASA Astrophysics Data System (ADS)

    Freud, Eyal; Koussevitzky, Hagai; Goren, Tom; Rosenfeld, Daniel

    2015-05-01

    The modest amount of rainfall in Israel occurs in winter storms that bring convective clouds from the Mediterranean Sea when the cold post frontal air interacts with its relatively warm surface. These clouds were seeded in the Israel-1 and Israel-2 cloud glaciogenic seeding experiments, which have shown statistically significant positive effect of added rainfall of at least 13% in northern Israel, whereas the Israel-3 experiment showed no added rainfall in the south. This was followed by operational seeding in the north since 1975. The lack of physical evidence for the causes of the positive effects in the north caused a lack of confidence in the statistical results and led to the Israel-4 randomized seeding experiment in northern Israel. This experiment started in the winter of 2013/14. The main difference from the previous experiments is the focus on the orographic clouds in the catchment of the Sea of Galilee. The decision to commence the experiment was partially based on evidence supporting the existence of seeding potential, which is reported here. Aircraft and satellite microphysical and dynamic measurements of the clouds document the critical roles of aerosols, especially sea spray, on cloud microstructure and precipitation forming processes. It was found that the convective clouds over sea and coastal areas are naturally seeded hygroscopically by sea spray and develop precipitation efficiently. The diminution of the large sea spray aerosols farther inland along with the increase in aerosol concentrations causes the clouds to develop precipitation more slowly. The short time available for the precipitation forming processes in super-cooled orographic clouds over the Golan Heights farthest inland represents the best glaciogenic seeding potential.

  6. 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.

  7. Mesoscale cloud phenomena observed by LANDSAT

    NASA Technical Reports Server (NTRS)

    Ormsby, J. P.

    1977-01-01

    Examples of certain mesoscale cloud features - jet cirrus, eddies/vortices, cloud banding, and wave clouds - were collected from LANDSAT imagery and placed into Mason's four groups of causes of cloud formation based on the mechanism of vertical motion which produces condensation. These groups are as follows: (1) layer clouds formed by widespread regular ascent; (2) layer clouds caused by irregular stirring motions; (3) convective clouds; and (4) clouds formed by orographic disturbances. These mechanisms explain general cloud formation. Once formed, other forces may play a role in the deformation of a cloud or cloud mass into unusual and unique meso- and microscale patterns. Each example presented is followed by a brief discussion describing the synoptic situation, and some inference into the formation and occurrence of the more salient features. No major attempt was made to discuss in detail the meteorological and topographic interplay producing these mesoscale features.

  8. 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

  9. Clouds Near Mie Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-572, 12 December 2003

    Mie Crater, a large basin formed by asteroid or comet impact in Utopia Planitia, lies at the center of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image. The crater is approximately 104 km (65 mi) across. To the east and southeast (toward the lower right) of Mie, in this 5 December 2003 view, are clouds of dust and water ice kicked up by local dust storm activity. It is mid-winter in the northern hemisphere of Mars, a time when passing storms are common on the northern plains of the red planet. Sunlight illuminates this image from the lower left; Mie Crater is located at 48.5oN, 220.3oW. Viking 2 landed west/southwest of Mie Crater, off the left edge of this image, in September 1976.

  10. Relation of Cloud Occurrence Frequency, Overlap, and Effective Thickness Derived from CALIPSO and CloudSat Merged Cloud Vertical Profiles

    NASA Technical Reports Server (NTRS)

    Kato, Seiji; Sun-Mack, Sunny; Miller, Walter F.; Rose, Fred G.; Chen, Yan; Minnis, Patrick; Wielicki, Bruce A.

    2009-01-01

    A cloud frequency of occurrence matrix is generated using merged cloud vertical profile derived from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR). The matrix contains vertical profiles of cloud occurrence frequency as a function of the uppermost cloud top. It is shown that the cloud fraction and uppermost cloud top vertical pro les can be related by a set of equations when the correlation distance of cloud occurrence, which is interpreted as an effective cloud thickness, is introduced. The underlying assumption in establishing the above relation is that cloud overlap approaches the random overlap with increasing distance separating cloud layers and that the probability of deviating from the random overlap decreases exponentially with distance. One month of CALIPSO and CloudSat data support these assumptions. However, the correlation distance sometimes becomes large, which might be an indication of precipitation. The cloud correlation distance is equivalent to the de-correlation distance introduced by Hogan and Illingworth [2000] when cloud fractions of both layers in a two-cloud layer system are the same.

  11. Statistical analysis of an LES shallow cumulus cloud ensemble using a cloud tracking algorithm

    NASA Astrophysics Data System (ADS)

    Dawe, J. T.; Austin, P. H.

    2012-01-01

    A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on an LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rates display moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

  12. Statistical analysis of a LES shallow cumulus cloud ensemble using a cloud tracking algorithm

    NASA Astrophysics Data System (ADS)

    Dawe, J. T.; Austin, P. H.

    2011-08-01

    A technique for the tracking of individual clouds in a Large Eddy Simulation (LES) is presented. We use this technique on a LES of a shallow cumulus cloud field based upon the Barbados Oceanographic and Meteorological Experiment (BOMEX) to calculate statistics of cloud height, lifetime, and other physical properties for individual clouds in the model. We also examine the question of nature versus nurture in shallow cumulus clouds: do properties at cloud base determine the upper-level properties of the clouds (nature), or are cloud properties determined by the environmental conditions they encounter (nurture). We find that clouds which ascend through an environment that has been pre-moistened by previous cloud activity are no more likely to reach the inversion than clouds that ascend through a drier environment. Cloud base thermodynamic properties are uncorrelated with upper-level cloud properties, while mean fractional entrainment and detrainment rate displays moderate correlations with cloud properties up to the inversion. Conversely, cloud base area correlates well with upper-level cloud area and maximum cloud height. We conclude that cloud thermodynamic properties are primarily influenced by entrainment and detrainment processes, cloud area and height are primarily influenced by cloud base area, and thus nature and nurture both play roles in the dynamics of BOMEX shallow cumulus clouds.

  13. Analytical optical scattering in clouds

    NASA Technical Reports Server (NTRS)

    Phanord, Dieudonne D.

    1989-01-01

    An analytical optical model for scattering of light due to lightning by clouds of different geometry is being developed. The self-consistent approach and the equivalent medium concept of Twersky was used to treat the case corresponding to outside illumination. Thus, the resulting multiple scattering problem is transformed with the knowledge of the bulk parameters, into scattering by a single obstacle in isolation. Based on the size parameter of a typical water droplet as compared to the incident wave length, the problem for the single scatterer equivalent to the distribution of cloud particles can be solved either by Mie or Rayleigh scattering theory. The super computing code of Wiscombe can be used immediately to produce results that can be compared to the Monte Carlo computer simulation for outside incidence. A fairly reasonable inverse approach using the solution of the outside illumination case was proposed to model analytically the situation for point sources located inside the thick optical cloud. Its mathematical details are still being investigated. When finished, it will provide scientists an enhanced capability to study more realistic clouds. For testing purposes, the direct approach to the inside illumination of clouds by lightning is under consideration. Presently, an analytical solution for the cubic cloud will soon be obtained. For cylindrical or spherical clouds, preliminary results are needed for scattering by bounded obstacles above or below a penetrable surface interface.

  14. Chemistry in dynamically evolving clouds

    NASA Technical Reports Server (NTRS)

    Tarafdar, S. P.; Prasad, S. S.; Huntress, W. T., Jr.; Villere, K. R.; Black, D. C.

    1985-01-01

    A unified model of chemical and dynamical evolution of isolated, initially diffuse and quiescent interstellar clouds is presented. The model uses a semiempirically derived dependence of the observed cloud temperatures on the visual extinction and density. Even low-mass, low-density, diffuse clouds can collapse in this model, because the inward pressure gradient force assists gravitational contraction. In contrast, previous isothermal collapse models required the low-mass diffuse clouds to be unrealistically cold before gravitational contraction could start. Theoretically predicted dependences of the column densities of various atoms and molecules, such as C and CO, on visual extinction in diffuse clouds are in accord with observations. Similarly, the predicted dependences of the fractional abundances of various chemical species (e.g., CO, H2CO, HCN, HCO(+)) on the total hydrogen density in the core of the dense clouds also agree with observations reported to date in the literature. Compared with previous models of interstellar chemistry, the present model has the potential to explain the wide spectrum of chemical and physical properties of both diffuse and dense clouds with a common formalism employing only a few simple initial conditions.

  15. Densities of Galcatic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark

    2015-01-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3, this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  16. Densities of Galactic Center Clouds

    NASA Astrophysics Data System (ADS)

    Barnes, Jonathan; Mills, Elisabeth A. C.; Morris, Mark R.

    2015-04-01

    The central 300 parsecs of the Galaxy is full of giant molecular clouds containing 107 solar masses worth of gas. However, our Galactic center is not forming as many stars as we think it can, based on the amount of molecular gas in this region. By studying the densities of the Galactic center clouds we hope to better understand why there is not much star formation occurring. Using data from the Green Bank and MOPRA telescopes we have observed multiple rotation transitions of HC3N and its 13C isotopologues. By measuring the integrated intensity of the HC3 N we are able to calculate the densities of these giant molecular clouds. The measured intensities are used with a radiative transfer code called RADEX, to determine volume densities. Our initial results suggest that there may be either less dense or cooler gas in these clouds that previously thought. If there is a significant quantity of gas less dense than 104 molecules/cm3 , this could explain the lack of ongoing star formation in these clouds, and might also suggest a shorter timescale for dynamical disruption of theses clouds. In the future, we plan to improve these results by observing additional HC3N transitions, allowing us better to constrain the relative contributions of multiple temperature and density components in Galactic center clouds.

  17. CCN Cloud Processing Interhemispheric Comparisons

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Cloud processing of CCN spectra is described by Hudson and Noble (2014) and Noble and Hudson (2014). Bimodal CCN spectra have also been observed in 4 Southern Hemisphere (SH) cloud research projects: SOCEX1, July 1993 and 2, Jan-Feb, 1995 and ACE1, Nov-Dec, 1995 all off Tasmania and INDOEX, Feb-Mar, 1999 Indian Ocean (Fig.). However, as in the Northern Hemisphere (NH) bimodal CCN spectra are interspersed with monomodal spectra, which indicates that cloudy boundary layers are not as well-mixed as conventional wisdom. Hoppel minima between the modes provide estimates of cloud effective supersaturations (Seff). Unlike DMA measurements particle composition/hygroscopicity (κ) is not needed for these Seff estimate because CCN are measured in terms of S. However, these Hoppel Seff often tend to be lower than Seff obtained by comparing below cloud CCN spectra with nearby cloud droplet concentrations (Nc). These Seff differences may be due to less cloud processing by smaller cloud droplets. However, this may be a smaller issue in the SH due to larger droplets in cleaner air masses. Furthermore, SH Seff may also tend to be higher for the same reason. This might reduce the Seff differences of the two types of estimates compared to the more polluted NH. SH/NH comparisons of detailed differential CCN spectra can provide an important baseline for preindustrial aerosol. Relative differences between the contribution of chemical and physical cloud processing between hemispheres also provide important baseline characteristics. Chemical processing enhance the indirect aerosol effect (IAE) by moving CCN to lower critical S (Sc), which increases droplet concentrations (Nc) whereas physical processing reduces IAE by inherently reducing CCN (Noble and Hudson 2014). The extent of cloud processing is as important as CCN sources. Hudson and Noble 2014, this meeting. Noble and Hudson 2014, this meeting.

  18. Mixed phase clouds, cloud electrification and remote sensing.

    SciTech Connect

    Chylek, P.; Borel, C. C.; Klett, James

    2004-01-01

    Most of hypothesis trying to explain charge separation in thunderstorm clouds require presence of ice and supercooled water. Thus the existence of ice or at least mixed phase regions near cloud tops should be a necessary (but not a sufficient) condition for development of lightning. We show that multispectral satellite based instruments, like the DOE MTI (Multispectral Thermal Imager) or NASA MODIS (Moderate Resolution Imaging Spectroradiometer), using the near infrared and visible spectral bands are able to distinguish between water, ice and mixed phase cloud regions. An analysis of the MTI images of mixed phase clouds - with spatial resolution of about 20 m - shows regions of pure water, pure ice as well as regions of water/ice mixtures. We suggest that multispectral satellite instruments may be useful for a short time forecast of lightning probabilities.

  19. "Plane tracks" in cirrus clouds

    NASA Astrophysics Data System (ADS)

    Tesche, M.; Achtert, P.; Glantz, P.; Noone, K. J.

    2015-12-01

    Determining the effects of aircraft emissions on cirrus clouds already present in the atmosphere has proven to be challenging. Quantifying any such effects is necessary if we are to properly account for the influence of aviation on climate. Here we quantify the effect of aircraft on the optical thickness of already-existing cirrus clouds by matching actual aircraft flight tracks to satellite lidar measurements. We show that there are systematic, statistically significant increases in normalized cirrus cloud optical thickness inside mid-latitude flight corridors compared with adjacent areas immediately outside the corridors.

  20. Discrete cloud structure on Neptune

    NASA Astrophysics Data System (ADS)

    Hammel, H. B.

    1989-07-01

    Recent CCD imaging data for the discrete cloud structure of Neptune shows that while cloud features at CH4-band wavelengths are manifest in the southern hemisphere, they have not been encountered in the northern hemisphere since 1986. A literature search has shown the reflected CH4-band light from the planet to have come from a single discrete feature at least twice in the last 10 years. Disk-integrated photometry derived from the imaging has demonstrated that a bright cloud feature was responsible for the observed 8900 A diurnal variation in 1986 and 1987.

  1. Gas clouds in galactic bulges

    SciTech Connect

    Mathews, W.G.; Murray, S.D.

    1987-01-01

    An analytical model is defined for the orbits of gas clouds moving through a low-density, hot resisting medium in a spiral galactic bulge. The model includes a virial equation that accounts for internal and magnetic energy, external self-pressure, self-gravity and tidal and differential shear stresses, and a criterion for assessing the Rayleigh-Taylor stability of clouds moving within a confining medium. Results are discussed from use of the model to predict the orbital decay efficiency of clouds at different radii moving in a galactic bulge similar to that of the Galaxy. 52 references.

  2. Cloud Thickness from Diffusion of Lidar Pulses in Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Davis, A.; McGill, Matthew

    1999-01-01

    Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo

  3. Implications of using transmitted vs. reflected light for determining cloud properties, cloud radiative effects and aerosol-cloud-interactions

    NASA Astrophysics Data System (ADS)

    LeBlanc, S. E.; Redemann, J.; Segal-Rosenhaimer, M.; Kacenelenbogen, M. S.; Shinozuka, Y.; Flynn, C. J.; Schmidt, S.; Pilewskie, P.; Song, S.; Woods, S.; Lawson, P.; Nenes, A.; Lin, J. J.; Ziemba, L. D.

    2015-12-01

    Light transmitted through clouds is sensitive to a different cloud volume than reflected light at cloud top. This difference in sampling volumes has implications when calculating the radiative effects of clouds (CRE) and aerosol-cloud-interactions (ACI). We present a comparison of retrieved cloud properties and the corresponding CRE and ACI based on transmitted and reflected light for a cloud sampled during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, 2013) field campaign. Measurements of zenith radiances were obtained from the NASA DC-8 aircraft using the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) instrument. 4STAR was deployed on an airborne platform during SEAC4RS alongside the Solar Spectral Flux Radiometer (SSFR). To retrieve cloud properties from transmitted shortwave radiation, we use a retrieval utilizing spectrally resolved measurements. Spectral features in shortwave radiation transmitted through clouds are sensitive to changes in cloud optical thickness, effective radius, and thermodynamic phase. The spectral features due to absorption and scattering processes by liquid water and ice cloud particles include shifts in spectral slopes, curvatures, maxima, and minima of cloud-transmitted radiance. These spectral features have been quantified by 15 parameters used to retrieve cloud properties from the 4STAR zenith radiances. Retrieved cloud optical thicknesses and effective radii based on transmitted shortwave radiation are compared to their counterparts obtained from reflected shortwave radiation measured above cloud with MODIS and with the enhanced MODIS Airborne Simulator (eMAS), the Research Scanning Polarimeter (RSP), and SSFR operating aboard the NASA ER-2 aircraft. Remotely sensed cloud particle effective radius are combined with in situ measurements of cloud and aerosol particles from the NASA Langley Aerosol Research Group Experiment (LARGE) CCN Counter

  4. When STAR meets the Clouds - Virtualization & Cloud Computing Experiences

    NASA Astrophysics Data System (ADS)

    Lauret, J.; Walker, M.; Goasguen, S.; Stout, L.; Fenn, M.; Balewski, J.; Hajdu, L.; Keahey, K.

    2011-12-01

    In recent years, Cloud computing has become a very attractive paradigm and popular model for accessing distributed resources. The Cloud has emerged as the next big trend. The burst of platform and projects providing Cloud resources and interfaces at the very same time that Grid projects are entering a production phase in their life cycle has however raised the question of the best approach to handling distributed resources. Especially, are Cloud resources scaling at the levels shown by Grids? Are they performing at the same level? What is their overhead on the IT teams and infrastructure? Rather than seeing the two as orthogonal, the STAR experiment has viewed them as complimentary and has studied merging the best of the two worlds with Grid middleware providing the aggregation of both Cloud and traditional resources. Since its first use of Cloud resources on Amazon EC2 in 2008/2009 using a Nimbus/EC2 interface, the STAR software team has tested and experimented with many novel approaches: from a traditional, native EC2 approach to the Virtual Organization Cluster (VOC) at Clemson University and Condor/VM on the GLOW resources at the University of Wisconsin. The STAR team is also planning to run as part of the DOE/Magellan project. In this paper, we will present an overview of our findings from using truly opportunistic resources and scaling-out two orders of magnitude in both tests and practical usage.

  5. Continuous growth of cloud droplets in cumulus cloud

    NASA Astrophysics Data System (ADS)

    Gotoh, Toshiyuki; Suehiro, Tamotsu; Saito, Izumi

    2016-04-01

    A new method to seamlessly simulate the continuous growth of droplets advected by turbulent flow inside a cumulus cloud was developed from first principle. A cubic box ascending with a mean updraft inside a cumulus cloud was introduced and the updraft velocity was self-consistently determined in such a way that the mean turbulent velocity within the box vanished. All the degrees of freedom of the cloud droplets and turbulence fields were numerically integrated. The box ascended quickly inside the cumulus cloud due to the updraft and the mean radius of the droplets grew from 10 to 24 μm for about 10 min. The turbulent flow tended to slow down the time evolutions of the updraft velocity, the box altitude and the mean cloud droplet radius. The size distribution of the cloud droplets in the updraft case was narrower than in the absence of the updraft. It was also found that the wavenumeber spectra of the variances of the temperature and water vapor mixing ratio were nearly constant in the low wavenumber range. The future development of the new method was argued.

  6. CALIPSO Observations of Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Wood, Robert

    2015-01-01

    This paper uses spaceborne lidar data to study how near-cloud aerosol statistics of attenuated backscatter depend on cloud fraction. The results for a large region around the Azores show that: (1) far-from-cloud aerosol statistics are dominated by samples from scenes with lower cloud fractions, while near-cloud aerosol statistics are dominated by samples from scenes with higher cloud fractions; (2) near-cloud enhancements of attenuated backscatter occur for any cloud fraction but are most pronounced for higher cloud fractions; (3) the difference in the enhancements for different cloud fractions is most significant within 5km from clouds; (4) near-cloud enhancements can be well approximated by logarithmic functions of cloud fraction and distance to clouds. These findings demonstrate that if variability in cloud fraction across the scenes used to composite aerosol statistics are not considered, a sampling artifact will affect these statistics calculated as a function of distance to clouds. For the Azores-region dataset examined here, this artifact occurs mostly within 5 km from clouds, and exaggerates the near-cloud enhancements of lidar backscatter and color ratio by about 30. This shows that for accurate characterization of the changes in aerosol properties with distance to clouds, it is important to account for the impact of changes in cloud fraction.

  7. Characterization of Cloud Water-Content Distribution

    NASA Technical Reports Server (NTRS)

    Lee, Seungwon

    2010-01-01

    The development of realistic cloud parameterizations for climate models requires accurate characterizations of subgrid distributions of thermodynamic variables. To this end, a software tool was developed to characterize cloud water-content distributions in climate-model sub-grid scales. This software characterizes distributions of cloud water content with respect to cloud phase, cloud type, precipitation occurrence, and geo-location using CloudSat radar measurements. It uses a statistical method called maximum likelihood estimation to estimate the probability density function of the cloud water content.

  8. Raman lidar observations of cloud liquid water.

    PubMed

    Rizi, Vincenzo; Iarlori, Marco; Rocci, Giuseppe; Visconti, Guido

    2004-12-10

    We report the design and the performances of a Raman lidar for long-term monitoring of tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio, and cloud liquid water. We focus on the system's capabilities of detecting Raman backscattering from cloud liquid water. After describing the system components, along with the current limitations and options for improvement, we report examples of observations in the case of low-level cumulus clouds. The measurements of the cloud liquid water content, as well as the estimations of the cloud droplet effective radii and number densities, obtained by combining the extinction coefficient and cloud water content within the clouds, are critically discussed. PMID:15617280

  9. Raman lidar observations of cloud liquid water.

    PubMed

    Rizi, Vincenzo; Iarlori, Marco; Rocci, Giuseppe; Visconti, Guido

    2004-12-10

    We report the design and the performances of a Raman lidar for long-term monitoring of tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio, and cloud liquid water. We focus on the system's capabilities of detecting Raman backscattering from cloud liquid water. After describing the system components, along with the current limitations and options for improvement, we report examples of observations in the case of low-level cumulus clouds. The measurements of the cloud liquid water content, as well as the estimations of the cloud droplet effective radii and number densities, obtained by combining the extinction coefficient and cloud water content within the clouds, are critically discussed.

  10. Research computing in a distributed cloud environment

    NASA Astrophysics Data System (ADS)

    Fransham, K.; Agarwal, A.; Armstrong, P.; Bishop, A.; Charbonneau, A.; Desmarais, R.; Hill, N.; Gable, I.; Gaudet, S.; Goliath, S.; Impey, R.; Leavett-Brown, C.; Ouellete, J.; Paterson, M.; Pritchet, C.; Penfold-Brown, D.; Podaima, W.; Schade, D.; Sobie, R. J.

    2010-11-01

    The recent increase in availability of Infrastructure-as-a-Service (IaaS) computing clouds provides a new way for researchers to run complex scientific applications. However, using cloud resources for a large number of research jobs requires significant effort and expertise. Furthermore, running jobs on many different clouds presents even more difficulty. In order to make it easy for researchers to deploy scientific applications across many cloud resources, we have developed a virtual machine resource manager (Cloud Scheduler) for distributed compute clouds. In response to a user's job submission to a batch system, the Cloud Scheduler manages the distribution and deployment of user-customized virtual machines across multiple clouds. We describe the motivation for and implementation of a distributed cloud using the Cloud Scheduler that is spread across both commercial and dedicated private sites, and present some early results of scientific data analysis using the system.

  11. Cloud computing in medical imaging.

    PubMed

    Kagadis, George C; Kloukinas, Christos; Moore, Kevin; Philbin, Jim; Papadimitroulas, Panagiotis; Alexakos, Christos; Nagy, Paul G; Visvikis, Dimitris; Hendee, William R

    2013-07-01

    Over the past century technology has played a decisive role in defining, driving, and reinventing procedures, devices, and pharmaceuticals in healthcare. Cloud computing has been introduced only recently but is already one of the major topics of discussion in research and clinical settings. The provision of extensive, easily accessible, and reconfigurable resources such as virtual systems, platforms, and applications with low service cost has caught the attention of many researchers and clinicians. Healthcare researchers are moving their efforts to the cloud, because they need adequate resources to process, store, exchange, and use large quantities of medical data. This Vision 20/20 paper addresses major questions related to the applicability of advanced cloud computing in medical imaging. The paper also considers security and ethical issues that accompany cloud computing. PMID:23822402

  12. Zero-gravity cloud physics.

    NASA Technical Reports Server (NTRS)

    Hollinden, A. B.; Eaton, L. R.; Vaughan, W. W.

    1972-01-01

    The first results of an ongoing preliminary-concept and detailed-feasibility study of a zero-gravity earth-orbital cloud physics research facility are reviewed. Current planning and thinking are being shaped by two major conclusions of this study: (1) there is a strong requirement for and it is feasible to achieve important and significant research in a zero-gravity cloud physics facility; and (2) some very important experiments can be accomplished with 'off-the-shelf' type hardware by astronauts who have no cloud-physics background; the most complicated experiments may require sophisticated observation and motion subsystems and the astronaut may need graduate level cloud physics training; there is a large number of experiments whose complexity varies between these two extremes.

  13. Drop processes in natural clouds

    NASA Technical Reports Server (NTRS)

    Latham, J.

    1982-01-01

    A model of the diffusive mixing of dry and cloudy air, a process considered to be fundamental to the development of natural clouds, is presented. Water drops are formed at the cloud base by condensation upon nuclei and as they rise they grow by vapor diffusion in the slightly supersaturated environment of the clouds. Turbulent mixing between cloudy air and undersaturated air entrained from outside produces fluctuations in supersaturation, not linked to changes in vertical velocity, which cause broadening of the condensate spectrum and the rapid production of droplets large enough to engage in growth by coalescence. The probabilities of permanent union or the production of satellite droplets following the collision of a pair of raindrops is a sensitive function of several parameters. In some circumstances electrohydrodynamic bursting may influence the properties of clouds.

  14. Cloud computing in medical imaging.

    PubMed

    Kagadis, George C; Kloukinas, Christos; Moore, Kevin; Philbin, Jim; Papadimitroulas, Panagiotis; Alexakos, Christos; Nagy, Paul G; Visvikis, Dimitris; Hendee, William R

    2013-07-01

    Over the past century technology has played a decisive role in defining, driving, and reinventing procedures, devices, and pharmaceuticals in healthcare. Cloud computing has been introduced only recently but is already one of the major topics of discussion in research and clinical settings. The provision of extensive, easily accessible, and reconfigurable resources such as virtual systems, platforms, and applications with low service cost has caught the attention of many researchers and clinicians. Healthcare researchers are moving their efforts to the cloud, because they need adequate resources to process, store, exchange, and use large quantities of medical data. This Vision 20/20 paper addresses major questions related to the applicability of advanced cloud computing in medical imaging. The paper also considers security and ethical issues that accompany cloud computing.

  15. 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.

  16. Ultraviolet Mars Reveals Cloud Formation

    NASA Video Gallery

    Images from MAVEN's Imaging UltraViolet Spectrograph were used to make this movie of rapid cloud formation on Mars on July 9-10, 2016. The ultraviolet colors of the planet have been rendered in fal...

  17. Low-Velocity Halo Clouds

    NASA Astrophysics Data System (ADS)

    Peek, J. E. G.; Heiles, Carl; Putman, M. E.; Douglas, Kevin

    2009-02-01

    Models that reproduce the observed high-velocity clouds (HVCs) also predict clouds at lower radial velocities that may easily be confused with Galactic disk (|z|< 1 kpc) gas. We describe the first search for these low-velocity halo clouds (LVHCs) using Infrared Astronomical Satellite (IRAS) data and the initial data from the Galactic Arecibo L-band Feed Array survey in H I. The technique is based upon the expectation that such clouds should, like HVCs, have very limited infrared (IR) thermal dust emission as compared to their H I column density. We describe our "displacement-map" technique for robustly determining the dust-to-gas ratio (DGR) of clouds and the associated errors that take into account the significant scatter in the IR flux from the Galactic disk gas. We find that there exist lower-velocity clouds that have extremely low DGRs, consistent with being in the Galactic halo—candidate LVHCs. We also confirm the lack of dust in many HVCs with the notable exception of complex M, which we consider to be the first detection of dust in HVCs. We do not confirm the previously reported detection of dust in complex C. In addition, we find that most intermediate- and low-velocity clouds that are part of the Galactic disk have a higher 60 μm/100 μm flux ratio than is typically seen in Galactic H I, which is consistent with a previously proposed picture in which fast-moving Galactic clouds have smaller, hotter dust grains.

  18. Open Ocean, Sunglint and Clouds

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This interesting and well composed view of open ocean, sunglint and clouds, location unknown, illustrates the reflective nature of water. Smooth water surfaces have a very high reflective surface like a mirror but rough water surfaces with lots of choppy waves, have a very low reflective potential and appear as mostly dark patches. The combination of low sun angle, clouds, shadows and sea states produces an attractive composition of contrasts.

  19. Titan's Mid-latitude Clouds

    NASA Astrophysics Data System (ADS)

    Roe, Henry G.; Schaller, E. L.; Trujillo, C. A.; Brown, M. E.

    2007-10-01

    In the first few years of spatially resolved observations of Titan's tropospheric methane clouds (2001-2003) all of the clouds were clustered in the south polar region. This time period coincided with the southern summer solstice (October 2002) and these south polar clouds are almost certainly a seasonal phenomenon. Starting in December 2003 we began seeing clouds in a narrow latitude range centered at 40°S latitude. In Roe et al. (2005a) we published this initial discovery and speculated that the clouds might be due either to changes in the seasonal circulation pattern or a process linked to surface geography. Further observations soon revealed that the clouds were significantly clustered over one region of longitude (near 350°W), strongly suggesting a geographically controlled origin (Roe et al. 2005b), although Cassini observations suggest a circulation-induced convergence origin (Griffith et al. 2005). The actual answer is most likely a combination of geographic surface effects with the atmospheric circulation. We report here on our continuing ground-based observation campaign, including observations on 65 nights in the 2006-2007 apparition with the Gemini 8-m telescope. With two more years of observations since the data shown in Roe et al. (2005b) we now have much firmer conclusions with respect to the spatial distribution and temporal characteristics of the mid-latitude clouds. We will present our latest understanding of Titan's mid-latitude clouds given the entire dataset now available to us. References Griffith, C.A., & 26 co-authors 2005. Science, 310, 474. Roe, H.G., A.H. Bouchez, C.A. Trujillo, E.L. Schaller, & M.E. Brown 2005a. ApJL, 618, 49. Roe, H.G., M.E. Brown, E.L. Schaller, A.H. Bouchez, & C.A. Trujillo 2005b. Science, 310, 477. This work is supported by NASA under Grant #NNX07AK74G issued through the Planetary Astronomy Program.

  20. Cloud Top Scanning radiometer (CTS)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A scanning radiometer to be used for measuring cloud radiances in each of three spectral regions is described. Significant features incorporated in the Cloud Top Scanner design are: (1) flexibility and growth potential through use of easily replaceable modular detectors and filters; (2) full aperture, multilevel inflight calibration; (3) inherent channel registration through employment of a single shared field stop; and (4) radiometric sensitivity margin in a compact optical design through use of Honeywell developed (Hg,Cd)Te detectors and preamplifiers.

  1. Lidar evaluation of smoke and dust clouds.

    PubMed

    Uthe, E E

    1981-05-01

    Lidar provides the means to evaluate quantitatively the spatial and temporal variability of smoke and dust clouds as they are transported downwind from particulate sources. Quantitative evaluation of cloud optical and physical densities from cloud backscatter is complicated by effects from particle size, shape, and composition and by attenuation and multiple scattering for dense clouds. Examples are presented that review use of the lidar technique to provide useful evaluations of smoke and dust clouds.

  2. Entrainment and mixing mechanism in monsoon clouds

    NASA Astrophysics Data System (ADS)

    Bera, Sudarsan; Prabhakaran, Thara; Pandithurai, Govindan; Brenguier, Jean-Louis

    2015-04-01

    Entrainment and consequent mixing impacts the cloud microphysical parameters and droplet size distribution (DSD) significantly which are very important for cloud radiative properties and the mechanism for first rain drop formation. The entrainment and mixing mechanisms are investigated in this study using in situ observations in warm cumulus clouds over monsoon region. Entrainment is discussed in the framework of the homogeneous and inhomogeneous mixing concepts and their effects on cloud droplet size distribution, number concentration, liquid water content and mean radius are described. The degree of homogeneity increases with droplet number concentration and adiabatic fraction, indicating homogeneous type mixing in the cloud core where dilution is less. Inhomogeneous mixing is found to be a dominating process at cloud edges where dilution is significant. Cloud droplet size distribution (DSD) is found to shift towards lower sizes during a homogeneous mixing event in the cloud core whereas spectral width of DSD decreases due to inhomogeneous mixing at cloud edges. Droplet size spectra suggests that largest droplets are mainly formed in the less diluted cloud core while diluted cloud edges have relatively smaller droplets, so that raindrop formation occurs mainly in the core of the cloud. The origin of the entrained parcels in deep cumulus clouds is investigated using conservative thermodynamical parameters. The entrained parcels originate from a level close to the observation level or slightly below through lateral edges. Cloud edges are significantly diluted due to entrainment of sub-saturated environmental air which can penetrate several hundred meters inside the cloud before it gets mixed completely with the cloud mass. Less diluted parcels inside the cloud core originates from a level much below the cloud base height. Penetrating downdraft from cloud top is seldom observed at the observation level and strong downdrafts may be attributed to in-cloud oscillation

  3. Pluvial Inhibition by Urban Cloud Condensation Nuclei

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Yum, S. S.

    2002-05-01

    Cloud microphysics and sub-cloud aerosol measurements in urban and cleaner air masses showed the effects of anthropogenic air pollution. Cloud condensation nuclei (CCN) measurements in three different parts of the world displayed typical urban/clean air mass differences in concentrations. Near-simultaneous cloud droplet measurements (diameter < 50 micrometers) showed the higher concentrations and smaller sizes expected for higher CCN concentrations. The commensurate lower concentrations of large cloud droplets (30-50 micrometers) in urban air indicated that the higher CCN concentrations were responsible for the order(s) of magnitude lower drizzle drop (diameter > 50 micrometers) concentrations in the urban-influenced clouds. The similarity of the clean and urban- influenced cloud droplet spectra near cloud base suggested no differences in giant nuclei concentrations that have been suggested to be responsible for greater precipitation in cleaner clouds. This suppression of warm rain by higher CCN concentrations occurred hundreds of km from the urban sources. Similar effects were found for three different cloud types in these three field projects: 1) stratocumulus clouds in the eastern Atlantic (ASTEX); 2) small cumulus clouds in eastern Florida (SCMS); and small trade wind cumuli in the Indian Ocean (INDOEX). Comparisons of CCN and cloud droplet concentrations in the three projects showed a more-or-less linear relationship between CCN and cloud droplet concentrations. Comparisons of CCN and cloud droplet spectra showed that supersaturations were lower in the urban-influenced clouds due to greater competition for condensed water. This means that a smaller percentage of the higher urban CCN concentrations actually produced cloud droplets. However, the supersaturation suppression was smaller because droplet sizes were so reduced that many urban cloud droplets escaped detection. This underestimation of cloud droplet concentrations suggested a greater suppression of

  4. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect

    KB Widener; K Johnson

    2005-01-30

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  5. Clouds of high contrast on Uranus.

    PubMed

    Karkoschka, E

    1998-04-24

    Near-infrared images of Uranus taken with the Hubble Space Telescope in July and October 1997 revealed discrete clouds with contrasts exceeding 10 times the highest contrast observed before with other techniques. At visible wavelengths, these 10 clouds had lower contrasts than clouds seen by Voyager 2 in 1986. Uranus' rotational rates for southern latitudes were identical in 1986 and 1997. Clouds in northern latitudes rotate slightly more slowly than clouds in opposite southern latitudes. PMID:9554844

  6. Clouds of high contrast on Uranus.

    PubMed

    Karkoschka, E

    1998-04-24

    Near-infrared images of Uranus taken with the Hubble Space Telescope in July and October 1997 revealed discrete clouds with contrasts exceeding 10 times the highest contrast observed before with other techniques. At visible wavelengths, these 10 clouds had lower contrasts than clouds seen by Voyager 2 in 1986. Uranus' rotational rates for southern latitudes were identical in 1986 and 1997. Clouds in northern latitudes rotate slightly more slowly than clouds in opposite southern latitudes.

  7. Cloud Radiative Forcing in the Tropics

    NASA Technical Reports Server (NTRS)

    Christopher, Sundar Anand

    1995-01-01

    Understanding the role of clouds is one of the highest priority science objectives in the global climate change program. In particular there has been a renewed interest in understanding the cloud radiative interactions in the tropical regions. Although a number of studies have emphasized the importance of cloud optical properties on the earth's radiative energy balance, information concerning cloud optical depth and particle size as a function of cloud type is lacking.

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

    NASA Technical Reports Server (NTRS)

    Welch, Ronald M.

    1993-01-01

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

  9. VIIRS Cloud Mask Validation Exercises

    NASA Astrophysics Data System (ADS)

    Frey, R.; Heidinger, A. K.; Hutchison, K.; Dutcher, S.

    2011-12-01

    The NPP Satellite is scheduled for launch October 25, 2011. Included on the platform is the VIIRS (Visible/Infrared Imager/Suite) instrument which features 16 bands at about 0.75 m spatial resolution and 5 imager bands at roughly 0.375 m resolution. The basic VIIRS cloud mask (VCM) output is a flag that indicates one of four possible cloudy vs. clear conditions for each 0.75 m pixel: confident clear, probably clear, probably cloudy, and confident cloudy. Pre-launch assessment of the VCM algorithm has been performed with use of MODIS observations as proxy input. Several comparisons are shown between VCM results and cloud detection from other instruments and/or algorithms: MODIS cloud mask (MOD35) at the five-minute granule level (L2), global and regional monthly average cloud amounts from MODIS (MOD35) and MODIS-CERES, ISCCP, PATMOS-x (AVHRR), and CALIOP (lidar). In addition to overall results, collocated MODIS observations, CALIOP and VCM cloud determinations are used to evaluate VCM cloud test thresholds and other tunable parameters. The methods shown will be among those used during the Intensive Calibration and Validation period and beyond.

  10. Cloud computing for comparative genomics

    PubMed Central

    2010-01-01

    Background Large comparative genomics studies and tools are becoming increasingly more compute-expensive as the number of available genome sequences continues to rise. The capacity and cost of local computing infrastructures are likely to become prohibitive with the increase, especially as the breadth of questions continues to rise. Alternative computing architectures, in particular cloud computing environments, may help alleviate this increasing pressure and enable fast, large-scale, and cost-effective comparative genomics strategies going forward. To test this, we redesigned a typical comparative genomics algorithm, the reciprocal smallest distance algorithm (RSD), to run within Amazon's Elastic Computing Cloud (EC2). We then employed the RSD-cloud for ortholog calculations across a wide selection of fully sequenced genomes. Results We ran more than 300,000 RSD-cloud processes within the EC2. These jobs were farmed simultaneously to 100 high capacity compute nodes using the Amazon Web Service Elastic Map Reduce and included a wide mix of large and small genomes. The total computation time took just under 70 hours and cost a total of $6,302 USD. Conclusions The effort to transform existing comparative genomics algorithms from local compute infrastructures is not trivial. However, the speed and flexibility of cloud computing environments provides a substantial boost with manageable cost. The procedure designed to transform the RSD algorithm into a cloud-ready application is readily adaptable to similar comparative genomics problems. PMID:20482786

  11. Cloud-cloud collision in the Galactic center 50 km s-1 molecular cloud

    NASA Astrophysics Data System (ADS)

    Tsuboi, Masato; Miyazaki, Atsushi; Uehara, Kenta

    2015-12-01

    We performed a search of star-forming sites influenced by external factors, such as SNRs, H II regions, and cloud-cloud collisions (CCCs), to understand the star-forming activity in the Galactic center region using the NRO Galactic Center Survey in SiO v = 0, J = 2-1, H13CO+J = 1-0, and CS J = 1-0 emission lines obtained with the Nobeyama 45 m telescope. We found a half-shell-like feature (HSF) with a high integrated line intensity ratio of ∫TB(SiO v = 0, J = 2-1)dv/∫TB(H13CO+J = 1-0)dv ˜ 6-8 in the 50 km s-1 molecular cloud; the HSF is a most conspicuous molecular cloud in the region and harbors an active star-forming site where several compact H II regions can be seen. The high ratio in the HSF indicates that the cloud contains huge shocked molecular gas. The HSF can be also seen as a half-shell feature in the position-velocity diagram. A hypothesis explaining the chemical and kinetic properties of the HSF is that the feature originates from a CCC. We analyzed the CS J = 1-0 emission line data obtained with the Nobeyama Millimeter Array to reveal the relation between the HSF and the molecular cloud cores in the cloud. We made a cumulative core mass function (CMF) of the molecular cloud cores within the HSF. The CMF in the CCC region is not truncated at least up to ˜2500 M⊙, although the CMF of the non-CCC region reaches the upper limit of ˜1500 M⊙. Most massive molecular cores with Mgas > 750 M⊙ are located only around the ridge of the HSF and adjoin the compact H II region. These may be a sign of massive star formation induced by CCCs in the Galactic center region.

  12. The Community Cloud Atlas - Building an Informed Cloud Watching Community

    NASA Astrophysics Data System (ADS)

    Guy, N.; Rowe, A.

    2014-12-01

    The sky is dynamic, from long lasting cloud systems to ethereal, fleeting formations. After years of observing the sky and growing our personal collections of cloud photos, we decided to take to social media to share pictures, as well as build and educate a community of cloud enthusiasts. We began a Facebook page, the Community Cloud Atlas, described as "...the place to show off your pictures of the sky, identify clouds, and to discuss how specific cloud types form and what they can tell you about current and future weather." Our main goal has been to encourage others to share their pictures, while we describe the scenes from a meteorological perspective and reach out to the general public to facilitate a deeper understanding of the sky. Nearly 16 months later, we have over 1400 "likes," spanning 45 countries with ages ranging from 13 to over 65. We have a consistent stream of submissions; so many that we decided to start a corresponding blog to better organize the photos, provide more detailed explanations, and reach a bigger audience. Feedback from users has been positive in support of not only sharing cloud pictures, but also to "learn the science as well as admiring" the clouds. As one community member stated, "This is not 'just' a place to share some lovely pictures." We have attempted to blend our social media presence with providing an educational resource, and we are encouraged by the response we have received. Our Atlas has been informally implemented into classrooms, ranging from a 6th grade science class to Meteorology courses at universities. NOVA's recent Cloud Lab also made use of our Atlas as a supply of categorized pictures. Our ongoing goal is to not only continue to increase understanding and appreciation of the sky among the public, but to provide an increasingly useful tool for educators. We continue to explore different social media options to interact with the public and provide easier content submission, as well as software options for

  13. The clouds are hazes of Venus

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Knollenberg, R. G.; Marov, M. IA.; Toon, O. B.; Turco, R. P.

    1983-01-01

    Pioneer Venus and Venera probe data for the clouds of Venus are considered. These clouds consist of a main cloud deck at 45-70 km altitude, with thinner hazes above and below, although the microphysical properties of the main cloud are further subdivided into upper, middle and lower cloud levels. Much of the cloud exhibits a multimodal particle size distribution, with the mode most visible from the earth being H2SO4 droplets having 2-3 micron diameters. Despite variations, the vertical structure of the clouds indicates persistent features at sites separated by years and by great distances. The clouds are more strongly affected by radiation than by latent heat release, and the small particle size and weak convective activity observed are incompatible with lightning of cloud origin.

  14. Transport of infrared radiation in cuboidal clouds

    NASA Technical Reports Server (NTRS)

    HARSHVARDHAN; Weinman, J. A.; Davies, R.

    1981-01-01

    The transport of infrared radiation in a single cuboidal cloud using a vertical two steam approximation was modeled. The emittance of the top face of the model cloud is always less than that for a plane parallel cloud of the same optical depth. The hemisphere flux escaping from the cloud top has a gradient from the center to the edges which brighten when the cloud is over warmer ground. Cooling rate calculations in the 8 to 13.6 micrometer region show that there is cooling from the sides of the cloud at all levels even when there is heating of the core from the ground below. The radiances exiting from model cuboidal clouds were computed by path integration over the source function obtained with the two stream approximation. It is suggested that the brightness temperature measured from finite clouds will overestimate the cloud top temperature.

  15. Automated Detection of Clouds in Satellite Imagery

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary

    2010-01-01

    Many different approaches have been used to automatically detect clouds in satellite imagery. Most approaches are deterministic and provide a binary cloud - no cloud product used in a variety of applications. Some of these applications require the identification of cloudy pixels for cloud parameter retrieval, while others require only an ability to mask out clouds for the retrieval of surface or atmospheric parameters in the absence of clouds. A few approaches estimate a probability of the presence of a cloud at each point in an image. These probabilities allow a user to select cloud information based on the tolerance of the application to uncertainty in the estimate. Many automated cloud detection techniques develop sophisticated tests using a combination of visible and infrared channels to determine the presence of clouds in both day and night imagery. Visible channels are quite effective in detecting clouds during the day, as long as test thresholds properly account for variations in surface features and atmospheric scattering. Cloud detection at night is more challenging, since only courser resolution infrared measurements are available. A few schemes use just two infrared channels for day and night cloud detection. The most influential factor in the success of a particular technique is the determination of the thresholds for each cloud test. The techniques which perform the best usually have thresholds that are varied based on the geographic region, time of year, time of day and solar angle.

  16. Generalized scale invariance, clouds and radiative transfer on multifractal clouds

    SciTech Connect

    Lovejoy, S.; Schertzer, D.

    1995-09-01

    Recent systematic satellite studies (LANDSAT, AVHRR, METEOSAT) of cloud radiances using (isotropic) energy spectra have displayed excellent scaling from at least about 300m to about 4000km, even for individual cloud pictures. At first sight, this contradicts the observed diversity of cloud morphology, texture and type. The authors argue that the explanation of this apparent paradox is that the differences are due to anisotropy, e.g. differential stratification and rotation. A general framework for anisotropic scaling expressed in terms of isotropic self-similar scaling and fractals and multifractals is needed. Schertzer and Lovejoy have proposed Generalized Scale Invariance (GSI) in response to this need. In GSI, the statistics of the large and small scales of system can be related to each other by a scale changing operator T{sub {lambda}} which depends only on the scale ratio {lambda}{sub i} there is no characteristic size. 3 refs., 1 fig.

  17. Fast Simulators for Satellite Cloud Optical Centroid Pressure Retrievals, 1. Evaluation of OMI Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Joiner, J.; Vasilkov, A.; Gupta, P.; Bhartia, P. K.; Veefkind, P.; Sneep, M.; de Haan, J.; Polonsky, I.; Spurr, R.

    2012-01-01

    The cloud Optical Centroid Pressure (OCP), also known as the effective cloud pressure, is a satellite-derived parameter that is commonly used in trace-gas retrievals to account for the effects of clouds on near-infrared through ultraviolet radiance measurements. Fast simulators are desirable to further expand the use of cloud OCP retrievals into the operational and climate communities for applications such as data assimilation and evaluation of cloud vertical structure in general circulation models. In this paper, we develop and validate fast simulators that provide estimates of the cloud OCP given a vertical profile of optical extinction. We use a pressure-weighting scheme where the weights depend upon optical parameters of clouds and/or aerosol. A cloud weighting function is easily extracted using this formulation. We then use fast simulators to compare two different satellite cloud OCP retrievals from the Ozone Monitoring Instrument (OMI) with estimates based on collocated cloud extinction profiles from a combination of CloudS at radar and MODIS visible radiance data. These comparisons are made over a wide range of conditions to provide a comprehensive validation of the OMI cloud OCP retrievals. We find generally good agreement between OMI cloud OCPs and those predicted by CloudSat. However, the OMI cloud OCPs from the two independent algorithms agree better with each other than either does with the estimates from CloudSat/MODIS. Differences between OMI cloud OCPs and those based on CloudSat/MODIS may result from undetected snow/ice at the surface, cloud 3-D effects, low altitude clouds missed by CloudSat, and the fact that CloudSat only observes a relatively small fraction of an OMI field-of-view.

  18. ASTROCHEMICAL CORRELATIONS IN MOLECULAR CLOUDS

    SciTech Connect

    Gaches, Brandt A. L.; Offner, Stella S. R.; Rosolowsky, Erik W.; Bisbas, Thomas G. E-mail: soffner@astro.umass.edu E-mail: tb@star.ucl.ac.uk

    2015-02-01

    We investigate the spectral correlations between different species used to observe molecular clouds. We use hydrodynamic simulations and a full chemical network to study the abundances of over 150 species in typical Milky Way molecular clouds. We perform synthetic observations in order to produce emission maps of a subset of these tracers. We study the effects of different lines of sight and spatial resolution on the emission distribution and perform a robust quantitative comparison of the species to each other. We use the Spectral Correlation Function (SCF), which quantifies the root mean squared difference between spectra separated by some length scale, to characterize the structure of the simulated cloud in position-position-velocity (PPV) space. We predict the observed SCF for a broad range of observational tracers, and thus identify homologous species. In particular, we show that the pairs C and CO, C{sup +} and CN, and NH{sub 3} and H{sub 2}CS have very similar SCFs. We measure the SCF slope variation as a function of beam size for all species and demonstrate that the beam size has a distinct effect on different species emission. However, for beams of up to 10'', placing the cloud at 1 kpc, the change is not large enough to move the SCF slopes into different regions of parameter space. The results from this study provide observational guidance for choosing the best tracer to probe various cloud length scales.

  19. Advances in the TRIDEC Cloud

    NASA Astrophysics Data System (ADS)

    Hammitzsch, Martin; Spazier, Johannes; Reißland, Sven

    2016-04-01

    The TRIDEC Cloud is a platform that merges several complementary cloud-based services for instant tsunami propagation calculations and automated background computation with graphics processing units (GPU), for web-mapping of hazard specific geospatial data, and for serving relevant functionality to handle, share, and communicate threat specific information in a collaborative and distributed environment. The platform offers a modern web-based graphical user interface so that operators in warning centres and stakeholders of other involved parties (e.g. CPAs, ministries) just need a standard web browser to access a full-fledged early warning and information system with unique interactive features such as Cloud Messages and Shared Maps. Furthermore, the TRIDEC Cloud can be accessed in different modes, e.g. the monitoring mode, which provides important functionality required to act in a real event, and the exercise-and-training mode, which enables training and exercises with virtual scenarios re-played by a scenario player. The software system architecture and open interfaces facilitate global coverage so that the system is applicable for any region in the world and allow the integration of different sensor systems as well as the integration of other hazard types and use cases different to tsunami early warning. Current advances of the TRIDEC Cloud platform will be summarized in this presentation.

  20. Grain Growth in Collapsing Clouds

    NASA Astrophysics Data System (ADS)

    Rossi, S. C. F.; Benevides-Soares, P.; Barbuy, B.

    1990-11-01

    RESUMEN. Se ha considerado un proceso de coagulaci6n de granos en nubes colapsantes de diferentes metalicidades. Se aplicaron los calculos al intervalo de densidades n = lO to , forrespondiendo a la fase isotermica de contracci6n de nubes. A lo largo de esta fase en el colap- so, la temperatura es por lo tanto constante, en donde se alcanza T Q lOKpara nubes de metalicidad solar y T 100 K para nubes de baja metalicidad. El tamano final del grano es mayor para las mayores metali- cidades. ABSTRACT. A process of grain coagulation in collapsing clouds of different metallicities is considered. The calculations are applied to the density range n = 1O to , corresponding to the isothermal phase of cloud contraction. Along this phase in the collapse, the temperature is thus a constant, where T % 10 K for solar-metallicity clouds, and T % 100 K for low metallicity clouds is reached. The final grain size is larger for the higher metallicities. Keq : INTERSTELLAR-CLOUDS - INTERSTELLAR-CRAINS

  1. 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.

  2. Cirrus Cloud Modeling: Overview and Issues

    NASA Technical Reports Server (NTRS)

    Starr, David OC.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    A review of cirrus cloud modeling will be given with special attention to the role of dynamical processes in regulating cloud microphysical properties and the interactions with radiative process in determining cloud lifecycle. The talk will draw heavily on the papers by Starr and Quante, Quante and Starr and Demoz et al., as well as recent results from the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems (WG2) Idealized Cirrus Model Comparison and Cirrus Parcel Model Comparison projects, as described in Starr et al. and Lin et al. Key issues in current cirrus cloud modeling will be described and discussed.

  3. Are cloud thermals slippery or sticky?

    NASA Astrophysics Data System (ADS)

    Romps, David; Oktem, Rusen; Charn, Alexander

    2015-04-01

    What role does drag play in the vertical momentum budget of convecting clouds? Are cloud thermals slippery, as recently suggested, or are they sticky? This question is addressed here using stereo photogrammetric observations of clouds in Miami, Florida and a cloud-tracking algorithm implemented in a large-eddy simulations. In both observations and large-eddy simulations, cloud thermals can be tracked throughout significant portions of their life cycles. These data can then be fit against simple parcel theories to infer the dominant balance in the momentum budget. These conclusions can then be confirmed by diagnosing individual terms in the cloud-thermal momentum budget from large-eddy simulations.

  4. Are Cloud Thermals Slippery or Sticky?

    NASA Astrophysics Data System (ADS)

    Romps, D. M.; Oktem, R.; Charn, A. B.

    2015-12-01

    What role does drag play in the vertical momentum budget of convecting clouds? Are cloud thermals slippery, as recently suggested, or are they sticky? This question is addressed here using stereo photogrammetric observations of clouds in Miami, Florida and a cloud-tracking algorithm implemented in large-eddy simulations. In both observations and large-eddy simulations, cloud thermals can be tracked throughout significant portions of their life cycles. These data can then be fit against simple parcel theories to infer the dominant balance in the momentum budget. These conclusions are then confirmed by diagnosing individual terms in the cloud-thermal momentum budget from large-eddy simulations.

  5. Enhanced Cloud Disruption by Magnetic Field Interaction.

    PubMed

    Gregori; Miniati; Ryu; Jones

    1999-12-20

    We present results from the first three-dimensional numerical simulations of moderately supersonic cloud motion through a tenuous, magnetized medium. We show that the interaction of the cloud with a magnetic field perpendicular to its motion has a great dynamical impact on the development of instabilities at the cloud surface. Even for initially spherical clouds, magnetic field lines become trapped in surface deformations and undergo stretching. The consequent field amplification that occurs there and, in particular, its variation across the cloud face then dramatically enhance the growth rate of Rayleigh-Taylor unstable modes, hastening the cloud disruption.

  6. Cloud condensation nuclei near marine stratus

    NASA Technical Reports Server (NTRS)

    Hudson, James G.; Frisbie, Paul R.

    1991-01-01

    Extensive airborne measurements of cloud condensation nucleus (CCN) spectra and concentrations of total particles, or condensation nuclei (CN), below, in, and above the stratus cloud decks off the southern California coast point to important aerosol-cloud interactions. Consistently low CCN concentrations below cloud appear to be due to cloud scavenging processes which include Brownian coagulation, nucleation, coalescence, and drizzle. The higher CCN and CN concentrations above cloud are associated with ambient ozone concentrations which suggest a link with continental, probably anthropogenic, sources, even at distances of 500 km from the California coast.

  7. Marine cloud brightening: regional applications

    PubMed Central

    Latham, John; Gadian, Alan; Fournier, Jim; Parkes, Ben; Wadhams, Peter; Chen, Jack

    2014-01-01

    The general principle behind the marine cloud brightening (MCB) climate engineering technique is that seeding marine stratocumulus clouds with substantial concentrations of roughly monodisperse sub-micrometre-sized seawater particles might significantly enhance cloud albedo and longevity, thereby producing a cooling effect. This paper is concerned with preliminary studies of the possible beneficial application of MCB to three regional issues: (1) recovery of polar ice loss, (2) weakening of developing hurricanes and (3) elimination or reduction of coral bleaching. The primary focus is on Item 1. We focus discussion herein on advantages associated with engaging in limited-area seeding, regional effects rather than global; and the levels of seeding that may be required to address changing current and near-term conditions in the Arctic. We also mention the possibility that MCB might be capable of producing a localized cooling to help stabilize the West Antarctic Ice Sheet. PMID:25404682

  8. 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.

  9. Clouds of Neptune and Uranus

    NASA Technical Reports Server (NTRS)

    Atreya, Sushil K.; Wong, Ah-San

    2005-01-01

    We present results on the bases and concentrations of methane ice, ammonia ice, ammonium hydrosulfide-solid, water ice, and aqueous-ammonia solution (droplet) clouds of Neptune and Uranus, based on an equilibrium cloud condensation model. Due to their similar p-T structures, the model results for Neptune and Uranus are similar. Assuming 30-50x solar enhancement for the condensibles species, as expected from formation models, we find that the base of the droplet cloud is at the 370 bars for 30 solar, and at 500 bars for 50 solar cases. Despite this, entry probes need to be deployed to only 50-100 bars to obtain all the critical information needed to constrain models of the formation of these planets and their atmospheres.

  10. Scientific Services on the Cloud

    NASA Astrophysics Data System (ADS)

    Chapman, David; Joshi, Karuna P.; Yesha, Yelena; Halem, Milt; Yesha, Yaacov; Nguyen, Phuong

    Scientific Computing was one of the first every applications for parallel and distributed computation. To this date, scientific applications remain some of the most compute intensive, and have inspired creation of petaflop compute infrastructure such as the Oak Ridge Jaguar and Los Alamos RoadRunner. Large dedicated hardware infrastructure has become both a blessing and a curse to the scientific community. Scientists are interested in cloud computing for much the same reason as businesses and other professionals. The hardware is provided, maintained, and administrated by a third party. Software abstraction and virtualization provide reliability, and fault tolerance. Graduated fees allow for multi-scale prototyping and execution. Cloud computing resources are only a few clicks away, and by far the easiest high performance distributed platform to gain access to. There may still be dedicated infrastructure for ultra-scale science, but the cloud can easily play a major part of the scientific computing initiative.

  11. Marine cloud brightening: regional applications.

    PubMed

    Latham, John; Gadian, Alan; Fournier, Jim; Parkes, Ben; Wadhams, Peter; Chen, Jack

    2014-12-28

    The general principle behind the marine cloud brightening (MCB) climate engineering technique is that seeding marine stratocumulus clouds with substantial concentrations of roughly monodisperse sub-micrometre-sized seawater particles might significantly enhance cloud albedo and longevity, thereby producing a cooling effect. This paper is concerned with preliminary studies of the possible beneficial application of MCB to three regional issues: (1) recovery of polar ice loss, (2) weakening of developing hurricanes and (3) elimination or reduction of coral bleaching. The primary focus is on Item 1. We focus discussion herein on advantages associated with engaging in limited-area seeding, regional effects rather than global; and the levels of seeding that may be required to address changing current and near-term conditions in the Arctic. We also mention the possibility that MCB might be capable of producing a localized cooling to help stabilize the West Antarctic Ice Sheet.

  12. Microphysical Characteristics of Tropical Clouds

    NASA Technical Reports Server (NTRS)

    Grainger, Cedric A.; Anderson, Nicholas

    2004-01-01

    This report summarizes the analysis of data collected by the University of North Dakota Citation II measurement platform during three TRMM Field measurement campaigns. The Citation II made cloud measurements during TEFLUN B in Florida, the LBA program in Brazil, and KWAJEX in Kwajalein. The work performed can be divided into two parts. The first part consisted of reformatting the Citation data into a form more easily used to compare to the satellite information. The second part consisted of examination of the cloud data in order to characterize the properties of the tropical clouds. The reformatting of the Citation data was quite labor intensive and, due to the fact that the aircraft was involved in three of the field campaigns, it required a substantial number of person-hours to complete. Much of the analysis done on the second part was done in conjunction with the thesis work of Nicholas Anderson, then a graduate student at the University of North Dakota.

  13. Equation predicts diesel cloud points

    SciTech Connect

    Tsang, C.Y.; Ker, V.S.F.; Miranda, R.D.; Wesch, J.C.

    1988-03-28

    Diesel fuel cloud points can be predicted by an empirical equation developed by NOCA/Husky Research Corp. The equation can accurately predict cloud points from feedstock and product data readily available in the refinery. The applicability of the equation to a full range of summer, winter, and arctic diesel blends was proven by studies conducted on data from four Canadian refineries that process a wide variety of conventional crude oils and synthetic crude from bitumen. Results of the studies show that the variance between equation predicted and measured cloud point values are within acceptable reproducibility of measured data. Considerable time can be saved in the refinery when the equation is used for optimizing diesel fuel blend formulations. Applicability ranges from daily blending calculations, to use in linear programs for long-term planning for distillate utilization.

  14. Geometric Effects on Electron Cloud

    SciTech Connect

    Wang, L

    2007-07-06

    The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit the machine performances by inducing beam instabilities, beam emittance increase, beam loss, vacuum pressure increases and increased heat load on the vacuum chamber wall. The electron multipacting is a kind of geometric resonance phenomenon and thus is sensitive to the geometric parameters such as the aperture of the beam pipe, beam shape and beam bunch fill pattern, etc. This paper discusses the geometric effects on the electron cloud build-up in a beam chamber and examples are given for different beams and accelerators.

  15. Collisions in the Oort Cloud

    SciTech Connect

    Stern, S.A.

    1988-03-01

    The present assessment of the consequentiality of physical collisions between Oort Cloud objects by a first-generation model indicates that natural power-law population structures produce significant numbers of collisions between each comet and smaller objects over the age of the solar system. These collisions are held to constitute a feedback mechanism for small debris production. The impacts yield extensive comet surface evolution in the cloud, in conditions where the number of small orbiting objects conforms to the standard power-law populations. 16 references.

  16. Warm/cold cloud processes

    NASA Technical Reports Server (NTRS)

    Bowdle, D. A.

    1979-01-01

    Technical assistance continued in support of the Atmospheric Cloud Physics Laboratory is discussed. A study of factors affecting warm cloud formation showed that the time of formation during an arbitrary expansion is independent of carrier gas composition for ideal gases and independent of aerosol concentration for low concentrations of very small aerosols. Equipment and procedures for gravimetric evaluation of a precision saturator were laboratory tested. A numerical feasibility study was conducted for the stable levitation of charged solution droplets by an electric field in a one-g static diffusion chamber. The concept, operating principles, applications, limits, and sensitivity of the levitation technique are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  18. GCM Simulations of Cirrus Clouds and Cloud Feedbacks

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony D.

    1998-01-01

    Cirrus clouds are a particularly uncertain component of general circulation model (GCM simulations of long-term climate change for a variety of reasons: (1) They encompass a wide range of optical thicknesses and altitudes, from thin tropopause cirrus to thick anvil cirrus that descend to the freezing level, and thus can exert both positive and negative forcing and feedback on the climate; (2) The dynamical processes that create them are poorly resolved in climate GCMs and different in the tropics and midlatitudes; (3) Predictions of their formation and microphysical properties depend on the accuracy of dynamical transports of small concentrations of water vapor to and within the upper troposphere; (4) The relative humidity conditions at which they form depends on the nature and concentration of nucleating particles and is poorly understood; (5) They are more difficult to observe than other cloud types, and hence their parameterization is more loosely constrained by available data. We will illustrate the potential sensitivity of the perturbed climate to uncertainties in cirrus cloud formulation. We will also examine the processes that form cirrus in climate models and discuss the accuracy with which climate GCMs represent these processes. We will also discuss ways in which GCM grid-scale parameterizations might be derived from cloud-scale observations. Finally, we will emphasize the types of global observations needed to constrain parameterizations of cirrus in climate GCMs.

  19. 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.

  20. A parameterization of cloud droplet nucleation

    SciTech Connect

    Ghan, S.J.; Chuang, C.C.; Penner, J.E.

    1994-01-01

    Droplet nucleation is a fundamental cloud process. The number of aerosols activated to form cloud droplets influences not only the number of aerosols scavenged by clouds but also the size of the cloud droplets. Cloud droplet size influences the cloud albedo and the conversion of cloud water to precipitation. Global aerosol models are presently being developed with the intention of coupling with global atmospheric circulation models to evaluate the influence of aerosols and aerosol-cloud interactions on climate. If these and other coupled models are to address issues of aerosol-interactions, the droplet nucleation process must be adequately represented. Ghan et al. have introduced a droplet nucleation parameterization for a single aerosol type that offers certain advantages over the popular Twomey parameterization. Here we describe the generalization of that parameterization to the case of multiple aerosol types, with estimation of aerosol mass as well as number activated.

  1. NASA Now: A-Train: Clouds

    NASA Video Gallery

    During this episode of NASA Now, you’ll meet NASA physical scientist Lin Chambers, learn about the role of clouds in the Earth's energy and water cycles, and find out how NASA collects cloud data...

  2. MedlinePlus FAQ: Search Cloud

    MedlinePlus

    ... gov/faq/searchcloud.html Question: How does the search cloud work? To use the sharing features on this page, please enable JavaScript. Answer: The search cloud displays the top 100 search terms typed ...

  3. Cloud Technology May Widen Genomic Bottleneck - TCGA

    Cancer.gov

    Computational biologist Dr. Ilya Shmulevich suggests that renting cloud computing power might widen the bottleneck for analyzing genomic data. Learn more about his experience with the Cloud in this TCGA in Action Case Study.

  4. The mass spectrum of interstellar clouds

    NASA Technical Reports Server (NTRS)

    Dickey, John M.; Garwood, Robert W.

    1989-01-01

    The abundances of diffuse clouds and molecular clouds in the inner Galaxy and at the solar circle are compared. Using results of recent low-latitude 21 cm absorption studies, the number of diffuse clouds per kiloparsec along the line of sight is derived as a function of the cloud column density, under two assumptions relating cloud densities and temperatures. The density of clouds is derived as a function of cloud mass. The results are consistent with a single, continuous mass spectrum for interstellar clouds from less than 1 solar mass to 1,000,000 solar masses, with perhaps a change of slope at masses where the atomic and molecular mass fractions are roughly equal.

  5. Reducing the uncertainty in subtropical cloud feedback

    NASA Astrophysics Data System (ADS)

    Myers, Timothy A.; Norris, Joel R.

    2016-03-01

    Large uncertainty remains on how subtropical clouds will respond to anthropogenic climate change and therefore whether they will act as a positive feedback that amplifies global warming or negative feedback that dampens global warming by altering Earth's energy budget. Here we reduce this uncertainty using an observationally constrained formulation of the response of subtropical clouds to greenhouse forcing. The observed interannual sensitivity of cloud solar reflection to varying meteorological conditions suggests that increasing sea surface temperature and atmospheric stability in the future climate will have largely canceling effects on subtropical cloudiness, overall leading to a weak positive shortwave cloud feedback (0.4 ± 0.9 W m-2 K-1). The uncertainty of this observationally based approximation of the cloud feedback is narrower than the intermodel spread of the feedback produced by climate models. Subtropical cloud changes will therefore complement positive cloud feedbacks identified by previous work, suggesting that future global cloud changes will amplify global warming.

  6. Comparison between SAGE II and ISCCP high-level clouds. 2: Locating clouds tops

    NASA Technical Reports Server (NTRS)

    Liao, Xiaohan; Rossow, William B.; Rind, David

    1995-01-01

    A comparison is made of the vertical distribution of high-level cloud tops derived from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements and from the International Satellite Cloud Climatology Project (ISCCP) for all Julys and Januarys in 1985 to 1990. The results suggest that ISCCP overestimates the pressure of high-level clouds by up to 50-150 mbar, particularly at low latitudes. This is caused by the frequent presence of clouds with diffuse tops (greater than 50% time when cloudy events are observed). The averaged vertical extent of the diffuse top is about 1.5 km. At midlatitudes where the SAGE II and ISCCP cloud top pressure agree best, clouds with distinct tops reach a maximum relative proportion of the total level cloud amount (about 30-40%), and diffuse-topped clouds are reduced to their minimum (30-40%). The ISCCP-defined cloud top pressure should be regarded not as the material physical height of the clouds but as the level which emits the same infrared radiance as observed. SAGE II and ISCCP cloud top pressures agree for clouds with distinct tops. There is also an indication that the cloud top pressures of optically thin clouds not overlying thicker clouds are poorly estimated by ISCCP at middle latitudes. The average vertical extent of these thin clouds is about 2.5 km.

  7. Mobile Cloud Learning for Higher Education: A Case Study of Moodle in the Cloud

    ERIC Educational Resources Information Center

    Wang, Minjuan; Chen, Yong; Khan, Muhammad Jahanzaib

    2014-01-01

    Mobile cloud learning, a combination of mobile learning and cloud computing, is a relatively new concept that holds considerable promise for future development and delivery in the education sectors. Cloud computing helps mobile learning overcome obstacles related to mobile computing. The main focus of this paper is to explore how cloud computing…

  8. Global aerosol effects on convective clouds

    NASA Astrophysics Data System (ADS)

    Wagner, Till; Stier, Philip

    2013-04-01

    Atmospheric aerosols affect cloud properties, and thereby the radiation balance of the planet and the water cycle. The influence of aerosols on clouds is dominated by increase of cloud droplet and ice crystal numbers (CDNC/ICNC) due to enhanced aerosols acting as cloud condensation and ice nuclei. In deep convective clouds this increase in CDNC/ICNC is hypothesised to increase precipitation because of cloud invigoration through enhanced freezing and associated increased latent heat release caused by delayed warm rain formation. Satellite studies robustly show an increase of cloud top height (CTH) and precipitation with increasing aerosol optical depth (AOD, as proxy for aerosol amount). To represent aerosol effects and study their influence on convective clouds in the global climate aerosol model ECHAM-HAM, we substitute the standard convection parameterisation, which uses one mean convective cloud for each grid column, with the convective cloud field model (CCFM), which simulates a spectrum of convective clouds, each with distinct values of radius, mixing ratios, vertical velocity, height and en/detrainment. Aerosol activation and droplet nucleation in convective updrafts at cloud base is the primary driver for microphysical aerosol effects. To produce realistic estimates for vertical velocity at cloud base we use an entraining dry parcel sub cloud model which is triggered by perturbations of sensible and latent heat at the surface. Aerosol activation at cloud base is modelled with a mechanistic, Köhler theory based, scheme, which couples the aerosols to the convective microphysics. Comparison of relationships between CTH and AOD, and precipitation and AOD produced by this novel model and satellite based estimates show general agreement. Through model experiments and analysis of the model cloud processes we are able to investigate the main drivers for the relationship between CTH / precipitation and AOD.

  9. The AppScale Cloud Platform

    PubMed Central

    Krintz, Chandra

    2013-01-01

    AppScale is an open source distributed software system that implements a cloud platform as a service (PaaS). AppScale makes cloud applications easy to deploy and scale over disparate cloud fabrics, implementing a set of APIs and architecture that also makes apps portable across the services they employ. AppScale is API-compatible with Google App Engine (GAE) and thus executes GAE applications on-premise or over other cloud infrastructures, without modification. PMID:23828721

  10. 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.

  11. Delivering Unidata Technology via the Cloud

    NASA Astrophysics Data System (ADS)

    Fisher, Ward; Oxelson Ganter, Jennifer

    2016-04-01

    Over the last two years, Docker has emerged as the clear leader in open-source containerization. Containerization technology provides a means by which software can be pre-configured and packaged into a single unit, i.e. a container. This container can then be easily deployed either on local or remote systems. Containerization is particularly advantageous when moving software into the cloud, as it simplifies the process. Unidata is adopting containerization as part of our commitment to migrate our technologies to the cloud. We are using a two-pronged approach in this endeavor. In addition to migrating our data-portal services to a cloud environment, we are also exploring new and novel ways to use cloud-specific technology to serve our community. This effort has resulted in several new cloud/Docker-specific projects at Unidata: "CloudStream," "CloudIDV," and "CloudControl." CloudStream is a docker-based technology stack for bringing legacy desktop software to new computing environments, without the need to invest significant engineering/development resources. CloudStream helps make it easier to run existing software in a cloud environment via a technology called "Application Streaming." CloudIDV is a CloudStream-based implementation of the Unidata Integrated Data Viewer (IDV). CloudIDV serves as a practical example of application streaming, and demonstrates how traditional software can be easily accessed and controlled via a web browser. Finally, CloudControl is a web-based dashboard which provides administrative controls for running docker-based technologies in the cloud, as well as providing user management. In this work we will give an overview of these three open-source technologies and the value they offer to our community.

  12. Polar stratospheric clouds and ozone depletion

    SciTech Connect

    Toon, O.B. ); Turco, R.P. )

    1991-06-01

    During the Antarctic winter, strange and often invisible clouds form in the stratosphere over the pole. These clouds of ice and frozen nitric acid play a crucial role in the chemical cycle responsible for the recent appearance of the annual ozone hole. Their chemistry removes compounds that would normally trap ozone-destroying free chlorine produced by the breakdown of CFCs. The paper describes these clouds, their formation, and the mechanisms by which these clouds help chlorine destroy ozone.

  13. Clouds caused by human activities: the anthropoclouds

    NASA Astrophysics Data System (ADS)

    Mazon, Jordi; Costa, Marcel; Pino, David; Lorente, Jeroni

    2013-04-01

    The classification of clouds is based on the pioneering classification carried out by Howard (1804). In this classification, and also in the successive editions of the International Classification of Clouds published by the World Meteorological Organization (WMO, 1975, 1987) 10 basic cloud genera are included and described. In all cases, the cause that leads to the formation of clouds remains as a secondary issue. It is assumed that all of them are exclusively produced by natural mechanisms without any human intervention. However, aerosol and water vapour emissions produced by human activity may increase cloud formation having an increasing importance in the atmospheric energy budget and consequently in the earth's climate. Effectively, since the end of the Nineteenth century, human activity has been injecting large amounts of water vapour into the atmosphere, cloud condensation nuclei and hot air mainly generated in the combustion processes that under certain spatial and temporal conditions can enhance cloud formation. These anthropogenic aerosols are linked to the climate and the water cycle (Kaufman et al, 2002). The aim of this communication is to point out the anthropic origin of some clouds in the cloud classification. Several cases of the 7 basic genera cloud caused by human activities will be shown to discuss the importance of differentiating the origin of clouds in weather observations. This differentiation would improve the understanding the contribution of these clouds to climate change. To differentiate the clouds formed by human activity, we propose to use the prefix anthropo- before the scientific name (and a- before the abbreviation) in some of the 10 basic clouds defined by the International Classification of Clouds, those which could have an anthropic origin, and thus begin new data of cloud observations that could help future research to improve the effect of human activity in the troposphere.

  14. Microphysics of Exoplanet Clouds and Hazes

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Benneke, Björn; Knutson, Heather; Yung, Yuk

    2015-12-01

    Clouds and hazes are ubiquitous in the atmospheres of exoplanets. However, as most of these planets have temperatures between 600 and 2000 K, their clouds and hazes are likely composed of exotic condensates such as silicates, metals, and salts. We currently lack a satisfactory understanding of the microphysical processes that govern the distribution of these clouds and hazes, thus creating a gulf between the cloud properties retrieved from observations and the cloud composition predictions from condensation equilibrium models. In this work we present a 1D microphysical cloud model that calculates, from first principles, the rates of condensation, evaporation, coagulation, and vertical transport of chemically mixed cloud and haze particles in warm and hot exoplanet atmospheres. The model outputs the equilibrium number density of cloud particles with altitude, the particle size distribution, and the chemical makeup of the cloud particles as a function of altitude and particle mass. The model aims to (1) explain the observed variability in “cloudiness” of individual exoplanets, (2) assess whether the proposed cloud materials are capable of forming the observed particle distributions, and (3) examine the role clouds have in the transport of (cloud-forming) heavy elements in exoplanet atmospheres.

  15. Microphysics of Exoplanet Clouds and Hazes

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Benneke, Björn; Knutson, Heather; Yung, Yuk

    2016-01-01

    Clouds and hazes are ubiquitous in the atmospheres of exoplanets. However, as most of these planets have temperatures between 600 and 2000 K, their clouds and hazes are likely composed of exotic condensates such as silicates, metals, and salts. We currently lack a satisfactory understanding of the microphysical processes that govern the distribution of these clouds and hazes, thus creating a gulf between the cloud properties retrieved from observations and the cloud composition predictions from condensation equilibrium models. In this work we present a 1D microphysical cloud model that calculates, from first principles, the rates of condensation, evaporation, coagulation, and vertical transport of chemically mixed cloud and haze particles in warm and hot exoplanet atmospheres. The model outputs the equilibrium number density of cloud particles with altitude, the particle size distribution, and the chemical makeup of the cloud particles as a function of altitude and particle mass. The model aims to (1) explain the observed variability in "cloudiness" of individual exoplanets, (2) assess whether the proposed cloud materials are capable of forming the observed particle distributions, and (3) examine the role clouds have in the transport of (cloud-forming) heavy elements in exoplanet atmospheres.

  16. Microphysics of Exoplanet Clouds and Hazes

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Benneke, Björn; Knutson, Heather A.; Yung, Yuk L.

    2015-11-01

    Clouds and hazes are ubiquitous in the atmospheres of exoplanets. However, as most of these planets have temperatures between 600 and 2000 K, their clouds and hazes are likely composed of exotic condensates such as silicates, metals, and salts. We currently lack a satisfactory understanding of the microphysical processes that govern the distribution of these clouds and hazes, thus creating a gulf between the cloud properties retrieved from observations and the cloud composition predictions from condensation equilibrium models. In this work we present a 1D microphysical cloud model that calculates, from first principles, the rates of condensation, evaporation, coagulation, and vertical transport of chemically mixed cloud and haze particles in warm and hot exoplanet atmospheres. The model outputs the equilibrium number density of cloud particles with altitude, the particle size distribution, and the chemical makeup of the cloud particles as a function of altitude and particle mass. The model aims to (1) explain the observed variability in “cloudiness” of individual exoplanets, (2) assess whether the proposed cloud materials are capable of forming the observed particle distributions, and (3) examine the role clouds have in the transport of (cloud-forming) heavy elements in exoplanet atmospheres.

  17. The Mixed-Phase Arctic Cloud Experiment.

    SciTech Connect

    Verlinde, J.; Harrington, Jerry Y.; McFarquhar, Greg; Yannuzzi, V. T.; Avramov, Alexander; Greenburg, S.; Johnson, N.; Zhang, G.; Poellot, Michael; Mather, Jim H.; Turner, David D.; Eloranta, E. W.; Zak, Bernard D.; Prenni, Anthony J.; Daniel, J. S.; Kok, G. L.; Tobin, D. C.; Holz, R. E.; Sassen, Kenneth; Spangenberg, D.; Minnis, Patrick; Tooman, Tim P.; Ivey, Mark D.; Richardson, S. J.; Bahrmann, C. P.; Shupe, Matthew D.; DeMott, Paul J.; Heymsfield, Andrew J.; Schofield, R.

    2007-02-01

    In order to help bridge the gaps in our understanding of mixed-phase Arctic clouds, the Department of Energy Atmospheric Radiation Measurement Program (DOE-ARM) funded an integrated, systematic observational study. The major objective of the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted September 27–October 22, 2004 during the autumnal transition season, was to collect a focused set of observations needed to advance our understanding of the cloud microphysics, cloud dynamics, thermodynamics, radiative properties, and evolution of Arctic mixed-phase clouds. These data would then be used to improve to both detailed models of Arctic clouds and large-scale climate models. M-PACE successfully documented the microphysical structure of arctic mixed-phase clouds, with multiple in situ profiles in both single-layer and multi-layer clouds, over the two ground-based remote sensing sites at Barrow and Oliktok Point. Liquid was found in clouds with temperatures down to -30C, the coldest cloud top temperature below -40C sampled by the aircraft. The remote sensing instruments suggest that ice was present in low concentrations, mostly concentrated in precipitation shafts, although there are indications of light ice precipitation present below the optically thick single-layer clouds. Flights into arctic cirrus clouds revealed microphysics properties very similar to their mid-latitude in situ formed cousins, with dominant ice crystal habit bullet rosettes.

  18. MISR Level 3 Cloud Motion Vector

    Atmospheric Science Data Center

    2013-07-10

    MISR Level 3 Cloud Motion Vector Level 3 Wednesday, November 7, 2012 ... A new version, F02_0002, of the MISR L3 CMV (Cloud Motion Vector) data product is now available. This new release provides finer ... coverage. These enhancements are the result of reorganizing motion vector information present in the recent Level 2 Cloud product as ...

  19. Digital cloud stereography from geostationary orbit

    NASA Technical Reports Server (NTRS)

    Dalton, J. T.; Desjardins, M. L.; Hasler, A. F.; Minzner, R. A.

    1979-01-01

    It has been demonstrated that geostationary satellite imagery provides an effective means of extracting two-dimensional cloud motion wind measurements over large areas. The addition of cloud height information is necessary, however, for the proper assignment of altitude to the wind vectors. This paper discusses the methodology and accuracy of extracting multilevel cloud motion measurements from stereo digital imagery acquired from geostationary orbit.

  20. Anomalous scaling of cumulus cloud boundaries

    PubMed

    Siebesma; Jonker

    2000-07-01

    The geometrical properties of cumulus clouds modeled by a numerical technique called large-eddy simulation are investigated. Surface-volume analyses reconfirm previous scaling results based on satellite data. This technique allows for the first time a direct analysis of the scaling behavior of cloud boundaries of individual clouds.

  1. Simple Cloud Chambers Using Gel Ice Packs

    ERIC Educational Resources Information Center

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

  2. Cloud Computing. Technology Briefing. Number 1

    ERIC Educational Resources Information Center

    Alberta Education, 2013

    2013-01-01

    Cloud computing is Internet-based computing in which shared resources, software and information are delivered as a service that computers or mobile devices can access on demand. Cloud computing is already used extensively in education. Free or low-cost cloud-based services are used daily by learners and educators to support learning, social…

  3. The Education Value of Cloud Computing

    ERIC Educational Resources Information Center

    Katzan, Harry, Jr.

    2010-01-01

    Cloud computing is a technique for supplying computer facilities and providing access to software via the Internet. Cloud computing represents a contextual shift in how computers are provisioned and accessed. One of the defining characteristics of cloud software service is the transfer of control from the client domain to the service provider.…

  4. Introducing Cloud Computing Topics in Curricula

    ERIC Educational Resources Information Center

    Chen, Ling; Liu, Yang; Gallagher, Marcus; Pailthorpe, Bernard; Sadiq, Shazia; Shen, Heng Tao; Li, Xue

    2012-01-01

    The demand for graduates with exposure in Cloud Computing is on the rise. For many educational institutions, the challenge is to decide on how to incorporate appropriate cloud-based technologies into their curricula. In this paper, we describe our design and experiences of integrating Cloud Computing components into seven third/fourth-year…

  5. Cloud manufacturing: from concept to practice

    NASA Astrophysics Data System (ADS)

    Ren, Lei; Zhang, Lin; Tao, Fei; Zhao, Chun; Chai, Xudong; Zhao, Xinpei

    2015-02-01

    The concept of cloud manufacturing is emerging as a new promising manufacturing paradigm, as well as a business model, which is reshaping the service-oriented, highly collaborative, knowledge-intensive and eco-efficient manufacturing industry. However, the basic concepts about cloud manufacturing are still in discussion. Both academia and industry will need to have a commonly accepted definition of cloud manufacturing, as well as further guidance and recommendations on how to develop and implement cloud manufacturing. In this paper, we review some of the research work and clarify some fundamental terminologies in this field. Further, we developed a cloud manufacturing systems which may serve as an application example. From a systematic and practical perspective, the key requirements of cloud manufacturing platforms are investigated, and then we propose a cloud manufacturing platform prototype, MfgCloud. Finally, a public cloud manufacturing system for small- and medium-sized enterprises (SME) is presented. This paper presents a new perspective for cloud manufacturing, as well as a cloud-to-ground solution. The integrated solution proposed in this paper, including the terminology, MfgCloud, and applications, can push forward this new paradigm from concept to practice.

  6. Scaling the CERN OpenStack cloud

    NASA Astrophysics Data System (ADS)

    Bell, T.; Bompastor, B.; Bukowiec, S.; Castro Leon, J.; Denis, M. K.; van Eldik, J.; Fermin Lobo, M.; Fernandez Alvarez, L.; Fernandez Rodriguez, D.; Marino, A.; Moreira, B.; Noel, B.; Oulevey, T.; Takase, W.; Wiebalck, A.; Zilli, S.

    2015-12-01

    CERN has been running a production OpenStack cloud since July 2013 to support physics computing and infrastructure services for the site. In the past year, CERN Cloud Infrastructure has seen a constant increase in nodes, virtual machines, users and projects. This paper will present what has been done in order to make the CERN cloud infrastructure scale out.

  7. In situ exhaust cloud measurements. [particle size distribution and cloud physics of rocket exhaust clouds

    NASA Technical Reports Server (NTRS)

    Wornom, D.

    1980-01-01

    Airborne in situ exhaust cloud measurements were conducted to obtain definitions of cloud particle size range, Cl2 content, and HCl partitioning. Particle size distribution data and Cl2 measurements were made during the May, August, and September 1977 Titan launches. The measurements of three basic effluents - HCl, NO sub X, and particles - against minutes after launch are plotted. The maximum observed HCl concentration to the maximum Cl2 concentration are compared and the ratios of the Cl2 to the HCl is calculated.

  8. Can cirrus clouds produce glories?

    PubMed

    Sassen, K; Arnott, W P; Barnett, J M; Aulenbach, S

    1998-03-20

    A vague glory display was photographed over central Utah from an airplane beginning its descent through a cirrus cloud layer with an estimated cloud top temperature of -45 and -55 degrees C. Photographic analysis reveals a single reddish-brown ring of 2.5-3.0 degrees radius around the antisolar point, although a second ring appeared visually to have been present over the brief observation period. Mie and approximate nonspherical theory scattering simulations predict a population of particles with modal diameters between 9 and 15 mum. Although it is concluded that multiple-ringed glories can be accounted for only through the backscattering of light from particles that are strictly spherical in shape, the poor glory colorization in this case could imply the presence of slightly aspherical ice particles. The location of this display over mountainous terrain suggests that it was generated by an orographic wave cloud, which we speculate produced numerous frozen cloud droplets that only gradually took on crystalline characteristics during growth.

  9. The Oort cloud in transition

    NASA Technical Reports Server (NTRS)

    Weissman, P. R.

    1986-01-01

    The evolution of theoretical and empirical models of the Oort cloud (OC) since it was first proposed by Oort in 1950 is traced, and the main features of current models are discussed, in a general review. Consideration is given to work on the classical OC (Monte Carlo simulations of OC evolution, population and mass estimates, and OC perturbation by passing stars and giant molecular clouds), models of a massive inner OC (simulations of planetesimal-swarm evolution in the Uranus-Neptune zone and IRAS observations of circumstellar dust shells), evidence for random and/or periodic comet showers, and the possible role of the Galactic missing mass. The current OC model comprises an almost spherical outer (10,000-100,000-AU) cloud of mass 7-8 earth mass and population (1.4-2.3) x 10 to the 12th, and a flat disklike inner (40-10,000 AU) cloud of mass 100-200 earth mass and population (1-10) x 10 to the 13th.

  10. Space shuttle exhaust cloud properties

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Keller, V. W.

    1983-01-01

    A data base describing the properties of the exhaust cloud produced by the launch of the Space Transportation System and the acidic fallout observed after each of the first four launches was assembled from a series of ground and aircraft based measurements made during the launches of STS 2, 3, and 4. Additional data were obtained from ground-based measurements during firings of the 6.4 percent model of the Solid Rocket Booster at the Marshall Center. Analysis indicates that the acidic fallout is produced by atomization of the deluge water spray by the rocket exhaust on the pad followed by rapid scavening of hydrogen chloride gas aluminum oxide particles from the Solid Rocket Boosters. The atomized spray is carried aloft by updrafts created by the hot exhaust and deposited down wind. Aircraft measurements in the STS-3 ground cloud showed an insignificant number of ice nuclei. Although no measurements were made in the column cloud, the possibility of inadvertent weather modification caused by the interaction of ice nuclei with natural clouds appears remote.

  11. The CloudSat Mission

    NASA Technical Reports Server (NTRS)

    Vane, D.; Stephens, G.

    2000-01-01

    CloudSat is an international mission, made possible by partnerships and contributions from the Canadian Space Agency, the U.S. Air Force, the Communications Research Laboratory of Japan, the U.S. Department of Energy, and research institutions in the USA, Japan, Canada and Europe.

  12. HPC on Competitive Cloud Resources

    NASA Astrophysics Data System (ADS)

    Bientinesi, Paolo; Iakymchuk, Roman; Napper, Jeff

    Computing as a utility has reached the mainstream. Scientists can now easily rent time on large commercial clusters that can be expanded and reduced on-demand in real-time. However, current commercial cloud computing performance falls short of systems specifically designed for scientific applications. Scientific computing needs are quite different from those of the web applications that have been the focus of cloud computing vendors. In this chapter we demonstrate through empirical evaluation the computational efficiency of high-performance numerical applications in a commercial cloud environment when resources are shared under high contention. Using the Linpack benchmark as a case study, we show that cache utilization becomes highly unpredictable and similarly affects computation time. For some problems, not only is it more efficient to underutilize resources, but the solution can be reached sooner in realtime (wall-time). We also show that the smallest, cheapest (64-bit) instance on the studied environment is the best for price to performance ration. In light of the high-contention we witness, we believe that alternative definitions of efficiency for commercial cloud environments should be introduced where strong performance guarantees do not exist. Concepts like average, expected performance and execution time, expected cost to completion, and variance measures--traditionally ignored in the high-performance computing context--now should complement or even substitute the standard definitions of efficiency.

  13. Fast-response cloud chamber

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.

    1977-01-01

    Wall structure keeps chambers at constant, uniform temperature, yet allows them to be cooled rapidly if necessary. Wall structure, used in fast-response cloud chamber, has surface heater and coolant shell separated by foam insulation. It is lightweight and requires relatively little power.

  14. Optical pulse propagation through clouds.

    PubMed

    Matter, J C; Bradley, R G

    1981-02-15

    The cloud impulse response (spatial and temporal) to optical pulse propagation has been measured. Experimental data are reported for the radiance function, pulse stretching, and (the first published) delay time. The results have been confirmed by Monte Carlo modeling. A geometric scattering model is presented explaining the temporal results for the test conditions.

  15. Optical pulse propagation through clouds.

    PubMed

    Matter, J C; Bradley, R G

    1981-07-01

    The cloud impulse response (spatial and temporal) to optical pulse propagation has been measured. Experimental data are reported for the radiance function, pulse stretching, and (the first published) delay time. The results have been confirmed by Monte Carlo modeling. A geometric scattering model is presented explaining the temporal results for the test conditions.

  16. More than a Word Cloud

    ERIC Educational Resources Information Center

    Filatova, Olga

    2016-01-01

    Word cloud generating applications were originally designed to add visual attractiveness to posters, websites, slide show presentations, and the like. They can also be an effective tool in reading and writing classes in English as a second language (ESL) for all levels of English proficiency. They can reduce reading time and help to improve…

  17. Violent relaxation of ellipsoidal clouds

    NASA Astrophysics Data System (ADS)

    Benhaiem, David; Sylos Labini, Francesco

    2015-04-01

    An isolated, initially cold and ellipsoidal cloud of self-gravitating particles represents a relatively simple system in which to study the effects of deviations from spherical symmetry in the mechanism of violent relaxation. Initial deviations from spherical symmetry are shown to play a dynamical role that is equivalent to that of density fluctuations in the case of an initially spherical cloud. Indeed, these deviations control the amount of particle-energy change and thus determine the properties of the final energy distribution, particularly the appearance of two species of particles: bound and free. Ejection of mass and energy from the system, together with the formation of a density profile decaying as ρ(r) ˜ r-4 and a Keplerian radial velocity dispersion profile, are prominent features similar to those observed after the violent relaxation of spherical clouds. In addition, we find that ejected particles are characterized by highly non-spherical shapes, the features of which can be traced in the initial deviations from spherical symmetry that are amplified during the dynamical evolution: particles can indeed form anisotropic configurations, like bars and/or discs, even though the initial cloud was very close to spherical.

  18. Clouds Dominate the Galactic Halo

    NASA Astrophysics Data System (ADS)

    2003-01-01

    Using the exquisite sensitivity of the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT), astronomer Jay Lockman of the National Radio Astronomy Observatory (NRAO) in Green Bank, W. Va., has produced the best cross-section ever of the Milky Way Galaxy's diffuse halo of hydrogen gas. This image confirms the presence of discrete hydrogen clouds in the halo, and could help astronomers understand the origin and evolution of the rarefied atmosphere that surrounds our Galaxy. Lockman presented his findings at the American Astronomical Society meeting in Seattle, WA. Hydrogen Clouds Graphic Artist's Rendering of the Milky Way (background) with insert showing GBT image of cross-section of neutral atomic Hydrogen Credit: Kirk Woellert/National Science Foundation Patricia Smiley, NRAO. "The first observations with the Green Bank Telescope suggested that the hydrogen in the lower halo, the transition zone between the Milky Way and intergalactic space, is very clumpy," said Lockman. "The latest data confirm these results and show that instead of trailing away smoothly from the Galactic plane, a significant fraction of the hydrogen gas in the halo is concentrated in discrete clouds. There are even some filaments." Beyond the star-filled disk of the Milky Way, there exists an extensive yet diffuse halo of hydrogen gas. For years, astronomers have speculated about the origin and structure of this gas. "Even the existence of neutral hydrogen in the halo has been somewhat of a puzzle," Lockman remarked. "Unlike the Earth's atmosphere, which is hot enough to hold itself up against the force of gravity, the hydrogen in the halo is too cool to support itself against the gravitational pull of the Milky Way." Lockman points out that some additional factor has to be involved to get neutral hydrogen to such large distances from the Galactic plane. "This force could be cosmic rays, a supersonic wind, the blast waves from supernovae, or something we have not thought of

  19. The "Mushroom Cloud" Demonstration Revisited

    ERIC Educational Resources Information Center

    Panzarasa, Guido; Sparnacci, Katia

    2013-01-01

    A revisitation of the classical "mushroom cloud" demonstration is described. Instead of aniline and benzoyl peroxide, the proposed reaction involves household chemicals such as alpha-pinene (turpentine oil) and trichloroisocyanuric acid ("Trichlor") giving an impressive demonstration of oxidation and combustion reactions that…

  20. Cloud-Based Data Storage

    ERIC Educational Resources Information Center

    Waters, John K.

    2011-01-01

    The vulnerability and inefficiency of backing up data on-site is prompting school districts to switch to more secure, less troublesome cloud-based options. District auditors are pushing for a better way to back up their data than the on-site, tape-based system that had been used for years. About three years ago, Hendrick School District in…

  1. Ground cloud air quality effects

    NASA Technical Reports Server (NTRS)

    Brubaker, K. L.

    1980-01-01

    The effects of the ground cloud associated with launching of a large rocket on air quality are discussed. The ground cloud consists of the exhaust emitted by the rocket during the first 15 to 25 seconds following ignition and liftoff, together with a large quantity of entrained air, cooling water, dust and other debris. Immediately after formation, the ground cloud rises in the air due to the buoyant effect of its high thermal energy content. Eventually, at an altitude typically between 0.7 and 3 km, the cloud stabilizes and is carried along by the prevailing wind at that altitude. For the use of heavy lift launch vehicles small quantities of nitrogen oxides, primarily nitric oxide and nitrogen dioxide, are expected to be produced from a molecular nitrogen impurity in the fuel or liquid oxygen, or from entrainment and heating of ambient air in the hot rocket exhaust. In addition, possible impurities such as sulfur in the fuel would give rise to a corresponding amount of oxidation products such as sulfur dioxide.

  2. Study Pollution Impacts on Upper-Tropospheric Clouds with Aura, CloudSat, and CALIPSO Data

    NASA Technical Reports Server (NTRS)

    Wu, Dong

    2007-01-01

    This viewgraph presentation reviews the impact of pollution on clouds in the Upper Troposphere. Using the data from the Aura Microwave Limb Sounder (MLS), CloudSat, CALIPSO the presentation shows signatures of pollution impacts on clouds in the upper troposphere. The presentation demonstrates the complementary sensitivities of MLS , CloudSat and CALIPSO to upper tropospheric clouds. It also calls for careful analysis required to sort out microphysical changes from dynamical changes.

  3. CaFe interstellar clouds

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Kozak, M.; Gnaciński, P.; Galazutdinov, G. A.; Beletsky, Y.; Krełowski, J.

    2007-07-01

    A new kind of interstellar cloud is proposed. These are rare (just a few examples among ~300 lines of sight) objects with the CaI 4227-Å, FeI 3720-Å and 3860-Å lines stronger than those of KI (near 7699 Å) and NaI (near 3302 Å). We propose the name `CaFe' for these clouds. Apparently they occupy different volumes from the well-known interstellar HI clouds where the KI and ultraviolet NaI lines are dominant features. In the CaFe clouds we have not found either detectable molecular features (CH, CN) or diffuse interstellar bands which, as commonly believed, are carried by some complex, organic molecules. We have found the CaFe clouds only along sightlines toward hot, luminous (and thus distant) objects with high rates of mass loss. In principle, the observed gas-phase interstellar abundances reflect the combined effects of the nucleosynthetic history of the material, the depletion of heavy elements into dust grains and the ionization state of these elements which may depend on irradiation by neighbouring stars. Based on data collected using the Maestro spectrograph at the Terskol 2-m telescope, Russia; and on data collected using the ESO Feros spectrograph; and on data obtained from the ESO Science Archive Facility acquired with the UVES spectrograph, Chile. E-mail: `arctur'@rambler.ru (AB); marizak@astri.uni.torun.pl (MK); pg@iftia.univ.gda.pl (PG); gala@boao.re.kr (GAG); ybialets@eso.org (YB); jacek@astri.uni.torun.pl (JK)

  4. Comparison of different cloud types from surface and satellite cloud classification products over China

    NASA Astrophysics Data System (ADS)

    Wang, Minyan; Zeng, Le; Wang, Shengjie; Gu, Junxia; Yang, Runzhi

    2016-04-01

    Different cloud types usually have different cloud dynamic process and micro-physical characteristics, and the relative cloud radiation forcing effects vary much. In recent years, the focus of cloud classification is the algorithm development, as well as the analysis on total cloud amount, high/middle/low cloud amount. While, research on the different cloud types (like cirrus, stratus, and cumulonimbus) is not enough. In this research, we use multi-resources cloud classification products including FY-2, Cloudsat and surface observation to obtain the temporal-spatial distribution characteristics and evolvement of different cloud types in different regions of China, analyze the quantitative difference of multi-source products and the reasons. According to the temporal and spatial scales of cloud, and temporal-spatial representation of cloud classification products based on CloudSat, etc, the scaling is necessary to explore in temporal-spatial matching/validation research. This research have important scientific significances on understanding the regional characteristics of different cloud types in China, improving the remote sensing retrieve algorithms on cloud classification, temporal-spatial matching/validation techniques of satellite data, and cloud vertical structure parameterized methods in numerical models.

  5. Comparison of IR and Visible Cloud Imagers

    NASA Astrophysics Data System (ADS)

    Mandeville, W.; McLaughlin, T.; Bygren, S.; Randell, C.

    This paper presents a comparison between the Infrared Cloud Imager (IRCI) used at Ground-based Electro-Optical Deep Space Surveillance (GEODSS) sites and the Visible Cloud Imager (VCI) developed using a COTS all-sky camera. The cloud imagers are used to create exclusion maps for GEODSS observations based on detected cloud locations. Excluding observation attempts in obscured areas of the sky is done to improve the allocation of sensor resources. Estimates are made for atmospheric extinction across the entire sky by comparing known star brightness to measured brightness. Data for the comparison were collected at the GEODSS test site located in Yoder, Colorado for a variety of cloud conditions.

  6. Cloud manufacturing: a new manufacturing paradigm

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Luo, Yongliang; Tao, Fei; Li, Bo Hu; Ren, Lei; Zhang, Xuesong; Guo, Hua; Cheng, Ying; Hu, Anrui; Liu, Yongkui

    2014-03-01

    Combining with the emerged technologies such as cloud computing, the Internet of things, service-oriented technologies and high performance computing, a new manufacturing paradigm - cloud manufacturing (CMfg) - for solving the bottlenecks in the informatisation development and manufacturing applications is introduced. The concept of CMfg, including its architecture, typical characteristics and the key technologies for implementing a CMfg service platform, is discussed. Three core components for constructing a CMfg system, i.e. CMfg resources, manufacturing cloud service and manufacturing cloud are studied, and the constructing method for manufacturing cloud is investigated. Finally, a prototype of CMfg and the existing related works conducted by the authors' group on CMfg are briefly presented.

  7. Diffuse cloud chemistry. [in interstellar matter

    NASA Technical Reports Server (NTRS)

    Van Dishoeck, Ewine F.; Black, John H.

    1988-01-01

    The current status of models of diffuse interstellar clouds is reviewed. A detailed comparison of recent gas-phase steady-state models shows that both the physical conditions and the molecular abundances in diffuse clouds are still not fully understood. Alternative mechanisms are discussed and observational tests which may discriminate between the various models are suggested. Recent developments regarding the velocity structure of diffuse clouds are mentioned. Similarities and differences between the chemistries in diffuse clouds and those in translucent and high latitude clouds are pointed out.

  8. Transfer of infrared radiation through clouds.

    PubMed

    Kuhn, P M; Weickmann, H K; Lojko, M J; Stearns, L P

    1974-03-01

    Calculations of radiative through and resulting ir cooling of cloud forms is certainly more difficult than observations. Based on observations, a radiative transfer model has been developed for absorption in clouds employing an observationally determined volume absorption coefficient, ranging from 0.0005 to 0.0007 cm(-1). This model does not require any assumption of cloud blackness or thickness and permits clouds to remain partially transparent or opaque as their thickness and absorption dictate. Agreement within a standard deviation of 12.0 W m(-2) between observation and calculation has been maintained in approximately twenty profiles through clouds. The standard deviation was determined from some 140 observations.

  9. Chemical abundances in cold, dark interstellar clouds.

    PubMed

    Irvine, W M; Ohishi, M; Kaifu, N

    1991-05-01

    The Sun may well have formed in the type of interstellar cloud currently referred to as a cold, dark cloud. We present current tabulations of the totality of known interstellar molecules and of the subset which have been identified in cold clouds. Molecular abundances are given for two such clouds which show interesting chemical differences in spite of strong physical similarities, Taurus Molecular Cloud 1 (TMC-1) and Lynd's 134N (L134N, also referred to as L183). These regions may be at different evolutionary stages.

  10. Transitioning ISR architecture into the cloud

    NASA Astrophysics Data System (ADS)

    Lash, Thomas D.

    2012-06-01

    Emerging cloud computing platforms offer an ideal opportunity for Intelligence, Surveillance, and Reconnaissance (ISR) intelligence analysis. Cloud computing platforms help overcome challenges and limitations of traditional ISR architectures. Modern ISR architectures can benefit from examining commercial cloud applications, especially as they relate to user experience, usage profiling, and transformational business models. This paper outlines legacy ISR architectures and their limitations, presents an overview of cloud technologies and their applications to the ISR intelligence mission, and presents an idealized ISR architecture implemented with cloud computing.

  11. Potential New Lidar Observations for Cloud Studies

    NASA Technical Reports Server (NTRS)

    Winker, Dave; Hu, Yong; Narir, Amin; Cai, Xia

    2015-01-01

    The response of clouds to global warming represents a major uncertainty in estimating climate sensitivity. These uncertainties have been tracked to shallow marine clouds in the tropics and subtropics. CALIOP observations have already been used extensively to evaluate model predictions of shallow cloud fraction and top height (Leahy et al. 2013; Nam et al 2012). Tools are needed to probe the lowest levels of the troposphere. The large footprint of satellite lidars gives large multiple scattering from clouds which presents new possibilities for cloud retrievals to constrain model predictions.

  12. Precipitating Condensation Clouds in Substellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Ackerman, Andrew S.; Marley, Mark S.; Gore, Warren J. (Technical Monitor)

    2000-01-01

    We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and precipitation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with previous methods. An adjustable parameter describing the efficiency of precipitation allows the new model to span the range of predictions from previous models. Calculations for the Jovian ammonia cloud are found to be consistent with observational constraints. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet.

  13. Separating Cloud Forming Nuclei from Interstitial Aerosol

    SciTech Connect

    Kulkarni, Gourihar R.

    2012-09-12

    It has become important to characterize the physicochemical properties of aerosol that have initiated the warm and ice clouds. The data is urgently needed to better represent the aerosol-cloud interaction mechanisms in the climate models. The laboratory and in-situ techniques to separate precisely the aerosol particles that act as cloud condensation nuclei (CCN) and ice nuclei (IN), termed as cloud nuclei (CN) henceforth, have become imperative in studying aerosol effects on clouds and the environment. This review summarizes these techniques, design considerations, associated artifacts and challenges, and briefly discusses the need for improved designs to expand the CN measurement database.

  14. Cloud feedback on climate change and variability

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Dessler, A. E.; Yang, P.

    2014-12-01

    Cloud feedback on climate change and variability follow similar mechanism in climate models, and the magnitude of cloud feedback on climate change and variability are well correlated among models. Therefore, the cloud feedback on short-term climate fluctuations correlates with the equilibrium climate sensitivity in climate models. Using this correlation and the observed short-term climate feedback, we infer a climate sensitivity of ~2.9K. The cloud response to inter-annual surface warming is generally consistent in observations and climate models, except for the tropical boundary-layer low clouds.

  15. A Study to Investigate Cloud Feedback Processes and Evaluate GCM Cloud Variations Using Statistical Cloud Property Composites From ARM Data

    SciTech Connect

    George Tselioudis

    2009-08-11

    The representation of clouds in Global Climate Models (GCMs) remains a major source of uncertainty in climate change simulations. Cloud climatologies have been widely used to either evaluate climate model cloud fields or examine, in combination with other data sets, climate-scale relationships between cloud properties and dynamical or microphysical parameters. Major cloud climatologies have been based either on satellite observations of cloud properties or on surface observers views of cloud type and amount. Such data sets provide either the top-down view of column-integrated cloud properties (satellites) or the bottom-up view of the cloud field morphology (surface observers). Both satellite-based and surface cloud climatologies have been successfully used to examine cloud properties, to support process studies, and to evaluate climate and weather models. However, they also present certain limitations, since the satellite cloud types are defined using radiative cloud boundaries and surface observations are based on cloud boundaries visible to human observers. As a result, these data sets do not resolve the vertical distribution of cloud layers, an issue that is important in calculating both the radiative and the hydrologic effects of the cloud field. Ground-based cloud radar observations, on the other hand, resolve with good accuracy the vertical distribution of cloud layers and could be used to produce cloud type climatologies with vertical layering information. However, these observations provide point measurements only and it is not immediately clear to what extent they are representative of larger regimes. There are different methods that can be applied to minimize this problem and to produce cloud layering climatologies useful for both cloud process and model evaluation studies. If a radar system is run continuously over a number of years, it eventually samples a large number of dynamical and microphysical regimes. If additional data sets are used to put the

  16. Cloud supersaturations from CCN spectra Hoppel minima

    NASA Astrophysics Data System (ADS)

    Hudson, James G.; Noble, Stephen; Tabor, Samantha

    2015-04-01

    High-resolution cloud condensation nucleus (CCN) spectral measurements in two aircraft field projects, Marine Stratus/Stratocumulus Experiment (MASE) and Ice in Clouds Experiment-Tropical (ICE-T), often showed bimodality that had previously been observed in submicrometer aerosol size distributions obtained by differential mobility analyzers. However, a great deal of spectral shape variability from very bimodal to very monomodal was observed in close proximity. Cloud supersaturation (S) estimates based on critical S, Sc, at minimal CCN concentrations between two modes (Hoppel minima) were ascertained for 63% of 325 measured spectra. These cloud S were lower than effective S (Seff) determined by comparing ambient CCN spectra with nearby cloud droplet concentrations (Nc). Averages for the polluted MASE stratus were 0.15 and 0.23% and for the cumulus clouds of ICE-T 0.44 and 1.03%. This cloud S disagreement between the two methods might in part be due to the fact that Hoppel minima include the effects of cloud processing, which push CCN spectra toward lower S. Furthermore, there is less cloud processing by the smaller cloud droplets, which might be related to smaller droplets evaporating more readily. Significantly lower concentrations within the more bimodal spectra compared with the monomodal spectra indicated active physical processes: Brownian capture of interstitial CCN and droplet coalescence. Chemical cloud processing also contributed to bimodality, especially in MASE.

  17. The Evolution of Cloud Computing in ATLAS

    NASA Astrophysics Data System (ADS)

    Taylor, Ryan P.; Berghaus, Frank; Brasolin, Franco; Domingues Cordeiro, Cristovao Jose; Desmarais, Ron; Field, Laurence; Gable, Ian; Giordano, Domenico; Di Girolamo, Alessandro; Hover, John; LeBlanc, Matthew; Love, Peter; Paterson, Michael; Sobie, Randall; Zaytsev, Alexandr

    2015-12-01

    The ATLAS experiment at the LHC has successfully incorporated cloud computing technology and cloud resources into its primarily grid-based model of distributed computing. Cloud R&D activities continue to mature and transition into stable production systems, while ongoing evolutionary changes are still needed to adapt and refine the approaches used, in response to changes in prevailing cloud technology. In addition, completely new developments are needed to handle emerging requirements. This paper describes the overall evolution of cloud computing in ATLAS. The current status of the virtual machine (VM) management systems used for harnessing Infrastructure as a Service resources are discussed. Monitoring and accounting systems tailored for clouds are needed to complete the integration of cloud resources within ATLAS' distributed computing framework. We are developing and deploying new solutions to address the challenge of operation in a geographically distributed multi-cloud scenario, including a system for managing VM images across multiple clouds, a system for dynamic location-based discovery of caching proxy servers, and the usage of a data federation to unify the worldwide grid of storage elements into a single namespace and access point. The usage of the experiment's high level trigger farm for Monte Carlo production, in a specialized cloud environment, is presented. Finally, we evaluate and compare the performance of commercial clouds using several benchmarks.

  18. Physical processes in polar stratospheric ice clouds

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Turco, Richard; Jordan, Joseph

    1988-01-01

    A one dimensional model of cloud microphysics was used to simulate the formation and evolution of polar stratospheric ice clouds. Some of the processes which are included in the model are outlined. It is found that the clouds must undergo preferential nucleation upon the existing aerosols just as do tropospheric cirrus clouds. Therefore, there is an energy barrier between stratospheric nitric acid particles and ice particles implying that nitric acid does not form a continuous set of solutions between the trihydrate and ice. The Kelvin barrier is not significant in controlling the rate of formation of ice particles. It was found that the cloud properties are sensitive to the rate at which the air parcels cool. In wave clouds, with cooling rates of hundreds of degrees per day, most of the existing aerosols nucleate and become ice particles. Such clouds have particles with sizes on the order of a few microns, optical depths on order of unity and are probably not efficient at removing materials from the stratosphere. In clouds which form with cooling rates of a few degrees per day or less, only a small fraction of the aerosols become cloud particles. In such clouds the particle radius is larger than 10 microns, the optical depths are low and water vapor is efficiently removed. Seasonal simulations show that the lowest water vapor mixing ratio is determined by the lowest temperature reached, and that the time when clouds disappear is controlled by the time when temperatures begin to rise above the minimum values.

  19. Magnetohydrodynamic stability of broad line region clouds

    NASA Astrophysics Data System (ADS)

    Krause, Martin; Schartmann, Marc; Burkert, Andreas

    2012-10-01

    Hydrodynamic stability has been a longstanding issue for the cloud model of the broad line region in active galactic nuclei. We argue that the clouds may be gravitationally bound to the supermassive black hole. If true, stabilization by thermal pressure alone becomes even more difficult. We further argue that if magnetic fields are present in such clouds at a level that could affect the stability properties, they need to be strong enough to compete with the radiation pressure on the cloud. This would imply magnetic field values of a few gauss for a sample of active galactic nuclei we draw from the literature. We then investigate the effect of several magnetic configurations on cloud stability in axisymmetric magnetohydrodynamic simulations. For a purely azimuthal magnetic field which provides the dominant pressure support, the cloud first gets compressed by the opposing radiative and gravitational forces. The pressure inside the cloud then increases, and it expands vertically. Kelvin-Helmholtz and column density instabilities lead to a filamentary fragmentation of the cloud. This radiative dispersion continues until the cloud is shredded down to the resolution level. For a helical magnetic field configuration, a much more stable cloud core survives with a stationary density histogram which takes the form of a power law. Our simulated clouds develop sub-Alfvénic internal motions on the level of a few hundred km s-1.

  20. IRAS images of nearby dark clouds

    NASA Technical Reports Server (NTRS)

    Wood, Douglas O. S.; Myers, Philip C.; Daugherty, Debra A.

    1994-01-01

    We have investigated approximately 100 nearby molecular clouds using the extensive, all-sky database of IRAS. The clouds in this study cover a wide range of physical properties including visual extinction, size, mass, degree of isolation, homogeneity and morphology. IRAS 100 and 60 micron co-added images were used to calculate the 100 micron optical depth of dust in the clouds. These images of dust optical depth compare very well with (12)CO and (13)CO observations, and can be related to H2 column density. From the optical depth images we locate the edges of dark clouds and the dense cores inside them. We have identified a total of 43 `IRAS clouds' (regions with A(sub v) greater than 2) which contain a total of 255 `IRAS cores' (regions with A(sub v) greater than 4) and we catalog their physical properties. We find that the clouds are remarkably filamentary, and that the cores within the clouds are often distributed along the filaments. The largest cores are usually connected to other large cores by filaments. We have developed selection criteria to search the IRAS Point Source Catalog for stars that are likely to be associated with the clouds and we catalog the IRAS sources in each cloud or core. Optically visible stars associated with the clouds have been identified from the Herbig and Bell catalog. From these data we characterize the physical properties of the clouds including their star-formation efficiency.

  1. Little Massive Substructure in CMZ Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Kauffmann, J.; Pillai, T.; Zhang, Q.; Menten, K. M.; Goldsmith, P. F.; Lu, X.; Guzman, A. E.

    2016-05-01

    The Central Molecular Zone (CMZ; inner ˜100pc) hosts some of the most dense and massive molecular clouds of the Milky Way. Studying these clouds can potentially lead to a better understanding of the dense clouds seen in the central starburst regions in nearby galaxies or in the early universe. The clouds share an unusual feature: they form stars at an unusually slow rate compared to other Milky Way clouds of similar mass and density. Here we use interferometer data from ALMA and the SMA to show that this reduced star formation rate is a consequence of the cloud density structure: CMZ clouds have unusually flat density slopes. The clouds do, for example, exceed the average density of the Orion A molecular cloud by an order of magnitude on spatial scales ˜5 pc, but the cores of CMZ clouds with ˜0.1 pc radius often have masses and densities lower than what is found in the Orion KL region. This relative absence of highest-density gas probably explains the suppression of star formation. The clouds are relatively turbulent, and ALMA observations of H2CO and SiO indicate that the turbulence is induced by high-velocity shocks. We speculate that these shocks might prevent the formation of high-mass cores.

  2. Model calculations for diffuse molecular clouds. [interstellar hydrogen cloud model

    NASA Technical Reports Server (NTRS)

    Glassgold, A. E.; Langer, W. D.

    1974-01-01

    A steady state isobaric cloud model is developed. The pressure, thermal, electrical, and chemical balance equations are solved simultaneously with a simple one dimensional approximation to the equation of radiative transfer appropriate to diffuse clouds. Cooling is mainly by CII fine structure transitions, and a variety of heating mechanisms are considered. Particular attention is given to the abundance variation of H2. Inhomogeneous density distributions are obtained because of the attenuation of the interstellar UV field and the conversion from atomic to molecular hyrodgen. The effects of changing the model parameters are described and the applicability of the model to OAO-3 observations is discussed. Good qualitative agreement with the fractional H2 abundance determinations has been obtained. The observed kinetic temperatures near 80 K can also be achieved by grain photoelectron heating. The problem of the electron density is solved taking special account of the various hydrogen ions as well as heavier ones.

  3. Dynamical history of the Oort cloud

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.

    1991-01-01

    An overview of recent dynamical studies on the Oort cloud of comets surrounding the solar system is presented. Cometary orbits in the cloud evolve under the complex interaction of stellar, galactic, and giant molecular cloud perturbations, as well as planetary and nongravitational perturbations when the orbits reenter the planetary region. There is mounting evidence for a dense, inner Oort cloud of comets which acts as a reservoir to replenish the outer cloud as comets there are stripped away. A ring of comets beyond the orbit of Neptune, which may be the source of the short-period comets, is also likely. Temporal variations in the flux of comets from the Oort cloud into the planetary region by a factor of 50 percent are typical, and by factors of 20 to 200 are possible. Comets in the Oort cloud are processed by galactic cosmic rays, heated by nearby supernovae, eroded by interstellar dust impacts, and disrupted by mutual collisions.

  4. Microphysics and Southern Ocean Cloud Feedback

    NASA Astrophysics Data System (ADS)

    McCoy, Daniel T.

    Global climate models (GCMs) change their cloud properties in the Southern Ocean (SO) with warming in a qualitatively consistent fashion. Cloud albedo increases in the mid-latitudes and cloud fraction decreases in the subtropics. This creates a distinctive 'dipole' structure in the SW cloud feedback. However, the shape of the dipole varies from model to model. In this thesis we discuss the microphysical mechanisms underlying the SW cloud feedback over the mid-latitude SO. We will focus on the negative lobe of the dipole. The negative SW cloud feedback in the mid-latitudes is created by transitions from ice to liquid in models. If ice transitions to liquid in mixed-phase clouds the cloud albedo increases because ice crystals are larger than liquid droplets and therefore more reflective for a constant mass of water. Decreases in precipitation efficiency further enhance this effect by decreasing sinks of cloud water. This transition is dependent on the mixed-phase cloud parameterization. Parameterizations vary wildly between models and GCMs disagree by up to 35 K on the temperature where ice and liquid are equally prevalent. This results in a wide spread in the model predictions of the increase in liquid water path (LWP, where the path is the vertically integrated mass of water) with warming that drives the negative optical depth cloud feedback. It is found that this disagreement also results in a wide array of climate mean-states as models that create liquid at lower temperatures have a higher mean-state LWP, lower ice water path (IWP), and higher condensed (ice and liquid) water path (CWP). This presents a problem in climate models. GCMs need to have a reasonable planetary albedo in their climate mean-state. We show evidence that GCMs have tuned cloud fraction to compensate for the variation in mid-latitude cloud albedo driven by the mixed-phase cloud parameterization. This tuning results in mid-latitude clouds that are both too few and too bright as well as a

  5. Smoking rain clouds over the Amazon.

    PubMed

    Andreae, M O; Rosenfeld, D; Artaxo, P; Costa, A A; Frank, G P; Longo, K M; Silva-Dias, M A F

    2004-02-27

    Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear "smoking" as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation. PMID:14988556

  6. Smoking rain clouds over the Amazon.

    PubMed

    Andreae, M O; Rosenfeld, D; Artaxo, P; Costa, A A; Frank, G P; Longo, K M; Silva-Dias, M A F

    2004-02-27

    Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear "smoking" as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation.

  7. A survey of Io's potassium cloud

    NASA Technical Reports Server (NTRS)

    Trafton, L.

    1981-01-01

    Io's potassium cloud exhibits spatial and temporal variations similar to those observed for Io's sodium cloud. Spectra from five apparitions show that the potassium cloud is elongated so that it extends forward from Io's leading, inner hemisphere and makes an angle with Io's orbit of 10-30 deg, slightly less than the angle for the sodium cloud. The potassium cloud is a long-lived phenomenon which undergoes periodic fluctuations in response to solar radiation pressure and the ionizing influence of Jupiter's plasma torus. These give rise to east-west and north-south asymmetry variations similar to those observed for the sodium cloud. Evidence for temporary jets of potassium streaming from Io have also been observed. These similarities with the sodium cloud suggest that both sodium and potassium are ejected from nearly the same regions of Io by the same physical mechanism.

  8. Enabling Earth Science Through Cloud Computing

    NASA Technical Reports Server (NTRS)

    Hardman, Sean; Riofrio, Andres; Shams, Khawaja; Freeborn, Dana; Springer, Paul; Chafin, Brian

    2012-01-01

    Cloud Computing holds tremendous potential for missions across the National Aeronautics and Space Administration. Several flight missions are already benefiting from an investment in cloud computing for mission critical pipelines and services through faster processing time, higher availability, and drastically lower costs available on cloud systems. However, these processes do not currently extend to general scientific algorithms relevant to earth science missions. The members of the Airborne Cloud Computing Environment task at the Jet Propulsion Laboratory have worked closely with the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) mission to integrate cloud computing into their science data processing pipeline. This paper details the efforts involved in deploying a science data system for the CARVE mission, evaluating and integrating cloud computing solutions with the system and porting their science algorithms for execution in a cloud environment.

  9. Operational Cloud Detection in GEOS Imagery

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary J.; Laws, Kevin; Arnold, James E. (Technical Monitor)

    2001-01-01

    The bispectral spatial coherence approach for the detection and masking of clouds is revisited with modifications for operational applications to Geostationary Operational Environmental Satellite (GOES) Imager and Sounder data. The approach applies an edge detection algorithm to a "difference" image to identify the edges or contours of the clouds. The difference image is generated as the difference between the 3.9 and 11 micrometer channels of the GOES sensors. This difference image better highlights cloud edges than either image alone and draws upon the emissivity differences in the various channels. The cloud contours are "filled-in" by referencing the thermal gradients in the 11-micrometer channel or difference image associated with the cloud edge. This paper and associate poster will present a preliminary validation of the bispectral spatial coherence approach and will compare the cloud masks generated with this approach to the National Oceanic and Atmospheric Administration/National Environmental Satellite, Data, and Information Service (NOAA/NESDIS) operational cloud products.

  10. Modeling and parameterization of horizontally inhomogeneous cloud radiative properties

    NASA Technical Reports Server (NTRS)

    Welch, R. M.

    1995-01-01

    One of the fundamental difficulties in modeling cloud fields is the large variability of cloud optical properties (liquid water content, reflectance, emissivity). The stratocumulus and cirrus clouds, under special consideration for FIRE, exhibit spatial variability on scales of 1 km or less. While it is impractical to model individual cloud elements, the research direction is to model a statistical ensembles of cloud elements with mean-cloud properties specified. The major areas of this investigation are: (1) analysis of cloud field properties; (2) intercomparison of cloud radiative model results with satellite observations; (3) radiative parameterization of cloud fields; and (4) development of improved cloud classification algorithms.

  11. Jovian Lightning and Moonlit Clouds

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian lightning and moonlit clouds. These two images, taken 75 minutes apart, show lightning storms on the night side of Jupiter along with clouds dimly lit by moonlight from Io, Jupiter's closest moon. The images were taken in visible light and are displayed in shades of red. The images used an exposure time of about one minute, and were taken when the spacecraft was on the opposite side of Jupiter from the Earth and Sun. Bright storms are present at two latitudes in the left image, and at three latitudes in the right image. Each storm was made visible by multiple lightning strikes during the exposure. Other Galileo images were deliberately scanned from east to west in order to separate individual flashes. The images show that Jovian and terrestrial lightning storms have similar flash rates, but that Jovian lightning strikes are a few orders of magnitude brighter in visible light.

    The moonlight from Io allows the lightning storms to be correlated with visible cloud features. The latitude bands where the storms are seen seem to coincide with the 'disturbed regions' in daylight images, where short-lived chaotic motions push clouds to high altitudes, much like thunderstorms on Earth. The storms in these images are roughly one to two thousand kilometers across, while individual flashes appear hundreds of kilometer across. The lightning probably originates from the deep water cloud layer and illuminates a large region of the visible ammonia cloud layer from 100 kilometers below it.

    There are several small light and dark patches that are artifacts of data compression. North is at the top of the picture. The images span approximately 50 degrees in latitude and longitude. The lower edges of the images are aligned with the equator. The images were taken on October 5th and 6th, 1997 at a range of 6.6 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for

  12. Spherical combustion clouds in explosions

    NASA Astrophysics Data System (ADS)

    Kuhl, A. L.; Bell, J. B.; Beckner, V. E.; Balakrishnan, K.; Aspden, A. J.

    2013-05-01

    This study explores the properties of spherical combustion clouds in explosions. Two cases are investigated: (1) detonation of a TNT charge and combustion of its detonation products with air, and (2) shock dispersion of aluminum powder and its combustion with air. The evolution of the blast wave and ensuing combustion cloud dynamics are studied via numerical simulations with our adaptive mesh refinement combustion code. The code solves the multi-phase conservation laws for a dilute heterogeneous continuum as formulated by Nigmatulin. Single-phase combustion (e.g., TNT with air) is modeled in the fast-chemistry limit. Two-phase combustion (e.g., Al powder with air) uses an induction time model based on Arrhenius fits to Boiko's shock tube data, along with an ignition temperature criterion based on fits to Gurevich's data, and an ignition probability model that accounts for multi-particle effects on cloud ignition. Equations of state are based on polynomial fits to thermodynamic calculations with the Cheetah code, assuming frozen reactants and equilibrium products. Adaptive mesh refinement is used to resolve thin reaction zones and capture the energy-bearing scales of turbulence on the computational mesh (ILES approach). Taking advantage of the symmetry of the problem, azimuthal averaging was used to extract the mean and rms fluctuations from the numerical solution, including: thermodynamic profiles, kinematic profiles, and reaction-zone profiles across the combustion cloud. Fuel consumption was limited to ˜ 60-70 %, due to the limited amount of air a spherical combustion cloud can entrain before the turbulent velocity field decays away. Turbulent kinetic energy spectra of the solution were found to have both rotational and dilatational components, due to compressibility effects. The dilatational component was typically about 1 % of the rotational component; both seemed to preserve their spectra as they decayed. Kinetic energy of the blast wave decayed due to the

  13. 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.

  14. 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

  15. Comparison Between CCCM and CloudSat Radar-Lidar (RL) Cloud and Radiation Products

    NASA Technical Reports Server (NTRS)

    Ham, Seung-Hee; Kato, Seiji; Rose, Fred G.; Sun-Mack, Sunny

    2015-01-01

    To enhance cloud properties, LaRC and CIRA developed each combination algorithm for obtained properties from passive, active and imager in A-satellite constellation. When comparing global cloud fraction each other, LaRC-produced CERES-CALIPSO-CloudSat-MODIS (CCCM) products larger low-level cloud fraction over tropic ocean, while CIRA-produced Radar-Lidar (RL) shows larger mid-level cloud fraction for high latitude region. The reason for different low-level cloud fraction is due to different filtering method of lidar-detected cloud layers. Meanwhile difference in mid-level clouds is occurred due to different priority of cloud boundaries from lidar and radar.

  16. Measured and modeled cloud-aerosol radiative effects in polluted cumulus clouds

    NASA Astrophysics Data System (ADS)

    Schmidt, K. S.; Feingold, G.; Pilewskie, P.; Jiang, H.; Coddington, O.

    2009-04-01

    Recent studies have emphasized the need to consider aerosol particles and clouds as an entity rather than artificially separating aerosol and cloud radiative forcing. A particularly difficult situation is that of cumulus clouds in a polluted background where radiative effects from heterogeneous clouds, aerosol particles, and surface albedo can only be distinguished by their spectral signature. We have used spectral irradiance measurements from the Gulf of Mexico Atmospheric Composition and Climate Study, and extensive three-dimensional radiative transfer calculations applied to the output of large eddy simulations, to show that measurements below clouds or cloud gaps are only reproduced when including aerosol particles in the calculations. Our technique enables the derivation of measurement-based spectral forcing and absorption of the cloud-aerosol-system. Furthermore, we present a new spectral effect caused by a combination of molecular scattering and cumulus cloud effects that is also relevant to cloud remote sensing.

  17. Evaluation of a GCM subgrid cloud-radiation interaction parameterization using cloud-resolving model simulations

    NASA Astrophysics Data System (ADS)

    Liang, Xin-Zhong; Wu, Xiaoqing

    2005-03-01

    The mosaic approach of Liang and Wang (1997) for the general circulation model (GCM) parameterization of subgrid cloud-radiation interactions is evaluated against the validated cloud-resolving model (CRM) simulation of the Atmospheric Radiation Measurement (ARM) intensive observation period (IOP, June 22-July 17, 1997) at the Southern Great Plains (SGP) site. The CRM-generated cloud statistics determines the required characteristic structure differences between three primary cloud genera (convective, anvil and stratiform). It is demonstrated that the mosaic approach with the CRM cloud statistics well simulates the CRM domain-averaged radiative quantities. The result indicates that the mosaic approach of the cloud overlap based on the cloud genera differing in formation mechanisms and of the optical inhomogeneity by cloud water path scaling can capture, respectively, the dominant effects of the cloud geometric association and optical property variability within a GCM grid.

  18. 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.

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

    PubMed

    Han, Yong; Lü, Da-Ren

    2013-04-01

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

  20. Quantifying Diurnal Cloud Radiative Effects by Cloud Type in the Tropical Western Pacific

    SciTech Connect

    Burleyson, Casey D.; Long, Charles N.; Comstock, Jennifer M.

    2015-06-01

    Cloud radiative effects are examined using long-term datasets collected at the three Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facilities in the tropical western Pacific. We quantify the surface radiation budget, cloud populations, and cloud radiative effects by partitioning the data by cloud type, time of day, and as a function of large scale modes of variability such as El Niño Southern Oscillation (ENSO) phase and wet/dry seasons at Darwin. The novel facet of our analysis is that we break aggregate cloud radiative effects down by cloud type across the diurnal cycle. The Nauru cloud populations and subsequently the surface radiation budget are strongly impacted by ENSO variability whereas the cloud populations over Manus only shift slightly in response to changes in ENSO phase. The Darwin site exhibits large seasonal monsoon related variations. We show that while deeper convective clouds have a strong conditional influence on the radiation reaching the surface, their limited frequency reduces their aggregate radiative impact. The largest source of shortwave cloud radiative effects at all three sites comes from low clouds. We use the observations to demonstrate that potential model biases in the amplitude of the diurnal cycle and mean cloud frequency would lead to larger errors in the surface energy budget compared to biases in the timing of the diurnal cycle of cloud frequency. Our results provide solid benchmarks to evaluate model simulations of cloud radiative effects in the tropics.

  1. Operational implications of a cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Zak, J. A.

    1989-01-01

    A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud would grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. Results are discussed with operational weather forecasters in mind. The model successfully produced clouds with dimensions, rise, decay, liquid water contents, and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. An empirical forecast technique for Shuttle cloud rise is presented and differences between natural atmospheric convection and exhaust clouds are discussed.

  2. Mature Deep Convective Cloud Morphology as Observed by CloudSat

    NASA Astrophysics Data System (ADS)

    Igel, M.; van den Heever, S. C.

    2013-12-01

    The role of oceanic deep convective tropical clouds in weather and climate systems remains poorly defined for individual, deep convective clouds in the tropics. It is the goal of this work to try to determine those roles by analyzing cloud length scales observed by CloudSat. It is shown that misperceptions of cloud scales could lead consequently to a misunderstanding of the roles of deep convection. Using a recently developed cloud identification algorithm, CloudSat data is parsed into individual cloud objects that are present in large enough numbers to provide powerful statistics. The methodology also provides a means of counting the number of convective cores within the 'pedestal' of a cloud object. As the number of convective cores within a single cloud object increases, various changes in the morphology of storms occur. Not only do they get wider as the number of cores increases, but the anvil base lowers and the storm deepens. Correlations between different aspects of cloud morphology are evaluated with a focus on the up scale relationship of pedestals to anvils. The results implicate mesoscale organization of tropical clouds as being important for the general circulation. Finally, the sensitivity to local environmental characteristics of the cloud morphology is assessed and connections are made between the environment and the role of the cloud.

  3. Evaluation of Tropical Cloud Simulations in CAM3 Forecasts Using CloudSat and CALIPSO Data

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Klein, S.; Boyle, J.; Mace, G.

    2008-12-01

    Clouds and their radiative feedback cannot be represented correctly in current GCMs. The new revolutionary observations from the CloudSat and CALIPSO provide global measurements for vertical structures of hydrometeor fields aiming to improve our understanding of clouds and their processes. The merged satellite data including most accurate 3-dimensional description on hydrometeor distributions are employed to exam cloud representations in the NCAR's CAM3. The cloud mesoscale patterns are characterized by joint histograms of altitude and radar reflectivity/lidar signal. A revised clustering method is used to analyze the observational data and create principal cloud regimes in tropical regions. A simulator package applying a model-to-satellite approach facilitates the model-data comparison. The strategy for the comparison of modeled clouds with observed ones is to assign the model simulations on to the observational clusters. It is found that the model underestimates low clouds and mid- level clouds, but overestimate high clouds. The cumulus congestus precipitate too heavily, and the scales of the deep convection and heavy precipitation are relatively small compared to observations. The simulated clouds are too reflective. We also evaluate a different version of the model with new parameterizations. The cloud simulations with the new parameterization of deep convection compare more favorable with the observations. By sorting the cloud clusters into large-scale dynamic regions using 500mb vertical pressure velocity, it has been proved the model with new parameterizations produce clouds in appropriate dynamic regions.

  4. Validation of AIRS/AMSU Cloud Retrievals Using MODIS Cloud Analyses

    NASA Technical Reports Server (NTRS)

    Molnar, Gyula I.; Susskind, Joel

    2005-01-01

    The AIRS/AMSU (flying on the EOS-AQUA satellite) sounding retrieval methodology allows for the retrieval of key atmospheric/surface parameters under partially cloudy conditions (Susskind et al.). In addition, cloud parameters are also derived from the AIRS/AMSU observations. Within each AIRS footprint, cloud parameters at up to 2 cloud layers are determined with differing cloud top pressures and effective (product of infrared emissivity at 11 microns and physical cloud fraction) cloud fractions. However, so far the AIRS cloud product has not been rigorously evaluated/validated. Fortunately, collocated/coincident radiances measured by MODIS/AQUA (at a much lower spectral resolution but roughly an order of-magnitude higher spatial resolution than that of AIRS) are used to determine analogous cloud products from MODIS. This allows us for a rather rare and interesting possibility: the intercomparisons and mutual validation of imager vs. sounder-based cloud products obtained from the same satellite positions. First, we present results of small-scale (granules) instantaneous intercomparisons. Next, we will evaluate differences of temporally averaged (monthly) means as well as the representation of inter-annual variability of cloud parameters as presented by the two cloud data sets. In particular, we present statistical differences in the retrieved parameters of cloud fraction and cloud top pressure. We will investigate what type of cloud systems are retrieved most consistently (if any) with both retrieval schemes, and attempt to assess reasons behind statistically significant differences.

  5. INFRARED DARK CLOUDS IN THE SMALL MAGELLANIC CLOUD?

    SciTech Connect

    Lee, Min-Young; Stanimirovic, Snezana; Devine, Kathryn E.; Ott, Juergen; Van Loon, Jacco Th.; Oliveira, Joana M.; Bolatto, Alberto D.; Jones, Paul A.; Cunningham, Maria R. E-mail: sstanimi@astro.wisc.edu E-mail: jott@nrao.edu E-mail: joana@astro.keele.ac.uk E-mail: pjones@phys.unsw.edu.au

    2009-10-15

    We have applied the unsharp-masking technique to the 24 {mu}m image of the Small Magellanic Cloud (SMC), obtained with the Spitzer Space Telescope, to search for high-extinction regions. This technique has been used to locate very dense and cold interstellar clouds in the Galaxy, particularly infrared dark clouds (IRDCs). Fifty-five candidate regions of high extinction, namely, high-contrast regions (HCRs), have been identified from the generated decremental contrast image of the SMC. Most HCRs are located in the southern bar region and mainly distributed in the outskirts of CO clouds, but most likely contain a significant amount of H{sub 2}. HCRs have a peak contrast at 24 {mu}m of 2%-2.5% and a size of 8-14 pc. This corresponds to the size of typical and large Galactic IRDCs, but Galactic IRDCs are 2-3 times darker at 24 {mu}m than our HCRs. To constrain the physical properties of the HCRs, we have performed NH{sub 3}, N{sub 2}H{sup +}, HNC, HCO{sup +}, and HCN observations toward one of the HCRs, HCR LIRS36-east, using the Australia Telescope Compact Array and the Mopra single-dish radio telescope. We did not detect any molecular line emission, however, our upper limits to the column densities of molecular species suggest that HCRs are most likely moderately dense with n {approx} 10{sup 3} cm{sup -3}. This volume density is in agreement with predictions for the cool atomic phase in low-metallicity environments. We suggest that HCRs may be tracing clouds at the transition from atomic to molecule-dominated medium, and could be a powerful way to study early stages of gas condensation in low-metallicity galaxies. Alternatively, if made up of dense molecular clumps <0.5 pc in size, HCRs could be counterparts of Galactic IRDCs, and/or regions with highly unusual abundance of very small dust grains.

  6. Interannual Variability of Total Cloud Cover and Cloud Types over Eastern Part of Romania

    NASA Astrophysics Data System (ADS)

    Bostan, D. C.; Stefan, S.

    2009-04-01

    Clouds play a key role in climate and weather forecasting. The observations of clouds and cloud cover at regional scale are very important in the study of clouds' radiative forcing, and consequently, in changing the radiative budget in the climatic system. This paper is focused on the analysis of spatial and temporal distribution of clouds and cloud cover. These observational data can be used in regional climate models. Synoptic surface cloud observations from 14 stations are used to examine the variability of the cloud cover in 2006 over Moldova, which is the extra Carpathian area of Romania. The hourly data of the total cloud cover and partial cloud ceiling were processed and statistically analyzed. The observational database was completed using a simple algorithm that improved the middle cloudiness environment by more than 39% and the high clouds environment by 100%, compared to the initial data. Trends in total and low cloud cover were investigated in detail by examining changes in the frequency of appearance. The significant underestimation for the middle and high clouds was obvious for low cloudiness values of 6, 7 and 8 oktas, and it has reduced the average cloud cover up to 4.5% and the top up to 15.4%. Seasonal analysis performed in January and July 2006 showed that the low cloud cover was 50% higher in winter as compared to the warm season. The presence of the middle cloud cover was constant during the two seasons (generally between 60-70%), while the high cloudiness dominated during the summer months. The investigations of smaller regions and interannual variability are important, although the real fluctuations in cloud cover are relatively large in such instances. As such, a study of the fluctuations in cloud cover will be necessary in the future.

  7. Cloud microphysical relationships in continental stratocumulus clouds measured during the RACORO campaign

    NASA Astrophysics Data System (ADS)

    Yeom, J. M.; Yum, S. S.; Liu, Y.; Lu, C.

    2015-12-01

    Cloud microphysical relationships are determined by various processes that occur in clouds. The simplest and the most important process that occurs during cloud development would be the adiabatic condensational growth of cloud droplets. However, what have been observed in real clouds are often different from the cloud microphysical relationships predicted based on adiabatic condensational growth. There could be various reasons why the measured relationships deviated from adiabatic prediction but turbulent entrainment and mixing of the air above cloud top is considered to be the most important process that modulates cloud microphysical relationships especially in stratocumulus clouds. There were many studies on this issue for marine stratocumulus clouds but studies on continental stratocumulus clouds are rare. Compared to maritime stratocumulus clouds, continental stratocumulus clouds usually have very different thermodynamic and aerosol conditions. So in this study we examined microphysical relationships in continental stratocumulus clouds measured during the Routine AAF CLOUD Optical Radiative Observations (RACORO) campaign as an attempt to reveal the most dominant entrainment-mixing mechanism in these clouds. We used so called the mixing diagram and found that most cases suggested homogeneous mixing of entrained air. We also estimated the scale parameters (i.e., transition length and scale number) because they are indicative of whether entrainment-mixing mechanism is homogeneous or inhomogeneous. The estimated values were found to be critically dependent on turbulent dissipation rate and were suggestive of homogeneous mixing, compared to those estimated for marine stratocumulus clouds in our recent study. We will try to explain why such is the case for continental stratocumulus clouds.

  8. Structures in Molecular Clouds: Modeling

    SciTech Connect

    Kane, J O; Mizuta, A; Pound, M W; Remington, B A; Ryutov, D D

    2006-04-20

    We attempt to predict the observed morphology, column density and velocity gradient of Pillar II of the Eagle Nebula, using Rayleigh Taylor (RT) models in which growth is seeded by an initial perturbation in density or in shape of the illuminated surface, and cometary models in which structure is arises from a initially spherical cloud with a dense core. Attempting to mitigate suppression of RT growth by recombination, we use a large cylindrical model volume containing the illuminating source and the self-consistently evolving ablated outflow and the photon flux field, and use initial clouds with finite lateral extent. An RT model shows no growth, while a cometary model appears to be more successful at reproducing observations.

  9. !CHAOS: A cloud of controls

    NASA Astrophysics Data System (ADS)

    Angius, S.; Bisegni, C.; Ciuffetti, P.; Di Pirro, G.; Foggetta, L. G.; Galletti, F.; Gargana, R.; Gioscio, E.; Maselli, D.; Mazzitelli, G.; Michelotti, A.; Orrù, R.; Pistoni, M.; Spagnoli, F.; Spigone, D.; Stecchi, A.; Tonto, T.; Tota, M. A.; Catani, L.; Di Giulio, C.; Salina, G.; Buzzi, P.; Checcucci, B.; Lubrano, P.; Piccini, M.; Fattibene, E.; Michelotto, M.; Cavallaro, S. R.; Diana, B. F.; Enrico, F.; Pulvirenti, S.

    2016-01-01

    The paper is aimed to present the !CHAOS open source project aimed to develop a prototype of a national private Cloud Computing infrastructure, devoted to accelerator control systems and large experiments of High Energy Physics (HEP). The !CHAOS project has been financed by MIUR (Italian Ministry of Research and Education) and aims to develop a new concept of control system and data acquisition framework by providing, with a high level of aaabstraction, all the services needed for controlling and managing a large scientific, or non-scientific, infrastructure. A beta version of the !CHAOS infrastructure will be released at the end of December 2015 and will run on private Cloud infrastructures based on OpenStack.

  10. Silicon chemistry in interstellar clouds

    NASA Technical Reports Server (NTRS)

    Langer, William D.; Glassgold, A. E.

    1990-01-01

    A new model of interstellar silicon chemistry is presented that explains the lack of SiO detections in cold clouds and contains an exponential temperature dependence for the SiO abundance. A key aspect of the model is the sensitivity of SiO production by neutral silicon reactions to density and temperature, which arises from the dependence of the rate coefficients on the population of the excited fine-structure levels of the silicon atom. As part of the explanation of the lack of SiO detections at low temperatures and densities, the model also emphasizes the small efficiencies of the production routes and the correspondingly long times needed to reach equilibrium. Measurements of the abundance of SiO, in conjunction with theory, can provide information on the physical properties of interstellar clouds such as the abundance of oxygen bearing molecules and the depletion of interstellar silicon.

  11. Spinning gas clouds - without vorticity

    NASA Astrophysics Data System (ADS)

    Gaffet, B.

    2000-06-01

    Ovsiannikov and Dyson have considered an ordinary differential reduction of the gas-dynamical equations for an ideal gas which is adiabatically expanding and rotating. Gaffet has shown, based on its Painlevé property, the complete integrability of that ellipsoidal gas cloud model, when there is neither rotation nor vorticity and the gas is monatomic (γ = 5/3), and has conjectured that the integrability might persist in more general cases including rotation. In this paper we show that the presence of vorticity in general destroys the integrability property, but the conjecture is otherwise verified, under the simplifying assumption of rotation around a fixed axis. In a future work we hope to extend the present result to Dyson's most general spinning gas cloud without vorticity.

  12. Interstellar molecules and dense clouds.

    NASA Technical Reports Server (NTRS)

    Rank, D. M.; Townes, C. H.; Welch, W. J.

    1971-01-01

    Current knowledge of the interstellar medium is discussed on the basis of recent published studies. The subjects considered include optical identification of interstellar molecules, radio molecular lines, interstellar clouds, isotopic abundances, formation and disappearance of interstellar molecules, and interstellar probing techniques. Diagrams are plotted for the distribution of galactic sources exhibiting molecular lines, for hydrogen molecule, hydrogen atom and electron abundances due to ionization, for the densities, velocities and temperature of NH3 in the direction of Sagitarius B2, for the lower rotational energy levels of H2CO, and for temporal spectral variations in masing H2O clouds of the radio source W49. Future applications of the maser and of molecular microscopy in this field are visualized.

  13. Molecular Clouds: Observation to Experiment

    SciTech Connect

    Kane, J O; Ryutov, D D; Mizuta, A; Remington, B A; Pound, M W

    2004-05-06

    Our ongoing investigation of how 'Pillars' and other structure form in molecular clouds irradiated by ultraviolet (UV) stars has revealed that the Rayleigh-Taylor instability is strongly suppressed by recombination in the photoevaporated outflow, that clumps and filaments may be key, that the evolution of structure is well-modeled by compressible hydrodynamics, and that directionality of the UV radiation may have significant effects. We discuss a generic, flexible set of laboratory experiments that can address these issues.

  14. Dust in High Velocity Clouds

    NASA Astrophysics Data System (ADS)

    Wakker, B. P.

    The facilities available in Groningen to produce IRAS maps were used to make comparatively high-quality maps of two fields where a high-velocity cloud (HVC) is observed in the 21-cm line. The HVC's are not discernable in these maps although one would expect to see them if the relation between 100 micron emission and H I column density found by Boulanger, Baud & van Albada (1985) is used. The implications of this non-detection are discussed in this contribution.

  15. Astrochemical Correlations in Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Gaches, Brandt A.L.; Offner, Stella

    2014-06-01

    We investigate the spectral correlations between different chemical tracers used to observe molecular clouds. We study a 600 Solar Mass molecular cloud with Mach number 6.6 modeled using the magnetohydrodynamic code ORION. The chemical abundances are calculated by 3D-PDR, a three-dimensional astrochemical code using a full network of 3300 reactions and 215 species. We take synthetic observations of 16 different species using the non-LTE radiative transfer code RADMC-3D. The effects of different lines of sight and spatial resolution on the emission maps of the 16 different species will be discussed in this talk.We use the Spectral Correlation Function to quantify the structure of the simulated cloud in position-position-velocity space, which measures the average rms velocity between spectra separated by a given length scale. This statistic has been shown to be sensitive to global hydrodynamic parameters, such as the sonic Mach number and velocity dispersion. The SCF is analytically fit by a power law, with the slope being the one free parameter. We verify that the SCF is generally insensitive to the sightline through the cloud. We discover that the beam size has a distinct effect on different chemical tracers. However, the change is not large enough to move the SCF slopes into different parts of the parameter space. This is the first quantitative 3D study of the spectral similarity of a variety of species. We predict the observed SCF for a broad range of observational tracers, and thus, identify complementary species. In particular, we show that the pairs C and CO, C+ and CN, NH3 and H2CS have very similar SCFs. The results from this study will also give observers a guide for selecting which chemical tracers would be best for observing different length scales.

  16. Risk in the Clouds?: Security Issues Facing Government Use of Cloud Computing

    NASA Astrophysics Data System (ADS)

    Wyld, David C.

    Cloud computing is poised to become one of the most important and fundamental shifts in how computing is consumed and used. Forecasts show that government will play a lead role in adopting cloud computing - for data storage, applications, and processing power, as IT executives seek to maximize their returns on limited procurement budgets in these challenging economic times. After an overview of the cloud computing concept, this article explores the security issues facing public sector use of cloud computing and looks to the risk and benefits of shifting to cloud-based models. It concludes with an analysis of the challenges that lie ahead for government use of cloud resources.

  17. Satellite remote sensing and cloud modeling of St. Anthony, Minnesota storm clouds and dew point depression

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.

    1988-01-01

    Rawinsonde data and geosynchronous satellite imagery were used to investigate the life cycles of St. Anthony, Minnesota's severe convective storms. It is found that the fully developed storm clouds, with overshooting cloud tops penetrating above the tropopause, collapsed about three minutes before the touchdown of the tornadoes. Results indicate that the probability of producing an outbreak of tornadoes causing greater damage increases when there are higher values of potential energy storage per unit area for overshooting cloud tops penetrating the tropopause. It is also found that there is less chance for clouds with a lower moisture content to be outgrown as a storm cloud than clouds with a higher moisture content.

  18. Relating A-Train Water Vapor Observations to Cloud Classes from CloudSat

    NASA Astrophysics Data System (ADS)

    Fetzer, E. J.; Kahn, B. H.; Teixeira, J.; Fishbein, E. F.; Wilson, B. D.; Waliser, D. E.

    2008-12-01

    Three of the standard data sets from the NASA A-Train satellite constellation are CloudSat cloud classes, Atmospheric Infrared Sounder (AIRS) moist thermodynamic observations, and Advanced Microwave Sounding Radiometer for EOS (AMSR-E) total precipitable water vapor. We describe AIRS and AMSR-E water vapor observability, and the associated climatologies, conditional on CloudSat cloud classes. Because cloud classes represent unique physical processes, each scene type can be expected to have distinct temperature and water vapor signatures. Understanding the sampling characteristics of the water vapor observations is critical to interpreting them in the context of changing cloud and water vapor regimes.

  19. An Automated Cloud-edge Detection Algorithm Using Cloud Physics and Radar Data

    NASA Technical Reports Server (NTRS)

    Ward, Jennifer G.; Merceret, Francis J.; Grainger, Cedric A.

    2003-01-01

    An automated cloud edge detection algorithm was developed and extensively tested. The algorithm uses in-situ cloud physics data measured by a research aircraft coupled with ground-based weather radar measurements to determine whether the aircraft is in or out of cloud. Cloud edges are determined when the in/out state changes, subject to a hysteresis constraint. The hysteresis constraint prevents isolated transient cloud puffs or data dropouts from being identified as cloud boundaries. The algorithm was verified by detailed manual examination of the data set in comparison to the results from application of the automated algorithm.

  20. Cloud shortwave radiative effect and cloud properties estimated from airborne measurements of transmitted and reflected light

    NASA Astrophysics Data System (ADS)

    LeBlanc, Samuel E.; Redemann, Jens; Segal-Rosenheimer, Michal; Kacenelenbogen, Meloë; Shinozuka, Yohei; Flynn, Connor; Russell, Philip; Schmid, Beat; Schmidt, K. Sebastian; Pilewskie, Peter; Song, Shi

    2015-04-01

    Surface cloud radiative effect, or the perturbation of sunlight by clouds, is often estimated by cloud properties retrieved from reflected sunlight, however transmission-based retrievals may lead to a more representative surface radiative effect than reflection-based counterparts. Transmitted light interacts with cloud particles throughout the vertical extent of the cloud, while reflected light, commonly used for satellite remote sensing of clouds, is more influenced by the top-most cloud particles. We showcase the difference in measurement-based estimates of cloud radiative effect at the surface when using transmitted light instead of reflected light for particular cases during recent field missions. Along with cloud radiative effect, we present the retrieved cloud properties based on light transmitted and reflected by clouds in the Gulf of Mexico, sampled during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), and in the Gulf of Maine, sampled during the Two-Column Aerosol Project (TCAP). To quantify cloud properties from transmitted shortwave radiation, a new retrieval utilizing spectrally resolved measurements is employed. Spectral features in shortwave radiation transmitted through clouds are sensitive to changes in cloud properties including cloud optical thickness, effective radius, and thermodynamic phase. The absorption and scattering of light by liquid water and ice clouds result in shifts in spectral slopes, curvatures, maxima, and minima of cloud-transmitted radiance. A new framework is introduced to quantify these spectral features that are observed in measured and modeled transmittance. This new framework consists of 15 parameters that are independent of spectrally neutral variations in radiometric calibration quantifying spectral slopes, derivatives, spectral curvature calculations, and ratios. These parameters are used to retrieve cloud properties from measurements of zenith radiance

  1. Comparison of modern icing cloud instruments

    NASA Technical Reports Server (NTRS)

    Takeuchi, D. M.; Jahnsen, L. J.; Callander, S. M.; Humbert, M. C.

    1983-01-01

    Intercomparison tests with Particle Measuring Systems (PMS) were conducted. Cloud liquid water content (LWC) measurements were also taken with a Johnson and Williams (JW) hot-wire device and an icing rate device (Leigh IDS). Tests include varying cloud LWC (0.5 to 5 au gm), cloud median volume diameter (MVD) (15 to 26 microns), temperature (-29 to 20 C), and air speeds (50 to 285 mph). Comparisons were based upon evaluating probe estimates of cloud LWC and median volume diameter for given tunnel settings. Variations of plus or minus 10% and plus or minus 5% in LWC and MVD, respectively, were determined of spray clouds between test made at given tunnel settings (fixed LWC, MVD, and air speed) indicating cloud conditions were highly reproducible. Although LWC measurements from JW and Leigh devices were consistent with tunnel values, individual probe measurements either consistently over or underestimated tunnel values by factors ranging from about 0.2 to 2. Range amounted to a factor of 6 differences between LWC estimates of probes for given cloud conditions. For given cloud conditions, estimates of cloud MVD between probes were within plus or minus 3 microns and 93% of the test cases. Measurements overestimated tunnel values in the range between 10 to 20 microns. The need for improving currently used calibration procedures was indicated. Establishment of test facility (or facilities) such as an icing tunnel where instruments can be calibrated against known cloud standards would be a logical choice.

  2. Exploiting Virtualization and Cloud Computing in ATLAS

    NASA Astrophysics Data System (ADS)

    Harald Barreiro Megino, Fernando; Benjamin, Doug; De, Kaushik; Gable, Ian; Hendrix, Val; Panitkin, Sergey; Paterson, Michael; De Silva, Asoka; van der Ster, Daniel; Taylor, Ryan; Vitillo, Roberto A.; Walker, Rod

    2012-12-01

    The ATLAS Computing Model was designed around the concept of grid computing; since the start of data-taking, this model has proven very successful in the federated operation of more than one hundred Worldwide LHC Computing Grid (WLCG) sites for offline data distribution, storage, processing and analysis. However, new paradigms in computing, namely virtualization and cloud computing, present improved strategies for managing and provisioning IT resources that could allow ATLAS to more flexibly adapt and scale its storage and processing workloads on varied underlying resources. In particular, ATLAS is developing a “grid-of-clouds” infrastructure in order to utilize WLCG sites that make resources available via a cloud API. This work will present the current status of the Virtualization and Cloud Computing R&D project in ATLAS Distributed Computing. First, strategies for deploying PanDA queues on cloud sites will be discussed, including the introduction of a “cloud factory” for managing cloud VM instances. Next, performance results when running on virtualized/cloud resources at CERN LxCloud, StratusLab, and elsewhere will be presented. Finally, we will present the ATLAS strategies for exploiting cloud-based storage, including remote XROOTD access to input data, management of EC2-based files, and the deployment of cloud-resident LCG storage elements.

  3. Lidar cloud studies for FIRE and ECLIPS

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Grund, Christian J.; Spinhirne, James D.; Hardesty, Michael; Alvarez, James

    1990-01-01

    Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32 h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO) program. The lidar systems were variously equipped to collect linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. The cirrus cloud types include: dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex (MUC), a large-scale deep cloud that developed into an organized cirrus structure within the lidar array, and a series of intensifying mesoscale cirrus cloud masses. Although the cirrus frequently developed in the vertical from particle fall-streaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30 to -35 C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects are indicated. The generating regions ranged in scale from approximately 1.0 km cirrus uncinus cells, to organized MUC structures up to approximately 120 km across.

  4. Observing atmospheric clouds through stereo reconstruction

    NASA Astrophysics Data System (ADS)

    Öktem, Ruşen; Romps, David M.

    2015-03-01

    Observing cloud lifecycles and obtaining measurements on cloud features are significant problems in atmospheric cloud research. Scanning radars have been the most capable instruments to provide such measurements, but they have shortcomings when it comes to spatial and temporal resolution. High spatial and temporal resolution is particularly important to capture the variations in developing convections. Stereo photogrammetry can complement scanning radars with the potential to observe clouds as distant as tens of kilometers and to provide high temporal and spatial resolution, although it comes with the calibration challenges peculiar to various outdoor settings required to collect measurements on atmospheric clouds. This work explores the use of stereo photogrammetry in atmospheric cloud research, focusing on tracking vertical motion in developing convections. Calibration challenges and strategies to overcome these challenges are addressed within two different stereo settings in Miami, Florida and in the plains of Oklahoma. A feature extraction and matching algorithm is developed and implemented to identify cloud features of interest. A two-level resolution hierarchy is exploited in feature extraction and matching. 3D positions of cloud features are reconstructed from matched pixel pairs, and cloud tops of developing turrets in shallow to deep convection are tracked in time to estimate vertical accelerations. Results show that stereophotogrammetry provides a useful tool to observe cloud lifecycles and track the vertical acceleration of turrets exceeding 10 km height.

  5. Transport of infrared radiation in cuboidal clouds

    NASA Technical Reports Server (NTRS)

    Harshvardhan, MR.; Weinman, J. A.; Davies, R.

    1981-01-01

    The transport of infrared radiation in a single cuboidal cloud is modeled using a variable azimuth two-stream approximation. Computations are made at 10 microns for a Deirmendjian (1969) C-1 water cloud where the single scattering albedo is equal to 0.638 and the asymmetry parameter is 0.865. The results indicate that the emittance of the top face of the model cloud is always less than that for a plane parallel cloud of the same optical depth. The hemispheric flux escaping from the cloud top possesses a gradient from the center to the edges which are warmer when the cloud is over warmer ground. Cooling rate calculations in the 8-13.6 micron region demonstrate that there is cooling out of the sides of the cloud at all levels even when there is heating of the core from the ground below. The radiances exiting from model cuboidal clouds are computed by path integration over the source function obtained with the two-stream approximation. Results indicate that the brightness temperature measured from finite clouds will overestimate the cloud-top temperature.

  6. Cloud Macroscopic Organization: Order Emerging from Randomness

    NASA Technical Reports Server (NTRS)

    Yuan, Tianle

    2011-01-01

    Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds, and that it follows a power-law distribution with exponent gamma close to 2. gamma is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also demonstrate symmetry between clear and cloudy skies in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random local interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. We also propose a concept of cloud statistic mechanics approach. This approach is fully complementary to deterministic models, and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.

  7. 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.

  8. Secure data sharing in public cloud

    NASA Astrophysics Data System (ADS)

    Venkataramana, Kanaparti; Naveen Kumar, R.; Tatekalva, Sandhya; Padmavathamma, M.

    2012-04-01

    Secure multi-party protocols have been proposed for entities (organizations or individuals) that don't fully trust each other to share sensitive information. Many types of entities need to collect, analyze, and disseminate data rapidly and accurately, without exposing sensitive information to unauthorized or untrusted parties. Solutions based on secure multiparty computation guarantee privacy and correctness, at an extra communication (too costly in communication to be practical) and computation cost. The high overhead motivates us to extend this SMC to cloud environment which provides large computation and communication capacity which makes SMC to be used between multiple clouds (i.e., it may between private or public or hybrid clouds).Cloud may encompass many high capacity servers which acts as a hosts which participate in computation (IaaS and PaaS) for final result, which is controlled by Cloud Trusted Authority (CTA) for secret sharing within the cloud. The communication between two clouds is controlled by High Level Trusted Authority (HLTA) which is one of the hosts in a cloud which provides MgaaS (Management as a Service). Due to high risk for security in clouds, HLTA generates and distributes public keys and private keys by using Carmichael-R-Prime- RSA algorithm for exchange of private data in SMC between itself and clouds. In cloud, CTA creates Group key for Secure communication between the hosts in cloud based on keys sent by HLTA for exchange of Intermediate values and shares for computation of final result. Since this scheme is extended to be used in clouds( due to high availability and scalability to increase computation power) it is possible to implement SMC practically for privacy preserving in data mining at low cost for the clients.

  9. Progress in Understanding the Impacts of 3-D Cloud Structure on MODIS Cloud Property Retrievals for Marine Boundary Layer Clouds

    NASA Technical Reports Server (NTRS)

    Zhang, Zhibo; Werner, Frank; Miller, Daniel; Platnick, Steven; Ackerman, Andrew; DiGirolamo, Larry; Meyer, Kerry; Marshak, Alexander; Wind, Galina; Zhao, Guangyu

    2016-01-01

    Theory: A novel framework based on 2-D Tayler expansion for quantifying the uncertainty in MODIS retrievals caused by sub-pixel reflectance inhomogeneity. (Zhang et al. 2016). How cloud vertical structure influences MODIS LWP retrievals. (Miller et al. 2016). Observation: Analysis of failed MODIS cloud property retrievals. (Cho et al. 2015). Cloud property retrievals from 15m resolution ASTER observations. (Werner et al. 2016). Modeling: LES-Satellite observation simulator (Zhang et al. 2012, Miller et al. 2016).

  10. Jupiter's High-Altitude Clouds

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons Multispectral Visible Imaging Camera (MVIC) snapped this incredibly detailed picture of Jupiter's high-altitude clouds starting at 06:00 Universal Time on February 28, 2007, when the spacecraft was only 2.3 million kilometers (1.4 million miles) from the solar system's largest planet. Features as small as 50 kilometers (30 miles) are visible. The image was taken through a narrow filter centered on a methane absorption band near 890 nanometers, a considerably redder wavelength than what the eye can see. Images taken through this filter preferentially pick out clouds that are relatively high in the sky of this gas giant planet because sunlight at the wavelengths transmitted by the filter is completely absorbed by the methane gas that permeates Jupiter's atmosphere before it can reach the lower clouds.

    The image reveals a range of diverse features. The south pole is capped with a haze of small particles probably created by the precipitation of charged particles into the polar regions during auroral activity. Just north of the cap is a well-formed anticyclonic vortex with rising white thunderheads at its core. Slightly north of the vortex are the tendrils of some rather disorganized storms and more pinpoint-like thunderheads. The dark 'measles' that appear a bit farther north are actually cloud-free regions where light is completely absorbed by the methane gas and essentially disappears from view. The wind action considerably picks up in the equatorial regions where giant plumes are stretched into a long wave pattern. Proceeding north of the equator, cirrus-like clouds are shredded by winds reaching speeds of up to 400 miles per hour, and more pinpoint-like thunderheads are visible. Although some of the famous belt and zone structure of Jupiter's atmosphere is washed out when viewed at this wavelength, the relatively thin North Temperate Belt shows up quite nicely, as does a series of waves just north of the belt. The north polar region of

  11. Multilayer cloud detection and retrieval of cloud physical and optical properties from thermal infrared measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, H.; Tokoro, Y.; Saito, M.; Putri, N. S.; Katagiri, S.; Sekiguchi, M.

    2015-12-01

    Recent studies using active remote sensing have revealed significant occurrence of multi-layer cloud. Detection of multi-layer cloud is important in passive remote sensing for quality assessment of cloud property retrieval and identification of uncertain retrievals. An algorithm using several thermal infrared (TIR) bands at 6-13.5 micron wavelengths to detect multilayer cloud and retrieve cloud physical and optical properties including cloud thermodynamic phase is developed. This significantly extends applicability of passive remote sensing and improves accuracy of cloud property retrieval. The method uses the split window bands as well as the carbon dioxide and water vapor absorption bands. The forward model uses the two-stream approximation to solve radiative transfer with gaseous absorption treated by the correlated-k distribution method. Brightness temperature errors are evaluated by model-to-model and model-to-measurement comparisons. Top pressure of lower cloud in multi-layer cloud column can be retrieved if the upper cloud optical thickness is less than 6. The optimal estimation method is used to simultaneously infer several cloud properties including water path, effective particle radius and cloud-top pressure. The method is applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) using 10 TIR bands and compared to MODIS operational product and active remote sensing measurements, showing promising results. The TIR method well detects optically thin clouds and retrieve their properties with relatively high accuracy. Particularly, cloud-top of optically thin cloud is estimated well. Multi-layer cloud detection works usually, while the TIR measurements miss very thin cloud that appears near the tropopause. The algorithm will be applied to frequent observation data from a new Japanese geostationary satellite, Himawari-8.

  12. What does Reflection from Cloud Sides tell us about Vertical Distribution of Cloud Droplet Sizes?

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Martins, J. V.; Zubko, V.; Kaufman, Y. J.

    2006-01-01

    Cloud development, the onset of precipitation and the effect of aerosol on clouds depend on the structure of the cloud profiles of droplet size and phase. Aircraft measurements of cloud profiles are limited in their temporal and spatial extent. Satellites were used to observe cloud tops not cloud profiles with vertical profiles of precipitation-sized droplets anticipated from CloudSat. The recently proposed CLAIM-3D satellite mission (cloud aerosol interaction mission in 3-D) suggests to measure profiles of cloud microphysical properties by retrieving them from the solar and infrared radiation reflected or emitted from cloud sides. Inversion of measurements from the cloud sides requires rigorous understanding of the 3-dimentional(3-D) properties of clouds. Here we discuss the reflected sunlight from the cloud sides and top at two wavelengths: one nonabsorbing to solar radiation (0.67 microns) and one with liquid water efficient absorption of solar radiation (2.1 microns). In contrast to the plane-parallel approximation, a conventional approach to all current operational retrievals, 3-D radiative transfer is used for interpreting the observed reflectances. General properties of the radiation reflected from the sides of an isolated cloud are discussed. As a proof of concept, the paper shows a few examples of radiation reflected from cloud fields generated by a simple stochastic cloud model with the prescribed vertically resolved microphysics. To retrieve the information about droplet sizes, we propose to use the probability density function of the droplet size distribution and its first two moments instead of the assumption about fixed values of the droplet effective radius. The retrieval algorithm is based on the Bayesian theorem that combines prior information about cloud structure and microphysics with radiative transfer calculations.

  13. Exploring the Effects of Cloud Vertical Structure on Cloud Microphysical Retrievals based on Polarized Reflectances

    NASA Astrophysics Data System (ADS)

    Miller, D. J.; Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Cornet, C.; Baum, B. A.

    2013-12-01

    A polarized cloud reflectance simulator was developed by coupling an LES cloud model with a polarized radiative transfer model to assess the capabilities of polarimetric cloud retrievals. With future remote sensing campaigns like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important for the cloud remote sensing community to understand the retrievable information available and the related systematic/methodical limitations. The cloud retrieval simulator we have developed allows us to probe these important questions in a realistically relevant test bed. Our simulator utilizes a polarized adding-doubling radiative transfer model and an LES cloud field from a DHARMA simulation (Ackerman et al. 2004) with cloud properties based on the stratocumulus clouds observed during the DYCOMS-II field campaign. In this study we will focus on how the vertical structure of cloud microphysics can influence polarized cloud effective radius retrievals. Numerous previous studies have explored how retrievals based on total reflectance are affected by cloud vertical structure (Platnick 2000, Chang and Li 2002) but no such studies about the effects of vertical structure on polarized retrievals exist. Unlike the total cloud reflectance, which is predominantly multiply scattered light, the polarized reflectance is primarily the result of singly scattered photons. Thus the polarized reflectance is sensitive to only the uppermost region of the cloud (tau~<1) where photons can scatter once and still escape before being scattered again. This means that retrievals based on polarized reflectance have the potential to reveal behaviors specific to the cloud top. For example cloud top entrainment of dry air, a major influencer on the microphysical development of cloud droplets, can be potentially studied with polarimetric retrievals.

  14. CloudSat observations of multi layered clouds across the globe

    NASA Astrophysics Data System (ADS)

    Subrahmanyam, K. Venkata; Kumar, Karanam Kishore

    2016-09-01

    Vertically resolved multi-layer cloud distributions over the globe using 4 years of CloudSat/CALIPSO observations during 2007-2010 are discussed. The quantitative information on the frequency of occurrence of one- to five-layered clouds across the globe is established, which are of immense importance from the global climate standpoint. After segregating the CloudSat observations into different seasons, the 4 years of mean global maps of frequency of occurrence of one to five-layered clouds are discussed in details. These global maps provide much needed quantification of vertically resolved multi-layer clouds by revealing when and where the frequency of occurrence of multi-layer clouds are maximum including the number of layers. On an average, it is observed that over the globe one-, two-, three-, four- and five-layer clouds occur 53, 20, 3.5, 0.4 and 0.04 % of the time respectively. High fraction of single layer clouds is observed over the descending limbs of Hadley cell where relatively large lower tropospheric stability is found. The regions where multi-layer clouds are more frequent are identified and discussed along with large scale circulation. Apart from quantifying the frequency of occurrence of multi-layer clouds, the latitudinal distribution of zonal mean occurrence of cloud base and top altitudes of each cloud layer is constructed for boreal winter and summer. These analyses provide the cloud base and top altitudes of one to five-layered clouds, which are important to understand the vertical structure of the multi-layered clouds. The significance of the present study lies in establishing the global distribution of vertically resolved multi-layer clouds and the role of large-scale dynamics in controlling their distribution for the first time.

  15. Aerosol and Cloud Microphysical Characteristics of Rifts and Gradients in Maritime Stratocumulus Clouds

    NASA Technical Reports Server (NTRS)

    Sharon, Tarah M.; Albrecht, Bruce A.; Jonsson, Haflidi H.; Minnis, Patrick; Khaiyer, Mandana M.; Van Reken, Timothy; Seinfeld, John; Flagan, Rick

    2008-01-01

    A cloud rift is characterized as a large-scale, persistent area of broken, low reflectivity stratocumulus clouds usually surrounded by a solid deck of stratocumulus. A rift observed off the coast of Monterey Bay, California on 16 July 1999 was studied to compare the aerosol and cloud microphysical properties in the rift with those of the surrounding solid stratus deck. Variables measured from an instrumented aircraft included temperature, water vapor, and cloud liquid water. These measurements characterized the thermodynamic properties of the solid deck and rift areas. Microphysical measurements made included aerosol, cloud drop and drizzle drop concentrations and cloud condensation nuclei (CCN) concentrations. The microphysical characteristics in a solid stratus deck differ substantially from those of a broken, cellular rift where cloud droplet concentrations are a factor of 2 lower than those in the solid cloud. Further, CCN concentrations were found to be about 3 times greater in the solid cloud area compared with those in the rift and aerosol concentrations showed a similar difference as well. Although drizzle was observed near cloud top in parts of the solid stratus cloud, the largest drizzle rates were associated with the broken clouds within the rift area. In addition to marked differences in particle concentrations, evidence of a mesoscale circulation near the solid cloud rift boundary is presented. This mesoscale circulation provides a mechanism for maintaining a rift, but further study is required to understand the initiation of a rift and the conditions that may cause it to fill.

  16. Integrated Cloud-Aerosol-Radiation Product using CERES, MODIS, CALIPSO and CloudSat Data

    NASA Technical Reports Server (NTRS)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Gibson, Sharon; Yi, Yuhong; Trepte, Qing; Wielicki, Bruce; Kato, Seiji; Winker, Dave

    2007-01-01

    This paper documents the development of the first integrated data set of global vertical profiles of clouds, aerosols, and radiation using the combined NASA A-Train data from the Aqua Clouds and Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS), Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and CloudSat. As part of this effort, cloud data from the CALIPSO lidar and the CloudSat radar are merged with the integrated column cloud properties from the CERES-MODIS analyses. The active and passive datasets are compared to determine commonalities and differences in order to facilitate the development of a 3- dimensional cloud and aerosol dataset that will then be integrated into the CERES broadband radiance footprint. Preliminary results from the comparisons for April 2007 reveal that the CERES-MODIS global cloud amounts are, on average, 0.14 less and 0.15 greater than those from CALIPSO and CloudSat, respectively. These new data will provide unprecedented ability to test and improve global cloud and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, cloud, and radiation data sets especially in polar regions and for multi-layered cloud conditions.

  17. Observations of photoevaporating interstellar clouds

    NASA Astrophysics Data System (ADS)

    McCullough, Peter Rankin

    1993-01-01

    In the first part of this thesis, we present a tabulation of parameters for 50 globules, most of which are bright-rimmed clouds, observed in transitions of (12)CO, (13)CS, CS, and HCO(+) with a 1 diameter beam. H-alpha images for many bright-rimmed clouds and long-slit H-alpha spectra of two such clouds are presented. The observations are interpreted in terms of the rocket effect and D-critical ionization fronts. The elongated clouds (the so-called elephant trunk globules and cometary clouds) tend to point toward their source of ionization, although a possible counter example is presented. They often have velocity gradients along their lengths; a few examples are newly presented along with others collected from the literature. Mechanisms for forming elongated clouds are discussed. Also, means of determining the three-dimensional geometry of an H II region are discussed. The hypothesis that bright rims implode clouds and induce star formation is reviewed and found to be controversial . In the second part, we present images of the Orion Trapezium made with a unique adaptive optics system that uses either starlight or Rayleigh-backscattered laser light to correct for atmospheric wavefront distortion. The H-alpha and I band images reveal the region around the bright Trapezium stars, which has been studied extensively at radio wavelengths. Approximately one half of the stars in this region are positionally associated with knots of ionized gas, known as pigs, which are interpreted as photoevaporating envelopes of low mass stars. Disks are not observed directly but are inferred from the relatively low extinction to the stars inside the pigs. The comet-like morphology of the pigs is the result of an equilibrium between photoionization, recombination, and shadowing, interaction with the wind from theta1C Ori is not required. The sizes of the ionized component of the envelopes increase with distance from the source of ionization, theta1C Ori. The size-distance relationship

  18. Observations of Photoevaporating Interstellar Clouds

    NASA Astrophysics Data System (ADS)

    McCullough, Peter Rankin

    1995-01-01

    In the first part of this thesis, we present a tabulation of parameters for 50 globules, most of which are bright-rimmed clouds, observed in transitions of 12CO, 13CO, CS, and HCO+ with a 1 arcminute diameter beam. H-alpha images for many bright-rimmed clouds and long-slit H-alpha spectra of two such clouds are presented. The observations are interpreted in terms of the rocket effect and D-critical ionization fronts. The elongated clouds (the so called elephant trunk globules and cometary clouds) tend to point toward their source of ionization, although a possible counter-example is presented. They often have velocity gradients along their lengths; a few examples are newly presented along with others collected from the literature. Mechanisms for forming elongated clouds are discussed. Also, means of determining the three-dimensional geometry of an H II region are discussed. The hypothesis that bright rims implode clouds and induce star formation is reviewed and found to be controversial. In the second part, we present images of the Orion Trapezium made with a unique adaptive optics system that uses either starlight or Rayleigh-backscattered laser light to correct for atmospheric wavefront distortion. The H-alpha and I band images reveal the region around the bright Trapezium stars, which has been studied extensively at radio wavelengths. Approximately one half of the stars in this region are positionally associated with knots of ionized gas, known as pigs, which are interpreted as photoevaporating envelopes of low mass stars. Disks are not observed directly but are inferred from the relatively low extinction to the stars inside the pigs. The comet-like morphology of the pigs is the result of an equilibrium between photoionization, recombination, and shadowing; interaction with the wind from theta-1C ~Ori is not required. The sizes of the ionized component of the envelopes increase with distance from the source of ionization, theta-1C Ori. The size

  19. Properties of aerosol processed by ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Adler, G.; Moise, T.; Erlick-Haspel, C.

    2012-12-01

    We suggest that highly porous aerosol (HPA) can form in the upper troposphere/lower stratosphere when ice particles encounter sub-saturation leading to ice sublimation similar to freeze drying. This process can occur at the lower layers of cirrus clouds (few km), at anvils of high convective clouds and thunderstorms, in clouds forming in atmospheric gravitational waves, in contrails and in high convective clouds injecting to the stratosphere. A new experimental system that simulates freeze drying of proxies for atmospheric aerosol at atmospheric pressure was constructed and various proxies for atmospheric soluble aerosol were studied. The properties of resulting HPA were characterized by various methods. It was found that the resulting aerosol have larger sizes (extent depends on substance and mixing), lower density (largevoid fraction), lower optical extinction and higher CCN activity and IN activity. Implication of HPA's unique properties and their atmospheric consequences to aerosol processing in ice clouds and to cloud cycles will be discussed.

  20. Dynamical history of the Oort Cloud

    NASA Technical Reports Server (NTRS)

    Weissman, P. R.

    1982-01-01

    Oort's hypothesis for the origin of long-period comets is reviewed, along with evidence for the existence of the Oort Cloud and recent research in stellar perturbations of cometary orbits. A Monte Carlo model is used to analyze the dynamics of comets in the Oort Cloud, to estimate the present and original populations of the cloud, and to examine implications for various theories of the origin of comets. The problem of interstellar comets is briefly considered. It is concluded that: (1) the weight of evidence favors Oort's hypothesis of a cloud of a trillion comets surrounding the solar system and extending out to about 100,000 AU; (2) the dynamical evolution of the cloud is consistent with observational data on long-period comets; and (3) estimates of the population necessary to produce the observed flux of dynamically new comets lead to physically reasonable values for the current and initial cloud masses.

  1. Implementation of cloud computing in higher education

    NASA Astrophysics Data System (ADS)

    Asniar; Budiawan, R.

    2016-04-01

    Cloud computing research is a new trend in distributed computing, where people have developed service and SOA (Service Oriented Architecture) based application. This technology is very useful to be implemented, especially for higher education. This research is studied the need and feasibility for the suitability of cloud computing in higher education then propose the model of cloud computing service in higher education in Indonesia that can be implemented in order to support academic activities. Literature study is used as the research methodology to get a proposed model of cloud computing in higher education. Finally, SaaS and IaaS are cloud computing service that proposed to be implemented in higher education in Indonesia and cloud hybrid is the service model that can be recommended.

  2. Thin cloud removal from single satellite images.

    PubMed

    Liu, Jun; Wang, Xing; Chen, Min; Liu, Shuguang; Zhou, Xiran; Shao, Zhenfeng; Liu, Ping

    2014-01-13

    A novel method for removing thin clouds from single satellite image is presented based on a cloud physical model. Given the unevenness of clouds, the cloud background is first estimated in the frequency domain and an adjustment function is used to suppress the areas with greater gray values and enhance the dark objects. An image, mainly influenced by transmission, is obtained by subtracting the cloud background from the original cloudy image. The final image with proper color and contrast is obtained by decreasing the effect of transmission using the proposed max-min radiation correction approach and an adaptive brightness factor. The results indicate that the proposed method can more effectively remove thin clouds, improve contrast, restore color information, and retain detailed information compared with the commonly used image enhancement and haze removal methods.

  3. Wyoming Cloud Lidar: instrument description and applications.

    PubMed

    Wang, Zhien; Wechsler, Perry; Kuestner, William; French, Jeffrey; Rodi, Alfred; Glover, Brent; Burkhart, Matthew; Lukens, Donal

    2009-08-01

    The Wyoming Cloud Lidar (WCL), a compact two-channel elastic lidar, was designed to obtain cloud measurements together with the Wyoming Cloud Radar (WCR) on the University of Wyoming King Air and the National Science Foundation/National Center of Atmospheric Research C-130 aircraft. The WCL has been deployed in four field projects under a variety of atmospheric and cloud conditions during the last two years. Throughout these campaigns, it has exhibited the needed reliability for turn-key operation from aircraft. We provide here an overview of the instrument and examples to illustrate the measurements capability of the WCL. Although the WCL as a standalone instrument can provide unique measurements for cloud and boundary layer aerosol studies, the synergy of WCL and WCR measurements coupled with in situ sampling from an aircraft provide a significant step forward in our ability to observe and understand cloud microphysical property evolution.

  4. Cloud Computing and Its Applications in GIS

    NASA Astrophysics Data System (ADS)

    Kang, Cao

    2011-12-01

    Cloud computing is a novel computing paradigm that offers highly scalable and highly available distributed computing services. The objectives of this research are to: 1. analyze and understand cloud computing and its potential for GIS; 2. discover the feasibilities of migrating truly spatial GIS algorithms to distributed computing infrastructures; 3. explore a solution to host and serve large volumes of raster GIS data efficiently and speedily. These objectives thus form the basis for three professional articles. The first article is entitled "Cloud Computing and Its Applications in GIS". This paper introduces the concept, structure, and features of cloud computing. Features of cloud computing such as scalability, parallelization, and high availability make it a very capable computing paradigm. Unlike High Performance Computing (HPC), cloud computing uses inexpensive commodity computers. The uniform administration systems in cloud computing make it easier to use than GRID computing. Potential advantages of cloud-based GIS systems such as lower barrier to entry are consequently presented. Three cloud-based GIS system architectures are proposed: public cloud- based GIS systems, private cloud-based GIS systems and hybrid cloud-based GIS systems. Public cloud-based GIS systems provide the lowest entry barriers for users among these three architectures, but their advantages are offset by data security and privacy related issues. Private cloud-based GIS systems provide the best data protection, though they have the highest entry barriers. Hybrid cloud-based GIS systems provide a compromise between these extremes. The second article is entitled "A cloud computing algorithm for the calculation of Euclidian distance for raster GIS". Euclidean distance is a truly spatial GIS algorithm. Classical algorithms such as the pushbroom and growth ring techniques require computational propagation through the entire raster image, which makes it incompatible with the distributed nature

  5. Coherent Forward Broadening in Cold Atom Clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, Francis

    2016-05-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Further, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single photon wavefunction model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms in the back of the cloud are more excited than the atoms in the front. These calculations are conducted at low densities relevant to recent experiments. This work was supported by the National Science Foundation under Grant No. 1404419-PHY.

  6. Coherent forward broadening in cold atom clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, F.

    2016-02-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Furthermore, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single-photon wave-function model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms at the back of the cloud are more excited than the atoms at the front. These calculations are conducted at the low densities relevant to recent experiments.

  7. 4-D display of satellite cloud images

    NASA Technical Reports Server (NTRS)

    Hibbard, William L.

    1987-01-01

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

  8. Thermodynamic control of anvil cloud amount.

    PubMed

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A; Voigt, Aiko; Medeiros, Brian

    2016-08-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative-convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.

  9. Star formation in Lynds dark clouds

    NASA Astrophysics Data System (ADS)

    Spuck, Tim; Rebull, Luisa

    2008-03-01

    Recent research on star formation in large molecular cloud complexes, such as the Cepheus Flare (Kun 1995), Orion, Perseus (Rebull et al. 2007), and Taurus molecular clouds, have included studies of a number of Lynds dark nebulae (LDN). Less attention has been given to isolated Lynds clouds. Both LDN 981 and LDN 425 are smaller, more isolated, dark molecular clouds that could contain regions of active star formation within them -- they both are associated with IRAS sources, and based on prior shallow surveys, they both have a YSO candidate in the neigborhood. Spitzer observations with IRAC and MIPS will allow us to see deep inside the cloud, deeper than any prior observations could see, and reveal any hidden star formation that is ongoing in these clouds. This project is part of the Spitzer Teachers Program.

  10. Thermodynamic control of anvil cloud amount

    NASA Astrophysics Data System (ADS)

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko; Medeiros, Brian

    2016-08-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative-convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.

  11. The kinetic chemistry of dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Graedel, T. E.; Langer, W. D.; Frerking, M. A.

    1982-01-01

    A model of the time-dependent chemistry of dense interstellar clouds is formulated to study the dominant chemical processes in carbon and oxygen isotope fractionation, the formation of nitrogen-containing molecules, and the evolution of product molecules as a function of cloud density and temperature. The abundances of the dominant isotopes of the carbon- and oxygen-bearing molecules are calculated. The chemical abundances are found to be quite sensitive to electron concentration since the electron concentration determines the ratio of H3(+) to He(+), and the electron density is strongly influenced by the metals abundance. For typical metal abundances and for H2 cloud density not less than 10,000 molecules/cu cm, nearly all carbon exists as CO at late cloud ages. At high cloud density, many aspects of the chemistry are strongly time dependent. Finally, model calculations agree well with abundances deduced from observations of molecular line emission in cold dense clouds.

  12. Cloud condensation nuclei near marine cumulus

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1993-01-01

    Extensive airborne measurements of cloud condensation nucleus (CCN) spectra and condensation nuclei below, in, between, and above the cumulus clouds near Hawaii point to important aerosol-cloud interactions. Consistent particle concentrations of 200/cu cm were found above the marine boundary layer and within the noncloudy marine boundary layer. Lower and more variable CCN concentrations within the cloudy boundary layer, especially very close to the clouds, appear to be a result of cloud scavenging processes. Gravitational coagulation of cloud droplets may be the principal cause of this difference in the vertical distribution of CCN. The results suggest a reservoir of CCN in the free troposphere which can act as a source for the marine boundary layer.

  13. Thermodynamic control of anvil cloud amount

    NASA Astrophysics Data System (ADS)

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko; Medeiros, Brian

    2016-08-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.

  14. Continuation of point clouds via persistence diagrams

    NASA Astrophysics Data System (ADS)

    Gameiro, Marcio; Hiraoka, Yasuaki; Obayashi, Ippei

    2016-11-01

    In this paper, we present a mathematical and algorithmic framework for the continuation of point clouds by persistence diagrams. A key property used in the method is that the persistence map, which assigns a persistence diagram to a point cloud, is differentiable. This allows us to apply the Newton-Raphson continuation method in this setting. Given an original point cloud P, its persistence diagram D, and a target persistence diagram D‧, we gradually move from D to D‧, by successively computing intermediate point clouds until we finally find a point cloud P‧ having D‧ as its persistence diagram. Our method can be applied to a wide variety of situations in topological data analysis where it is necessary to solve an inverse problem, from persistence diagrams to point cloud data.

  15. Access Control of Cloud Service Based on UCON

    NASA Astrophysics Data System (ADS)

    Danwei, Chen; Xiuli, Huang; Xunyi, Ren

    Cloud computing is an emerging computing paradigm, and cloud service is also becoming increasingly relevant. Most research communities have recently embarked in the area, and research challenges in every aspect. This paper mainly discusses cloud service security. Cloud service is based on Web Services, and it will face all kinds of security problems including what Web Services face. The development of cloud service closely relates to its security, so the research of cloud service security is a very important theme. This paper introduces cloud computing and cloud service firstly, and then gives cloud services access control model based on UCON and negotiation technologies, and also designs the negotiation module.

  16. Some Technical Aspects of a CALIOP and MODIS Data Analysis that Examines Near-Cloud Aerosol Properties as a Function of Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Yang, Weidong; Marshak, Alexander

    2016-01-01

    CALIOP shows stronger near-cloud changes in aerosol properties at higher cloud fractions. Cloud fraction variations explain a third of near-cloud changes in overall aerosol statistics. Cloud fraction and aerosol particle size distribution have a complex relationship.

  17. Classification of Big Point Cloud Data Using Cloud Computing

    NASA Astrophysics Data System (ADS)

    Liu, K.; Boehm, J.

    2015-08-01

    Point cloud data plays an significant role in various geospatial applications as it conveys plentiful information which can be used for different types of analysis. Semantic analysis, which is an important one of them, aims to label points as different categories. In machine learning, the problem is called classification. In addition, processing point data is becoming more and more challenging due to the growing data volume. In this paper, we address point data classification in a big data context. The popular cluster computing framework Apache Spark is used through the experiments and the promising results suggests a great potential of Apache Spark for large-scale point data processing.

  18. Cloud seeding as a technique for studying aerosol-cloud interactions in marine stratocumulus

    NASA Astrophysics Data System (ADS)

    Ghate, Virendra P.; Albrecht, Bruce A.; Kollias, Pavlos; Jonsson, Haflidi H.; Breed, Daniel W.

    2007-07-01

    Giant hygroscopic aerosols were introduced into a solid marine stratocumulus cloud (200 m thick) by burning hygroscopic flares mounted on an aircraft. The cloud microphysical response in two parallel seeding plumes was observed using an instrumented aircraft making 16 transects of the plumes. The cloud drop size distribution width increased in the plumes due to an increased number of small cloud drops (3-5 μm) on the earlier transects and a 5-fold increase in the number of large drops (20-40 μm) relative to the background cloud 30 minutes later. The cloud effective diameter increased from about 11 μm in the background to 13 μm in the plumes. Although the giant nuclei were only a small fraction of the total aerosols produced by the flares, they dominated the cloud response. The merit of the seeding approach for controlled observational studies of aerosol-cloud interactions in marine stratocumulus was demonstrated.

  19. Clouds in a Bottle: Qualitative and Quantiative Demonstrations for Cloud Formation in a Learning Environment

    NASA Astrophysics Data System (ADS)

    Ellis, T. D.

    2015-12-01

    The NASA CloudSat mission has been revealing the inner secrets of clouds since 2006 using its one-of-a-kind spaceborne cloud radar. During its mission, the CloudSat Education Network, consisting of schools in Asia, Europe, and North America, have been collecting data on Clouds when CloudSat passes overhead. The education team has spent many hours researching and presenting different methods for making clouds for demonstrations in formal and informal settings. In this presentation, we will present several variations on methods for doing the cloud in a bottle demonstration, including strengths and weaknesses for each, and a brief overview of the science involved in the various demonstrations.

  20. Lower mass limit of an evolving interstellar cloud and chemistry in an evolving oscillatory cloud

    NASA Technical Reports Server (NTRS)

    Tarafdar, S. P.

    1986-01-01

    Simultaneous solution of the equation of motion, equation of state and energy equation including heating and cooling processes for interstellar medium gives for a collapsing cloud a lower mass limit which is significantly smaller than the Jeans mass for the same initial density. The clouds with higher mass than this limiting mass collapse whereas clouds with smaller than critical mass pass through a maximum central density giving apparently similar clouds (i.e., same Av, size and central density) at two different phases of its evolution (i.e., with different life time). Preliminary results of chemistry in such an evolving oscillatory cloud show significant difference in abundances of some of the molecules in two physically similar clouds with different life times. The problems of depletion and short life time of evolving clouds appear to be less severe in such an oscillatory cloud.

  1. 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.

  2. Personal healthcare system using cloud computing.

    PubMed

    Takeuchi, Hiroshi; Mayuzumi, Yuuki; Kodama, Naoki; Sato, Keiichi

    2013-01-01

    A personal healthcare system used with cloud computing has been developed. It enables a daily time-series of personal health and lifestyle data to be stored in the cloud through mobile devices. The cloud automatically extracts personally useful information, such as rules and patterns concerning lifestyle and health conditions embedded in the personal big data, by using a data mining technology. The system provides three editions (Diet, Lite, and Pro) corresponding to users' needs.

  3. 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.

  4. Multiple scattering in atmospheric clouds: lidar observations.

    PubMed

    Pal, S R; Carswell, A I

    1976-08-01

    The contribution of multiple scattering in lidar backscattering from clouds has been investigated using a ruby laser at 694 nm. The depolarization of an incident linearly polarized signal is measured with a multichannel lidar receiver. An analysis is presented whereby this information can be utilized to measure the multiple scattering in clouds in which single scattering retains the incident linear polarization. Experimental data are presented for cumulus clouds and for ground level fog, and the results are compared with some recent theoretical computations.

  5. Venus clouds: a dirty hydrochloric Acid model.

    PubMed

    Hapke, B

    1972-02-18

    The spectral and polarization data for Venus are consistent with micrometer-sized aerosol cloud particles of hydrochloric acid with soluble and insoluble iron compounds, whose source could be volcanic or crustal dust. The yellow color of the clouds could be due to absorption bands in the near ultraviolet involving ferric iron and chlorine complexes. The ultraviolet features could arise from variations in the concentrations of iron and hydrochloric acid in the cloud particles.

  6. Interstellar cloud material: contribution to planetary atmospheres.

    PubMed

    Butler, D M; Newman, M J; Talbot, R J

    1978-08-11

    A statistical analysis of the properties of dense interstellar clouds indicates that the solar system has encountered at least a dozen clouds of sufficient density to cause planets to accumulate nonnegligible amounts of some isotopes. The effect is most pronounced for neon. This mechanism could be responsible for much of the neon in Earth's atmosphere. For Mars, the predicted amount of neon added by cloud encounters greatly exceeds the present abundance.

  7. Mesoscale wake clouds in Skylab pictures.

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.; Tecson, J. J.

    1974-01-01

    The recognition of cloud patterns formed in the wake of orographic obstacles was investigated using pictures from Skylab, for the purpose of estimating atmospheric motions. The existence of ship-wake-type wave clouds in contrast to vortex sheets were revealed during examination of the pictures, and an attempt was made to characterize the pattern of waves as well as the transition between waves and vortices. Examples of mesoscale cloud patterns which were analyzed photogrammetrically and meteorologically are presented.

  8. Deepstar 902 cloud point round robin

    SciTech Connect

    Williams, T.M.; Santamaria, M.M.

    1995-12-01

    Wax deposition is a problem in many oil fields and wells. Since wax precipitates and may cause deposition problems when the oil is cooled below its cloud point, an accurate method to determine an oil`s cloud point is needed. Samples of oil from three wells were collected and distributed to ten laboratories. The results indicate that cloud point temperature measurement is not as well defined as expected. The results of this study are discussed in this paper.

  9. Cloud computing can simplify HIT infrastructure management.

    PubMed

    Glaser, John

    2011-08-01

    Software as a Service (SaaS), built on cloud computing technology, is emerging as the forerunner in IT infrastructure because it helps healthcare providers reduce capital investments. Cloud computing leads to predictable, monthly, fixed operating expenses for hospital IT staff. Outsourced cloud computing facilities are state-of-the-art data centers boasting some of the most sophisticated networking equipment on the market. The SaaS model helps hospitals safeguard against technology obsolescence, minimizes maintenance requirements, and simplifies management.

  10. Cloud computing can simplify HIT infrastructure management.

    PubMed

    Glaser, John

    2011-08-01

    Software as a Service (SaaS), built on cloud computing technology, is emerging as the forerunner in IT infrastructure because it helps healthcare providers reduce capital investments. Cloud computing leads to predictable, monthly, fixed operating expenses for hospital IT staff. Outsourced cloud computing facilities are state-of-the-art data centers boasting some of the most sophisticated networking equipment on the market. The SaaS model helps hospitals safeguard against technology obsolescence, minimizes maintenance requirements, and simplifies management. PMID:21866720

  11. Cloud effects on middle ultraviolet global radiation

    NASA Technical Reports Server (NTRS)

    Borkowski, J.; Chai, A.-T.; Mo, T.; Green, A. E. O.

    1977-01-01

    An Eppley radiometer and a Robertson-Berger sunburn meter are employed along with an all-sky camera setup to study cloud effects on middle ultraviolet global radiation at the ground level. Semiempirical equations to allow for cloud effects presented in previous work are compared with the experimental data. The study suggests a means of defining eigenvectors of cloud patterns and correlating them with the radiation at the ground level.

  12. Cloud variations and the Earth's energy budget

    NASA Astrophysics Data System (ADS)

    Dessler, A. E.

    2011-10-01

    The question of whether clouds are the cause of surface temperature changes, rather than acting as a feedback in response to those temperature changes, is explored using data obtained between 2000 and 2010. An energy budget calculation shows that the radiative impact of clouds accounts for little of the observed climate variations. It is also shown that observations of the lagged response of top-of-atmosphere (TOA) energy fluxes to surface temperature variations are not evidence that clouds are causing climate change.

  13. Venus clouds - A dirty hydrochloric acid model.

    NASA Technical Reports Server (NTRS)

    Hapke, B.

    1972-01-01

    The spectral and polarization data for Venus are consistent with micrometer-sized aerosol cloud particles of hydrochloric acid with soluble and insoluble iron compounds, whose source could be volcanic or crustal dust. The yellow color of the clouds could be due to absorption bands in the near UV involving ferric iron and chlorine complexes. It is pointed out that the UV features could arise from variations in the concentrations of iron and hydrochloric acid in the cloud particles.

  14. Influence of Subpixel Scale Cloud Top Structure on Reflectances from Overcast Stratiform Cloud Layers

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Varnai, Tamas; Winker, David M.

    1998-01-01

    Recent observational studies have shown that satellite retrievals of cloud optical depth based on plane-parallel model theory suffer from systematic biases that depend on viewing geometry, even when observations are restricted to overcast marine stratus layers, arguably the closest to plane parallel in nature. At moderate to low sun elevations, the plane-parallel model significantly overestimates the reflectance dependence on view angle in the forward-scattering direction but shows a similar dependence in the backscattering direction. Theoretical simulations are performed that show that the likely cause for this discrepancy is because the plane-parallel model assumption does not account for subpixel, scale variations in cloud-top height (i.e., "cloud bumps"). Monte Carlo simulation, comparing ID model radiances to radiances from overcast cloud field with 1) cloud-top height variation, but constant cloud volume extinction; 2) flat tops but horizontal variations in cloud volume extinction; and 3) variations in both cloud top height and cloud extinction are performed over a approximately equal to 4 km x 4 km domain (roughly the size of an individual GAC AVHRR pixel). The comparisons show that when cloud-top height variations are included, departures from 1D theory are remarkably similar (qualitatively) to those obtained observationally. In contrast, when clouds are assumed flat and only cloud extinction is variable, reflectance differences are much smaller and do not show any view-angle dependence. When both cloud-top height and cloud extinction variations are included, however, large increases in cloud extinction variability can enhance reflectance difference. The reason 3D-1D reflectance differences are more sensitive to cloud-top height variations in the forward-scattering direction (at moderate to low, sun elevations) is because photons leaving the cloud field in that direction experience fewer scattering events (low-order scattering) and are restricted to the

  15. The frequency and nature of `cloud-cloud collisions' in galaxies

    NASA Astrophysics Data System (ADS)

    Dobbs, C. L.; Pringle, J. E.; Duarte-Cabral, A.

    2015-02-01

    We investigate cloud-cloud collisions and giant molecular cloud evolution in hydrodynamic simulations of isolated galaxies. The simulations include heating and cooling of the interstellar medium (ISM), self-gravity and stellar feedback. Over time-scales <5 Myr most clouds undergo no change, and mergers and splits are found to be typically two-body processes, but evolution over longer time-scales is more complex and involves a greater fraction of intercloud material. We find that mergers or collisions occur every 8-10 Myr (1/15th of an orbit) in a simulation with spiral arms, and once every 28 Myr (1/5th of an orbit) with no imposed spiral arms. Both figures are higher than expected from analytic estimates, as clouds are not uniformly distributed in the galaxy. Thus, clouds can be expected to undergo between zero and a few collisions over their lifetime. We present specific examples of cloud-cloud interactions in our results, including synthetic CO maps. We would expect cloud-cloud interactions to be observable, but find they appear to have little or no impact on the ISM. Due to a combination of the clouds' typical geometries, and moderate velocity dispersions, cloud-cloud interactions often better resemble a smaller cloud nudging a larger cloud. Our findings are consistent with the view that spiral arms make little difference to overall star formation rates in galaxies, and we see no evidence that collisions likely produce massive clusters. However, to confirm the outcome of such massive cloud collisions we ideally need higher resolution simulations.

  16. Molecular clouds in galaxies with different Z - Fragmentation of diffuse clouds driven by opacity

    NASA Technical Reports Server (NTRS)

    Franco, Jose; Cox, Donald P.

    1986-01-01

    Molecular clouds are formed from diffuse interstellar clouds when the external ultraviolet radiation field is prevented from penetrating into the cloud. The opacity is provided mainly by dust grains and the required column density to the cloud center is larger than about 5 x 10 to the 20th (solar Z/Z)/sq cm. This high-opacity criterion could have a significant impact on the radial trends observed in spiral galaxies, and on the distinctions between spiral and dwarf irregular galaxies.

  17. A cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Chen, C.; Zak, J. A.

    1989-01-01

    A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud could grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. The model successfully produced clouds with dimensions, rise, decay, liquid water contents and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. In moist, unstable atmospheres simulated clouds rose to about 3.5 km in the first 4 to 8 minutes then decayed. Liquid water contents ranged from 0.3 to 1.0 g kg-1 mixing ratios and vertical motions were from 2 to 10 ms-1. An inversion served both to reduce entrainment (and erosion) at the top and to prevent continued cloud rise. Even in the most unstable atmospheres, the ground cloud did not rise beyond 4 km and in stable atmospheres with strong low level inversions the cloud could be trapped below 500 m. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. One case of a simulated TITAN rocket explosion is also discussed.

  18. What Does Reflection from Cloud Sides Tell Us About Vertical Distribution of Cloud Droplet Sizes?

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Martins, J. Vanderlei; Zubko, Victor; Kaufman, Yoram, J.

    2005-01-01

    Cloud development, the onset of precipitation and the effect of aerosol on clouds depend on the structure of the cloud profiles of droplet size and phase. Aircraft measurements of cloud profiles are limited in their temporal and spatial extent. Satellites were used to observe cloud tops not cloud profiles with vertical profiles of precipitation-sized droplets anticipated from Cloudsat. The recently proposed CLAIM-3D satellite mission (cloud aerosol interaction mission in 3D) suggests to measure profiles of cloud microphysical properties by retrieving them from the solar and infrared radiation reflected or emitted from cloud sides. Inversion of measurements from the cloud sides requires rigorous understanding of the 3-dimensional (3D) properties of clouds. Here we discuss the reflected sunlight from the cloud sides and top at two wavelengths: one nonabsorbing to solar radiation (0.67 micrometers) and one with liquid water efficient absorption of solar radiation (2.1 micrometers). In contrast to the plane-parallel approximation, a conventional approach to all current operational retrievals, 3D radiative transfer is used for interpreting the observed reflectances. General properties of the radiation reflected from the sides of an isolated cloud are discussed. As a proof of concept, the paper shows a few examples of radiation reflected from cloud fields generated by a simple stochastic cloud model with the prescribed vertically resolved microphysics. To retrieve the information about droplet sizes, we propose to use the probability density function of the droplet size distribution and its first two moments instead of the assumption about fixed values of the droplet effective radius. The retrieval algorithm is based on the Bayesian theorem that combines prior information about cloud structure and microphysics with radiative transfer calculations.

  19. Investigating CloudSat Retrievals Sensitivity to Forward Iterative Algorithm Parameters in the Mixed Cloud Layers

    NASA Astrophysics Data System (ADS)

    Qiu, Yujun; Lu, Chunsong

    2016-08-01

    When millimeter-wave cloud radar data are used for the forward iterative retrieval of the liquid water content (LWC) and effective radius of cloud droplets (R e) in a cloud layer, the prior values and tolerance ranges of the cloud droplet number density (N t), scale parameter (R g) and spectral width parameter (W g) in the iterative algorithm are the main factors that affect the retrieval accuracy. In this study, we used data from stratus and convective clouds that were simultaneously observed by CloudSat and aircraft to conduct a sensitivity analysis of N t, R g, and W g for the retrieval accuracies of LWC and R e in both stratus and convective clouds. N t is the least sensitive parameter for accurately retrieving stratus LWC and R e in both stratus and convective clouds, except for retrieving the convective cloud LWC. Opposite to N t, R g is the most sensitive parameter for both LWC and R e retrievals. As to the effects of parameter tolerance ranges on the retrievals of LWC and R e, the least important parameter is the N t tolerance range; the most important one is the W g tolerance range for retrieving convective cloud LWC and R e, the R g is the important parameter for retrieving stratus LWC and R e. To obtain accurate retrieved values for clouds in a specific region, it is important to use typical values of the sensitive parameters, which could be calculated from in situ observations of cloud droplet size distributions. In addition, the sensitivities of the LWC and R e to the three parameters are stronger in convective clouds than in stratus clouds. This may be related to the melting and merging of solid cloud droplets during the convective mixing process in the convective clouds.

  20. Investigating CloudSat Retrievals Sensitivity to Forward Iterative Algorithm Parameters in the Mixed Cloud Layers

    NASA Astrophysics Data System (ADS)

    Qiu, Yujun; Lu, Chunsong

    2016-09-01

    When millimeter-wave cloud radar data are used for the forward iterative retrieval of the liquid water content (LWC) and effective radius of cloud droplets ( R e) in a cloud layer, the prior values and tolerance ranges of the cloud droplet number density ( N t), scale parameter ( R g) and spectral width parameter ( W g) in the iterative algorithm are the main factors that affect the retrieval accuracy. In this study, we used data from stratus and convective clouds that were simultaneously observed by CloudSat and aircraft to conduct a sensitivity analysis of N t, R g, and W g for the retrieval accuracies of LWC and R e in both stratus and convective clouds. N t is the least sensitive parameter for accurately retrieving stratus LWC and R e in both stratus and convective clouds, except for retrieving the convective cloud LWC. Opposite to N t, R g is the most sensitive parameter for both LWC and R e retrievals. As to the effects of parameter tolerance ranges on the retrievals of LWC and R e, the least important parameter is the N t tolerance range; the most important one is the W g tolerance range for retrieving convective cloud LWC and R e, the R g is the important parameter for retrieving stratus LWC and R e. To obtain accurate retrieved values for clouds in a specific region, it is important to use typical values of the sensitive parameters, which could be calculated from in situ observations of cloud droplet size distributions. In addition, the sensitivities of the LWC and R e to the three parameters are stronger in convective clouds than in stratus clouds. This may be related to the melting and merging of solid cloud droplets during the convective mixing process in the convective clouds.

  1. The dynamics behind Titan's methane clouds

    PubMed Central

    Mitchell, Jonathan L.; Pierrehumbert, Raymond T.; Frierson, Dargan M. W.; Caballero, Rodrigo

    2006-01-01

    We present results of an axisymmetric global circulation model of Titan with a simplified suite of atmospheric physics forced by seasonally varying insolation. The recent discovery of midlatitude tropospheric clouds on Titan has caused much excitement about the roles of surface sources of methane and the global circulation in forming clouds. Although localized surface sources, such as methane geysers or “cryovolcanoes,” have been invoked to explain these clouds, we find in this work that clouds appear in regions of convergence by the mean meridional circulation and over the poles during solstices, where the solar forcing reaches its seasonal maximum. Other regions are inhibited from forming clouds because of dynamical transports of methane and strong subsidence. We find that for a variety of moist regimes, i.e., with the effect of methane thermodynamics included, the observed cloud features can be explained by the large-scale dynamics of the atmosphere. Clouds at the solsticial pole are found to be a robust feature of Titan's dynamics, whereas isolated midlatitude clouds are present exclusively in a variety of moist dynamical regimes. In all cases, even without including methane thermodynamics, our model ceases to produce polar clouds ≈4–6 terrestrial years after solstices. PMID:17121992

  2. Light scattering by cirrus cloud layers.

    NASA Technical Reports Server (NTRS)

    Liou, K.-N.

    1972-01-01

    The properties of the reflection, transmission, and absorption of the cirrus cloud layers are calculated under the assumption that the ice crystals in cirrus clouds may be approximated long circular cylinders randomly oriented in space. The phase function, the single scattering albedo, and the extinction cross section are obtained on the basis of Liou's (1972) calculations of light scattering by ice clouds in the visible and infrared. A modified two-stream approximation for radiative transfer is developed and is used to evaluate the radiative properties of the cirrus cloud layers.

  3. Clouds and Aerosols on the Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Colaprete, A.; English, J. M.; Haberle, R. M.; Kahre, M. A.

    Clouds and aerosols are common on the terrestrial planets, highly variable on Earth and Mars, and completely covering Venus. Clouds form by condensation and photochemical processes. Nucleation of cloud droplets by certain aerosols provides an indirect linkage. Earth clouds cover over half of the planet, are composed of mainly liquid water or ice, and are a significant component of Earth's surface and top of atmosphere energy balance. On Venus, H2SO4 is the dominant cloud constituent, produced by chemical cycles operating on SO2, likely produced from geologic activity. Martian water ice clouds generally have smaller particles than on Earth, although they form by the same processes. Mars clouds affect the deposition of radiation, drive photochemical reactions, and couple to the dust cycle. In the past, Mars clouds may have produced a significant greenhouse effect at times of high obliquity and early in its history. Mars atmospheric dust has both a seasonal cycle and great dust storms. Dust significantly influences the thermal and dynamical structure of the martian atmosphere. Mars CO2 clouds provide both latent heat and radiative effects on the atmosphere, possibly more important on the early, wet, and warmer Mars climate.

  4. Meteorology: dusty ice clouds over Alaska.

    PubMed

    Sassen, Kenneth

    2005-03-24

    Particles lofted into the atmosphere by desert dust storms can disperse widely and affect climate directly through aerosol scattering and absorption. They can also affect it indirectly by changing the scattering properties of clouds and, because desert dusts are particularly active ice-forming agents, by affecting the formation and thermodynamic phase of clouds. Here I show that dust storms that occurred in Asia early in 2004 created unusual ice clouds over Alaska at temperatures far warmer than those expected for normal cirrus-cloud formation.

  5. The Broad-Line Region Cloud Model

    NASA Astrophysics Data System (ADS)

    Dietrich, Matthias

    Generally, it is believed that the broad-emission lines are emitted by rapidly moving clouds or filaments within the BLR. The line profiles are expected to be variable on time scales of years due to redistribution of the clouds. However, observations show that profile changes can occur more rapidly than this indicating that hydrodynamical instabilities are associated with the BLR clouds themselves. Since the number of clouds is estimated to at least ~ 10^7 it is difficult to explain how stochastic events affecting individual clouds can yield detectable profile variations. Small-scale fluctuations due to as many as 4 x 10^6 clouds would be still observable in emission-line profiles taken with high spectral resolution and high S/N ratio (cf. Capriotti et al. 1981). Echelle spectra of 3C 273 and NGC 5548 will be presented. The line profiles of H\\alpha and H\\beta have been studied with high spectral resolution (\\Delta v ~ 10 km s^{-1}). The statistical variations of the residua of the H\\alpha and H\\beta line profiles will be used to test whether this is consistent with the expected statistical scatter due to the finite number of line emitting clouds. Based on these fluctuations it will be possible to derive an estimation of the total number of emission-line clouds. The results will be compared with simulations of cloud ensembles with different distributions, geometries, and numbers of individual emitters.

  6. Chemical abundances in cold, dark interstellar clouds

    NASA Technical Reports Server (NTRS)

    Irvine, William M.; Kaifu, Norio; Ohishi, Masatoshi

    1991-01-01

    Current tabulations are presented of the entire range of known interstellar molecules, giving attention to that subset which has been identified in the cold, dark interstellar clouds out of which the sun has been suggested to have formed. The molecular abundances of two such clouds, Taurus Molecular Cloud 1 and Lynd's 134N, exhibit prepossessing chemical differences despite considerable physical similarities. This discrepancy may be accounted for by the two clouds' differing evolutionary stages. Two novel classes of interstellar molecules are noted: sulfur-terminated carbon chains and silicon-terminated ones.

  7. Secure Document Service for Cloud Computing

    NASA Astrophysics Data System (ADS)

    Xu, Jin-Song; Huang, Ru-Cheng; Huang, Wan-Ming; Yang, Geng

    The development of cloud computing is still in its initial stage, and the biggest obstacle is data security. How to guarantee the privacy of user data is a worthwhile study. This paper has proposed a secure document service mechanism based on cloud computing. Out of consideration of security, in this mechanism, the content and the format of documents were separated prior to handling and storing. In addition, documents could be accessed safely within an optimized method of authorization. This mechanism would protect documents stored in cloud environment from leakage and provide an infrastructure for establishing reliable cloud services.

  8. Characterization of clouds in Titan's tropical atmosphere

    USGS Publications Warehouse

    Griffith, C.A.; Penteado, P.; Rodriguez, S.; Le, Mouelic S.; Baines, K.H.; Buratti, B.; Clark, R.; Nicholson, P.; Jaumann, R.; Sotin, C.

    2009-01-01

    Images of Titan's clouds, possible over the past 10 years, indicate primarily discrete convective methane clouds near the south and north poles and an immense stratiform cloud, likely composed of ethane, around the north pole. Here we present spectral images from Cassini's Visual Mapping Infrared Spectrometer that reveal the increasing presence of clouds in Titan's tropical atmosphere. Radiative transfer analyses indicate similarities between summer polar and tropical methane clouds. Like their southern counterparts, tropical clouds consist of particles exceeding 5 ??m. They display discrete structures suggestive of convective cumuli. They prevail at a specific latitude band between 8??-20?? S, indicative of a circulation origin and the beginning of a circulation turnover. Yet, unlike the high latitude clouds that often reach 45 km altitude, these discrete tropical clouds, so far, remain capped to altitudes below 26 km. Such low convective clouds are consistent with the highly stable atmospheric conditions measured at the Huygens landing site. Their characteristics suggest that Titan's tropical atmosphere has a dry climate unlike the south polar atmosphere, and despite the numerous washes that carve the tropical landscape. ?? 2009. The American Astronomical Society.

  9. When cloud computing meets bioinformatics: a review.

    PubMed

    Zhou, Shuigeng; Liao, Ruiqi; Guan, Jihong

    2013-10-01

    In the past decades, with the rapid development of high-throughput technologies, biology research has generated an unprecedented amount of data. In order to store and process such a great amount of data, cloud computing and MapReduce were applied to many fields of bioinformatics. In this paper, we first introduce the basic concepts of cloud computing and MapReduce, and their applications in bioinformatics. We then highlight some problems challenging the applications of cloud computing and MapReduce to bioinformatics. Finally, we give a brief guideline for using cloud computing in biology research.

  10. Suppressing Electron Cloud in Future Linear Colliders

    SciTech Connect

    Pivi, M; Kirby, R.E.; Raubenheimer, T.O.; Le Pimpec, F.; /PSI, Villigen

    2005-05-27

    Any accelerator circulating positively charged beams can suffer from a build-up of an electron cloud (EC) in the beam pipe. The cloud develops through ionization of residual gases, synchrotron radiation and secondary electron emission and, when severe, can cause instability, emittance blow-up or loss of the circulating beam. The electron cloud is potentially a luminosity limiting effect for both the Large Hadron Collider (LHC) and the International Linear Collider (ILC). For the ILC positron damping ring, the development of the electron cloud must be suppressed. This paper discusses the state-of-the-art of the ongoing SLAC and international R&D program to study potential remedies.

  11. Layer Trends in Earth's Cloud Cover

    NASA Astrophysics Data System (ADS)

    Hearty, T. J.; Kahn, B. H.; Fishbein, E. F.

    2006-12-01

    Clouds are an important component to the Earth's radiation budget. Depending on their height and type they can either cool or warm the Earth's surface and atmosphere. Recent Earthshine observations indicate an increase in Earth's albedo, suggesting an increase in reflective clouds. This increase in cloudiness is corroborated by ISCCP, GOME, and SCIAMACHY observations. However, the CERES instrument on Terra has observed a decrease in Earth's albedo. The discrepancies in the observations could be due to temporal, spatial, or physical differences in the clouds to which each method is sensitive. We utilize the vertical resolution of the AIRS/AMSU down-looking effective cloudfraction and cloud height retrieval to understand changes in the vertical distribution of clouds that might account for the observed discrepancy. We find that AIRS/AMSU observations may suggest a slight decrease in the total effective cloud fraction of Earth. However, the effective cloud fraction is decreasing from ~400-700 mbar and it is increasing from ~700 mbar to the surface. This would be consistent with the Earthshine, ISCCP, GOME, and SCIAMACHY observations being more sensitive to low clouds, while CERES and AIRS/AMSU are more sensitive to all clouds.

  12. The dynamics behind Titan's methane clouds.

    PubMed

    Mitchell, Jonathan L; Pierrehumbert, Raymond T; Frierson, Dargan M W; Caballero, Rodrigo

    2006-12-01

    We present results of an axisymmetric global circulation model of Titan with a simplified suite of atmospheric physics forced by seasonally varying insolation. The recent discovery of midlatitude tropospheric clouds on Titan has caused much excitement about the roles of surface sources of methane and the global circulation in forming clouds. Although localized surface sources, such as methane geysers or "cryovolcanoes," have been invoked to explain these clouds, we find in this work that clouds appear in regions of convergence by the mean meridional circulation and over the poles during solstices, where the solar forcing reaches its seasonal maximum. Other regions are inhibited from forming clouds because of dynamical transports of methane and strong subsidence. We find that for a variety of moist regimes, i.e., with the effect of methane thermodynamics included, the observed cloud features can be explained by the large-scale dynamics of the atmosphere. Clouds at the solsticial pole are found to be a robust feature of Titan's dynamics, whereas isolated midlatitude clouds are present exclusively in a variety of moist dynamical regimes. In all cases, even without including methane thermodynamics, our model ceases to produce polar clouds approximately 4-6 terrestrial years after solstices.

  13. Clouds of venus: particle size distribution measurements.

    PubMed

    Knollenberg, R G; Hunten, D M

    1979-02-23

    Data from the Pioneer Venus cloud particle size spectrometer experiment has revealed the Venus cloud system to be a complicated mixture of particles of various chemical composition distinguishable by their multimodal size distributions. The appearance, disappearance, growth, and decay of certain size modes has aided the preliminary identification of both sulfuric acid and free sulfur cloud regions. The discovery of large particles > 30 micrometers, significant particle mass loading, and size spectral features suggest that precipitation is likely produced; a peculiar aerosol structure beneath the lowest cloud layer could be residue from a recent shower.

  14. 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.

  15. Expansion-cooled Lyman-alpha clouds

    NASA Astrophysics Data System (ADS)

    Duncan, Robert C.; Vishniac, Ethan T.; Ostriker, Jeremiah P.

    1991-02-01

    It is shown that recent observations by Pettini et al. (1990) which indicate that low-N H I Ly-alpha forest lines have small velocity widths and that the velocity widths are positively correlated with N (H I) can be understood as the result of adiabatic cooling of expanding clouds. It is argued that expansion cooling can efficiently lower temperatures and velocity widths of diffuse ionized clouds, and that this trend of diminishing temperature and velocity width in a wide range of plausible cloud models is consistent with double-quasar data. Expansion can provide a natural explanation for the steep z-evolution of the cloud numbers.

  16. Polar stratospheric clouds and the ozone hole

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Toon, Owen B.

    1991-01-01

    An account is given of physical processes governing the formation of stratospheric particles, in order to dramatize the interactions between polar stratospheric clouds and the Antarctic ozone-destruction mechanism. Attention is given to the successive stages of particle nucleation, condensation/evaporation and sedimentation/coagulation phenomena, and the ways in which polar stratospheric clouds are observed. Considerable evidence exists that polar stratospheric cloud particles are composed of nitric acid. The relatively small Arctic ozone hole depletion is due to the much smaller duration of Arctic stratospheric clouds.

  17. A Fourier approach to cloud motion estimation

    NASA Technical Reports Server (NTRS)

    Arking, A.; Lo, R. C.; Rosenfield, A.

    1977-01-01

    A Fourier technique is described for estimating cloud motion from pairs of pictures using the phase of the cross spectral density. The method allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. Results obtained are presented and compared with the results of a Fourier domain cross correlation scheme. Using both artificial and real cloud data show that the technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects.

  18. Optimization of over-provisioned clouds

    NASA Astrophysics Data System (ADS)

    Balashov, N.; Baranov, A.; Korenkov, V.

    2016-09-01

    The functioning of modern applications in cloud-centers is characterized by a huge variety of computational workloads generated. This causes uneven workload distribution and as a result leads to ineffective utilization of cloud-centers' hardware. The proposed article addresses the possible ways to solve this issue and demonstrates that it is a matter of necessity to optimize cloud-centers' hardware utilization. As one of the possible ways to solve the problem of the inefficient resource utilization in heterogeneous cloud-environments an algorithm of dynamic re-allocation of virtual resources is suggested.

  19. Get Your Head into the Clouds: Using Word Clouds for Analyzing Qualitative Assessment Data

    ERIC Educational Resources Information Center

    DePaolo, Concetta A.; Wilkinson, Kelly

    2014-01-01

    Word clouds (or tag clouds) are popular, fun ways to display text data in graphical form; however, we contend that they can also be useful tools in assessment. Using word clouds, instructors can quickly and easily produce graphical depictions of text representing student knowledge. By investigating the patterns of words or phrases, or lack…

  20. If It's in the Cloud, Get It on Paper: Cloud Computing Contract Issues

    ERIC Educational Resources Information Center

    Trappler, Thomas J.

    2010-01-01

    Much recent discussion has focused on the pros and cons of cloud computing. Some institutions are attracted to cloud computing benefits such as rapid deployment, flexible scalability, and low initial start-up cost, while others are concerned about cloud computing risks such as those related to data location, level of service, and security…

  1. Embracing the Cloud: Six Ways to Look at the Shift to Cloud Computing

    ERIC Educational Resources Information Center

    Ullman, David F.; Haggerty, Blake

    2010-01-01

    Cloud computing is the latest paradigm shift for the delivery of IT services. Where previous paradigms (centralized, decentralized, distributed) were based on fairly straightforward approaches to technology and its management, cloud computing is radical in comparison. The literature on cloud computing, however, suffers from many divergent…

  2. Precipitation effects of giant cloud condensation nuclei artificially introduced into stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Jung, E.; Albrecht, B. A.; Jonsson, H. H.; Chen, Y.-C.; Seinfeld, J. H.; Sorooshian, A.; Metcalf, A. R.; Song, S.; Fang, M.; Russell, L. M.

    2015-05-01

    To study the effect of giant cloud condensation nuclei (GCCN) on precipitation processes in stratocumulus clouds, 1-10 μm diameter salt particles (salt powder) were released from an aircraft while flying near the cloud top on 3 August 2011 off the central coast of California. The seeded area was subsequently sampled from the aircraft that was equipped with aerosol, cloud, and precipitation probes and an upward-facing cloud radar. During post-seeding sampling, made 30-60 min after seeding, the mean cloud droplet size increased, the droplet number concentration decreased, and large drop (e.g., diameter larger than 10 μm) concentration increased. Average drizzle rates increased from about 0.05 to 0.20 mm h-1, and the liquid water path decreased from about 52 to 43 g m-2. Strong radar returns associated with drizzle were observed on the post-seeding cloud-base level-leg flights and were accompanied by a substantial depletion of the cloud liquid water content. The changes were large enough to suggest that the salt particles with concentrations estimated to be 10-2 to 10-4 cm-3 resulted in a four-fold increase in the cloud-base rainfall rate and depletion of the cloud water due to rainout. In contrast, a case is shown where the cloud was already precipitating (on 10 August) and the effect of adding GCCN to the cloud was insignificant.

  3. Precipitation effects of giant cloud condensation nuclei artificially introduced into stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Jung, E.; Albrecht, B. A.; Jonsson, H. H.; Chen, Y.-C.; Seinfeld, J. H.; Sorooshian, A.; Metcalf, A. R.; Song, S.; Fang, M.; Russell, L. M.

    2015-01-01

    To study the effect of giant cloud condensation nuclei (GCCN) on precipitation processes in stratocumulus clouds, 1-10 μm diameter salt particles (salt powder) were released from an aircraft while flying near cloud top on 3 August 2011 off the central coast of California. The seeded area was subsequently sampled from the aircraft that was equipped with aerosol, cloud, and precipitation probes and an upward-facing cloud radar. During post-seeding sampling, made 30-60 min after seeding, the mean cloud droplet size increased, the droplet number concentration decreased, and large drop (e.g., diameter larger than 10 μm) concentration increased. Average drizzle rates increased from about 0.05 to 0.20 mm h-1, and liquid water path decreased from about 52 to 43 g m-2. Strong radar returns associated with drizzle were observed on the post-seeding cloud-base level-leg flights and were accompanied by a substantial depletion of the cloud liquid water content. The changes were large enough to suggest that the salt particles with concentrations estimated to be 10-2 to 10-4 cm-3 resulted in a four-fold increase in the cloud base rainfall rate and depletion of the cloud water due to rainout. In contrast, a case is shown where the cloud was already precipitating (on 10 August) and the effect of adding GCCN to the cloud was insignificant.

  4. Evaluation of Multilayer Cloud Detection Using a MODIS CO2-Slicing Algorithm With CALIPSO-CloudSat Measurements

    NASA Technical Reports Server (NTRS)

    Viudez-Mora, Antonio; Kato, Seiji

    2015-01-01

    This work evaluates the multilayer cloud (MCF) algorithm based on CO2-slicing techniques against CALISPO-CloudSat (CLCS) measurement. This evaluation showed that the MCF underestimates the presence of multilayered clouds compared with CLCS and are retrained to cloud emissivities below 0.8 and cloud optical septs no larger than 0.3.

  5. AEROSOL, CLOUDS, AND CLIMATE CHANGE

    SciTech Connect

    SCHWARTZ, S.E.

    2005-09-01

    Earth's climate is thought to be quite sensitive to changes in radiative fluxes that are quite small in absolute magnitude, a few watts per square meter, and in relation to these fluxes in the natural climate. Atmospheric aerosol particles exert influence on climate directly, by scattering and absorbing radiation, and indirectly by modifying the microphysical properties of clouds and in turn their radiative effects and hydrology. The forcing of climate change by these indirect effects is thought to be quite substantial relative to forcing by incremental concentrations of greenhouse gases, but highly uncertain. Quantification of aerosol indirect forcing by satellite- or ground-based remote sensing has proved quite difficult in view of inherent large variation in the pertinent observables such as cloud optical depth, which is controlled mainly by liquid water path and only secondarily by aerosols. Limited work has shown instances of large magnitude of aerosol indirect forcing, with local instantaneous forcing upwards of 50 W m{sup 66}-2. Ultimately it will be necessary to represent aerosol indirect effects in climate models to accurately identify the anthropogenic forcing at present and over secular time and to assess the influence of this forcing in the context of other forcings of climate change. While the elements of aerosol processes that must be represented in models describing the evolution and properties of aerosol particles that serve as cloud condensation particles are known, many important components of these processes remain to be understood and to be represented in models, and the models evaluated against observation, before such model-based representations can confidently be used to represent aerosol indirect effects in climate models.

  6. 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.

  7. Metastable Phases in Ice Clouds

    NASA Astrophysics Data System (ADS)

    Weiss, Fabian; Baloh, Philipp; Kubel, Frank; Hoelzel, Markus; Parker, Stewart; Grothe, Hinrich

    2014-05-01

    Polar Stratospheric Clouds and Cirrus Clouds contain both, pure water ice and phases of nitric acid hydrates. Preferentially for the latter, the thermodynamically stable phases have intensively been investigated in the past (e.g. nitric acid trihydrate, beta-NAT). As shown by Peter et al. [1] the water activity inside clouds is higher than expected, which might be explained by the presence of metastable stable phases (e.g. cubic ice). However, also metastable nitric acid hydrates might be important due to the inherent non-equilibrium freezing conditions in the upper atmosphere. The delta ice theory of Gao et al. [2] presents a model approach to solve this problem by involving both metastable ice and NAT as well. So it is of high interest to investigate the metastable phase of NAT (i.e. alpha-NAT), the structure of which was unknown up to the presence. In our laboratory a production procedure for metastable alpha-NAT has been developed, which gives access to neutron diffraction and X-ray diffraction measurements, where sample quantities of several Gramm are required. The diffraction techniques were used to solve the unknown crystalline structure of metastable alpha-NAT, which in turn allows the calculation of the vibrational spectra, which have also been recorded by us in the past. Rerefences [1] Peter, T., C. Marcolli, P. Spichtinger, T. Corti, M. B. Baker, and T. Koop. When dry air is too humid. Science, 314:1399-1402, 2006. [2] Gao, R., P. Popp, D. Fahey, T. Marcy, R. L. Herman, E. Weinstock, D. Baumgardener, T. Garrett, K. Rosenlof, T. Thompson, T. P. Bui, B. Ridley, S. C. Wofsy, O. B. Toon, M. Tolbert, B. Kärcher, Th. Peter, P. K. Hudson, A. Weinheimer, and A. Heymsfield. Evidence That Nitric Acid Increases Relative Humidity in Low-Temperature Cirrus Clouds, Science, 303:516-520, 2004. [3] Tizek, H., E. Knözinger, and H. Grothe. Formation and phase distribution of nitric acid hydrates in the mole fraction range xHNO3<0.25: A combined XRD and IR study, PCCP, 6

  8. Transmittance through anthropogenic dust clouds.

    PubMed

    Seagraves, M A; Duncan, L D

    1981-07-01

    Measurements of transmittance through dust and debris clouds generated by explosions and moving vehicles from five field tests involving 120 trials were analyzed to determine the degree to which transmittance is wavelength dependent. Statistical tests to determine whether the amounts of time transmittance were reduced to specified levels that were significantly different for various wavelengths revealed, in general, no consistent wavelength dependence. Relationships between the extinction coefficient for IR spectral and visible regions have been established for specific explosive types and soil conditions involved in some of these tests.

  9. Turbulence effect on cloud radiation.

    PubMed

    Matsuda, K; Onishi, R; Kurose, R; Komori, S

    2012-06-01

    The effect of turbulent clustering of water droplets on radiative transfer is investigated by means of both a three-dimensional direct numerical simulation of particle-laden homogeneous isotropic turbulence and a radiative transfer simulation based on a Monte Carlo photon tracing method. The results show that turbulent clustering causes the formation of void regions of droplets and hence increases the direct transmittance. This effect decreases as the turbulent Reynolds number increases and is estimated to be negligibly small under the conditions in real clouds.

  10. Electron Cloud Effects in Accelerators

    SciTech Connect

    Furman, M.A.

    2012-11-30

    Abstract We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire ?ECLOUD? series [1?22]. In addition, the proceedings of the various flavors of Particle Accelerator Conferences [23] contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series [24] contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC [25].

  11. 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.

  12. Cloud flexibility using DIRAC interware

    NASA Astrophysics Data System (ADS)

    Fernandez Albor, Víctor; Seco Miguelez, Marcos; Fernandez Pena, Tomas; Mendez Muñoz, Victor; Saborido Silva, Juan Jose; Graciani Diaz, Ricardo

    2014-06-01

    Communities of different locations are running their computing jobs on dedicated infrastructures without the need to worry about software, hardware or even the site where their programs are going to be executed. Nevertheless, this usually implies that they are restricted to use certain types or versions of an Operating System because either their software needs an definite version of a system library or a specific platform is required by the collaboration to which they belong. On this scenario, if a data center wants to service software to incompatible communities, it has to split its physical resources among those communities. This splitting will inevitably lead to an underuse of resources because the data centers are bound to have periods where one or more of its subclusters are idle. It is, in this situation, where Cloud Computing provides the flexibility and reduction in computational cost that data centers are searching for. This paper describes a set of realistic tests that we ran on one of such implementations. The test comprise software from three different HEP communities (Auger, LHCb and QCD phenomelogists) and the Parsec Benchmark Suite running on one or more of three Linux flavors (SL5, Ubuntu 10.04 and Fedora 13). The implemented infrastructure has, at the cloud level, CloudStack that manages the virtual machines (VM) and the hosts on which they run, and, at the user level, the DIRAC framework along with a VM extension that will submit, monitorize and keep track of the user jobs and also requests CloudStack to start or stop the necessary VM's. In this infrastructure, the community software is distributed via the CernVM-FS, which has been proven to be a reliable and scalable software distribution system. With the resulting infrastructure, users are allowed to send their jobs transparently to the Data Center. The main purpose of this system is the creation of flexible cluster, multiplatform with an scalable method for software distribution for several

  13. Scalable cloud without dedicated storage

    NASA Astrophysics Data System (ADS)

    Batkovich, D. V.; Kompaniets, M. V.; Zarochentsev, A. K.

    2015-05-01

    We present a prototype of a scalable computing cloud. It is intended to be deployed on the basis of a cluster without the separate dedicated storage. The dedicated storage is replaced by the distributed software storage. In addition, all cluster nodes are used both as computing nodes and as storage nodes. This solution increases utilization of the cluster resources as well as improves fault tolerance and performance of the distributed storage. Another advantage of this solution is high scalability with a relatively low initial and maintenance cost. The solution is built on the basis of the open source components like OpenStack, CEPH, etc.

  14. A New "Cloud Mode" for the AERONET

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Barker, H.; Knyazikhin, Y.; Wiscombe, W.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A key to predicting climate change is to observe an understand the global distribution of clouds and their physical properties such as optical thickness and droplet size. Since clouds change rapidly over short time and space intervals, they are difficult to simulate in computer models. But it is essential that global climate models predict realistic spatial and temporal distribution of cloud optical depth. The best way to verify these distributions is to infer optical depth from global coverage satellite data. However, satellite methods have many sources of uncertainty; thus, independent and reliable ground-based estimates are essential for validation. For aerosol, there is the AERONET - a ground based monitoring network that consists of identical multi-channel radiometers for assessing aerosol optical properties and validating their satellite retrievals. In addition to AEROSOL, we want the network monitoring CLOUD optical properties. It will use AERONET "time" (inappropriate for aerosol studies) to make basic new measurements related to cloud physics. In the presentation we will report on a new technique that retrieves cloud optical thickness for even broken clouds above green vegetation from surface measurements of zenith radiance in the visible (VIS) and near-IR (NIR) spectral regions. The idea of the method is simple: since green vegetation reflects 40-50% of incoming radiation in the NIR and only 5-10% in the VIS region, ground measurements under thin clouds have little spectral contrast between VIS and NIR, while thick clouds reflect much more of the surface-reflected radiation in the NIR than in VIS. Based on this idea, we use a combination of measurements (spectral indices) in VIS and NIR to estimate cloud optical thickness. By analogy with NDVI, the simplest index that can be defined is the Normalized Difference Cloud Index (NDCI) which is a ratio between the difference and the sum of two radiances measured for two narrow spectral bands in VIS and NIR.

  15. 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.

  16. Assessing MODIS Macrophysical Cloud Property Uncertainties

    NASA Astrophysics Data System (ADS)

    Maddux, B. C.; Ackerman, S. A.; Frey, R.; Holz, R.

    2013-12-01

    Cloud, being multifarious and ephemeral, is difficult to observe and quantify in a systematic way. Even basic terminology used to describe cloud observations is fraught with ambiguity in the scientific literature. Any observational technique, method, or platform will contain inherent and unavoidable measurement uncertainties. Quantifying these uncertainties in cloud observations is a complex task that requires an understanding of all aspects of the measurement. We will use cloud observations obtained from the Moderate Resolution Imaging Spectroradiameter(MODIS) to obtain metrics of the uncertainty of its cloud observations. Our uncertainty analyses will contain two main components, 1) an attempt to create a bias or uncertainty with respect to active measurements from CALIPSO and 2) a relative uncertainty within the MODIS cloud climatologies themselves. Our method will link uncertainty to the physical observation and its environmental/scene characteristics. Our aim is to create statistical uncertainties that are based on the cloud observational values, satellite view geometry, surface type, etc, for cloud amount and cloud top pressure. The MODIS instruments on the NASA Terra and Aqua satellites provide observations over a broad spectral range (36 bands between 0.415 and 14.235 micron) and high spatial resolution (250 m for two bands, 500 m for five bands, 1000 m for 29 bands), which the MODIS cloud mask algorithm (MOD35) utilizes to provide clear/cloud determinations over a wide array of surface types, solar illuminations and view geometries. For this study we use the standard MODIS products, MOD03, MOD06 and MOD35, all of which were obtained from the NASA Level 1 and Atmosphere Archive and Distribution System.

  17. Clouds enhance Greenland ice sheet mass loss

    NASA Astrophysics Data System (ADS)

    Van Tricht, Kristof; Gorodetskaya, Irina V.; L'Ecuyer, Tristan; Lenaerts, Jan T. M.; Lhermitte, Stef; Noel, Brice; Turner, David D.; van den Broeke, Michiel R.; van Lipzig, Nicole P. M.

    2015-04-01

    Clouds have a profound influence on both the Arctic and global climate, while they still represent one of the key uncertainties in climate models, limiting the fidelity of future climate projections. The potentially important role of thin liquid-containing clouds over Greenland in enhancing ice sheet melt has recently gained interest, yet current research is spatially and temporally limited, focusing on particular events, and their large scale impact on the surface mass balance remains unknown. We used a combination of satellite remote sensing (CloudSat - CALIPSO), ground-based observations and climate model (RACMO) data to show that liquid-containing clouds warm the Greenland ice sheet 94% of the time. High surface reflectivity (albedo) for shortwave radiation reduces the cloud shortwave cooling effect on the absorbed fluxes, while not influencing the absorption of longwave radiation. Cloud warming over the ice sheet therefore dominates year-round. Only when albedo values drop below ~0.6 in the coastal areas during summer, the cooling effect starts to overcome the warming effect. The year-round excess of energy due to the presence of liquid-containing clouds has an extensive influence on the mass balance of the ice sheet. Simulations using the SNOWPACK snow model showed not only a strong influence of these liquid-containing clouds on melt increase, but also on the increased sublimation mass loss. Simulations with the Community Earth System Climate Model for the end of the 21st century (2080-2099) show that Greenland clouds contain more liquid water path and less ice water path. This implies that cloud radiative forcing will be further enhanced in the future. Our results therefore urge the need for improving cloud microphysics in climate models, to improve future projections of ice sheet mass balance and global sea level rise.

  18. The albedo of fractal stratocumulus clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Ridgway, William; Wiscombe, Warren J.; Bell, Thomas L.; Snider, Jack B.

    1994-01-01

    An increase in the planetary albedo of the earth-atmosphere system by only 10% can decrease the equilibrium surface temperature to that of the last ice age. Nevertheless, albedo biases of 10% or greater would be introduced into large regions of current climate models if clouds were given their observed liquid water amounts, because of the treatment of clouds as plane parallel. The focus on marine stratocumulus clouds is due to their important role in cloud radiative forcing and also that, of the wide variety of earth's cloud types, they are most nearly plane parallel, so that they have the least albedo bias. The fractal model employed here reproduces both the probability distribution and the wavenumber spectrum of the stratocumulus liquid water path, as observed during the First ISCCP Regional Experiment (FIRE). A single new fractal parameter 0 less than or equal to f less than or equal to 1, is introduced and determined empirically by the variance of the logarithm of the vertically integrated liquid water. The reduced reflectivity of fractal stratocumulus clouds is approximately given by the plane-parallel reflectivity evaluated at a reduced 'effective optical thickness,' which when f = 0.5 is tau(sub eff) approximately equal to 10. Study of the diurnal cycle of stratocumulus liquid water during FIRE leads to a key unexpected result: the plane-parallel albedo bias is largest when the cloud fraction reaches 100%, that is, when any bias associated with the cloud fraction vanishes. This is primarily due to the variability increase with cloud fraction. Thus, the within-cloud fractal structure of stratocumulus has a more significant impact on estimates of its mesoscale-average albedo than does the cloud fraction.

  19. Insights from a refined decomposition of cloud feedbacks

    NASA Astrophysics Data System (ADS)

    Zelinka, Mark D.; Zhou, Chen; Klein, Stephen A.

    2016-09-01

    Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloud feedback but its anticorrelation with other components damps overall spread. The ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the "null hypothesis" climate sensitivity from well-understood and robustly simulated feedbacks are discussed.

  20. Impact of Aerosol Processing on Orographic Clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, Sara; Zubler, Elias M.; Lohmann, Ulrike

    2010-05-01

    Aerosol particles undergo significant modifications during their residence time in the atmosphere. Physical processes like coagulation, coating and water uptake, and aqueous surface chemistry alter the aerosol size distribution and composition. At this, clouds play a primary role as physical and chemical processing inside cloud droplets contributes considerably to the changes in aerosol particles. A previous study estimates that on global average atmospheric particles are cycled three times through a cloud before being removed from the atmosphere [1]. An explicit and detailed treatment of cloud-borne particles has been implemented in the regional weather forecast and climate model COSMO-CLM. The employed model version includes a two-moment cloud microphysical scheme [2] that has been coupled to the aerosol microphysical scheme M7 [3] as described by Muhlbauer and Lohmann, 2008 [4]. So far, the formation, transfer and removal of cloud-borne aerosol number and mass were not considered in the model. Following the parameterization for cloud-borne particles developed by Hoose et al., 2008 [5], distinction between in-droplet and in-crystal particles is made to more physically account for processes in mixed-phase clouds, such as the Wegener-Bergeron-Findeisen process and contact and immersion freezing. In our model, this approach has been extended to allow for aerosol particles in five different hydrometeors: cloud droplets, rain drops, ice crystals, snow flakes and graupel. We account for nucleation scavenging, freezing and melting processes, autoconversion, accretion, aggregation, riming and selfcollection, collisions between interstitial aerosol particles and hydrometeors, ice multiplication, sedimentation, evaporation and sublimation. The new scheme allows an evaluation of the cloud cycling of aerosol particles by tracking the particles even when scavenged into hydrometeors. Global simulations of aerosol processing in clouds have recently been conducted by Hoose et al

  1. Vertical thermodynamic phase distribution in convective clouds derived from cloud side observations

    NASA Astrophysics Data System (ADS)

    Jäkel, Evelyn; Wendisch, Manfred; Kanter, Sandra; Ewald, Florian; Kölling, Tobias

    2015-04-01

    Clouds are a dominant modulator of the Earth's climate. Depending on the cloud properties they have either cooling or warming effects on the Earth's atmosphere. Different processes influence the coagulation (collision and coalescence) and freezing mechanisms inside clouds which determine the precipitation formation, the lifetime and vertical extent of the cloud. To investigate these complex interactions, vertical profile measurements of microphysical properties are essential. Deep convective clouds have been observed during the ACRIDICON experiment conducted in September 2014 over the Brazilian rain forest near Manaus. One of the ACRIDICON missions was focused on cloud profiling to document the vertical evolution (from cloud base to anvil) of the cloud microstructure during the different phases of the cloud life cycle under various thermodynamic conditions. In particular the aerosol effect on the cloud profile was investigated by measurements downwind Manaus (polluted plume) and upwind Manaus (pristine conditions). Cloud penetrations by aircraft and so in situ measurements are limited due to the strong updraft and downdraft in these types of clouds. Therefore passive remote sensing methods by cloud side observations using imaging spectroradiometers (specMACS instrument) were used to complete the characterization of the cloud properties. This presentation will give an overview of the vertical distribution of the thermodynamic phase for different cloud scenes subdivided in pristine and polluted aerosol conditions. The retrieval method for phase discrimination uses the spectral slope of the reflected radiances in the near-infrared spectral range and has been applied for ground based observations (Jäkel et al., 2013) before. A pre-selection of only illuminated, non-shadowed cloud portions is required, since only for these cases the spectral signature is determined by the downward solar radiation and its spectral extinction by the observed cloud element. In contrast

  2. ProteoCloud: a full-featured open source proteomics cloud computing pipeline.

    PubMed

    Muth, Thilo; Peters, Julian; Blackburn, Jonathan; Rapp, Erdmann; Martens, Lennart

    2013-08-01

    We here present the ProteoCloud pipeline, a freely available, full-featured cloud-based platform to perform computationally intensive, exhaustive searches in a cloud environment using five different peptide identification algorithms. ProteoCloud is entirely open source, and is built around an easy to use and cross-platform software client with a rich graphical user interface. This client allows full control of the number of cloud instances to initiate and of the spectra to assign for identification. It also enables the user to track progress, and to visualize and interpret the results in detail. Source code, binaries and documentation are all available at http://proteocloud.googlecode.com.

  3. Impact of different cloud deployments on real-time video applications for mobile video cloud users

    NASA Astrophysics Data System (ADS)

    Khan, Kashif A.; Wang, Qi; Luo, Chunbo; Wang, Xinheng; Grecos, Christos

    2015-02-01

    The latest trend to access mobile cloud services through wireless network connectivity has amplified globally among both entrepreneurs and home end users. Although existing public cloud service vendors such as Google, Microsoft Azure etc. are providing on-demand cloud services with affordable cost for mobile users, there are still a number of challenges to achieve high-quality mobile cloud based video applications, especially due to the bandwidth-constrained and errorprone mobile network connectivity, which is the communication bottleneck for end-to-end video delivery. In addition, existing accessible clouds networking architectures are different in term of their implementation, services, resources, storage, pricing, support and so on, and these differences have varied impact on the performance of cloud-based real-time video applications. Nevertheless, these challenges and impacts have not been thoroughly investigated in the literature. In our previous work, we have implemented a mobile cloud network model that integrates localized and decentralized cloudlets (mini-clouds) and wireless mesh networks. In this paper, we deploy a real-time framework consisting of various existing Internet cloud networking architectures (Google Cloud, Microsoft Azure and Eucalyptus Cloud) and a cloudlet based on Ubuntu Enterprise Cloud over wireless mesh networking technology for mobile cloud end users. It is noted that the increasing trend to access real-time video streaming over HTTP/HTTPS is gaining popularity among both research and industrial communities to leverage the existing web services and HTTP infrastructure in the Internet. To study the performance under different deployments using different public and private cloud service providers, we employ real-time video streaming over the HTTP/HTTPS standard, and conduct experimental evaluation and in-depth comparative analysis of the impact of different deployments on the quality of service for mobile video cloud users. Empirical

  4. Statistical analyses of satellite cloud object data from CERES: Comparison with cloud-resolving model simulations of tropical convective clouds

    NASA Astrophysics Data System (ADS)

    Luo, Y. L.

    The present study attempts to evaluate the ability of a cloud-resolving model CRM that is currently being implemented into a multi-scale modeling framework to simulate the physical properties of tropical deep convective cloud objects identified from a Clouds and the Earth s Radiant Energy System CERES data product The emphasis of this study is the comparisons among the small- medium- and large-size categories of cloud objects observed during March 1998 strong El Nino and the large-size category of cloud objects observed during March 2000 weak La Nina Results from the CRM simulations are analyzed in a way that is consistent with the CERES retrieval algorithm and matches with the average scale of the CERES satellite footprints Cloud physical properties are analyzed in terms of their summary histograms for each category Summary histograms of cloud optical depth and top-of-the-atmosphere TOA albedo from the CRM simulations of the large-size category of cloud objects do not differ significantly between the March 1998 and 2000 periods consistent with the CERES observations However the CRM is unable to reproduce the significant differences in the observed cloud top height while overestimates the moderate differences in the observed outgoing longwave radiation and cloud top temperature between the two periods Comparisons between the CRM results and the observations for most parameters in March 1998 show the same consistent larger differences between the large- and small-size categories than between the large- and medium-size or between the medium- and

  5. Mission Investigates Tropical Cirrus Clouds

    NASA Astrophysics Data System (ADS)

    Jenson, Eric; Starr, David; Toon, Owen B.

    2004-02-01

    It has been a year since NASA conducted the highly successful Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment Study (CRYSTAL-FACE). The measurement campaign was designed to investigate the physical properties and formation processes of tropical cirrus clouds. CRYSTAL-FACE was sponsored by NASA's Earth Science Enterprise as an integral component of its Earth observation research strategy, and included substantial collaboration with the National Oceanic and Atmospheric Administration, the National Science Foundation, the Department of Energy, and the Naval Research Laboratory. During July 2002, the mission's six aircraft (NASA ER-2, NASA WB-57, Scaled Composites Proteus, University of North Dakota Citation, NSF-supported NRL P-3, and NRL Twin Otter) operated from the Key West Naval Air Facility. In addition, ground sites were located at the Tamiami airport on the east coast of Florida and near Everglades City on the west coast of Florida. Aircraft and ground site measurements are listed in Table 1. Data archiving is complete, and the data are now available to the general scientific community. Detailed instrument descriptions as well as the final data can be found on the CRYSTAL-FACE Web site (http://cloud1.arc.nasa.gov/crystalface/).

  6. Seismic waveform modeling over cloud

    NASA Astrophysics Data System (ADS)

    Luo, Cong; Friederich, Wolfgang

    2016-04-01

    With the fast growing computational technologies, numerical simulation of seismic wave propagation achieved huge successes. Obtaining the synthetic waveforms through numerical simulation receives an increasing amount of attention from seismologists. However, computational seismology is a data-intensive research field, and the numerical packages usually come with a steep learning curve. Users are expected to master considerable amount of computer knowledge and data processing skills. Training users to use the numerical packages, correctly access and utilize the computational resources is a troubled task. In addition to that, accessing to HPC is also a common difficulty for many users. To solve these problems, a cloud based solution dedicated on shallow seismic waveform modeling has been developed with the state-of-the-art web technologies. It is a web platform integrating both software and hardware with multilayer architecture: a well designed SQL database serves as the data layer, HPC and dedicated pipeline for it is the business layer. Through this platform, users will no longer need to compile and manipulate various packages on the local machine within local network to perform a simulation. By providing users professional access to the computational code through its interfaces and delivering our computational resources to the users over cloud, users can customize the simulation at expert-level, submit and run the job through it.

  7. Geospatial services in the Cloud

    NASA Astrophysics Data System (ADS)

    Evangelidis, Konstantinos; Ntouros, Konstantinos; Makridis, Stathis; Papatheodorou, Constantine

    2014-02-01

    Data semantics play an extremely significant role in spatial data infrastructures by providing semantic specifications to geospatial data and enabling in this way data sharing and interoperability. By applying, on the fly, composite geospatial processes on the above data it is possible to produce valuable geoinformation over the web directly available and applicable to a wide range of geo-activities of significant importance for the research and industry community. Cloud computing may enable geospatial processing since it refers to, among other things, efficient computing resources providing on demand processing services. In this context, we attempt to provide a design and architectural framework for web applications based on open geospatial standards. Our approach includes, in addition to geospatial processing, data acquisition services that are essential especially when dealing with satellite images and applications in the area of remote sensing and similar fields. As a result, by putting in a common framework all data and geoprocesses available in the Cloud, it is possible to combine the appropriate services in order to produce a solution for a specific need.

  8. Fragmentation in filamentary molecular clouds

    NASA Astrophysics Data System (ADS)

    Contreras, Yanett; Garay, Guido; Rathborne, Jill M.; Sanhueza, Patricio

    2016-02-01

    Recent surveys of dust continuum emission at sub-mm wavelengths have shown that filamentary molecular clouds are ubiquitous along the Galactic plane. These structures are inhomogeneous, with overdensities that are sometimes associated with infrared emission and active of star formation. To investigate the connection between filaments and star formation, requires an understanding of the processes that lead to the fragmentation of filaments and a determination of the physical properties of the overdensities (clumps). In this paper, we present a multiwavelength study of five filamentary molecular clouds, containing several clumps in different evolutionary stages of star formation. We analyse the fragmentation of the filaments and derive the physical properties of their clumps. We find that the clumps in all filaments have a characteristic spacing consistent with the prediction of the `sausage' instability theory, regardless of the complex morphology of the filaments or their evolutionary stage. We also find that most clumps have sufficient mass and density to form high-mass stars, supporting the idea that high-mass stars and clusters form within filaments.

  9. Deuteration in infrared dark clouds

    NASA Astrophysics Data System (ADS)

    Lackington, Matias; Fuller, Gary A.; Pineda, Jaime E.; Garay, Guido; Peretto, Nicolas; Traficante, Alessio

    2016-01-01

    Much of the dense gas in molecular clouds has a filamentary structure but the detailed structure and evolution of this gas is poorly known. We have observed 54 cores in infrared dark clouds (IRDCs) using N2H+ (1-0) and (3-2) to determine the kinematics of the densest material, where stars will form. We also observed N2D+ (3-2) towards 29 of the brightest peaks to analyse the level of deuteration which is an excellent probe of the quiescent of the early stages of star formation. There were 13 detections of N2D+ (3-2). This is one of the largest samples of IRDCs yet observed in these species. The deuteration ratio in these sources ranges between 0.003 and 0.14. For most of the sources the material traced by N2D+ and N2H+ (3-2) still has significant turbulent motions, however three objects show subthermal N2D+ velocity dispersion. Surprisingly the presence or absence of an embedded 70μm source shows no correlation with the detection of N2D+ (3-2), nor does it correlate with any change in velocity dispersion or excitation temperature. Comparison with recent models of deuteration suggest evolutionary time-scales of these regions of several free-fall times or less.

  10. Hubble Tracks Clouds on Uranus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Taking its first peek at Uranus, NASA Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has detected six distinct clouds in images taken July 28,1997.

    The image on the right, taken 90 minutes after the left-hand image, shows the planet's rotation. Each image is a composite of three near-infrared images. They are called false-color images because the human eye cannot detect infrared light. Therefore, colors corresponding to visible light were assigned to the images. (The wavelengths for the 'blue,' 'green,' and 'red' exposures are 1.1, 1.6, and 1.9 micrometers, respectively.)

    At visible and near-infrared light, sunlight is reflected from hazes and clouds in the atmosphere of Uranus. However, at near-infrared light, absorption by gases in the Uranian atmosphere limits the view to different altitudes, causing intense contrasts and colors.

    In these images, the blue exposure probes the deepest atmospheric levels. A blue color indicates clear atmospheric conditions, prevalent at mid-latitudes near the center of the disk. The green exposure is sensitive to absorption by methane gas, indicating a clear atmosphere; but in hazy atmospheric regions, the green color is seen because sunlight is reflected back before it is absorbed. The green color around the south pole (marked by '+') shows a strong local haze. The red exposure reveals absorption by hydrogen, the most abundant gas in the atmosphere of Uranus. Most sunlight shows patches of haze high in the atmosphere. A red color near the limb (edge) of the disk indicates the presence of a high-altitude haze. The purple color to the right of the equator also suggests haze high in the atmosphere with a clear atmosphere below.

    The five clouds visible near the right limb rotated counterclockwise during the time between both images. They reach high into the atmosphere, as indicated by their red color. Features of such high contrast have never been seen before on Uranus. The clouds are

  11. HUBBLE TRACKS CLOUDS ON URANUS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Taking its first peek at Uranus, NASA Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has detected six distinct clouds in images taken July 28,1997. The image on the right, taken 90 minutes after the left-hand image, shows the planet's rotation. Each image is a composite of three near-infrared images. They are called false-color images because the human eye cannot detect infrared light. Therefore, colors corresponding to visible light were assigned to the images. (The wavelengths for the 'blue,' 'green,' and 'red' exposures are 1.1, 1.6, and 1.9 micrometers, respectively.) At visible and near-infrared light, sunlight is reflected from hazes and clouds in the atmosphere of Uranus. However, at near-infrared light, absorption by gases in the Uranian atmosphere limits the view to different altitudes, causing intense contrasts and colors. In these images, the blue exposure probes the deepest atmospheric levels. A blue color indicates clear atmospheric conditions, prevalent at mid-latitudes near the center of the disk. The green exposure is sensitive to absorption by methane gas, indicating a clear atmosphere; but in hazy atmospheric regions, the green color is seen because sunlight is reflected back before it is absorbed. The green color around the south pole (marked by '+') shows a strong local haze. The red exposure reveals absorption by hydrogen, the most abundant gas in the atmosphere of Uranus. Most sunlight shows patches of haze high in the atmosphere. A red color near the limb (edge) of the disk indicates the presence of a high-altitude haze. The purple color to the right of the equator also suggests haze high in the atmosphere with a clear atmosphere below. The five clouds visible near the right limb rotated counterclockwise during the time between both images. They reach high into the atmosphere, as indicated by their red color. Features of such high contrast have never been seen before on Uranus. The clouds are almost as

  12. The Many Colors and Shapes of Cloud

    NASA Astrophysics Data System (ADS)

    Yeh, James T.

    While many enterprises and business entities are deploying and exploiting Cloud Computing, the academic institutes and researchers are also busy trying to wrestle this beast and put a leash on this possible paradigm changing computing model. Many have argued that Cloud Computing is nothing more than a name change of Utility Computing. Others have argued that Cloud Computing is a revolutionary change of the computing architecture. So it has been difficult to put a boundary of what is in Cloud Computing, and what is not. I assert that it is equally difficult to find a group of people who would agree on even the definition of Cloud Computing. In actuality, may be all that arguments are not necessary, as Clouds have many shapes and colors. In this presentation, the speaker will attempt to illustrate that the shape and the color of the cloud depend very much on the business goals one intends to achieve. It will be a very rich territory for both the businesses to take the advantage of the benefits of Cloud Computing and the academia to integrate the technology research and business research.

  13. Dynamical evolution of the Oort cloud

    NASA Technical Reports Server (NTRS)

    Weissman, P. R.

    1985-01-01

    New studies of the dynamical evolution of cometary orbits in the Oort cloud are made using a revised version of Weissman's (1982) Monte Carlo simulation model, which more accurately mimics the perturbation of comets by the giant planets. It is shown that perturbations by Saturn and Jupiter provide a substantial barrier to the diffusion of cometary perihelia into the inner solar system. Perturbations by Uranus and Neptune are rarely great enough to remove comets from the Oort cloud, but do serve to scatter the comets in the cloud in initial energy. The new model gives a population of 1.8 to 2.1 x 10 to the 12th comets for the present-day Oort cloud, and a mass of 7 to 8 earth masses. Perturbation of the Oort cloud by giant molecular clouds in the galaxy is discussed, as is evidence for a massive 'inner Oort cloud' internal to the observed one. The possibility of an unseen solar companion orbiting in the Oort cloud and causing periodic comet showers is shown to be dynamically plausible but unlikely, based on the observed cratering rate on the earth and moon.

  14. Magnetic diffusion in clumpy molecular clouds

    NASA Astrophysics Data System (ADS)

    Elmegreen, B. G.; Combes, F.

    1992-06-01

    Magnetic diffusion in a clumpy cloud is slower than in a uniform cloud with the same average density and field strength, by the square root of the clump filling factor, f. This implies that giant molecular clouds can maintain their supporting magnetic fields for at least 6/sq rt f free fall times, while allowing a moderate rate of star formation in the dense cores. The f dependence also implies that clouds or cloud cores larger than a thermal Jeans mass will lose their flux more slowly compared to the free-fall time than smaller cores because the larger regions have supersonic virialized motions, and this inevitably leads to small scale clumpy structure by nonlinear effects. Thus star formation may proceed rapidly via diffusion in uniform cores that have primarily thermal motions (large f), while the surrounding clumpy cloud can be supported by the field for a relatively long time (small f). The slower magnetic diffusion rate for clumpy clouds compared to uniform clouds also affects the local heating rate for neutral gas in a shock, giving more of a J-type than C-type structure by shortening the magnetic precursor and causing clump collisions at speeds exceeding the internal Alfven speed.

  15. Electron cloud in the Fermilab Booster

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2007-06-01

    Simulations of the Fermilab Booster reveal a substantial electron-cloud buildup both inside the unshielded combined-function magnets and the beam pipes joining the magnets, when the second-emission yield (SEY) is larger than {approx}1.6. The implication of the electron-cloud effects on space charge and collective instabilities of the beam is discussed.

  16. Uniform-Temperature Walls for Cloud Chambers

    NASA Technical Reports Server (NTRS)

    Fleischman, G.

    1985-01-01

    Flat heat pipes rapidly transfer heat to and from experimental volumes. Heat pipe vapor chamber carries heat to and from thermo electric modules. Critical surface acts as evaporator or condenser in cloud physics experiments. Used as walls of spaceborne atmospheric cloud chambers. On Earth, used as isothermal floors for environmental test chambers.

  17. Cloud microphysics and surface properties in climate

    SciTech Connect

    Stamnes, K.

    1995-09-01

    Cloud optical thickness is determined from ground-based measurements of broadband incoming solar irradiance using a radiation model in which the cloud optical depth is adjusted until computed irradiance agrees with the measured value. From spectral measurements it would be feasible to determine both optical thickness and mean drop size, which apart from cloud structure and morphology, are the most important climatic parameters of clouds. A radiative convective model is used to study the sensitivity of climate to cloud liquid water amount and cloud drop size. This is illustrated in Figure 21.1 which shows that for medium thick clouds a 10 % increase in drop size yields a surface warming of 1.5{degrees}C, which is the same as that due to a doubling of carbon dioxide. For thick clouds, a 5% decrease in drop size is sufficient to offset the warming due to doubling of carbon dioxide. A radiative transfer model for the coupled atmosphere/sea ice/ocean system is used to study the partitioning of radiative energy between the three strata, and the potential for testing such a model in terms of planned experiments in the Arctic is discussed.

  18. Spatial charge cloud size of microchannel plates.

    PubMed

    Saito, M; Saito, Y; Asamura, K; Mukai, T

    2007-02-01

    We examine the spatial evolution of charge clouds emitted by microchannel plates (MCPs). A model of this evolution is presented, along with a comparison to experimental results. We also present an experimental method to measure the charge cloud radius in which the radial charge cloud distribution is assumed to be Gaussian. When a charge cloud is released from the MCP, its initial size is determined by the number and distribution of excited channels. The size of the charge cloud is examined as a function acceleration voltage, distance between MCP and anode, and MCP bias voltage. Since electrons released from the MCP have various initial energies and angular divergence, the charge cloud size increases as it travels away from the MCP. Space charge effects also contribute to the growth of the charge cloud. The experimental results are in close agreement with our model, which includes these effects. From experiment, we also derive an approximate expression for charge cloud radius as a function of acceleration voltage and distance between MCP and anode. This expression can be used for the practical design and optimization of a position sensing system comprised of multiple anodes.

  19. Context-preserving, dynamic word cloud visualization.

    PubMed

    Weiwei Cui; Yingcai Wu; Shixia Liu; Furu Wei; Zhou, Michelle X; Huamin Qu

    2010-01-01

    The proposed method uses context-preserving, dynamic word clouds to illustrate content evolution. It generates a sequence of word clouds in which related words are grouped together. This sequence is then coupled with a trend chart that summarizes content changes so that users can better explore large collections of documents.

  20. Stochastic approximation to multiple scattering in clouds.

    PubMed

    Zahavi, E

    1979-05-15

    The problem of multiple radiation scattering in a 3-D cloud is considered. The radiation is considered as energy bundles that impinge on the cloud's particles and are scattered around. The probabilistic expressions for bundle distribution are developed. An expression for radiation diffusivity for the nonisotropic scatter is presented. Two numerical examples show the application of the present theory.

  1. Using Word Clouds to Develop Proactive Learners

    ERIC Educational Resources Information Center

    Miley, Frances; Read, Andrew

    2011-01-01

    This article examines student responses to a technique for summarizing electronically available information based on word frequency. Students used this technique to create word clouds, using those word clouds to enhance personal and small group study. This is a qualitative study. Small focus groups were used to obtain student feedback. Feedback…

  2. Compression of antiproton clouds for antihydrogen trapping.

    PubMed

    Andresen, G B; Bertsche, W; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; El Nasr, S Seif; Silveira, D M; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-05-23

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.

  3. Compression of Antiproton Clouds for Antihydrogen Trapping

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Silveira, D. M.; Fujiwara, M. C.; Gill, D. R.

    2008-05-23

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.

  4. Observations of anthropogenic cloud condensation nuclei

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1990-01-01

    Cloud Condensation Nuclei (CCN) concentrations and spectral measurements obtained with the DRI instantaneous CCN spectrometer (Hudson, 1989) over the last few years are presented. The climatic importance of cloud microphysics has been pointed out. The particles which affect cloud microphysics are cloud condensation nuclei (CCN). The commonly-observed order of magnitude difference in cloud droplet concentrations between maritime and continental air masses (i.e., Squires, 1958) was determined to be caused by systematic differences in the concentrations of CCN between continental and maritime air masses (e.g., Twomey and Wojciechowski, 1969). Twomey (1977) first pointed out that cloud microphysics also affects the radiative properties of clouds. Thus continental and anthropogenic CCN could affect global temperature. Resolution of this Twomey effect requires answers to two questions - whether antropogenic CCN are a significant contribution to atmospheric CCN, and whether they are actually affecting cloud microphysics to an extent which is of climatic importance. The reasons for the contrast between continental and maritime CCN concentration are not understood. The question of the relative importance of anthropogenic CCN is addressed. These observations should shed light on this complex question although further research is being conducted in order to produce more quantitative answers. Accompanying CN measurements made with a TSI 3020 condensation nucleus (CN) counter are also presented.

  5. Evolutionary Models of Cold, Magnetized, Interstellar Clouds

    NASA Technical Reports Server (NTRS)

    Gammie, Charles F.; Ostriker, Eve; Stone, James M.

    2004-01-01

    We modeled the long-term and small-scale evolution of molecular clouds using direct 2D and 3D magnetohydrodynamic (MHD) simulations. This work followed up on previous research by our group under auspices of the ATP in which we studied the energetics of turbulent, magnetized clouds and their internal structure on intermediate scales. Our new work focused on both global and smallscale aspects of the evolution of turbulent, magnetized clouds, and in particular studied the response of turbulent proto-cloud material to passage through the Galactic spiral potential, and the dynamical collapse of turbulent, magnetized (supercritical) clouds into fragments to initiate the formation of a stellar cluster. Technical advances under this program include developing an adaptive-mesh MHD code as a successor to ZEUS (ATHENA) in order to follow cloud fragmentation, developing a shearing-sheet MHD code which includes self-gravity and externally-imposed gravity to follow the evolution of clouds in the Galactic potential, and developing radiative transfer models to evaluate the internal ionization of clumpy clouds exposed to external photoionizing UV and CR radiation. Gammie's work at UIUC focused on the radiative transfer aspects of this program.

  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. Investigating expanded chemistry in CMAQ clouds

    EPA Science Inventory

    Clouds and fogs significantly impact the amount, composition, and spatial distribution of gas and particulate atmospheric species, not least of which through the chemistry that occurs in cloud droplets.ᅠ Atmospheric sulfate is an important component of fine aerosol mass an...

  8. Navigating the Challenges of the Cloud

    ERIC Educational Resources Information Center

    Ovadia, Steven

    2010-01-01

    Cloud computing is increasingly popular in education. Cloud computing is "the delivery of computer services from vast warehouses of shared machines that enables companies and individuals to cut costs by handing over the running of their email, customer databases or accounting software to someone else, and then accessing it over the internet."…

  9. Cloud formation, convection, and stratospheric dehydration

    NASA Astrophysics Data System (ADS)

    Schoeberl, Mark R.; Dessler, Andrew E.; Wang, Tao; Avery, Melody A.; Jensen, Eric J.

    2014-12-01

    Using the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis winds, temperatures, and anvil cloud ice, we use our domain-filling, forward trajectory model combined with a new cloud module to show that convective transport of saturated air and ice to altitudes below the tropopause has a significant impact on stratospheric water vapor and upper tropospheric clouds. We find that including cloud microphysical processes (rather than assuming that parcel water vapor never exceeds saturation) increases the lower stratospheric average H2O by 10-20%. Our model-computed cloud fraction shows reasonably good agreement with tropical upper troposphere (TUT) cloud frequency observed by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument in boreal winter with poorer agreement in summer. Our results suggest that over 40% of TUT cirrus is due to convection, and it is the saturated air from convection rather than injected cloud ice that primarily contributes to this increase. Convection can add up to 13% more water to the stratosphere. With just convective hydration (convection adds vapor up to saturation), the global lower stratospheric modeled water vapor is close to Microwave Limb Sounder observations. Adding convectively injected ice increases the modeled water vapor to ~8% over observations. Improving the representation of MERRA tropopause temperatures fields reduces stratospheric water vapor by ~4%.

  10. 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.

  11. What does reflection from cloud sides tell us about vertical distribution of cloud droplets?

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Kaufman, Yoram; Martins, V.; Zubko, Victor

    2006-01-01

    In order to accurately measure the interaction of clouds with aerosols, we have to resolve the vertical distribution of cloud droplet sizes and determine the temperature of glaciation for clean and polluted clouds. Knowledge of the droplet vertical profile is also essential for understanding precipitation. So far, all existing satellites either measure cloud microphysics only at cloud top (e.g., MODIS) or give a vertical profile of precipitation sized droplets (e.g., Cloudsat). What if one measures cloud microphysical properties in the vertical by retrieving them from the solar and infrared radiation reflected or emitted from cloud sides? This was the idea behind CLAIM-3D (A 3D - cloud aerosol interaction mission) recently proposed by NASA GSFC. This presentation will focus on the interpretation of the radiation reflected from cloud sides. In contrast to plane-parallel approximation, a conventional approach to all current operational retrievals, 3D radiative transfer will be used for interpreting the observed reflectances. As a proof of concept, we will show a few examples of radiation reflected from cloud fields generated by a simple stochastic cloud model with prescribed microphysics. Instead of fixed values of the retrieved effective radii, the probability density functions of droplet size distributions will serve as possible retrievals.

  12. Cloud water in windward and leeward mountain forests: The stable isotope signature of orographic cloud water

    USGS Publications Warehouse

    Scholl, M.A.; Giambelluca, T.W.; Gingerich, S.B.; Nullet, M.A.; Loope, L.L.

    2007-01-01

    Cloud water can be a significant hydrologic input to mountain forests. Because it is a precipitation source that is vulnerable to climate change, it is important to quantify amounts of cloud water input at watershed and regional scales. During this study, cloud water and rain samples were collected monthly for 2 years at sites on windward and leeward East Maui. The difference in isotopic composition between volume-weighted average cloud water and rain samples was 1.4??? ??18O and 12??? ??2H for the windward site and 2.8??? ??18O and 25??? ??2H for the leeward site, with the cloud water samples enriched in 18O and 2H relative to the rain samples. A summary of previous literature shows that fog and/or cloud water is enriched in 18O and 2H compared to rain at many locations around the world; this study documents cloud water and rain isotopic composition resulting from weather patterns common to montane environments in the trade wind latitudes. An end-member isotopic composition for cloud water was identified for each site and was used in an isotopic mixing model to estimate the proportion of precipitation input from orographic clouds. Orographic cloud water input was 37% of the total precipitation at the windward site and 46% at the leeward site. This represents an estimate of water input to the forest that could be altered by changes in cloud base altitude resulting from global climate change or deforestation.

  13. A boundary-layer cloud study using Southern Great Plains Cloud and radiation testbed (CART) data

    SciTech Connect

    Albrecht, B.; Mace, G.; Dong, X.; Syrett, W.

    1996-04-01

    Boundary layer clouds-stratus and fairweather cumulus - are closely coupled involves the radiative impact of the clouds on the surface energy budget and the strong dependence of cloud formation and maintenance on the turbulent fluxes of heat and moisture in the boundary layer. The continuous data collection at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site provides a unique opportunity to study components of the coupling processes associated with boundary layer clouds and to provide descriptions of cloud and boundary layer structure that can be used to test parameterizations used in climate models. But before the CART data can be used for process studies and parameterization testing, it is necessary to evaluate and validate data and to develop techniques for effectively combining the data to provide meaningful descriptions of cloud and boundary layer characteristics. In this study we use measurements made during an intensive observing period we consider a case where low-level stratus were observed at the site for about 18 hours. This case is being used to examine the temporal evolution of cloud base, cloud top, cloud liquid water content, surface radiative fluxes, and boundary layer structure. A method for inferring cloud microphysics from these parameters is currently being evaluated.

  14. 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.

  15. Feedback in Clouds II: UV Photoionisation and the first supernova in a massive cloud

    NASA Astrophysics Data System (ADS)

    Geen, Sam; Hennebelle, Patrick; Tremblin, Pascal; Rosdahl, Joakim

    2016-09-01

    Molecular cloud structure is regulated by stellar feedback in various forms. Two of the most important feedback processes are UV photoionisation and supernovae from massive stars. However, the precise response of the cloud to these processes, and the interaction between them, remains an open question. In particular, we wish to know under which conditions the cloud can be dispersed by feedback, which in turn can give us hints as to how feedback regulates the star formation inside the cloud. We perform a suite of radiative magnetohydrodynamic simulations of a 105 solar mass cloud with embedded sources of ionising radiation and supernovae, including multiple supernovae and a hypernova model. A UV source corresponding to 10% of the mass of the cloud is required to disperse the cloud, suggesting that the star formation efficiency should be on the order of 10%. A single supernova is unable to significantly affect the evolution of the cloud. However, energetic hypernovae and multiple supernovae are able to add significant quantities of momentum to the cloud, approximately 1043 g cm/s of momentum per 1051 ergs of supernova energy. We argue that supernovae alone are unable to regulate star formation in molecular clouds. We stress the importance of ram pressure from turbulence in regulating feedback in molecular clouds.

  16. Effect of CALIPSO Cloud Aerosol Discrimination (CAD) Confidence Levels on Observations of Aerosol Properties near Clouds

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Liu, Zhaoyan

    2012-01-01

    CALIPSO aerosol backscatter enhancement in the transition zone between clouds and clear sky areas is revisited with particular attention to effects of data selection based on the confidence level of cloud-aerosol discrimination (CAD). The results show that backscatter behavior in the transition zone strongly depends on the CAD confidence level. Higher confidence level data has a flatter backscatter far away from clouds and a much sharper increase near clouds (within 4 km), thus a smaller transition zone. For high confidence level data it is shown that the overall backscatter enhancement is more pronounced for small clear-air segments and horizontally larger clouds. The results suggest that data selection based on CAD reduces the possible effects of cloud contamination when studying aerosol properties in the vicinity of clouds.

  17. 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.

  18. A Study of Global Cirrus Cloud Morphology with AIRS Cloud-clear Radiances (CCRs)

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Gong, Jie

    2012-01-01

    Version 6 (V6) AIRS cloud-clear radiances (CCR) are used to derive cloud-induced radiance (Tcir=Tb-CCR) at the infrared frequencies of weighting functions peaked in the middle troposphere. The significantly improved V 6 CCR product allows a more accurate estimation of the expected clear-sky radiance as if clouds are absent. In the case where strong cloud scattering is present, the CCR becomes unreliable, which is reflected by its estimated uncertainty, and interpolation is employed to replace this CCR value. We find that Tcir derived from this CCR method are much better than other methods and detect more clouds in the upper and lower troposphere as well as in the polar regions where cloud detection is particularly challenging. The cloud morphology derived from the V6 test month, as well as some artifacts, will be shown.

  19. The NASA CloudSat Education Network

    NASA Astrophysics Data System (ADS)

    Krumm, D. K.

    2006-05-01

    CloudSat, a NASA Earth System Science Pathfinder Mission, will launch into orbit the world's most advanced weather radar designed to measure properties of clouds that are essential for accurate understanding of Earth's weather and climate processes. Providing the first vertical profiles of global measurements of cloud thickness, height, water and ice content and a wide range of precipitation data linked to cloud development, CloudSat measurements will fill a critical gap in understanding how clouds affect climate. Any mission of this nature requires extensive ground-based reference data. The CloudSat Education Network provides the opportunity for schools around the world to partner with the CloudSat Science Team and the NASA-sponsored GLOBE Program. The Network will link together scientists, students, teachers, and their communities to give students meaningful, authentic and contemporary science education experiences. Student activities and learning outcomes are being developed to meet both general education outcomes and specific standards or objectives from school curricula. The main focus of the knowledge development component of the project is to help students better understand long-term climate change and the climatic processes that maintain the Earth's Energy balance. Student research with CloudSat/GLOBE data will be strongly encouraged. Scientists will receive research-quality data in support of the mission and in return will interact with teachers and their students to promote interest in science. Participation in the network throughout the duration of the project will be monitored and schools will be asked to maintain levels of participation in order to give CloudSat scientists a solid consistent base of data to support their research. The preferred base level of participation is the reporting of cloud, temperature and precipitation data according to modified GLOBE protocols approximately every 16 days coinciding with the CloudSat satellite overpass. The

  20. The diurnal variability of marine stratocumulus clouds

    NASA Technical Reports Server (NTRS)

    Rogers, David P.; Olsen, Lola M.

    1990-01-01

    Observations of the diurnal variation of marine stratocumulus clouds obtained during July 1987 as part of the First ISCCP Regional Experiment are described. The observations show a clear diurnal signature in the structure of the cloud-topped marine boundary layer, with a large variation in the height of the cloud base, with lower heights observed at night. The observational results are numerically simulated using a 1D second-moment turbulence-closure model of Koracin and Rogers (1990) for a hydrostatically incompressible fluid. The model results indicate that the differential heating of the cloud layer promotes mixing in the upper part of the cloud and stabilizes the lower part of the layer.