WorldWideScience

Sample records for shortwave cloud transmissivity

  1. Shortwave radiative effects of unactivated aerosol particles in clouds

    International Nuclear Information System (INIS)

    Ackerman, T.; Baker, M.B.

    1977-01-01

    Clouds in some polluted areas may contain high concentrations of anthropogenic aerosol particles. The possible role of these particles in perturbing the optical and dynamical properties of the clouds is an important question for climate studies. The direct radiative effects of unactivated aerosol particles in stable stratus clouds have been calculated at lambda=0.5μm. Several simplifying asumptions have been made relating the behavior of such particles in the high humidity enviornment within the cloud to their physicochemical make-up. It is shown that the energy absorbed by particles within the clouds may be, for realistic concentrations, comparable to the latent heat released and thus may play a significant role in cloud dynamics in some areas. These results are shown to be relatively insensitive to the assumptions about the particle properties within the cloud

  2. A Novel Method for Estimating Shortwave Direct Radiative Effect of Above-Cloud Aerosols Using CALIOP and MODIS Data

    Science.gov (United States)

    Zhang, Z.; Meyer, K.; Platnick, S.; Oreopoulos, L.; Lee, D.; Yu, H.

    2014-01-01

    This paper describes an efficient and unique method for computing the shortwave direct radiative effect (DRE) of aerosol residing above low-level liquid-phase clouds using CALIOP and MODIS data. It accounts for the overlapping of aerosol and cloud rigorously by utilizing the joint histogram of cloud optical depth and cloud top pressure. Effects of sub-grid scale cloud and aerosol variations on DRE are accounted for. It is computationally efficient through using grid-level cloud and aerosol statistics, instead of pixel-level products, and a pre-computed look-up table in radiative transfer calculations. We verified that for smoke over the southeast Atlantic Ocean the method yields a seasonal mean instantaneous shortwave DRE that generally agrees with more rigorous pixel-level computation within 4. We have also computed the annual mean instantaneous shortwave DRE of light-absorbing aerosols (i.e., smoke and polluted dust) over global ocean based on 4 yr of CALIOP and MODIS data. We found that the variability of the annual mean shortwave DRE of above-cloud light-absorbing aerosol is mainly driven by the optical depth of the underlying clouds.

  3. Top-down and bottom-up aerosol-cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

    Science.gov (United States)

    Sanchez, Kevin J.; Roberts, Gregory C.; Calmer, Radiance; Nicoll, Keri; Hashimshoni, Eyal; Rosenfeld, Daniel; Ovadnevaite, Jurgita; Preissler, Jana; Ceburnis, Darius; O'Dowd, Colin; Russell, Lynn M.

    2017-08-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60 W m-2. After accounting for entrainment

  4. Economic Value of Narrowing the Uncertainty in Climate Sensitivity: Decadal Change in Shortwave Cloud Radiative Forcing and Low Cloud Feedback

    Science.gov (United States)

    Wielicki, B. A.; Cooke, R. M.; Golub, A. A.; Mlynczak, M. G.; Young, D. F.; Baize, R. R.

    2016-12-01

    Several previous studies have been published on the economic value of narrowing the uncertainty in climate sensitivity (Cooke et al. 2015, Cooke et al. 2016, Hope, 2015). All three of these studies estimated roughly 10 Trillion U.S. dollars for the Net Present Value and Real Option Value at a discount rate of 3%. This discount rate is the nominal discount rate used in the U.S. Social Cost of Carbon Memo (2010). The Cooke et al studies approached this problem by examining advances in accuracy of global temperature measurements, while the Hope 2015 study did not address the type of observations required. While temperature change is related to climate sensitivity, large uncertainties of a factor of 3 in current anthropogenic radiative forcing (IPCC, 2013) would need to be solved for advanced decadal temperature change observations to assist the challenge of narrowing climate sensitivity. The present study takes a new approach by extending the Cooke et al. 2015,2016 papers to replace observations of temperature change to observations of decadal change in the effects of changing clouds on the Earths radiative energy balance, a measurement known as Cloud Radiative Forcing, or Cloud Radiative Effect. Decadal change in this observation is direclty related to the largest uncertainty in climate sensitivity which is cloud feedback from changing amount of low clouds, primarily low clouds over the world's oceans. As a result, decadal changes in shortwave cloud radiative forcing are more directly related to cloud feedback uncertainty which is the dominant uncertainty in climate sensitivity. This paper will show results for the new approach, and allow an examination of the sensitivity of economic value results to different observations used as a constraint on uncertainty in climate sensitivity. The analysis suggests roughly a doubling of economic value to 20 Trillion Net Present Value or Real Option Value at 3% discount rate. The higher economic value results from two changes: a

  5. Evaluation of the shortwave cloud radiative effect over the ocean by use of ship and satellite observations

    Directory of Open Access Journals (Sweden)

    T. Hanschmann

    2012-12-01

    Full Text Available In this study the shortwave cloud radiative effect (SWCRE over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements. The ship observations yield cloud fraction, liquid water path from a microwave radiometer, cloud bottom height as well as temperature and humidity profiles from radiosonde ascents. Level-2 products of the Satellite Application Facility on Climate Monitoring (CM~SAF from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI have been used to characterize clouds. Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations. Four of these experiments are defined to investigate the advantage of including the satellite-based cloud droplet effective radius as additional cloud property. The modeled SWCRE based on satellite retrieved cloud properties has a comparable accuracy to the modeled SWCRE based on ship data. For several cases, an improvement through introducing the satellite-based estimate of effective radius as additional information to the ship based data was found. Due to their different measuring characteristics, however, each dataset shows best results for different atmospheric conditions.

  6. Characterizing the information content of cloud thermodynamic phase retrievals from the notional PACE OCI shortwave reflectance measurements

    Science.gov (United States)

    Coddington, O. M.; Vukicevic, T.; Schmidt, K. S.; Platnick, S.

    2017-08-01

    We rigorously quantify the probability of liquid or ice thermodynamic phase using only shortwave spectral channels specific to the National Aeronautics and Space Administration's Moderate Resolution Imaging Spectroradiometer, Visible Infrared Imaging Radiometer Suite, and the notional future Plankton, Aerosol, Cloud, ocean Ecosystem imager. The results show that two shortwave-infrared channels (2135 and 2250 nm) provide more information on cloud thermodynamic phase than either channel alone; in one case, the probability of ice phase retrieval increases from 65 to 82% by combining 2135 and 2250 nm channels. The analysis is performed with a nonlinear statistical estimation approach, the GEneralized Nonlinear Retrieval Analysis (GENRA). The GENRA technique has previously been used to quantify the retrieval of cloud optical properties from passive shortwave observations, for an assumed thermodynamic phase. Here we present the methodology needed to extend the utility of GENRA to a binary thermodynamic phase space (i.e., liquid or ice). We apply formal information content metrics to quantify our results; two of these (mutual and conditional information) have not previously been used in the field of cloud studies.

  7. Top-down and bottom-up aerosol–cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

    Directory of Open Access Journals (Sweden)

    K. J. Sanchez

    2017-08-01

    Full Text Available Top-down and bottom-up aerosol–cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding European collaborative project, with the goal of understanding key processes affecting aerosol–cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN concentration were used to initiate a 1-D microphysical aerosol–cloud parcel model (ACPM. UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF by between 25 and 60 W m−2. After

  8. A Novel Method for Estimating Shortwave Direct Radiative Effect of Above-cloud Aerosols over Ocean Using CALIOP and MODIS Data

    Science.gov (United States)

    Zhang, Z.; Meyer, K.; Platnick, S.; Oreopoulos, L.; Lee, D.; Yu, H.

    2013-01-01

    This paper describes an efficient and unique method for computing the shortwave direct radiative effect (DRE) of aerosol residing above low-level liquid-phase clouds using CALIOP and MODIS data. It accounts for the overlapping of aerosol and cloud rigorously by utilizing the joint histogram of cloud optical depth and cloud top pressure. Effects of sub-grid scale cloud and aerosol variations on DRE are accounted for. It is computationally efficient through using grid-level cloud and aerosol statistics, instead of pixel-level products, and a pre-computed look-up table in radiative transfer calculations. We verified that for smoke over the southeast Atlantic Ocean the method yields a seasonal mean instantaneous shortwave DRE that generally agrees with more rigorous pixel-level computation within 4%. We have also computed the annual mean instantaneous shortwave DRE of light-absorbing aerosols (i.e., smoke and polluted dust) over global ocean based on 4 yr of CALIOP and MODIS data. We found that the variability of the annual mean shortwave DRE of above-cloud light-absorbing aerosol is mainly driven by the optical depth of the underlying clouds.

  9. Ship track observations of a reduced shortwave aerosol indirect effect in mixed-phase clouds

    Science.gov (United States)

    Christensen, M. W.; Suzuki, K.; Zambri, B.; Stephens, G. L.

    2014-10-01

    Aerosol influences on clouds are a major source of uncertainty to our understanding of forced climate change. Increased aerosol can enhance solar reflection from clouds countering greenhouse gas warming. Recently, this indirect effect has been extended from water droplet clouds to other types including mixed-phase clouds. Aerosol effects on mixed-phase clouds are important because of their fundamental role on sea ice loss and polar climate change, but very little is known about aerosol effects on these clouds. Here we provide the first analysis of the effects of aerosol emitted from ship stacks into mixed-phase clouds. Satellite observations of solar reflection in numerous ship tracks reveal that cloud albedo increases 5 times more in liquid clouds when polluted and persist 2 h longer than in mixed-phase clouds. These results suggest that seeding mixed-phase clouds via shipping aerosol is unlikely to provide any significant counterbalancing solar radiative cooling effects in warming polar regions.

  10. Effect of surface albedo, water vapour, and atmospheric aerosols on the cloud-free shortwave radiative budget in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Di Biagio, C. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); University of Siena, Department of Earth Science, Siena (Italy); Di Sarra, A. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); Eriksen, P. [Danish Climate Centre, DMI, Danish Meteorological Institute, Copenhagen (Denmark); Ascanius, S.E. [DMI, Danish Meteorological Institute, Qaanaaq (Greenland); Muscari, G. [INGV, Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Holben, B. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2012-08-15

    This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth ({tau}) obtained at Thule Air Base (Greenland) in 2007-2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A ({Delta}SW{sub A}), wv ({Delta}SW{sub wv}), and aerosols ({Delta}SW{sub {tau}}) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as -100 Wm{sup -2} (-18%). The seasonal change of A produces an increase of SW by up to +25 Wm{sup -2} (+4.5%). The annual mean radiative effect is estimated to be -(21-22) Wm{sup -2} for wv, and +(2-3) Wm{sup -2} for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in {Delta}SW{sub wv} by 0.93 Wm{sup -2} (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by -0.027, with a corresponding decrease in {Delta}SW{sub A} by 0.41 Wm{sup -2} (-14.9%). Atmospheric aerosols produce a reduction of SW as low as -32 Wm{sup -2} (-6.7%). The instantaneous aerosol radiative forcing (RF{sub {tau}}) reaches values of -28 Wm{sup -2} and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FE{sub {tau}}) for solar zenith angles between 55 and 70 is estimated to be (-120.6 {+-} 4.3) for 0.1 < A < 0.2, and (-41.2 {+-} 1.6) Wm{sup -2} for 0.5 < A < 0.6. (orig.)

  11. Shortwave surface radiation network for observing small-scale cloud inhomogeneity fields

    Science.gov (United States)

    Lakshmi Madhavan, Bomidi; Kalisch, John; Macke, Andreas

    2016-03-01

    As part of the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE), a high-density network of 99 silicon photodiode pyranometers was set up around Jülich (10 km × 12 km area) from April to July 2013 to capture the small-scale variability of cloud-induced radiation fields at the surface. In this paper, we provide the details of this unique setup of the pyranometer network, data processing, quality control, and uncertainty assessment under variable conditions. Some exemplary days with clear, broken cloudy, and overcast skies were explored to assess the spatiotemporal observations from the network along with other collocated radiation and sky imager measurements available during the HOPE period.

  12. Measurement and modeling of shortwave irradiance components in cloud-free atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Halthore, R.N.

    1999-08-04

    Atmosphere scatters and absorbs incident solar radiation modifying its spectral content and decreasing its intensity at the surface. It is very useful to classify the earth-atmospheric solar radiation into several components--direct solar surface irradiance (E{sub direct}), diffuse-sky downward surface irradiance (E{sub diffuse}), total surface irradiance, and upwelling flux at the surface and at the top-of-the atmosphere. E{sub direct} depends only on the extinction properties of the atmosphere without regard to details of extinction, namely scattering or absorption; furthermore it can be accurately measured to high accuracy (0.3%) with the aid of an active cavity radiometer (ACR). E{sub diffuse} has relatively larger uncertainties both in its measurement using shaded pyranometers and in model estimates, owing to the difficulty in accurately characterizing pyranometers and in measuring model inputs such as surface reflectance, aerosol single scattering albedo, and phase function. Radiative transfer model simulations of the above surface radiation components in cloud-free skies using measured atmospheric properties show that while E{sub direct} estimates are closer to measurements, E{sub diffuse} is overestimated by an amount larger than the combined uncertainties in model inputs and measurements, illustrating a fundamental gap in the understanding of the magnitude of atmospheric absorption in cloud-free skies. The excess continuum type absorption required to reduce the E{sub diffuse} model overestimate ({approximately}3--8% absorptance) would significantly impact climate prediction and remote sensing. It is not clear at present what the source for this continuum absorption is. Here issues related to measurements and modeling of the surface irradiance components are discussed.

  13. GEWEX SRB Shortwave Release 4

    Science.gov (United States)

    Cox, S. J.; Stackhouse, P. W., Jr.; Mikovitz, J. C.; Zhang, T.

    2017-12-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The new Release 4 uses the newly processed ISCCP HXS product as its primary input for cloud and radiance data. The ninefold increase in pixel number compared to the previous ISCCP DX allows finer gradations in cloud fraction in each grid box. It will also allow higher spatial resolutions (0.5 degree) in future releases. In addition to the input data improvements, several important algorithm improvements have been made since Release 3. These include recalculated atmospheric transmissivities and reflectivities yielding a less transmissive atmosphere. The calculations also include variable aerosol composition, allowing for the use of a detailed aerosol history from the Max Planck Institut Aerosol Climatology (MAC). Ocean albedo and snow/ice albedo are also improved from Release 3. Total solar irradiance is now variable, averaging 1361 Wm-2. Water vapor is taken from ISCCP's nnHIRS product. Results from GSW Release 4 are presented and analyzed. Early comparison to surface measurements show improved agreement.

  14. Impact of ice particle shape on short-wave radiative forcing: A case study for an arctic ice cloud

    International Nuclear Information System (INIS)

    Kahnert, Michael; Sandvik, Anne Dagrun; Biryulina, Marina; Stamnes, Jakob J.; Stamnes, Knut

    2008-01-01

    We used four different non-spherical particle models to compute optical properties of an arctic ice cloud and to simulate corresponding cloud radiative forcings and fluxes. One important finding is that differences in cloud forcing, downward flux at the surface, and absorbed flux in the atmosphere resulting from the use of the four different ice cloud particle models are comparable to differences in these quantities resulting from changing the surface albedo from 0.4 to 0.8, or by varying the ice water content (IWC) by a factor of 2. These findings show that the use of a suitable non-spherical ice cloud particle model is very important for a realistic assessment of the radiative impact of arctic ice clouds. The differences in radiative broadband fluxes predicted by the four different particle models were found to be caused mainly by differences in the optical depth and the asymmetry parameter. These two parameters were found to have nearly the same impact on the predicted cloud forcing. Computations were performed first by assuming a given vertical profile of the particle number density, then by assuming a given profile of the IWC. In both cases, the differences between the cloud radiative forcings computed with the four different non-spherical particle models were found to be of comparable magnitude. This finding shows that precise knowledge of ice particle number density or particle mass is not sufficient for accurate prediction of ice cloud radiative forcing. It is equally important to employ a non-spherical shape model that accurately reproduces the ice particle's dimension-to-volume ratio and its asymmetry parameter. The hexagonal column/plate model with air-bubble inclusions seems to offer the highest degree of flexibility

  15. A strategy for testing the impact of clouds on the shortwave radiation budge of general circulation models: A prototype for the Atmospheric Radiation Measurement Program

    International Nuclear Information System (INIS)

    Cess, R.D.

    1994-01-01

    Cloud-climate interactions are one of the greatest uncertainties in contemporary general circulation models (GCMs), and this study has focused on one aspect of this. Specifically, combined satellite and near-surface shortwave (SW) flux measurements have been used to test the impact of clouds on the SW radiation budgets of two GCMs. Concentration is initially on SW rather than longwave (LW) radiation because, in one of the GCMs used in this study an SW radiation inconsistency causes a LW inconsistency. The surface data consist of near-surface insolation measured by the upward facing pyranometer at the Boulder Atmospheric Observatory tower. The satellite data consist of top of the atmosphere (TOA) albedo data, collocated with the tower location, as determined from the GOES SW spin-scan radiometer. Measurements are made every half hour, with hourly means taken by averaging successive measurements. The combined data are for a 21-day period encompassing 28 June through 18 July 1987 and consist of 202 combined albedo/insolation measurements

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

    Energy Technology Data Exchange (ETDEWEB)

    Line, Michael R. [NASA Ames Research Center, Moffet Field, CA 94035 (United States); Parmentier, Vivien, E-mail: mrline@ucsc.edu [Department of Astronomy and Astrophysics, University of California–Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2016-03-20

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

  17. Shortwave Direct Radiative Effects of Above-Cloud Aerosols Over Global Oceans Derived From 8 Years of CALIOP and MODIS Observations

    Science.gov (United States)

    Zhang, Zhibo; Meyer, Kerry; Yu, Hongbin; Platnick, Steven; Colarco, Peter; Liu, Zhaoyan; Oraiopoulos, Lazaros

    2016-01-01

    In this paper, we studied the frequency of occurrence and shortwave direct radiative effects (DREs) of above-cloud aerosols (ACAs) over global oceans using 8 years (2007-2014) of collocated CALIOP and MODIS observations. Similar to previous work, we found high ACA occurrence in four regions: southeastern (SE) Atlantic region, where ACAs are mostly light-absorbing aerosols, i.e., smoke and polluted dust according to CALIOP classification, originating from biomass burning over the African Savanna; tropical northeastern (TNE) Atlantic and the Arabian Sea, where ACAs are predominantly windblown dust from the Sahara and Arabian deserts, respectively; and the northwestern (NW) Pacific, where ACAs are mostly transported smoke and polluted dusts from Asia. From radiative transfer simulations based on CALIOP-MODIS observations and a set of the preselected aerosol optical models, we found the DREs of ACAs at the top of atmosphere (TOA) to be positive (i.e., warming) in the SE Atlantic and NW Pacific regions, but negative (i.e., cooling) in the TNE Atlantic Ocean and the Arabian Sea. The cancellation of positive and negative regional DREs results in a global ocean annual mean diurnally averaged cloudy-sky DRE of 0.015 W m(exp. -2) [range of -0.03 to 0.06 W m (exp. -2)] at TOA. The DREs at surface and within the atmosphere are -0.015 W m(exp. -2) [range of -0.09 to -0.21 W m(exp. -2)], and 0.17 W m(exp. -2) [range of 0.11 to 0.24 W m(exp. -2)], respectively. The regional and seasonal mean DREs are much stronger. For example, in the SE Atlantic region, the JJA (July-August) seasonal mean cloudy-sky DRE is about 0.7 W m(exp. -2) [range of 0.2 to 1.2 W m(exp. -2)] at TOA. All our DRE computations are publicly available. The uncertainty in our DRE computations is mainly caused by the uncertainties in the aerosol optical properties, in particular aerosol absorption, the uncertainties in the CALIOP operational aerosol optical thickness retrieval, and the ignorance of cloud and

  18. Frame Filtering and Skipping for Point Cloud Data Video Transmission

    Directory of Open Access Journals (Sweden)

    Carlos Moreno

    2017-01-01

    Full Text Available Sensors for collecting 3D spatial data from the real world are becoming more important. They are a prime research area topic and have applications in consumer markets, such as medical, entertainment, and robotics. However, a primary concern with collecting this data is the vast amount of information being generated, and thus, needing to be processed before being transmitted. To address the issue, we propose the use of filtering methods and frame skipping. To collect the 3D spatial data, called point clouds, we used the Microsoft Kinect sensor. In addition, we utilized the Point Cloud Library to process and filter the data being generated by the Kinect. Two different computers were used: a client which collects, filters, and transmits the point clouds; and a server that receives and visualizes the point clouds. The client is also checking for similarity in consecutive frames, skipping those that reach a similarity threshold. In order to compare the filtering methods and test the effectiveness of the frame skipping technique, quality of service (QoS metrics such as frame rate and percentage of filter were introduced. These metrics indicate how well a certain combination of filtering method and frame skipping accomplishes the goal of transmitting point clouds from one location to another. We found that the pass through filter in conjunction with frame skipping provides the best relative QoS. However, results also show that there is still too much data for a satisfactory QoS. For a real-time system to provide reasonable end-to-end quality, dynamic compression and progressive transmission need to be utilized.

  19. Progressive data transmission for anatomical landmark detection in a cloud.

    Science.gov (United States)

    Sofka, M; Ralovich, K; Zhang, J; Zhou, S K; Comaniciu, D

    2012-01-01

    In the concept of cloud-computing-based systems, various authorized users have secure access to patient records from a number of care delivery organizations from any location. This creates a growing need for remote visualization, advanced image processing, state-of-the-art image analysis, and computer aided diagnosis. This paper proposes a system of algorithms for automatic detection of anatomical landmarks in 3D volumes in the cloud computing environment. The system addresses the inherent problem of limited bandwidth between a (thin) client, data center, and data analysis server. The problem of limited bandwidth is solved by a hierarchical sequential detection algorithm that obtains data by progressively transmitting only image regions required for processing. The client sends a request to detect a set of landmarks for region visualization or further analysis. The algorithm running on the data analysis server obtains a coarse level image from the data center and generates landmark location candidates. The candidates are then used to obtain image neighborhood regions at a finer resolution level for further detection. This way, the landmark locations are hierarchically and sequentially detected and refined. Only image regions surrounding landmark location candidates need to be trans- mitted during detection. Furthermore, the image regions are lossy compressed with JPEG 2000. Together, these properties amount to at least 30 times bandwidth reduction while achieving similar accuracy when compared to an algorithm using the original data. The hierarchical sequential algorithm with progressive data transmission considerably reduces bandwidth requirements in cloud-based detection systems.

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

    OpenAIRE

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

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-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 fractio...

  1. Simple simulation training system for short-wave radio station

    Science.gov (United States)

    Tan, Xianglin; Shao, Zhichao; Tu, Jianhua; Qu, Fuqi

    2018-04-01

    The short-wave radio station is a most important transmission equipment of our signal corps, but in the actual teaching process, which exist the phenomenon of fewer equipment and more students, making the students' short-wave radio operation and practice time is very limited. In order to solve the above problems, to carry out shortwave radio simple simulation training system development is very necessary. This project is developed by combining hardware and software to simulate the voice communication operation and signal principle of shortwave radio station, and can test the signal flow of shortwave radio station. The test results indicate that this system is simple operation, human-machine interface friendly and can improve teaching more efficiency.

  2. Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results

    International Nuclear Information System (INIS)

    Sonnad, Kiran; Sonnad, Kiran; Furman, Miguel; Veitzer, Seth; Stoltz, Peter; Cary, John

    2007-01-01

    Simulation studies for transmission of microwaves through electron clouds show good agreement with analytic results. The electron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for accessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab main injector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations

  3. GTZ: a fast compression and cloud transmission tool optimized for FASTQ files.

    Science.gov (United States)

    Xing, Yuting; Li, Gen; Wang, Zhenguo; Feng, Bolun; Song, Zhuo; Wu, Chengkun

    2017-12-28

    The dramatic development of DNA sequencing technology is generating real big data, craving for more storage and bandwidth. To speed up data sharing and bring data to computing resource faster and cheaper, it is necessary to develop a compression tool than can support efficient compression and transmission of sequencing data onto the cloud storage. This paper presents GTZ, a compression and transmission tool, optimized for FASTQ files. As a reference-free lossless FASTQ compressor, GTZ treats different lines of FASTQ separately, utilizes adaptive context modelling to estimate their characteristic probabilities, and compresses data blocks with arithmetic coding. GTZ can also be used to compress multiple files or directories at once. Furthermore, as a tool to be used in the cloud computing era, it is capable of saving compressed data locally or transmitting data directly into cloud by choice. We evaluated the performance of GTZ on some diverse FASTQ benchmarks. Results show that in most cases, it outperforms many other tools in terms of the compression ratio, speed and stability. GTZ is a tool that enables efficient lossless FASTQ data compression and simultaneous data transmission onto to cloud. It emerges as a useful tool for NGS data storage and transmission in the cloud environment. GTZ is freely available online at: https://github.com/Genetalks/gtz .

  4. Rotating shadowband radiometer development and analysis of spectral shortwave data

    Energy Technology Data Exchange (ETDEWEB)

    Michalsky, J.; Harrison, L.; Min, Q. [State Univ. of New York, Albany, NY (United States)] [and others

    1996-04-01

    Our goals in the Atmospheric Radiation Measurement (ARM) Program are improved measurements of spectral shortwave radiation and improved techniques for the retrieval of climatologically sensitive parameters. The multifilter rotating shadowband radiometer (MFRSR) that was developed during the first years of the ARM program has become a workhorse at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site, and it is widely deployed in other climate programs. We have spent most of our effort this year developing techniques to retrieve column aerosol, water vapor, and ozone from direct beam spectral measurements of the MFRSR. Additionally, we have had some success in calculating shortwave surface diffuse spectral irradiance. Using the surface albedo and the global irradiance, we have calculated cloud optical depths. From cloud optical depth and liquid water measured with the microwave radiometer, we have calculated effective liquid cloud particle radii. The rest of the text will provide some detail regarding each of these efforts.

  5. Effects of 3-D clouds on atmospheric transmission of solar radiation: Cloud type dependencies inferred from A-train satellite data

    Science.gov (United States)

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

    2014-01-01

    Three-dimensional (3-D) effects on broadband shortwave top of atmosphere (TOA) nadir radiance, atmospheric absorption, and surface irradiance are examined using 3-D cloud fields obtained from one hour's worth of A-train satellite observations and one-dimensional (1-D) independent column approximation (ICA) and full 3-D radiative transfer simulations. The 3-D minus ICA differences in TOA nadir radiance multiplied by π, atmospheric absorption, and surface downwelling irradiance, denoted as πΔI, ΔA, and ΔT, respectively, are analyzed by cloud type. At the 1 km pixel scale, πΔI, ΔA, and ΔT exhibit poor spatial correlation. Once averaged with a moving window, however, better linear relationships among πΔI, ΔA, and ΔT emerge, especially for moving windows larger than 5 km and large θ0. While cloud properties and solar geometry are shown to influence the relationships amongst πΔI, ΔA, and ΔT, once they are separated by cloud type, their linear relationships become much stronger. This suggests that ICA biases in surface irradiance and atmospheric absorption can be approximated based on ICA biases in nadir radiance as a function of cloud type.

  6. Simulations of the electron cloud buildup and its influence on the microwave transmission measurement

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Oliver Sebastian, E-mail: o.haas@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Boine-Frankenheim, Oliver [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany); Petrov, Fedor [Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany)

    2013-11-21

    An electron cloud density in an accelerator can be measured using the Microwave Transmission (MWT) method. The aim of our study is to evaluate the influence of a realistic, nonuniform electron cloud on the MWT. We conduct electron cloud buildup simulations for beam pipe geometries and bunch parameters resembling roughly the conditions in the CERN SPS. For different microwave waveguide modes the phase shift induced by a known electron cloud density is obtained from three different approaches: 3D Particle-In-Cell (PIC) simulation of the electron response, a 2D eigenvalue solver for waveguide modes assuming a dielectric response function for cold electrons, a perturbative method assuming a sufficiently smooth density profile. While several electron cloud parameters, such as temperature, result in minor errors in the determined density, the transversely inhomogeneous density can introduce a large error in the measured electron density. We show that the perturbative approach is sufficient to describe the phase shift under realistic electron cloud conditions. Depending on the geometry of the beam pipe, the external magnetic field configuration and the used waveguide mode, the electron cloud density can be concentrated at the beam pipe or near the beam pipe center, leading to a severe over- or underestimation of the electron density. -- Author-Highlights: •Electron cloud distributions are very inhomogeneous, especially in dipoles. •These inhomogeneities affect the microwave transmission measurement results. •Electron density might be over- or underestimated, depending on setup. •This can be quantified with several models, e.g. a perturbative approach.

  7. Secure open cloud in data transmission using reference pattern and identity with enhanced remote privacy checking

    Science.gov (United States)

    Vijay Singh, Ran; Agilandeeswari, L.

    2017-11-01

    To handle the large amount of client’s data in open cloud lots of security issues need to be address. Client’s privacy should not be known to other group members without data owner’s valid permission. Sometime clients are fended to have accessing with open cloud servers due to some restrictions. To overcome the security issues and these restrictions related to storing, data sharing in an inter domain network and privacy checking, we propose a model in this paper which is based on an identity based cryptography in data transmission and intermediate entity which have client’s reference with identity that will take control handling of data transmission in an open cloud environment and an extended remote privacy checking technique which will work at admin side. On behalf of data owner’s authority this proposed model will give best options to have secure cryptography in data transmission and remote privacy checking either as private or public or instructed. The hardness of Computational Diffie-Hellman assumption algorithm for key exchange makes this proposed model more secure than existing models which are being used for public cloud environment.

  8. QUANTITATIVELY ASSESSING THE ROLE OF CLOUDS IN THE TRANSMISSION SPECTRUM OF GJ 1214b

    Energy Technology Data Exchange (ETDEWEB)

    Morley, Caroline V.; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Kempton, Eliza M.-R. [Department of Physics, Grinnell College, Grinnell, IA 50112 (United States); Marley, Mark S.; Zahnle, Kevin [NASA Ames Research Center, 245-3, Moffett Field, CA 94035 (United States); Vissher, Channon, E-mail: cmorley@ucolick.org [Southwest Research Institute, Boulder, CO 80302 (United States)

    2013-09-20

    Recent observations of the super-Earth GJ 1214b show that it has a relatively featureless transmission spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted absorption features. Previous models that incorporate clouds have included their effect without a strong physical motivation for their existence. Here, we present model atmospheres of GJ 1214b that include physically motivated clouds of two types. We model the clouds that are present in chemical equilibrium, as has been suggested to occur on brown dwarfs, which include KCl and ZnS for this planet. We also include clouds that form as a result of photochemistry, forming a hydrocarbon haze layer. We use a photochemical kinetics model to understand the vertical distribution and available mass of haze-forming molecules. We model both solar and enhanced-metallicity cloudy models and determine the cloud properties necessary to match observations. In enhanced-metallicity atmospheres, we find that the equilibrium clouds can match the observations of GJ 1214b if they are lofted high into the atmosphere and have a low sedimentation efficiency (f{sub sed} = 0.1). We find that models with a variety of hydrocarbon haze properties can match the observations. Particle sizes from 0.01 to 0.25 μm can match the transmission spectrum with haze-forming efficiencies as low as 1%-5%.

  9. Cloud-based shaft torque estimation for electric vehicle equipped with integrated motor-transmission system

    Science.gov (United States)

    Zhu, Xiaoyuan; Zhang, Hui; Yang, Bo; Zhang, Guichen

    2018-01-01

    In order to improve oscillation damping control performance as well as gear shift quality of electric vehicle equipped with integrated motor-transmission system, a cloud-based shaft torque estimation scheme is proposed in this paper by using measurable motor and wheel speed signals transmitted by wireless network. It can help reduce computational burden of onboard controllers and also relief network bandwidth requirement of individual vehicle. Considering possible delays during signal wireless transmission, delay-dependent full-order observer design is proposed to estimate the shaft torque in cloud server. With these random delays modeled by using homogenous Markov chain, robust H∞ performance is adopted to minimize the effect of wireless network-induced delays, signal measurement noise as well as system modeling uncertainties on shaft torque estimation error. Observer parameters are derived by solving linear matrix inequalities, and simulation results using acceleration test and tip-in, tip-out test demonstrate the effectiveness of proposed shaft torque observer design.

  10. Modeling Exoplanetary Haze and Cloud Effects for Transmission Spectroscopy in the TRAPPIST-1 System

    Science.gov (United States)

    Moran, Sarah E.; Horst, Sarah M.; Lewis, Nikole K.; Batalha, Natasha E.; de Wit, Julien

    2018-01-01

    We present theoretical transmission spectra of the planets TRAPPIST-1d, e, f, and g using a version of the CaltecH Inverse ModEling and Retrieval Algorithms (CHIMERA) atmospheric modeling code. We use particle size, aerosol production rates, and aerosol composition inputs from recent laboratory experiments relevant for the TRAPPIST-1 system to constrain cloud and haze behavior and their effects on transmission spectra. We explore these cloud and haze cases for a variety of theoretical atmospheric compositions including hydrogen-, nitrogen-, and carbon dioxide-dominated atmospheres. Then, we demonstrate the feasibility of physically-motivated, laboratory-supported clouds and hazes to obscure spectral features at wavelengths and resolutions relevant to instruments on the Hubble Space Telescope and the upcoming James Webb Space Telescope. Lastly, with laboratory based constraints of haze production rates for terrestrial exoplanets, we constrain possible bulk atmospheric compositions of the TRAPPIST-1 planets based on current observations. We show that continued collection of optical data, beyond the supported wavelength range of the James Webb Telescope, is necessary to explore the full effect of hazes for transmission spectra of exoplanetary atmospheres like the TRAPPIST-1 system.

  11. Novel technical solutions for wireless ECG transmission & analysis in the age of the internet cloud.

    Science.gov (United States)

    Al-Zaiti, Salah S; Shusterman, Vladimir; Carey, Mary G

    2013-01-01

    Current guidelines recommend early reperfusion therapy for ST-elevation myocardial infarction (STEMI) within 90 min of first medical encounter. Telecardiology entails the use of advanced communication technologies to transmit the prehospital 12-lead electrocardiogram (ECG) to offsite cardiologists for early triage to the cath lab; which has been shown to dramatically reduce door-to-balloon time and total mortality. However, hospitals often find adopting ECG transmission technologies very challenging. The current review identifies seven major technical challenges of prehospital ECG transmission, including: paramedics inconvenience and transport delay; signal noise and interpretation errors; equipment malfunction and transmission failure; reliability of mobile phone networks; lack of compliance with the standards of digital ECG formats; poor integration with electronic medical records; and costly hardware and software pre-requisite installation. Current and potential solutions to address each of these technical challenges are discussed in details and include: automated ECG transmission protocols; annotatable waveform-based ECGs; optimal routing solutions; and the use of cloud computing systems rather than vendor-specific processing stations. Nevertheless, strategies to monitor transmission effectiveness and patient outcomes are essential to sustain initial gains of implementing ECG transmission technologies. © 2013.

  12. Short-wave albedo of a pine forest

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, A.

    1985-06-01

    In this paper nine years of continuous records of the short-wave albedo above a Scotch pine forest in middle Europe were analysed. Special emphasis was given to the dependencies of the albedo on its diurnal variation, its annual variation, the solar altitude, the structure of the stand, the cloud cover, the soil moisture and the spectral reflectance. A long-termed trend of the albedo could not be found, e.g. caused by the stand growth. Finally the annual variation of the albedo of the Scotch pine forest was compared with measurements above different surface types in middle Europe.

  13. Aerosols, clouds and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Twomey, S [University of Arizona, Tucson, AZ (USA). Inst. of Atmospheric Physics

    1991-01-01

    Most of the so-called 'CO{sub 2} effect' is, in fact, an 'H{sub 2}O effect' brought into play by the climate modeler's assumption that planetary average temperature dictates water-vapor concentration (following Clapeyron-Clausius). That assumption ignores the removal process, which cloud physicists know to be influenced by the aerosol, since the latter primarily controls cloud droplet number and size. Droplet number and size are also influential for shortwave (solar) energy. The reflectance of many thin to moderately thick clouds changes when nuclei concentrations change and make shortwave albedo susceptible to aerosol influence.

  14. Study of Shortwave Spectra in Fully 3D Environment: Synergy Between Scanning Radars and Spectral Radiation Measurements

    Science.gov (United States)

    Wiscombe, Warren J.

    2012-01-01

    The main theme for our research is the understanding and closure of the surface spectral shortwave radiation problem in fully 3D cloud situations by combining the new ARM scanning radars, shortwave spectrometers, and microwave radiometers with the arsenal of radiative transfer tools developed by our group. In particular, we define first a large number of cloudy test cases spanning all 3D possibilities not just the customary uniform-overcast ones. Second, for each case, we define a "Best Estimate of Clouds That Affect Shortwave Radiation" using all relevant ARM instruments, notably the new scanning radars, and contribute this to the ARM Archive. Third, we test the ASR-signature radiative transfer model RRTMG_SW for those cases, focusing on the near-IR because of long-standing problems in this spectral region, and work with the developers to improve RRTMG_SW in order to increase its penetration into the modeling community.

  15. Preliminary Analysis and Simulation Results of Microwave Transmission Through an Electron Cloud

    International Nuclear Information System (INIS)

    Sonnad, Kiran; Sonnad, Kiran; Furman, Miguel; Veitzer, Seth; Stoltz, Peter; Cary, John

    2007-01-01

    The electromagnetic particle-in-cell (PIC) code VORPAL is being used to simulate the interaction of microwave radiation through an electron cloud. The results so far show good agreement with theory for simple cases. The study has been motivated by previous experimental work on this problem at the CERN SPS [1], experiments at the PEP-II Low Energy Ring (LER) at SLAC [4], and proposed experiments at the Fermilab Main Injector (MI). With experimental observation of quantities such as amplitude, phase and spectrum of the output microwave radiation and with support from simulations for different cloud densities and applied magnetic fields, this technique can prove to be a useful probe for assessing the presence as well as the density of electron clouds

  16. Numerical study of influence of different dispersed components of crystal cloud on transmission of radiant energy

    Science.gov (United States)

    Shefer, Olga

    2017-11-01

    The calculated results of the transmission of visible and infrared radiation by an atmosphere layer involving ensembles of large preferentially oriented crystals and spherical particles are presented. To calculate extinction characteristics, the physical optics method and the Mie theory are applied. Among all atmospheric particles, both the small particles that are commensurable with the wavelength of the incident radiation and the large plates and the columns are distinguished by the most pronounced dependence of the transmission on spectra of radiant energy. The work illustrates features of influence of parameters of the particle size distribution, particle aspect ratios, orientation and particle refractive index, also polarization state of the incident radiation on the transmission. The predominant effect of the plates on the wavelength dependence of the transmission is shown. A separated and cooperative contributes of the large plates and the small volume shape particles to the common transmission by medium are considered.

  17. Estimating shortwave solar radiation using net radiation and meteorological measurements

    Science.gov (United States)

    Shortwave radiation has a wide variety of uses in land-atmosphere interactions research. Actual evapotranspiration estimation that involves stomatal conductance models like Jarvis and Ball-Berry require shortwave radiation to estimate photon flux density. However, in most weather stations, shortwave...

  18. Risk Evaluation of a UHV Power Transmission Construction Project Based on a Cloud Model and FCE Method for Sustainability

    Directory of Open Access Journals (Sweden)

    Huiru Zhao

    2015-03-01

    Full Text Available In order to achieve the sustainable development of energy, Ultra High Voltage (UHV power transmission construction projects are being established in China currently. Their high-tech nature, the massive amount of money involved, and the need for multi-agent collaboration as well as complex construction environments bring many challenges and risks. Risk management, therefore, is critical to reduce the risks and realize sustainable development of projects. Unfortunately, many traditional risk assessment methods may not perform well due to the great uncertainty and randomness inherent in UHV power construction projects. This paper, therefore, proposes a risk evaluation index system and a hybrid risk evaluation model to evaluate the risk of UHV projects and find out the key risk factors. This model based on a cloud model and fuzzy comprehensive evaluation (FCE method combines the superiority of the cloud model for reflecting randomness and discreteness with the advantages of the fuzzy comprehensive evaluation method in handling uncertain and vague issues. For the sake of proving our framework, an empirical study of “Zhejiang-Fuzhou” UHV power transmission construction project is presented. As key contributions, we find the risk of this project lies at a “middle” to “high” level and closer to a “middle” level; the “management risk” and “social risk” are identified as the most important risk factors requiring more attention; and some risk control recommendations are proposed. This article demonstrates the value of our approach in risk identification, which seeks to improve the risk control level and the sustainable development of UHV power transmission construction projects.

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  20. Radiative properties of clouds

    International Nuclear Information System (INIS)

    Twomey, S.

    1993-01-01

    The climatic effects of condensation nuclei in the formation of cloud droplets and the subsequent role of the cloud droplets as contributors to the planetary short-wave albedo is emphasized. Microphysical properties of clouds, which can be greatly modified by the degree of mixing with cloud-free air from outside, are discussed. The effect of clouds on visible radiation is assessed through multiple scattering of the radiation. Cloudwater or ice absorbs more with increasing wavelength in the near-infrared region, with water vapor providing the stronger absorption over narrower wavelength bands. Cloud thermal infrared absorption can be solely related to liquid water content at least for shallow clouds and clouds in the early development state. Three-dimensional general circulation models have been used to study the climatic effect of clouds. It was found for such studies (which did not consider variations in cloud albedo) that the cooling effects due to the increase in planetary short-wave albedo from clouds were offset by heating effects due to thermal infrared absorption by the cloud. Two permanent direct effects of increased pollution are discussed in this chapter: (a) an increase of absorption in the visible and near infrared because of increased amounts of elemental carbon, which gives rise to a warming effect climatically, and (b) an increased optical thickness of clouds due to increasing cloud droplet number concentration caused by increasing cloud condensation nuclei number concentration, which gives rise to a cooling effect climatically. An increase in cloud albedo from 0.7 to 0.87 produces an appreciable climatic perturbation of cooling up to 2.5 K at the ground, using a hemispheric general circulation model. Effects of pollution on cloud thermal infrared absorption are negligible

  1. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Science.gov (United States)

    Gubler, S.; Gruber, S.; Purves, R. S.

    2012-06-01

    As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR) and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR). In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB) stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM) in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night. We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD) and the relative root mean squared deviance (RMSD) of the clear-sky global SDR scatter between between -2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations to local conditions

  2. Uncertainties of parameterized surface downward clear-sky shortwave and all-sky longwave radiation.

    Directory of Open Access Journals (Sweden)

    S. Gubler

    2012-06-01

    Full Text Available As many environmental models rely on simulating the energy balance at the Earth's surface based on parameterized radiative fluxes, knowledge of the inherent model uncertainties is important. In this study we evaluate one parameterization of clear-sky direct, diffuse and global shortwave downward radiation (SDR and diverse parameterizations of clear-sky and all-sky longwave downward radiation (LDR. In a first step, SDR is estimated based on measured input variables and estimated atmospheric parameters for hourly time steps during the years 1996 to 2008. Model behaviour is validated using the high quality measurements of six Alpine Surface Radiation Budget (ASRB stations in Switzerland covering different elevations, and measurements of the Swiss Alpine Climate Radiation Monitoring network (SACRaM in Payerne. In a next step, twelve clear-sky LDR parameterizations are calibrated using the ASRB measurements. One of the best performing parameterizations is elected to estimate all-sky LDR, where cloud transmissivity is estimated using measured and modeled global SDR during daytime. In a last step, the performance of several interpolation methods is evaluated to determine the cloud transmissivity in the night.

    We show that clear-sky direct, diffuse and global SDR is adequately represented by the model when using measurements of the atmospheric parameters precipitable water and aerosol content at Payerne. If the atmospheric parameters are estimated and used as a fix value, the relative mean bias deviance (MBD and the relative root mean squared deviance (RMSD of the clear-sky global SDR scatter between between −2 and 5%, and 7 and 13% within the six locations. The small errors in clear-sky global SDR can be attributed to compensating effects of modeled direct and diffuse SDR since an overestimation of aerosol content in the atmosphere results in underestimating the direct, but overestimating the diffuse SDR. Calibration of LDR parameterizations

  3. The commerce Clause and transmission infrastructure development: an answer to jurisdictional issues clouded by protectionism

    Energy Technology Data Exchange (ETDEWEB)

    Snarr, Steven W.

    2009-06-15

    Siting authority for interstate transmission facilities needs to rest with one federal agency, FERC, and federal eminent domain authority should be granted to those projects that meet the certification requirements of the siting authority. Establishment of a national renewable portfolio standard would be helpful to promote development of both renewable energy resources and cleaner power alternatives. (author)

  4. Does shortwave absorption by methane influence its effectiveness?

    Science.gov (United States)

    Modak, Angshuman; Bala, Govindasamy; Caldeira, Ken; Cao, Long

    2018-01-01

    In this study, using idealized step-forcing simulations, we examine the effective radiative forcing of CH4 relative to that of CO2 and compare the effects of CH4 and CO2 forcing on the climate system. A tenfold increase in CH4 concentration in the NCAR CAM5 climate model produces similar long term global mean surface warming ( 1.7 K) as a one-third increase in CO2 concentration. However, the radiative forcing estimated for CO2 using the prescribed-SST method is 81% that of CH4, indicating that the efficacy of CH4 forcing is 0.81. This estimate is nearly unchanged when the CO2 physiological effect is included in our simulations. Further, for the same long-term global mean surface warming, we simulate a smaller precipitation increase in the CH4 case compared to the CO2 case. This is because of the fast adjustment processes—precipitation reduction in the CH4 case is larger than that of the CO2 case. This is associated with a relatively more stable atmosphere and larger atmospheric radiative forcing in the CH4 case which occurs because of near-infrared absorption by CH4 in the upper troposphere and lower stratosphere. Within a month after an increase in CH4, this shortwave heating results in a temperature increase of 0.8 K in the lower stratosphere and upper troposphere. In contrast, within a month after a CO2 increase, longwave cooling results in a temperature decrease of 3 K in the stratosphere and a small change in the upper troposphere. These fast adjustments in the lower stratospheric and upper tropospheric temperature, along with the adjustments in clouds in the troposphere, influence the effective radiative forcing and the fast precipitation response. These differences in fast climate adjustments also produce differences in the climate states from which the slow response begins to evolve and hence they are likely associated with differing feedbacks. We also find that the tropics and subtropics are relatively warmer in the CH4 case for the same global mean

  5. Contrails and their impact on shortwave radiation and photovoltaic power production – a regional model study

    Directory of Open Access Journals (Sweden)

    S. Gruber

    2018-05-01

    Full Text Available A high-resolution regional-scale numerical model was extended by a parameterization that allows for both the generation and the life cycle of contrails and contrail cirrus to be calculated. The life cycle of contrails and contrail cirrus is described by a two-moment cloud microphysical scheme that was extended by a separate contrail ice class for a better representation of the high concentration of small ice crystals that occur in contrails. The basic input data set contains the spatially and temporally highly resolved flight trajectories over Central Europe derived from real-time data. The parameterization provides aircraft-dependent source terms for contrail ice mass and number. A case study was performed to investigate the influence of contrails and contrail cirrus on the shortwave radiative fluxes at the earth's surface. Accounting for contrails produced by aircraft enabled the model to simulate high clouds that were otherwise missing on this day. The effect of these extra clouds was to reduce the incoming shortwave radiation at the surface as well as the production of photovoltaic power by up to 10 %.

  6. Impact of clouds in the JWST and LUVOIR simulated transmission spectra of TRAPPIST-1 planets in the habitable zone

    Science.gov (United States)

    Fauchez, Thomas; Turbet, Martin; Mandell, Avi; Kopparapu, Ravi Kumar; Arney, Giada; Domagal-Goldman, Shawn

    2018-06-01

    M-dwarfs are the most common type of stars in our galaxy. Ultra-cool dwarfs (T Earth and frequent planetary transits.Atmospheric properties are major components of planet habitability. However, the detectability of gaseous features on rocky planets in the HZ may be severely impacted by the presence of clouds and/or hazes in their atmosphere. We have already seen this phenomenon in the “flat” transit transmission spectra of larger exoplanets such as GJ 1214b, WASP-31b, WASP-12b and HATP-12b.In this work, we use the LMDG global climate model to simulate several possibilities of atmospheres for TRAPPIST-1 e, f and 1g: 1) Archean Earth, 2) modern Earth and 3) CO2-dominated atmospheres. We also calculate synthetic transit spectra using the GSFC Planetary Spectrum Generator (PSG), and determine the number of transits needed to observe key spectral features for both JWST and future telescopes (ARIEL, LUVOIR, HabEx). We will identify differences in the spectra of cloudy vs non-cloudy, and determine how much information on spatial variability in atmosphere characteristics can be extracted from time-resolved transit and eclipse mapping. A particular attention will be given to the impact of the atmospheric variability when adding transit spectra, and how this may affect atmospheric parameter retrievals.

  7. Spatial variability of shortwave radiative fluxes in the context of snowmelt

    Science.gov (United States)

    Pinker, Rachel T.; Ma, Yingtao; Hinkelman, Laura; Lundquist, Jessica

    2014-05-01

    Snow-covered mountain ranges are a major source of water supply for run-off and groundwater recharge. Snowmelt supplies as much as 75% of surface water in basins of the western United States. Factors that affect the rate of snow melt include incoming shortwave and longwave radiation, surface albedo, snow emissivity, snow surface temperature, sensible and latent heat fluxes, ground heat flux, and energy transferred to the snowpack from deposited snow or rain. The net radiation generally makes up about 80% of the energy balance and is dominated by the shortwave radiation. Complex terrain poses a great challenge for obtaining the needed information on radiative fluxes from satellites due to elevation issues, spatially-variable cloud cover, rapidly changing surface conditions during snow fall and snow melt, lack of high quality ground truth for evaluation of the satellite based estimates, as well as scale issues between the ground observations and the satellite footprint. In this study we utilize observations of high spatial resolution (5-km) as available from the Moderate Resolution Imaging Spectro-radiometer (MODIS) to derive surface shortwave radiative fluxes in complex terrain, with attention to the impact of slopes on the amount of radiation received. The methodology developed has been applied to several water years (January to July during 2003, 2004, 2005 and 2009) over the western part of the United States, and the available information was used to derive metrics on spatial and temporal variability in the shortwave fluxes. It is planned to apply the findings from this study for testing improvements in Snow Water Equivalent (SWE) estimates.

  8. Evaluating the impact of above-cloud aerosols on cloud optical depth retrievals from MODIS

    Science.gov (United States)

    Alfaro, Ricardo

    Using two different operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical depth (COD) retrievals (visible and shortwave infrared), the impacts of above-cloud absorbing aerosols on the standard COD retrievals are evaluated. For fine-mode aerosol particles, aerosol optical depth (AOD) values diminish sharply from the visible to the shortwave infrared channels. Thus, a suppressed above-cloud particle radiance aliasing effect occurs for COD retrievals using shortwave infrared channels. Aerosol Index (AI) from the spatially and temporally collocated Ozone Monitoring Instrument (OMI) are used to identify above-cloud aerosol particle loading over the southern Atlantic Ocean, including both smoke and dust from the African sub-continent. MODIS and OMI Collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to constrain cloud phase and provide contextual above-cloud AOD values. The frequency of occurrence of above-cloud aerosols is depicted on a global scale for the spring and summer seasons from OMI and CALIOP, thus indicating the significance of the problem. Seasonal frequencies for smoke-over-cloud off the southwestern Africa coastline reach 20--50% in boreal summer. We find a corresponding low COD bias of 10--20% for standard MODIS COD retrievals when averaged OMI AI are larger than 1.0. No such bias is found over the Saharan dust outflow region off northern Africa, since both MODIS visible and shortwave in channels are vulnerable to dust particle aliasing, and thus a COD impact cannot be isolated with this method. A similar result is found for a smaller domain, in the Gulf of Tonkin region, from smoke advection over marine stratocumulus clouds and outflow into the northern South China Sea in spring. This study shows the necessity of accounting for the above-cloud aerosol events for future studies using standard MODIS cloud products in biomass burning outflow regions, through the use of

  9. Longwave scattering effects on fluxes in broken cloud fields

    Energy Technology Data Exchange (ETDEWEB)

    Takara, E.E.; Ellingson, R.G. [Univ. of Maryland, College Park, MD (United States)

    1996-04-01

    The optical properties of clouds in the radiative energy balance are important. Most works on the effects of scattering have been in the shortwave; but longwave effects can be significant. In this work, the fluxes above and below a single cloud layer are presented, along with the errors in assuming flat black plate clouds or black clouds. The predicted fluxes are the averaged results of analysis of several fields with the same cloud amount.

  10. Aerosols, cloud physics and radiation

    International Nuclear Information System (INIS)

    Twomey, S.

    1990-01-01

    Some aspects of climate physics are discussed with special attention given to cases where cloud physics is relevant for the phase and microstructure of clouds and, therefore, in the optical properties of the planet. It is argued that aerosol particles, through their strong effect on cloud microphysics, influence the shortwave energy input to earth, and that cloud microphysics strongly influence rain formation. Therefore, through their influence on microphysics, the aerosols play a central role in the atmospheric water cycle and, thus, on the planet's outgoing radiation. 20 refs

  11. Stratocumulus Cloud Top Radiative Cooling and Cloud Base Updraft Speeds

    Science.gov (United States)

    Kazil, J.; Feingold, G.; Balsells, J.; Klinger, C.

    2017-12-01

    Cloud top radiative cooling is a primary driver of turbulence in the stratocumulus-topped marine boundary. A functional relationship between cloud top cooling and cloud base updraft speeds may therefore exist. A correlation of cloud top radiative cooling and cloud base updraft speeds has been recently identified empirically, providing a basis for satellite retrieval of cloud base updraft speeds. Such retrievals may enable analysis of aerosol-cloud interactions using satellite observations: Updraft speeds at cloud base co-determine supersaturation and therefore the activation of cloud condensation nuclei, which in turn co-determine cloud properties and precipitation formation. We use large eddy simulation and an off-line radiative transfer model to explore the relationship between cloud-top radiative cooling and cloud base updraft speeds in a marine stratocumulus cloud over the course of the diurnal cycle. We find that during daytime, at low cloud water path (CWP correlated, in agreement with the reported empirical relationship. During the night, in the absence of short-wave heating, CWP builds up (CWP > 50 g m-2) and long-wave emissions from cloud top saturate, while cloud base heating increases. In combination, cloud top cooling and cloud base updrafts become weakly anti-correlated. A functional relationship between cloud top cooling and cloud base updraft speed can hence be expected for stratocumulus clouds with a sufficiently low CWP and sub-saturated long-wave emissions, in particular during daytime. At higher CWPs, in particular at night, the relationship breaks down due to saturation of long-wave emissions from cloud top.

  12. ARM Enhanced Shortwave Experiment (ARESE) Solar Radiation Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The ARM Enhanced Shortwave Experiment (ARESE) was conducted at the Department of Energy's ARM Southern Great Plains (SGP) Central Facility between September 22, 1995...

  13. Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

    Directory of Open Access Journals (Sweden)

    J. J. Morcrette

    2007-05-01

    increased downward (upward circulation in the winter (summer hemisphere. In addition, the comparison of the two simulations performed with the general circulation model shows that the increase in the spectral resolution of the shortwave radiation and the associated changes in the cloud optical properties result in a warming (0.5–1 K and moistening (3%–12% of the upper tropical troposphere. By comparing these modeled differences with previous works, it appears that the reported changes in the solar radiation scheme contribute to improve the model mean temperature also in the troposphere.

  14. Establishing BRDF calibration capabilities through shortwave infrared

    Science.gov (United States)

    Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

    2017-09-01

    Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laboratory and onorbit flight diffusers. A new measurement setup for BRDF measurements from 900 nm to 2500 nm located at NASA Goddard Space Flight Center (GSFC) is described. The GSFC setup employs an extended indium gallium arsenide detector, bandpass filters, and a supercontinuum light source. Comparisons of the GSFC BRDF measurements in the shortwave infrared (SWIR) with those made by the National Institute of Standards and Technology (NIST) Spectral Tri-function Automated Reference Reflectometer (STARR) are presented. The Spectralon sample used in this study was 2 inch diameter, 99% white pressed and sintered Polytetrafluoroethylene (PTFE) target. The NASA/NIST BRDF comparison measurements were made at an incident angle of 0° and viewing angle of 45° . Additional BRDF data not compared to NIST were measured at additional incident and viewing angle geometries and are not presented here. The total combined uncertainty for the measurement of BRDF in the SWIR range made by the GSFC scatterometer is less than 1% (k = 1). This study is in support of the calibration of the Radiation Budget Instrument (RBI) and Visible Infrared Imaging Radiometer Suit (VIIRS) instruments of the Joint Polar Satellite System (JPSS) and other current and future NASA remote sensing missions operating across the reflected solar wavelength region.

  15. Net Surface Shortwave Radiation from GOES Imagery—Product Evaluation Using Ground-Based Measurements from SURFRAD

    Directory of Open Access Journals (Sweden)

    Anand K. Inamdar

    2015-08-01

    Full Text Available The Earth’s surface net radiation controls the energy and water exchanges between the Earth’s surface and the atmosphere, and can be derived from satellite observations. The ability to monitor the net surface radiation over large areas at high spatial and temporal resolution is essential for many applications, such as weather forecasting, short-term climate prediction or water resources management. The objective of this paper is to derive the net surface radiation in the shortwave domain at high temporal (half-hourly and spatial resolution (~1 km using visible imagery from Geostationary Operational Environmental Satellite (GOES. The retrieval algorithm represents an adaptation to GOES data of a standard algorithm initially developed for the NASA-operated Clouds and Earth’s Radiant Energy System (CERES scanner. The methodology relies on: (1 the estimation of top of atmosphere shortwave radiation from GOES spectral measurements; and (2 the calculation of net surface shortwave (SW radiation accounting for atmospheric effects. Comparison of GOES-retrieved net surface shortwave radiation with ground-measurements at the National Oceanic and Atmospheric Administration’s (NOAA Surface Radiation (SURFRAD stations yields very good agreement with average bias lower than 5 W·m−2 and root mean square difference around 70 W·m−2. The algorithm performance is usually higher over areas characterized by low spatial variability in term of land cover type and surface biophysical properties. The technique does not involve retrieval and assessment of cloud properties and can be easily adapted to other meteorological satellites around the globe.

  16. Satellite observed impacts of wildfires on regional atmosphere composition and shortwave radiative forcing: multiple cases study

    Science.gov (United States)

    Fu, Y.; Li, R.; Huang, J.; Bergeron, Y.; Fu, Y.

    2017-12-01

    Emissions of aerosols and trace gases from wildfires and the direct shortwave radiative forcing were studied using multi-satellite/sensor observations from Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS), Aqua Atmospheric Infrared Sounder (AIRS), Aura Ozone Monitoring Instrument (OMI), and Aqua Cloud's and the Earth's Radiant Energy System (CERES). The selected cases occurred in Northeast of China (NEC), Siberia of Russia, California of America have dominant fuel types of cropland, mixed forest and needleleaf forest, respectively. The Fire radiative power (FRP) based emission coefficients (Ce) of aerosol, NOx (NO2+NO), formaldehyde (HCHO), and carbon monoxide (CO) showed significant differences from case to case. 1) the FRP of the cropland case in NEC is strongest, however, the Ce of aerosol is the lowest (20.51 ± 2.55 g MJ-1). The highest Ce of aerosol is 71.34 ± 13.24 g MJ-1 in the needleleaf fire case in California. 2) For NOx, the highest Ce existed in the cropland case in NEC (2.76 ± 0.25 g MJ-1), which is more than three times of those in the forest fires in Siberia and California. 3) The Ce of CO is 70.21±10.97 and 88.38±46.16 g MJ-1 in the forest fires in Western Siberia and California, which are about four times of that in cropland fire. 4) The variation of Ce of HCHO are relatively small among cases. Strong spatial correlations are found among aerosol optical depth (AOD), NOx, HCHO, and CO. The ratios of NOx to AOD, HCHO, and CO in the cropland case in NEC show much higher values than those in other cases. Although huge differences of emissions and composition ratios exist among cases, the direct shortwave (SW) radiative forcing efficiency (SWARFE) of smoke at the top of the atmosphere (TOA) are in good agreement, with the shortwave radiative forcing efficiencies values of 20.09 to 22.93 per unit AOD. Results in this study reveal noteworthy variations of the FRP-based emissions coefficient and relative chemical composition in the smoke

  17. Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

    International Nuclear Information System (INIS)

    De Santis, S.; Byrd, J.M.; Billing, M.; Palmer, M.; Sikora, J.; Carlson, B.

    2010-01-01

    A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated (S. De Santis, J.M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M.T.F. Pivi, and K.G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008).). We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

  18. Security Architecture of Cloud Computing

    OpenAIRE

    V.KRISHNA REDDY; Dr. L.S.S.REDDY

    2011-01-01

    The Cloud Computing offers service over internet with dynamically scalable resources. Cloud Computing services provides benefits to the users in terms of cost and ease of use. Cloud Computing services need to address the security during the transmission of sensitive data and critical applications to shared and public cloud environments. The cloud environments are scaling large for data processing and storage needs. Cloud computing environment have various advantages as well as disadvantages o...

  19. Reassessing the effect of cloud type on Earth's energy balance

    Science.gov (United States)

    Hang, A.; L'Ecuyer, T.

    2017-12-01

    Cloud feedbacks depend critically on the characteristics of the clouds that change, their location and their environment. As a result, accurately predicting the impact of clouds on future climate requires a better understanding of individual cloud types and their spatial and temporal variability. This work revisits the problem of documenting the effects of distinct cloud regimes on Earth's radiation budget distinguishing cloud types according to their signatures in spaceborne active observations. Using CloudSat's multi-sensor radiative fluxes product that leverages high-resolution vertical cloud information from CloudSat, CALIPSO, and MODIS observations to provide the most accurate estimates of vertically-resolved radiative fluxes available to date, we estimate the global annual mean net cloud radiative effect at the top of the atmosphere to be -17.1 W m-2 (-44.2 W m-2 in the shortwave and 27.1 W m-2 in the longwave), slightly weaker than previous estimates from passive sensor observations. Multi-layered cloud systems, that are often misclassified using passive techniques but are ubiquitous in both hemispheres, contribute about -6.2 W m-2 of the net cooling effect, particularly at ITCZ and higher latitudes. Another unique aspect of this work is the ability of CloudSat and CALIPSO to detect cloud boundary information providing an improved capability to accurately discern the impact of cloud-type variations on surface radiation balance, a critical factor in modulating the disposition of excess energy in the climate system. The global annual net cloud radiative effect at the surface is estimated to be -24.8 W m-2 (-51.1 W m-2 in the shortwave and 26.3 W m-2 in the longwave), dominated by shortwave heating in multi-layered and stratocumulus clouds. Corresponding estimates of the effects of clouds on atmospheric heating suggest that clouds redistribute heat from poles to equator enhancing the general circulation.

  20. Updated thermal model using simplified short-wave radiosity calculations

    International Nuclear Information System (INIS)

    Smith, J.A.; Goltz, S.M.

    1994-01-01

    An extension to a forest canopy thermal radiance model is described that computes the short-wave energy flux absorbed within the canopy by solving simplified radiosity equations describing flux transfers between canopy ensemble classes partitioned by vegetation layer and leaf slope. Integrated short-wave reflectance and transmittance-factors obtained from measured leaf optical properties were found to be nearly equal for the canopy studied. Short-wave view factor matrices were approximated by combining the average leaf scattering coefficient with the long-wave view factor matrices already incorporated in the model. Both the updated and original models were evaluated for a dense spruce fir forest study site in Central Maine. Canopy short-wave absorption coefficients estimated from detailed Monte Carlo ray tracing calculations were 0.60, 0.04, and 0.03 for the top, middle, and lower canopy layers corresponding to leaf area indices of 4.0, 1.05, and 0.25. The simplified radiosity technique yielded analogous absorption values of 0.55, 0.03, and 0.01. The resulting root mean square error in modeled versus measured canopy temperatures for all layers was less than 1°C with either technique. Maximum error in predicted temperature using the simplified radiosity technique was approximately 2°C during peak solar heating. (author)

  1. Updated thermal model using simplified short-wave radiosity calculations

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J. A.; Goltz, S. M.

    1994-02-15

    An extension to a forest canopy thermal radiance model is described that computes the short-wave energy flux absorbed within the canopy by solving simplified radiosity equations describing flux transfers between canopy ensemble classes partitioned by vegetation layer and leaf slope. Integrated short-wave reflectance and transmittance-factors obtained from measured leaf optical properties were found to be nearly equal for the canopy studied. Short-wave view factor matrices were approximated by combining the average leaf scattering coefficient with the long-wave view factor matrices already incorporated in the model. Both the updated and original models were evaluated for a dense spruce fir forest study site in Central Maine. Canopy short-wave absorption coefficients estimated from detailed Monte Carlo ray tracing calculations were 0.60, 0.04, and 0.03 for the top, middle, and lower canopy layers corresponding to leaf area indices of 4.0, 1.05, and 0.25. The simplified radiosity technique yielded analogous absorption values of 0.55, 0.03, and 0.01. The resulting root mean square error in modeled versus measured canopy temperatures for all layers was less than 1°C with either technique. Maximum error in predicted temperature using the simplified radiosity technique was approximately 2°C during peak solar heating. (author)

  2. Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

    Directory of Open Access Journals (Sweden)

    S. De Santis

    2010-07-01

    Full Text Available A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated [S. De Santis, J. M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M. T. F. Pivi, and K. G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008.PRLTAO0031-900710.1103/PhysRevLett.100.094801]. We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

  3. JUPITER AS AN EXOPLANET: UV TO NIR TRANSMISSION SPECTRUM REVEALS HAZES, A Na LAYER, AND POSSIBLY STRATOSPHERIC H{sub 2}O-ICE CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Montañés-Rodríguez, Pilar; González-Merino, B.; Pallé, E. [Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, E-38200 La Laguna (Spain); López-Puertas, Manuel [Departamento de Astrofísica, Universidad de La Laguna, Av., Astrofísico Francisco Sánchez, s/n, E-38206 La Laguna (Spain); García-Melendo, E., E-mail: pmr@iac.es [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, E-18080 Granada (Spain)

    2015-03-01

    Currently, the analysis of transmission spectra is the most successful technique to probe the chemical composition of exoplanet atmospheres. However, the accuracy of these measurements is constrained by observational limitations and the diversity of possible atmospheric compositions. Here, we show the UV–VIS–IR transmission spectrum of Jupiter as if it were a transiting exoplanet, obtained by observing one of its satellites, Ganymede, while passing through Jupiter’s shadow, i.e., during a solar eclipse from Ganymede. The spectrum shows strong extinction due to the presence of clouds (aerosols) and haze in the atmosphere and strong absorption features from CH{sub 4}. More interestingly, the comparison with radiative transfer models reveals a spectral signature, which we attribute here to a Jupiter stratospheric layer of crystalline H{sub 2}O ice. The atomic transitions of Na are also present. These results are relevant for the modeling and interpretation of giant transiting exoplanets. They also open a new technique to explore the atmospheric composition of the upper layers of Jupiter’s atmosphere.

  4. Multiyear Statistics of 2-D Shortwave Radiative Effects at Three ARM Sites

    Science.gov (United States)

    Varnai, Tamas

    2010-01-01

    This study examines the importance of horizontal photon transport effects, which are not considered in the 1-D calculations of solar radiative heating used by most atmospheric dynamical models. In particular, the paper analyzes the difference between 2-D and 1-D radiative calculations for 2-D vertical cross-sections of clouds that were observed at three sites over 2- to 3-year periods. The results show that 2-D effects increase multiyear 24-hour average total solar absorption by about 4.1 W/sq m, 1.2 W/sq m, and 0.3 W/sq m at a tropical, mid-latitude, and arctic site, respectively. However, 2-D effects are often much larger than these average values, especially for high sun and for convective clouds. The results also reveal a somewhat unexpected behavior, that horizontal photon transport often enhances solar heating even for oblique sun. These findings underscore the need for fast radiation calculation methods that can allow atmospheric dynamical simulations to consider the inherently multidimensional nature of shortwave radiative processes.

  5. Shortwave forcing and feedbacks in Last Glacial Maximum and Mid-Holocene PMIP3 simulations.

    Science.gov (United States)

    Braconnot, Pascale; Kageyama, Masa

    2015-11-13

    Simulations of the climates of the Last Glacial Maximum (LGM), 21 000 years ago, and of the Mid-Holocene (MH), 6000 years ago, allow an analysis of climate feedbacks in climate states that are radically different from today. The analyses of cloud and surface albedo feedbacks show that the shortwave cloud feedback is a major driver of differences between model results. Similar behaviours appear when comparing the LGM and MH simulated changes, highlighting the fingerprint of model physics. Even though the different feedbacks show similarities between the different climate periods, the fact that their relative strength differs from one climate to the other prevents a direct comparison of past and future climate sensitivity. The land-surface feedback also shows large disparities among models even though they all produce positive sea-ice and snow feedbacks. Models have very different sensitivities when considering the vegetation feedback. This feedback has a regional pattern that differs significantly between models and depends on their level of complexity and model biases. Analyses of the MH climate in two versions of the IPSL model provide further indication on the possibilities to assess the role of model biases and model physics on simulated climate changes using past climates for which observations can be used to assess the model results. © 2015 The Author(s).

  6. Estimating net short-wave radiation with the Bellani pyranometer

    International Nuclear Information System (INIS)

    Bernier, Y.; Plamondon, A.P.

    1983-01-01

    Two methods were developed by which daily net short-wave radiation (K∗) can be evaluated from Bellani pyranometer readings. The first method involves a simple regression equation. The second method uses a physical approach taking into account the effect of the Bellani's geometry on its response to direct and diffuse radiation throughout the day. Both methods, when tested on experimental data, tended to underestimate the measured K∗, the regression approach exhibiting a higher variance of the error [fr

  7. CLARREO shortwave observing system simulation experiments of the twenty-first century: Simulator design and implementation

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, D.R.; Algieri, C.A.; Ong, J.R.; Collins, W.D.

    2011-04-01

    Projected changes in the Earth system will likely be manifested in changes in reflected solar radiation. This paper introduces an operational Observational System Simulation Experiment (OSSE) to calculate the signals of future climate forcings and feedbacks in top-of-atmosphere reflectance spectra. The OSSE combines simulations from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report for the NCAR Community Climate System Model (CCSM) with the MODTRAN radiative transfer code to calculate reflectance spectra for simulations of current and future climatic conditions over the 21st century. The OSSE produces narrowband reflectances and broadband fluxes, the latter of which have been extensively validated against archived CCSM results. The shortwave reflectance spectra contain atmospheric features including signals from water vapor, liquid and ice clouds, and aerosols. The spectra are also strongly influenced by the surface bidirectional reflectance properties of predicted snow and sea ice and the climatological seasonal cycles of vegetation. By comparing and contrasting simulated reflectance spectra based on emissions scenarios with increasing projected and fixed present-day greenhouse gas and aerosol concentrations, we find that prescribed forcings from increases in anthropogenic sulfate and carbonaceous aerosols are detectable and are spatially confined to lower latitudes. Also, changes in the intertropical convergence zone and poleward shifts in the subsidence zones and the storm tracks are all detectable along with large changes in snow cover and sea ice fraction. These findings suggest that the proposed NASA Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission to measure shortwave reflectance spectra may help elucidate climate forcings, responses, and feedbacks.

  8. Cloud Impacts on Pavement Temperature in Energy Balance Models

    Science.gov (United States)

    Walker, C. L.

    2013-12-01

    Forecast systems provide decision support for end-users ranging from the solar energy industry to municipalities concerned with road safety. Pavement temperature is an important variable when considering vehicle response to various weather conditions. A complex, yet direct relationship exists between tire and pavement temperatures. Literature has shown that as tire temperature increases, friction decreases which affects vehicle performance. Many forecast systems suffer from inaccurate radiation forecasts resulting in part from the inability to model different types of clouds and their influence on radiation. This research focused on forecast improvement by determining how cloud type impacts the amount of shortwave radiation reaching the surface and subsequent pavement temperatures. The study region was the Great Plains where surface solar radiation data were obtained from the High Plains Regional Climate Center's Automated Weather Data Network stations. Road pavement temperature data were obtained from the Meteorological Assimilation Data Ingest System. Cloud properties and radiative transfer quantities were obtained from the Clouds and Earth's Radiant Energy System mission via Aqua and Terra Moderate Resolution Imaging Spectroradiometer satellite products. An additional cloud data set was incorporated from the Naval Research Laboratory Cloud Classification algorithm. Statistical analyses using a modified nearest neighbor approach were first performed relating shortwave radiation variability with road pavement temperature fluctuations. Then statistical associations were determined between the shortwave radiation and cloud property data sets. Preliminary results suggest that substantial pavement forecasting improvement is possible with the inclusion of cloud-specific information. Future model sensitivity testing seeks to quantify the magnitude of forecast improvement.

  9. FORWARD AND INVERSE MODELING OF THE EMISSION AND TRANSMISSION SPECTRUM OF GJ 436B: INVESTIGATING METAL ENRICHMENT, TIDAL HEATING, AND CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Morley, Caroline V. [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Knutson, Heather [Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Line, Michael [School of Earth and Space Exploration, Arizona State University, 781 South Terrace Road, Tempe, AZ 85281 (United States); Fortney, Jonathan J.; Teal, Dillon [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Thorngren, Daniel [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Marley, Mark S.; Lupu, Roxana, E-mail: caroline.morley@cfa.harvard.edu [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2017-02-01

    The Neptune-mass GJ 436b is one of the most studied transiting exoplanets with repeated measurements of its thermal emission and transmission spectra. We build on previous studies to answer outstanding questions about this planet, including its potentially high metallicity and tidal heating of its interior. We present new observations of GJ 436b’s thermal emission at 3.6 and 4.5 μ m, which reduce uncertainties in estimates of GJ 436b’s flux at those wavelengths and demonstrate consistency between Spitzer observations spanning more than 7 yr. We analyze the Spitzer thermal emission photometry and Hubble WFC3 transmission spectrum. We use a dual-pronged modeling approach of both self-consistent and retrieval models. We vary the metallicity, intrinsic luminosity from tidal heating, disequilibrium chemistry, and heat redistribution. We also study clouds and photochemical hazes, but do not find strong evidence for either. The self-consistent and retrieval models combine to suggest that GJ 436b has a high atmospheric metallicity, with best fits at or above several hundred times solar metallicity, tidal heating warming its interior with best-fit intrinsic effective temperatures around 300–350 K, and disequilibrium chemistry. High metal enrichments (>600× solar) occur from the accretion of rocky, rather than icy, material. Assuming the interior temperature T {sub int} ∼ 300–350 K, we find a dissipation factor Q ′ ∼ 2 × 10{sup 5}–10{sup 6}, larger than Neptune’s Q ′, implying a long tidal circularization timescale for the orbit. We suggest that Neptune-mass planets may be more diverse than imagined, with metal enhancements spanning several orders of magnitude, to perhaps over 1000× solar metallicity. High-fidelity observations with instruments like the James Webb Space Telescope will be critical for characterizing this diversity.

  10. ENSO surface shortwave radiation forcing over the tropical Pacific

    Directory of Open Access Journals (Sweden)

    K. G. Pavlakis

    2008-09-01

    Full Text Available We have studied the spatial and temporal variation of the downward shortwave radiation (DSR at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40° S–40° N, 90° E–75° W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters, and aerosol parameters from GADS (acronyms explained in main text. A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A time-series, in the region 7° S–5° N 160° E–160° W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm−2 during El Niño episodes to +40 Wm−2 during La Niña events. Within the Niño-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10° S–5° N, 120–140° E, where the mean DSR anomaly values range from +20 Wm−2 to −20 Wm−2 during El Niño and La Niña episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7–15° N 150–170° E, precedes the Niño-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Niño or La Niña conditions prevail.

  11. The influence of extratropical cloud phase and amount feedbacks on climate sensitivity

    Science.gov (United States)

    Frey, William R.; Kay, Jennifer E.

    2018-04-01

    Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Variability in modeled cloud feedback tied to differences in the climatological spatial pattern of clouds

    Science.gov (United States)

    Siler, Nicholas; Po-Chedley, Stephen; Bretherton, Christopher S.

    2018-02-01

    Despite the increasing sophistication of climate models, the amount of surface warming expected from a doubling of atmospheric CO_2 (equilibrium climate sensitivity) remains stubbornly uncertain, in part because of differences in how models simulate the change in global albedo due to clouds (the shortwave cloud feedback). Here, model differences in the shortwave cloud feedback are found to be closely related to the spatial pattern of the cloud contribution to albedo (α) in simulations of the current climate: high-feedback models exhibit lower (higher) α in regions of warm (cool) sea-surface temperatures, and therefore predict a larger reduction in global-mean α as temperatures rise and warm regions expand. The spatial pattern of α is found to be strongly predictive (r=0.84) of a model's global cloud feedback, with satellite observations indicating a most-likely value of 0.58± 0.31 Wm^{-2} K^{-1} (90% confidence). This estimate is higher than the model-average cloud feedback of 0.43 Wm^{-2} K^{-1}, with half the range of uncertainty. The observational constraint on climate sensitivity is weaker but still significant, suggesting a likely value of 3.68 ± 1.30 K (90% confidence), which also favors the upper range of model estimates. These results suggest that uncertainty in model estimates of the global cloud feedback may be substantially reduced by ensuring a realistic distribution of clouds between regions of warm and cool SSTs in simulations of the current climate.

  14. Shortwave Array Spectroradiometer–Zenith (SASZe) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Connor J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-04-01

    The Shortwave Array Spectroradiometer – Zenith (SASZe) provides measurements of zenith spectral shortwave radiance at 1Hz over a continuous spectral range from approximately 300 nm to 1700 nm. The SASZe design connects an optical collector located outdoors to a pair of spectrometers and data collections system located indoors within a climate-controlled building via an umbilical cable of fiber optic and electrical cables. The light collector incorporates a collimator yielding a 1-degree Full Width at Half Maximum (FWHM) field of view. The data-acquisition electronics and spectrometers include an in-line fiber optic shutter and two Avantes fiber-coupled grating spectroradiometers within a temperature-controlled container. The Avantes Avaspec ULS 2048 charge-coupled device (CCD) spectrometer covers the wavelength range from about 300-1100 nm with a pixel spacing of less than 0.6 nm and a spectral resolution of about 2.4 nm FWHM. The Avantes Avaspec NIR256-1.7 spectrometer covers the wavelength range from about 950 nm to 1700 nm with a pixel spacing of less than 4 nm and a spectral resolution of about 6 nm FWHM.

  15. Sensitivity of surface radiation budget to clouds over the Asian ...

    Indian Academy of Sciences (India)

    National Climate Centre, India Meteorological Department, Pune 400 005. ... down on the earth surface–atmosphere system also as an imbalance between surface netcloud ... the clouds produce more cooling effect in short-wave band than the warming effect in long-wave .... In the present study, we use the analysis method.

  16. Clouds enhance Greenland ice sheet mass loss

    Science.gov (United States)

    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.

  17. Seasonal and interannual variations of top-of-atmosphere irradiance and cloud cover over polar regions derived from the CERES data set

    Science.gov (United States)

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

    2006-10-01

    The daytime cloud fraction derived by the Clouds and the Earth's Radiant Energy System (CERES) cloud algorithm using Moderate Resolution Imaging Spectroradiometer (MODIS) radiances over the Arctic from March 2000 through February 2004 increases at a rate of 0.047 per decade. The trend is significant at an 80% confidence level. The corresponding top-of-atmosphere (TOA) shortwave irradiances derived from CERES radiance measurements show less significant trend during this period. These results suggest that the influence of reduced Arctic sea ice cover on TOA reflected shortwave radiation is reduced by the presence of clouds and possibly compensated by the increase in cloud cover. The cloud fraction and TOA reflected shortwave irradiance over the Antarctic show no significant trend during the same period.

  18. Shortwave and longwave radiative contributions to global warming under increasing CO2

    Science.gov (United States)

    Donohoe, Aaron; Armour, Kyle C.; Pendergrass, Angeline G.; Battisti, David S.

    2014-01-01

    In response to increasing concentrations of atmospheric CO2, high-end general circulation models (GCMs) simulate an accumulation of energy at the top of the atmosphere not through a reduction in outgoing longwave radiation (OLR)—as one might expect from greenhouse gas forcing—but through an enhancement of net absorbed solar radiation (ASR). A simple linear radiative feedback framework is used to explain this counterintuitive behavior. It is found that the timescale over which OLR returns to its initial value after a CO2 perturbation depends sensitively on the magnitude of shortwave (SW) feedbacks. If SW feedbacks are sufficiently positive, OLR recovers within merely several decades, and any subsequent global energy accumulation is because of enhanced ASR only. In the GCM mean, this OLR recovery timescale is only 20 y because of robust SW water vapor and surface albedo feedbacks. However, a large spread in the net SW feedback across models (because of clouds) produces a range of OLR responses; in those few models with a weak SW feedback, OLR takes centuries to recover, and energy accumulation is dominated by reduced OLR. Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR. PMID:25385628

  19. Shortwave and longwave radiative contributions to global warming under increasing CO2.

    Science.gov (United States)

    Donohoe, Aaron; Armour, Kyle C; Pendergrass, Angeline G; Battisti, David S

    2014-11-25

    In response to increasing concentrations of atmospheric CO2, high-end general circulation models (GCMs) simulate an accumulation of energy at the top of the atmosphere not through a reduction in outgoing longwave radiation (OLR)—as one might expect from greenhouse gas forcing—but through an enhancement of net absorbed solar radiation (ASR). A simple linear radiative feedback framework is used to explain this counterintuitive behavior. It is found that the timescale over which OLR returns to its initial value after a CO2 perturbation depends sensitively on the magnitude of shortwave (SW) feedbacks. If SW feedbacks are sufficiently positive, OLR recovers within merely several decades, and any subsequent global energy accumulation is because of enhanced ASR only. In the GCM mean, this OLR recovery timescale is only 20 y because of robust SW water vapor and surface albedo feedbacks. However, a large spread in the net SW feedback across models (because of clouds) produces a range of OLR responses; in those few models with a weak SW feedback, OLR takes centuries to recover, and energy accumulation is dominated by reduced OLR. Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR.

  20. Evaluation of cloud fraction and its radiative effect simulated by IPCC AR4 global models against ARM surface observations

    Directory of Open Access Journals (Sweden)

    Y. Qian

    2012-02-01

    Full Text Available Cloud Fraction (CF is the dominant modulator of radiative fluxes. In this study, we evaluate CF simulated in the IPCC AR4 GCMs against ARM long-term ground-based measurements, with a focus on the vertical structure, total amount of cloud and its effect on cloud shortwave transmissivity. Comparisons are performed for three climate regimes as represented by the Department of Energy Atmospheric Radiation Measurement (ARM sites: Southern Great Plains (SGP, Manus, Papua New Guinea and North Slope of Alaska (NSA. Our intercomparisons of three independent measurements of CF or sky-cover reveal that the relative differences are usually less than 10% (5% for multi-year monthly (annual mean values, while daily differences are quite significant. The total sky imager (TSI produces smaller total cloud fraction (TCF compared to a radar/lidar dataset for highly cloudy days (CF > 0.8, but produces a larger TCF value than the radar/lidar for less cloudy conditions (CF < 0.3. The compensating errors in lower and higher CF days result in small biases of TCF between the vertically pointing radar/lidar dataset and the hemispheric TSI measurements as multi-year data is averaged. The unique radar/lidar CF measurements enable us to evaluate seasonal variation of cloud vertical structures in the GCMs.

    Both inter-model deviation and model bias against observation are investigated in this study. Another unique aspect of this study is that we use simultaneous measurements of CF and surface radiative fluxes to diagnose potential discrepancies among the GCMs in representing other cloud optical properties than TCF. The results show that the model-observation and inter-model deviations have similar magnitudes for the TCF and the normalized cloud effect, and these deviations are larger than those in surface downward solar radiation and cloud transmissivity. This implies that other dimensions of cloud in addition to cloud amount, such as cloud optical thickness and

  1. Case studies of radiation in the cloud-capped atmospheric boundary layer

    International Nuclear Information System (INIS)

    Schmetz, J.; Raschke, E.

    1983-01-01

    This review presents observations of marine stratocumulus obtained by the three research aircraft that participated in the Joint Air-Sea Interaction Project (JASIN). Detailed measurements were made of the thermodynamic, cloud physics and radiation fields for a uniform cloud sheet on 8 August 1978. These show a well mixed boundary layer with cloud liquid water contents close to their adiabatic values. The longwave and shortwave radiative components of the cloud layer energy budget were measured and good agreement was obtained between the observations and several radiation schemes. In particular, the measured cloud shortwave absorption was close to the theoretical values. Observations of shortwave fluxes made from the Falcon aircraft beneath broken stratocumulus are also shown and compared with calculations made by using a Monte Carlo model. It is concluded that the radiative cloud-cloud interactions do not play a dominant role in the bulk radiative properties of cloud fields. These are mainly determined by cloud amount and the vertical and horizontal optical depths of the clouds within the field. (author)

  2. The Validation of the GEWEX SRB Surface Shortwave Flux Data Products Using BSRN Measurements: A Systematic Quality Control, Production and Application Approach

    Science.gov (United States)

    Zhang, Taiping; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Cox, Stephen J.; Mikovitz, J. Colleen; Hinkelman, Laura M.

    2013-01-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project has produced a 24.5-year continuous record of global shortwave and longwave radiation fluxes at TOA and the Earth's surface from satellite measurements. The time span of the data is from July 1983 to December 2007, and the spatial resolution is 11 latitude11 longitude. The inputs of the latest version (Release 3.0) include the GEOS Version 4.0.3 meteorological information and cloud properties derived from ISCCP DX data. The SRB products are available on 3-hourly, 3-hourly-monthly, daily and monthly time scales. To assess the quality of the product, we extensively validated the SRB data against 5969 site-months of groundbased measurements from 52 Baseline Surface Radiation Network (BSRN) stations. This paper describes first the characteristics of the BSRN data and the GEWEX SRB data, the methodology for quality control and processing of the shortwave BSRN data, and then the systematic SRB-BSRN comparisons. It is found that, except for occasional extreme outliers as seen in scatter plots, the satellite-based surface radiation data generally agree very well with BSRN measurements. Specifically, the bias/RMS for the daily and monthly mean shortwave fluxes are, respectively, -3.6/35.5 and -5.2/23.3W1 m2 under all-sky conditions.

  3. Profile vertical of temperature in an atmosphere semi-gray with a layer of clouds

    International Nuclear Information System (INIS)

    Pelkowski, Joaquin; Anduckia Avila, Juan Carlos

    2000-01-01

    We extend earlier models of planetary layers in radioactive equilibrium by including scattering within a homogeneous cloud layer in a single direction. The atmospheric layers above and below the cloud layer are taken to be in radioactive equilibrium, whose temperature profiles may be calculated. Though the resulting profile, being discontinuous, is unrealistic, the model adds to the effects of the earlier models a cloud albedo, resulting from the scattering of short-wave radiation

  4. Decadal changes in shortwave irradiance at the surface in the period from 1960 to 2000 estimated from Global Energy Balance Archive Data

    Science.gov (United States)

    Gilgen, H.; Roesch, A.; Wild, M.; Ohmura, A.

    2009-05-01

    Decadal changes in shortwave irradiance at the Earth's surface are estimated for the period from approximately 1960 through to 2000 from pyranometer records stored in the Global Energy Balance Archive. For this observational period, estimates could be calculated for a total of 140 cells of the International Satellite Cloud Climatology Project grid (an equal area 2.5° × 2.5° grid at the equator) using regression models allowing for station effects. In large regions worldwide, shortwave irradiance decreases in the first half of the observational period, recovers from the decrease in the 1980s, and thereafter increases, in line with previous reports. Years of trend reversals are determined for the grid cells which are best described with a second-order polynomial model. This reversal of the trend is observed in the majority of the grid cells in the interior of Europe and in Japan. In China, shortwave irradiance recovers during the 1990s in the majority of the grid cells in the southeast and northeast from the decrease observed in the period from 1960 through to 1990. A reversal of the trend in the 1980s or early 1990s is also observed for two grid cells in North America, and for the grid cells containing the Kuala Lumpur (Malaysia), Singapore, Casablanca (Morocco), Valparaiso (Chile) sites, and, noticeably, the remote South Pole and American Samoa sites. Negative trends persist, i.e., shortwave radiation decreases, for the observational period 1960 through to 2000 at the European coasts, in central and northwest China, and for three grid cells in India and two in Africa.

  5. Space power transmission

    Energy Technology Data Exchange (ETDEWEB)

    Kuribayashi, Shizuma [Mitsubishi Heavy Industries, Ltd., Tokyo, (Japan)

    1989-10-05

    There being a conception to utilize solar energy by use of a space power station (SPS), a method to bring that universal grace to mankind is wireless energy transmission. The wireless energy transmission is regarded to be microwave transmission or laser beam transmission. The microwave transmission is to transmit 2.45GHz band microwave from the SPS to a receiving station on the ground to meet power demand on earth. The microwave, as small in attenuation in atmosphere and resistant against rain and cloud, is made candidate and, however, problematic in influence on organism, necessary large area of receiving antenna and many other points to be studied. While the laser transmission, as more convergent of beam than the microwave transmission, is advantageous with enabling the receiving area to be small and, however, disadvantageous with being not resistant against dust, rain and cloud, if used for the energy transmission between the space and earth. 2 refs., 2 figs.

  6. Global distributions of cloud properties for CERES

    Science.gov (United States)

    Sun-Mack, S.; Minnis, P.; Heck, P.; Young, D.

    2003-04-01

    The microphysical and macrophysical properties of clouds play a crucial role in the earth's radiation budget. Simultaneous measurement of the radiation and cloud fields on a global basis has long been recognized as a key component in understanding and modeling the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. With the implementation of the NASA Clouds and Earth's Radiant Energy System (CERES) in 1998, this need is being met. Broadband shortwave and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth from the TRMM Visible Infrared Scanner and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. The combined cloud-radiation product has already been used for developing new, highly accurate anisotropic directional models for converting broadband radiances to flux. They also provide a consistent measure of cloud properties at different times of day over the globe since January 1998. These data will be valuable for determining the indirect effects of aerosols and for linking cloud water to cloud radiation. This paper provides an overview of the CERES cloud products from the three satellites including the retrieval methodology, validation, and global distributions. Availability and access to the datasets will also be discussed.

  7. Long-term global distribution of earth's shortwave radiation budget at the top of atmosphere

    Directory of Open Access Journals (Sweden)

    N. Hatzianastassiou

    2004-01-01

    Full Text Available The mean monthly shortwave (SW radiation budget at the top of atmosphere (TOA was computed on 2.5° longitude-latitude resolution for the 14-year period from 1984 to 1997, using a radiative transfer model with long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2 supplemented by data from the National Centers for Environmental Prediction – National Center for Atmospheric Research (NCEP-NCAR Global Reanalysis project, and other global data bases such as TIROS Operational Vertical Sounder (TOVS and Global Aerosol Data Set (GADS. The model radiative fluxes at TOA were validated against Earth Radiation Budget Experiment (ERBE S4 scanner satellite data (1985–1989. The model is able to predict the seasonal and geographical variation of SW TOA fluxes. On a mean annual and global basis, the model is in very good agreement with ERBE, overestimating the outgoing SW radiation at TOA (OSR by 0.93 Wm-2 (or by 0.92%, within the ERBE uncertainties. At pixel level, the OSR differences between model and ERBE are mostly within ±10 Wm-2, with ±5 Wm-2 over extended regions, while there exist some geographic areas with differences of up to 40 Wm-2, associated with uncertainties in cloud properties and surface albedo. The 14-year average model results give a planetary albedo equal to 29.6% and a TOA OSR flux of 101.2 Wm-2. A significant linearly decreasing trend in OSR and planetary albedo was found, equal to 2.3 Wm-2 and 0.6% (in absolute values, respectively, over the 14-year period (from January 1984 to December 1997, indicating an increasing solar planetary warming. This planetary SW radiative heating occurs in the tropical and sub-tropical areas (20° S–20° N, with clouds being the most likely cause. The computed global mean OSR anomaly ranges within ±4 Wm-2, with signals from El Niño and La Niña events or Pinatubo eruption, whereas significant negative OSR anomalies, starting from year 1992, are also

  8. A fast radiative transfer model for visible through shortwave infrared spectral reflectances in clear and cloudy atmospheres

    International Nuclear Information System (INIS)

    Wang, Chenxi; Yang, Ping; Nasiri, Shaima L.; Platnick, Steven; Baum, Bryan A.; Heidinger, Andrew K.; Liu, Xu

    2013-01-01

    A computationally efficient radiative transfer model (RTM) for calculating visible (VIS) through shortwave infrared (SWIR) reflectances is developed for use in satellite and airborne cloud property retrievals. The full radiative transfer equation (RTE) for combinations of cloud, aerosol, and molecular layers is solved approximately by using six independent RTEs that assume the plane-parallel approximation along with a single-scattering approximation for Rayleigh scattering. Each of the six RTEs can be solved analytically if the bidirectional reflectance/transmittance distribution functions (BRDF/BTDF) of the cloud/aerosol layers are known. The adding/doubling (AD) algorithm is employed to account for overlapped cloud/aerosol layers and non-Lambertian surfaces. Two approaches are used to mitigate the significant computational burden of the AD algorithm. First, the BRDF and BTDF of single cloud/aerosol layers are pre-computed using the discrete ordinates radiative transfer program (DISORT) implemented with 128 streams, and second, the required integral in the AD algorithm is numerically implemented on a twisted icosahedral mesh. A concise surface BRDF simulator associated with the MODIS land surface product (MCD43) is merged into a fast RTM to accurately account for non-isotropic surface reflectance. The resulting fast RTM is evaluated with respect to its computational accuracy and efficiency. The simulation bias between DISORT and the fast RTM is large (e.g., relative error >5%) only when both the solar zenith angle (SZA) and the viewing zenith angle (VZA) are large (i.e., SZA>45° and VZA>70°). For general situations, i.e., cloud/aerosol layers above a non-Lambertian surface, the fast RTM calculation rate is faster than that of the 128-stream DISORT by approximately two orders of magnitude. -- Highlights: ► An efficient radiative transfer model is developed for cloud remote sensing. ► Multi-layered clouds and a non-Lambertian surface can be fully considered.

  9. Cloud forming properties of ambient aerosol in the Netherlands and resultant shortwave radiative forcing of climate

    NARCIS (Netherlands)

    Khlystov, A.

    1998-01-01

    This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second

  10. Layered Atlantic Smoke Interactions with Clouds (LASIC) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Zuidema, P [University of Miami; Chiu, C [University of Reading; Fairall, CW [NOAA - Environmental Technology Laboratory; Ghan, SJ [Pacific Northwest National Laboratory; Kollias, P [Stony Brook University; McFarguhar, GM; Mechem, DB [University of Kansas; Romps, DM [Lawrence Berkeley National Laboratory; Wong, H; Yuter, SE [North Carolina State University; Alvarado, MJ [Atmospheric and Environmental Research, Inc.; DeSzoeke, SP; Feingold, G [NOAA - Earth System Research Laboratory; Haywood, JM; Lewis, ER [Brookhaven National Laboratory; McComiskey, A [National Oceanic and Atmospheric Administration; Redemann, J [NASA - Ames Research Center; Turner, DD [National Oceanic and Atmospheric Administration; Wood, R [University of Washington; Zhu, P [Florida International University

    2015-12-01

    Southern Africa is the world’s largest emitter of biomass-burning (BB) aerosols. Their westward transport over the remote southeast Atlantic Ocean colocates some of the largest atmospheric loadings of absorbing aerosol with the least examined of the Earth’s major subtropical stratocumulus decks. Global aerosol model results highlight that the largest positive top-of-atmosphere forcing in the world occurs in the southeast Atlantic, but this region exhibits large differences in magnitude and sign between reputable models, in part because of high variability in the underlying model cloud distributions. Many uncertainties contribute to the highly variable model radiation fields: the aging of shortwave-absorbing aerosol during transport, how much of the aerosol mixes into the cloudy boundary layer, and how the low clouds adjust to smoke-radiation and smoke-cloud interactions. In addition, the ability of the BB aerosol to absorb shortwave radiation is known to vary seasonally as the fuel type on land changes.

  11. Contributions of Different Cloud Types to Feedbacks and Rapid Adjustments in CMIP5*

    Energy Technology Data Exchange (ETDEWEB)

    Zelinka, Mark D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Klein, Stephen A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Taylor, Karl E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Andrews, Timothy [Met Office Hadley Center, Exeter (United Kingdom); Webb, Mark J. [Met Office Hadley Center, Exeter (United Kingdom); Gregory, Jonathan M. [Univ. of Reading, Exeter (United Kingdom). National Center for Atmospheric Science; Forster, Piers M. [Univ. of Leeds (United Kingdom)

    2013-07-01

    When using five climate model simulations of the response to an abrupt quadrupling of CO2, the authors perform the first simultaneous model intercomparison of cloud feedbacks and rapid radiative adjustments with cloud masking effects removed, partitioned among changes in cloud types and gross cloud properties. After CO2 quadrupling, clouds exhibit a rapid reduction in fractional coverage, cloud-top pressure, and optical depth, with each contributing equally to a 1.1 W m-2 net cloud radiative adjustment, primarily from shortwave radiation. Rapid reductions in midlevel clouds and optically thick clouds are important in reducing planetary albedo in every model. As the planet warms, clouds become fewer, higher, and thicker, and global mean net cloud feedback is positive in all but one model and results primarily from increased trapping of longwave radiation. As was true for earlier models, high cloud changes are the largest contributor to intermodel spread in longwave and shortwave cloud feedbacks, but low cloud changes are the largest contributor to the mean and spread in net cloud feedback. The importance of the negative optical depth feedback relative to the amount feedback at high latitudes is even more marked than in earlier models. Furthermore, the authors show that the negative longwave cloud adjustment inferred in previous studies is primarily caused by a 1.3 W m-2 cloud masking of CO2 forcing. Properly accounting for cloud masking increases net cloud feedback by 0.3 W m-2 K-1, whereas accounting for rapid adjustments reduces by 0.14 W m-2 K-1 the ensemble mean net cloud feedback through a combination of smaller positive cloud amount and altitude feedbacks and larger negative optical depth feedbacks.

  12. Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of unvertainty in deriving cloud radiative flux

    Science.gov (United States)

    Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.

    2017-12-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20 W m-2 after accounting for cloud-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after

  13. The impact of parametrized convection on cloud feedback

    Science.gov (United States)

    Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

    2015-01-01

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

  14. Incoming Shortwave Fluxes at the Surface--A Comparison of GCM Results with Observations.

    Science.gov (United States)

    Garratt, J. R.

    1994-01-01

    Evidence is presented that the exam surface net radiation calculated in general circulation models at continental surfaces is mostly due to excess incoming shortwave fluxes. Based on long-term observations from 22 worldwide inland stations and results from four general circulation models the overestimate in models of 20% (11 W m2) in net radiation on an annual basis compares with 6% (9 W m2) for shortwave fluxes for the same 22 locations, or 9% (18 W m2) for a larger set of 93 stations (71 having shortwave fluxes only). For annual fluxes, these differences appear to be significant.

  15. Cloud occurrences and cloud radiative effects (CREs) from CERES-CALIPSO-CloudSat-MODIS (CCCM) and CloudSat radar-lidar (RL) products

    Science.gov (United States)

    Ham, Seung-Hee; Kato, Seiji; Rose, Fred G.; Winker, David; L'Ecuyer, Tristan; Mace, Gerald G.; Painemal, David; Sun-Mack, Sunny; Chen, Yan; Miller, Walter F.

    2017-08-01

    Two kinds of cloud products obtained from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, and Moderate Resolution Imaging Spectroradiometer (MODIS) are compared and analyzed in this study: Clouds and the Earth's Radiant Energy System (CERES)-CALIPSO-CloudSat-MODIS (CCCM) product and CloudSat radar-lidar products such as GEOPROF-LIDAR and FLXHR-LIDAR. Compared to GEOPROF-LIDAR, low-level (40°). The difference occurs when hydrometeors are detected by CALIPSO lidar but are undetected by CloudSat radar. In the comparison of cloud radiative effects (CREs), global mean differences between CCCM and FLXHR-LIDAR are mostly smaller than 5 W m-2, while noticeable regional differences are found. For example, CCCM shortwave (SW) and longwave (LW) CREs are larger than FXLHR-LIDAR along the west coasts of Africa and America because the GEOPROF-LIDAR algorithm misses shallow marine boundary layer clouds. In addition, FLXHR-LIDAR SW CREs are larger than the CCCM counterpart over tropical oceans away from the west coasts of America. Over midlatitude storm-track regions, CCCM SW and LW CREs are larger than the FLXHR-LIDAR counterpart.

  16. Quantitative Comparison of the Variability in Observed and Simulated Shortwave Reflectance

    Science.gov (United States)

    Roberts, Yolanda, L.; Pilewskie, P.; Kindel, B. C.; Feldman, D. R.; Collins, W. D.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a climate observation system that has been designed to monitor the Earth's climate with unprecedented absolute radiometric accuracy and SI traceability. Climate Observation System Simulation Experiments (OSSEs) have been generated to simulate CLARREO hyperspectral shortwave imager measurements to help define the measurement characteristics needed for CLARREO to achieve its objectives. To evaluate how well the OSSE-simulated reflectance spectra reproduce the Earth s climate variability at the beginning of the 21st century, we compared the variability of the OSSE reflectance spectra to that of the reflectance spectra measured by the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY). Principal component analysis (PCA) is a multivariate decomposition technique used to represent and study the variability of hyperspectral radiation measurements. Using PCA, between 99.7%and 99.9%of the total variance the OSSE and SCIAMACHY data sets can be explained by subspaces defined by six principal components (PCs). To quantify how much information is shared between the simulated and observed data sets, we spectrally decomposed the intersection of the two data set subspaces. The results from four cases in 2004 showed that the two data sets share eight (January and October) and seven (April and July) dimensions, which correspond to about 99.9% of the total SCIAMACHY variance for each month. The spectral nature of these shared spaces, understood by examining the transformed eigenvectors calculated from the subspace intersections, exhibit similar physical characteristics to the original PCs calculated from each data set, such as water vapor absorption, vegetation reflectance, and cloud reflectance.

  17. The cloud-phase feedback in the Super-parameterized Community Earth System Model

    Science.gov (United States)

    Burt, M. A.; Randall, D. A.

    2016-12-01

    Recent comparisons of observations and climate model simulations by I. Tan and colleagues have suggested that the Wegener-Bergeron-Findeisen (WBF) process tends to be too active in climate models, making too much cloud ice, and resulting in an exaggerated negative cloud-phase feedback on climate change. We explore the WBF process and its effect on shortwave cloud forcing in present-day and future climate simulations with the Community Earth System Model, and its super-parameterized counterpart. Results show that SP-CESM has much less cloud ice and a weaker cloud-phase feedback than CESM.

  18. TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 1991-present, Downgoing Shortwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Downgoing Shortwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  19. TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, 1991-present, Net Shortwave Radiation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Net Shortwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

  20. Improvements of top-of-atmosphere and surface irradiance computations with CALIPSO-, CloudSat-, and MODIS-derived cloud and aerosol properties

    Science.gov (United States)

    Kato, Seiji; Rose, Fred G.; Sun-Mack, Sunny; Miller, Walter F.; Chen, Yan; Rutan, David A.; Stephens, Graeme L.; Loeb, Norman G.; Minnis, Patrick; Wielicki, Bruce A.; Winker, David M.; Charlock, Thomas P.; Stackhouse, Paul W., Jr.; Xu, Kuan-Man; Collins, William D.

    2011-10-01

    One year of instantaneous top-of-atmosphere (TOA) and surface shortwave and longwave irradiances are computed using cloud and aerosol properties derived from instruments on the A-Train Constellation: the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, the CloudSat Cloud Profiling Radar (CPR), and the Aqua Moderate Resolution Imaging Spectrometer (MODIS). When modeled irradiances are compared with those computed with cloud properties derived from MODIS radiances by a Clouds and the Earth's Radiant Energy System (CERES) cloud algorithm, the global and annual mean of modeled instantaneous TOA irradiances decreases by 12.5 W m-2 (5.0%) for reflected shortwave and 2.5 W m-2 (1.1%) for longwave irradiances. As a result, the global annual mean of instantaneous TOA irradiances agrees better with CERES-derived irradiances to within 0.5W m-2 (out of 237.8 W m-2) for reflected shortwave and 2.6W m-2 (out of 240.1 W m-2) for longwave irradiances. In addition, the global annual mean of instantaneous surface downward longwave irradiances increases by 3.6 W m-2 (1.0%) when CALIOP- and CPR-derived cloud properties are used. The global annual mean of instantaneous surface downward shortwave irradiances also increases by 8.6 W m-2 (1.6%), indicating that the net surface irradiance increases when CALIOP- and CPR-derived cloud properties are used. Increasing the surface downward longwave irradiance is caused by larger cloud fractions (the global annual mean by 0.11, 0.04 excluding clouds with optical thickness less than 0.3) and lower cloud base heights (the global annual mean by 1.6 km). The increase of the surface downward longwave irradiance in the Arctic exceeds 10 W m-2 (˜4%) in winter because CALIOP and CPR detect more clouds in comparison with the cloud detection by the CERES cloud algorithm during polar night. The global annual mean surface downward longwave irradiance of

  1. The cloud radiative feedback of a midlatitude squall line system and implication for climate study

    International Nuclear Information System (INIS)

    Chin, H.N.S.

    1992-01-01

    The main objectives of this study are (1) to study the impact of longwave and shortwave radiation on the thermodynamic and kinematic structure of a midlatitude squall line; and (2) to explore the influence of specifically including the ice phase in the cloud-radiation feedback mechanism for climate models

  2. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

    Science.gov (United States)

    Holland, Marika M; Landrum, Laura

    2015-07-13

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. A new telemetry-based system for assessing cardiovascular function in group-housed large animals. Taking the 3Rs to a new level with the evaluation of remote measurement via cloud data transmission.

    Science.gov (United States)

    Markert, Michael; Trautmann, Thomas; Krause, Florian; Cioaga, Marius; Mouriot, Sebastien; Wetzel, Miriam; Guth, Brian D

    2018-03-26

    A newly developed total implant telemetry system for cardiovascular (CV), electrophysiological and body temperature measurement was evaluated. A cloud-based transmission of the physiological signals allowed an assessment of the quality of the physiological signals despite the physical separation between the instrumented animals and the evaluating home laboratory. The new system is intended to be used for safety pharmacological evaluations of drug candidates in various species. Two female minipigs, 6 Labrador-mixed breed dogs and 4 female Cynomolgus monkeys were instrumented with a newly developed total implant system (TSE SYSTEMS). The implants feature a microprocessor, internal memory (1 GB), 2 solid state pressure-tipped catheters, amplifiers and a radio transmitter. Sampling rates for each measurement can be selected within a range between 0.1 and 1 kHz. Biological signals are selected in a programmable fashion on a session-by-session basis according to a user-defined protocol. The pressure sensors are at the tip of an electrical lead having a length customized to each species. Core temperature measurement and activity monitoring (3D accelerometer) are included in the system. Digital transmission range using a single antenna is 5 m with up to 16 animals held together and monitored simultaneously. The range can be expanded with more antennas in an array coupled to a single receiver. The antenna/receiver station consists of a single USB powered mobile unit connected to a PC or laptop. The battery life provides 110 days of continuous recording. The dogs and minipigs were instrumented and monitored in Germany. A novel cloud-based data transmission system was developed to monitor the physiological signals in real-time from the Cynomolgus monkeys, still kept in Mauritius, from the data evaluation laboratory in Germany. After recovery from the surgical implantation, aortic pressure (AP), left ventricular pressure (LVP), ECG and body temperature were recorded

  4. Uncertainty Estimate of Surface Irradiances Computed with MODIS-, CALIPSO-, and CloudSat-Derived Cloud and Aerosol Properties

    Science.gov (United States)

    Kato, Seiji; Loeb, Norman G.; Rutan, David A.; Rose, Fred G.; Sun-Mack, Sunny; Miller, Walter F.; Chen, Yan

    2012-07-01

    Differences of modeled surface upward and downward longwave and shortwave irradiances are calculated using modeled irradiance computed with active sensor-derived and passive sensor-derived cloud and aerosol properties. The irradiance differences are calculated for various temporal and spatial scales, monthly gridded, monthly zonal, monthly global, and annual global. Using the irradiance differences, the uncertainty of surface irradiances is estimated. The uncertainty (1σ) of the annual global surface downward longwave and shortwave is, respectively, 7 W m-2 (out of 345 W m-2) and 4 W m-2 (out of 192 W m-2), after known bias errors are removed. Similarly, the uncertainty of the annual global surface upward longwave and shortwave is, respectively, 3 W m-2 (out of 398 W m-2) and 3 W m-2 (out of 23 W m-2). The uncertainty is for modeled irradiances computed using cloud properties derived from imagers on a sun-synchronous orbit that covers the globe every day (e.g., moderate-resolution imaging spectrometer) or modeled irradiances computed for nadir view only active sensors on a sun-synchronous orbit such as Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation and CloudSat. If we assume that longwave and shortwave uncertainties are independent of each other, but up- and downward components are correlated with each other, the uncertainty in global annual mean net surface irradiance is 12 W m-2. One-sigma uncertainty bounds of the satellite-based net surface irradiance are 106 W m-2 and 130 W m-2.

  5. Dispersion bias, dispersion effect, and the aerosol-cloud conundrum

    International Nuclear Information System (INIS)

    Liu Yangang; Daum, Peter H; Guo Huan; Peng Yiran

    2008-01-01

    This work examines the influences of relative dispersion (the ratio of the standard deviation to the mean radius of the cloud droplet size distribution) on cloud albedo and cloud radiative forcing, derives an analytical formulation that accounts explicitly for the contribution from droplet concentration and relative dispersion, and presents a new approach to parameterize relative dispersion in climate models. It is shown that inadequate representation of relative dispersion in climate models leads to an overestimation of cloud albedo, resulting in a negative bias of global mean shortwave cloud radiative forcing that can be comparable to the warming caused by doubling CO 2 in magnitude, and that this dispersion bias is likely near its maximum for ambient clouds. Relative dispersion is empirically expressed as a function of the quotient between cloud liquid water content and droplet concentration (i.e., water per droplet), yielding an analytical formulation for the first aerosol indirect effect. Further analysis of the new expression reveals that the dispersion effect not only offsets the cooling from the Twomey effect, but is also proportional to the Twomey effect in magnitude. These results suggest that unrealistic representation of relative dispersion in cloud parameterization in general, and evaluation of aerosol indirect effects in particular, is at least in part responsible for several outstanding puzzles of the aerosol-cloud conundrum: for example, overestimation of cloud radiative cooling by climate models compared to satellite observations; large uncertainty and discrepancy in estimates of the aerosol indirect effect; and the lack of interhemispheric difference in cloud albedo.

  6. Some observations on stray magnetic fields and power outputs from short-wave diathermy equipment

    Energy Technology Data Exchange (ETDEWEB)

    Lau, R.W.M.; Dunscombe, P.B.

    1984-04-01

    Recent years have seen increasing interest in the possible hazards arising from the use of nonionizing electromagnetic radiation. Relatively large and potentially hazardous fields are to be found in the vicinity of short-wave and microwave equipment used in physiotherapy departments to produce therapeutic temperature rises. This note reports the results of measurements of the stray magnetic field and power output of a conventional short-wave diathermy unit when applied to tissue-equivalent phantoms. The dependence of these quantities on the variables, i.e. power setting of the unit, capacitor plate size, phantom size and phantom-capacitor plate separation, are discussed.

  7. Cloud Governance

    DEFF Research Database (Denmark)

    Berthing, Hans Henrik

    Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing.......Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing....

  8. Use of the ARM Measurements of Spectral Zenith Radiance for Better Understanding of 3D Cloud-Radiation Processes & Aerosol-Cloud Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Alexander Marshak; Warren Wiscombe; Yuri Knyazikhin; Christine Chiu

    2011-05-24

    We proposed a variety of tasks centered on the following question: what can we learn about 3D cloud-radiation processes and aerosol-cloud interaction from rapid-sampling ARM measurements of spectral zenith radiance? These ARM measurements offer spectacular new and largely unexploited capabilities in both the temporal and spectral domains. Unlike most other ARM instruments, which average over many seconds or take samples many seconds apart, the new spectral zenith radiance measurements are fast enough to resolve natural time scales of cloud change and cloud boundaries as well as the transition zone between cloudy and clear areas. In the case of the shortwave spectrometer, the measurements offer high time resolution and high spectral resolution, allowing new discovery-oriented science which we intend to pursue vigorously. Research objectives are, for convenience, grouped under three themes: • Understand radiative signature of the transition zone between cloud-free and cloudy areas using data from ARM shortwave radiometers, which has major climatic consequences in both aerosol direct and indirect effect studies. • Provide cloud property retrievals from the ARM sites and the ARM Mobile Facility for studies of aerosol-cloud interactions. • Assess impact of 3D cloud structures on aerosol properties using passive and active remote sensing techniques from both ARM and satellite measurements.

  9. The use of marine cloud water samples as a diagnostic tool for aqueous chemistry, cloud microphysical processes and dynamics

    Science.gov (United States)

    Crosbie, E.; Ziemba, L. D.; Moore, R.; Shook, M.; Jordan, C.; Thornhill, K. L., II; Winstead, E.; Shingler, T.; Brown, M.; MacDonald, A. B.; Dadashazar, H.; Sorooshian, A.; Weiss-Penzias, P. S.; Anderson, B.

    2017-12-01

    Clouds play several roles in the Earth's climate system. In addition to their clear significance to the hydrological cycle, they strongly modulate the shortwave and longwave radiative balance of the atmosphere, with subsequent feedback on the atmospheric circulation. Furthermore, clouds act as a conduit for the fate and emergence of important trace chemical species and are the predominant removal mechanism for atmospheric aerosols. Marine boundary layer clouds cover large swaths of the global oceans. Because of their global significance, they have attracted significant attention into understanding how changes in aerosols are translated into changes in cloud macro- and microphysical properties. The circular nature of the influence of clouds-on-aerosols and aerosols-on-clouds has been used to explain the chaotic patterns often seen in marine clouds, however, this feedback also presents a substantial hurdle in resolving the uncertain role of anthropogenic aerosols on climate. Here we discuss ways in which the chemical constituents found in cloud water can offer insight into the physical and chemical processes inherent in marine clouds, through the use of aircraft measurements. We focus on observational data from cloud water samples collected during flights conducted over the remote North Atlantic and along coastal California across multiple campaigns. We explore topics related to aqueous processing, wet scavenging and source apportionment.

  10. Manifestation of Aerosol Indirect Effects in Arctic Clouds

    Science.gov (United States)

    Lubin, D.; Vogelmann, A. M.

    2009-12-01

    The first aerosol indirect effect has traditionally been conceived as an enhancement of shortwave cloud reflectance in response to decreased effective droplet size at fixed liquid water path, as cloud nucleating aerosol becomes entrained in the cloud. The high Arctic, with its pervasive low-level stratiform cloud cover and frequent episodes of anthropogenic aerosol (Artic "haze"), has in recent years served as a natural laboratory for research on actual manifestations of aerosol indirect effects. This paper will review the surprising set of developments: (1) the detection of the indirect effect as a source of surface warming, rather than cooling, throughout early spring, (2) a transition to a cooling effect in late spring, corresponding to the beginning of the sea ice melt season, and (3) detection of an indirect effect during summer, outside of the "Arctic haze" season. This paper will also discuss measurements of spectral shortwave irradiance (350-2200 nm) made at Barrow, Alaska, during the U.S. Department of Energy's Indirect and Semi-Direct Aerosol Campaign (ISDAC), which reveal complications in our conception of the indirect effect related to the ice phase in Arctic stratiform clouds.

  11. The impact of cloud inhomogeneities on the Earth radiation budget: the 14 October 1989 I.C.E. convective cloud case study

    Directory of Open Access Journals (Sweden)

    F. Parol

    1994-01-01

    Full Text Available Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%; it might reach 40 W m-2 for an overhead sun and overcast cloud conditions.

  12. The impact of cloud inhomogeneities on the Earth radiation budget: the 14 October 1989 I.C.E. convective cloud case study

    Directory of Open Access Journals (Sweden)

    F. Parol

    Full Text Available Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%; it might reach 40 W m-2 for an overhead sun and overcast cloud conditions.

  13. Modeling microwave/electron-cloud interaction

    International Nuclear Information System (INIS)

    Mattes, M; Sorolla, E; Zimmermann, F

    2013-01-01

    Starting from the separate codes BI-RME and ECLOUD or PyECLOUD, we are developing a novel joint simulation tool, which models the combined effect of a charged particle beam and of microwaves on an electron cloud. Possible applications include the degradation of microwave transmission in telecommunication satellites by electron clouds; the microwave-transmission techniques being used in particle accelerators for the purpose of electroncloud diagnostics; the microwave emission by the electron cloud itself in the presence of a magnetic field; and the possible suppression of electron-cloud formation in an accelerator by injecting microwaves of suitable amplitude and frequency. A few early simulation results are presented. (author)

  14. A Stabilizing Feedback Between Cloud Radiative Effects and Greenland Surface Melt: Verification From Multi-year Automatic Weather Station Measurements

    Science.gov (United States)

    Zender, C. S.; Wang, W.; van As, D.

    2017-12-01

    Clouds have strong impacts on Greenland's surface melt through the interaction with the dry atmosphere and reflective surfaces. However, their effects are uncertain due to the lack of in situ observations. To better quantify cloud radiative effects (CRE) in Greenland, we analyze and interpret multi-year radiation measurements from 30 automatic weather stations encompassing a broad range of climatological and topographical conditions. During melt season, clouds warm surface over most of Greenland, meaning the longwave greenhouse effect outweighs the shortwave shading effect; on the other hand, the spatial variability of net (longwave and shortwave) CRE is dominated by shortwave CRE and in turn by surface albedo, which controls the potential absorption of solar radiation when clouds are absent. The net warming effect decreases with shortwave CRE from high to low altitudes and from north to south (Fig. 1). The spatial correlation between albedo and net CRE is strong (r=0.93, palbedo determines the net CRE seasonal trend, which decreases from May to July and increases afterwards. On an hourly timescale, we find two distinct radiative states in Greenland (Fig. 2). The clear state is characterized by clear-sky conditions or thin clouds, when albedo and solar zenith angle (SZA) weakly correlates with CRE. The cloudy state is characterized by opaque clouds, when the combination of albedo and SZA strongly correlates with CRE (r=0.85, palbedo and solar zenith angle, explains the majority of the CRE variation in spatial distribution, seasonal trend in the ablation zone, and in hourly variability in the cloudy radiative state. Clouds warm the brighter and colder surfaces of Greenland, enhance snow melt, and tend to lower the albedo. Clouds cool the darker and warmer surfaces, inhibiting snow melt, which increases albedo, and thus stabilizes surface melt. This stabilizing mechanism may also occur over sea ice, helping to forestall surface melt as the Arctic becomes dimmer.

  15. Low cloud investigations for project FIRE: Island studies of cloud properties, surface radiation, and boundary layer dynamics. A simulation of the reflectivity over a stratocumulus cloud deck by the Monte Carlo method. M.S. Thesis Final Report

    Science.gov (United States)

    Ackerman, Thomas P.; Lin, Ruei-Fong

    1993-01-01

    The radiation field over a broken stratocumulus cloud deck is simulated by the Monte Carlo method. We conducted four experiments to investigate the main factor for the observed shortwave reflectively over the FIRE flight 2 leg 5, in which reflectivity decreases almost linearly from the cloud center to cloud edge while the cloud top height and the brightness temperature remain almost constant through out the clouds. From our results, the geometry effect, however, did not contribute significantly to what has been observed. We found that the variation of the volume extinction coefficient as a function of its relative position in the cloud affects the reflectivity efficiently. Additional check of the brightness temperature of each experiment also confirms this conclusion. The cloud microphysical data showed some interesting features. We found that the cloud droplet spectrum is nearly log-normal distributed when the clouds were solid. However, whether the shift of cloud droplet spectrum toward the larger end is not certain. The decrease of number density from cloud center to cloud edges seems to have more significant effects on the optical properties.

  16. Cloud Computing

    CERN Document Server

    Antonopoulos, Nick

    2010-01-01

    Cloud computing has recently emerged as a subject of substantial industrial and academic interest, though its meaning and scope is hotly debated. For some researchers, clouds are a natural evolution towards the full commercialisation of grid systems, while others dismiss the term as a mere re-branding of existing pay-per-use technologies. From either perspective, 'cloud' is now the label of choice for accountable pay-per-use access to third party applications and computational resources on a massive scale. Clouds support patterns of less predictable resource use for applications and services a

  17. Vertical profiles of droplet effective radius in shallow convective clouds

    Directory of Open Access Journals (Sweden)

    S. Zhang

    2011-05-01

    >fad becomes smaller, representing a higher degree of mixing, and re becomes smaller (~10 % and more variable. However, for the clean case, smaller fad corresponds to larger re (and larger re variability, reflecting the additional influence of droplet collision-coalescence and sedimentation on re. Finally, profiles of the vertically inhomogeneous clouds as simulated by the LES and those of the vertically homogeneous clouds are used as input to a radiative transfer model to study the effect of cloud vertical inhomogeneity on shortwave radiative forcing. For clouds that have the same liquid water path, re of a vertically homogeneous cloud must be about 76–90 % of the cloud-top re of the vertically inhomogeneous cloud in order for the two clouds to have the same shortwave radiative forcing.

  18. Cloud effects on the SW radiation at the surface at a mid-latitude site in southwestern Europe

    Science.gov (United States)

    Salgueiro, Vanda; João Costa, Maria; Silva, Ana Maria; Lanconelli, Christian; Bortoli, Daniele

    2017-04-01

    This work presents a study of cloud radiative effects on shortwave (CRESW) radiation at the surface in Évora region (southwestern Europe) during 2015 and a case study is analyzed. CRESW (in Wm-2) is defined as the difference between the net shortwave irradiance (downward minus upward shortwave irradiance) in cloudy and clear sky conditions. This measure is usually used to translate changes in the SW radiation that reaches the surface due to changes in clouds (type and/or cover). The CRESW is obtained using measured SW irradiance recorded with a Kipp&Zonen CM 6B pyranometer (broadband 305 - 2800 nm) during the period from January to December 2015, and is related with the cloud liquid water path (LWP) and with cloud ice water path (IWP) showing the importance of the different type of clouds in attenuating the SW radiation at the surface. The cloud modification factor, also a measure of the cloud radiative effects (CMF; ratio between the measured SW irradiance under cloudy conditions and the estimated SW irradiance in clear-sky conditions) is related with the cloud optical thickness (COT; obtained from satellite data). This relation between CMF and COT is shown for different cloud fractions revealing an exponential decreasing of CMF as COT increases. Reductions in the SW radiation of the order of 80% (CMF = 0.2) as well enhancements in the SW radiation larger than 30% (CMF = 1.3) were found for small COT values and for different cloud fractions. A case study to analyse the enhancement events in a cloudy day was considered and the cloud properties, COT and LWP (from satellite and surface measurements), were related with the CRESW.

  19. Cluster analysis of midlatitude oceanic cloud regimes: mean properties and temperature sensitivity

    Directory of Open Access Journals (Sweden)

    N. D. Gordon

    2010-07-01

    Full Text Available Clouds play an important role in the climate system by reducing the amount of shortwave radiation reaching the surface and the amount of longwave radiation escaping to space. Accurate simulation of clouds in computer models remains elusive, however, pointing to a lack of understanding of the connection between large-scale dynamics and cloud properties. This study uses a k-means clustering algorithm to group 21 years of satellite cloud data over midlatitude oceans into seven clusters, and demonstrates that the cloud clusters are associated with distinct large-scale dynamical conditions. Three clusters correspond to low-level cloud regimes with different cloud fraction and cumuliform or stratiform characteristics, but all occur under large-scale descent and a relatively dry free troposphere. Three clusters correspond to vertically extensive cloud regimes with tops in the middle or upper troposphere, and they differ according to the strength of large-scale ascent and enhancement of tropospheric temperature and humidity. The final cluster is associated with a lower troposphere that is dry and an upper troposphere that is moist and experiencing weak ascent and horizontal moist advection.

    Since the present balance of reflection of shortwave and absorption of longwave radiation by clouds could change as the atmosphere warms from increasing anthropogenic greenhouse gases, we must also better understand how increasing temperature modifies cloud and radiative properties. We therefore undertake an observational analysis of how midlatitude oceanic clouds change with temperature when dynamical processes are held constant (i.e., partial derivative with respect to temperature. For each of the seven cloud regimes, we examine the difference in cloud and radiative properties between warm and cold subsets. To avoid misinterpreting a cloud response to large-scale dynamical forcing as a cloud response to temperature, we require horizontal and vertical

  20. Cloud Cover

    Science.gov (United States)

    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…

  1. Cloud Control

    Science.gov (United States)

    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…

  2. A Diagnostic PDF Cloud Scheme to Improve Subtropical Low Clouds in NCAR Community Atmosphere Model (CAM5)

    Science.gov (United States)

    Qin, Yi; Lin, Yanluan; Xu, Shiming; Ma, Hsi-Yen; Xie, Shaocheng

    2018-02-01

    Low clouds strongly impact the radiation budget of the climate system, but their simulation in most GCMs has remained a challenge, especially over the subtropical stratocumulus region. Assuming a Gaussian distribution for the subgrid-scale total water and liquid water potential temperature, a new statistical cloud scheme is proposed and tested in NCAR Community Atmospheric Model version 5 (CAM5). The subgrid-scale variance is diagnosed from the turbulent and shallow convective processes in CAM5. The approach is able to maintain the consistency between cloud fraction and cloud condensate and thus alleviates the adjustment needed in the default relative humidity-based cloud fraction scheme. Short-term forecast simulations indicate that low cloud fraction and liquid water content, including their diurnal cycle, are improved due to a proper consideration of subgrid-scale variance over the southeastern Pacific Ocean region. Compared with the default cloud scheme, the new approach produced the mean climate reasonably well with improved shortwave cloud forcing (SWCF) due to more reasonable low cloud fraction and liquid water path over regions with predominant low clouds. Meanwhile, the SWCF bias over the tropical land regions is also alleviated. Furthermore, the simulated marine boundary layer clouds with the new approach extend further offshore and agree better with observations. The new approach is able to obtain the top of atmosphere (TOA) radiation balance with a slightly alleviated double ITCZ problem in preliminary coupled simulations. This study implies that a close coupling of cloud processes with other subgrid-scale physical processes is a promising approach to improve cloud simulations.

  3. Examining the controlling factors on Southern Ocean clouds and their radiative effects in the context of midlatitude weather systems

    Science.gov (United States)

    Kelleher, M. K.; Grise, K. M.

    2017-12-01

    Clouds and their associated radiative effects are one of the largest sources of uncertainty in the present generation of global climate models. One region where model biases are especially large is over the Southern Ocean, where many models systematically underestimate the climatological shortwave cloud radiative effects (CRE) and/or misrepresent the relationship between shortwave CRE and atmospheric dynamics. Previous research has shown that two "cloud controlling factors", estimated inversion strength (EIS) and mid-tropospheric vertical velocity, are helpful in explaining the relationship between CRE and atmospheric dynamics on monthly timescales. For example, when the Southern Hemisphere midlatitude jet shifts poleward on monthly timescales, the high clouds and their associated longwave CRE shift poleward with the jet, consistent with a poleward shift of the storm track and the attendant vertical velocity anomalies. However, the observed changes in shortwave CRE with a poleward jet shift are small due to a trade-off between the competing effects of opposing EIS and vertical velocity anomalies. This study extends these previous findings to examine the relationship between Southern Ocean cloud controlling factors and CRE on daily timescales. On a daily timescale, the relationship of EIS and vertical velocity with CRE is more complex, due in part to the presence of transient weather systems. Composites of EIS, vertical velocity, longwave CRE, and shortwave CRE around extratropical cyclones and anticyclones are constructed to examine how the CRE anomalies vary in different sectors of midlatitude weather systems and the role that EIS and vertical velocity play in determining those anomalies. The relationships between the cloud controlling factors and CRE on daily timescales provide key insight into the underlying physical processes responsible for the relationships between midlatitude cloud controlling factors and CRE previously documented on monthly timescales.

  4. Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

    KAUST Repository

    Bangalath, Hamza Kunhu

    2016-06-13

    Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

  5. Integrable discretizations for the short-wave model of the Camassa-Holm equation

    International Nuclear Information System (INIS)

    Feng Baofeng; Maruno, Ken-ichi; Ohta, Yasuhiro

    2010-01-01

    The link between the short-wave model of the Camassa-Holm equation (SCHE) and bilinear equations of the two-dimensional Toda lattice equation is clarified. The parametric form of the N-cuspon solution of the SCHE in Casorati determinant is then given. Based on the above finding, integrable semi-discrete and full-discrete analogues of the SCHE are constructed. The determinant solutions of both semi-discrete and fully discrete analogues of the SCHE are also presented.

  6. Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

    KAUST Repository

    Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

    2016-01-01

    Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

  7. Single interval shortwave radiation scheme with parameterized optical saturation and spectral overlaps

    Czech Academy of Sciences Publication Activity Database

    Mašek, Jan; Geleyn, J.- F.; Brožková, Radmila; Giot, O.; Achom, H. O.; Kuma, P.

    2016-01-01

    Roč. 142, č. 659 (2016), s. 304-326 ISSN 0035-9009 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : shortwave radiative transfer * delta-two stream system * broadband approach * Malkmus band model * optical saturation * idealized optical paths * spectral overlap Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.444, year: 2016

  8. Arctic atmospheric preconditioning: do not rule out shortwave radiation just yet

    Science.gov (United States)

    Sedlar, J.

    2017-12-01

    Springtime atmospheric preconditioning of Arctic sea ice for enhanced or buffered sea ice melt during the subsequent melt year has received considerable research focus in recent years. A general consensus points to enhanced poleward atmospheric transport of moisture and heat during spring, effectively increasing the emission of longwave radiation to the surface. Studies have essentially ruled out the role of shortwave radiation as an effective preconditioning mechanism because of the relatively weak incident solar radiation and high surface albedo from sea ice and snow during spring. These conclusions, however, are derived primarily from atmospheric reanalysis data, which may not always represent an accurate depiction of the Arctic climate system. Here, observations of top of atmosphere radiation from state of the art satellite sensors are examined and compared with reanalysis and climate model data to examine the differences in the spring radiative budget over the Arctic Ocean for years with extreme low/high ice extent at the end of the ice melt season (September). Distinct biases are observed between satellite-based measurements and reanalysis/models, particularly for the amount of shortwave radiation trapped (warming effect) within the Arctic climate system during spring months. A connection between the differences in reanalysis/model surface albedo representation and the albedo observed by satellite is discussed. These results suggest that shortwave radiation should not be overlooked as a significant contributing mechanism to springtime Arctic atmospheric preconditioning.

  9. Estimating net surface shortwave radiation from Chinese geostationary meteorological satellite FengYun-2D (FY-2D) data under clear sky.

    Science.gov (United States)

    Zhang, Xiaoyu; Li, Lingling

    2016-03-21

    Net surface shortwave radiation (NSSR) significantly affects regional and global climate change, and is an important aspect of research on surface radiation budget balance. Many previous studies have proposed methods for estimating NSSR. This study proposes a method to calculate NSSR using FY-2D short-wave channel data. Firstly, a linear regression model is established between the top-of-atmosphere (TOA) broadband albedo (r) and the narrowband reflectivity (ρ1), based on data simulated with MODTRAN 4.2. Secondly, the relationship between surface absorption coefficient (as) and broadband albedo (r) is determined by dividing the surface type into land, sea, or snow&ice, and NSSR can then be calculated. Thirdly, sensitivity analysis is performed for errors associated with sensor noise, vertically integrated atmospheric water content, view zenith angle and solar zenith angle. Finally, validation using ground measurements is performed. Results show that the root mean square error (RMSE) between the estimated and actual r is less than 0.011 for all conditions, and the RMSEs between estimated and real NSSR are 26.60 W/m2, 9.99 W/m2, and 23.40 W/m2, using simulated data for land, sea, and snow&ice surfaces, respectively. This indicates that the proposed method can be used to adequately estimate NSSR. Additionally, we compare field measurements from TaiYuan and ChangWu ecological stations with estimates using corresponding FY-2D data acquired from January to April 2012, on cloud-free days. Results show that the RMSE between the estimated and actual NSSR is 48.56W/m2, with a mean error of -2.23W/m2. Causes of errors also include measurement accuracy and estimations of atmospheric water vertical contents. This method is only suitable for cloudless conditions.

  10. CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared

    Science.gov (United States)

    Guerin, François; Dantes, Didier; Savaria, Eric; Selingardi, Mario Luis; Montes, Amauri Silva

    2018-04-01

    This paper, "CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

  11. Cloud Computing Fundamentals

    Science.gov (United States)

    Furht, Borko

    In the introductory chapter we define the concept of cloud computing and cloud services, and we introduce layers and types of cloud computing. We discuss the differences between cloud computing and cloud services. New technologies that enabled cloud computing are presented next. We also discuss cloud computing features, standards, and security issues. We introduce the key cloud computing platforms, their vendors, and their offerings. We discuss cloud computing challenges and the future of cloud computing.

  12. Radiative budget and cloud radiative effect over the Atlantic from ship-based observations

    Directory of Open Access Journals (Sweden)

    J. Kalisch

    2012-10-01

    Full Text Available The aim of this study is to determine cloud-type resolved cloud radiative budgets and cloud radiative effects from surface measurements of broadband radiative fluxes over the Atlantic Ocean. Furthermore, based on simultaneous observations of the state of the cloudy atmosphere, a radiative closure study has been performed by means of the ECHAM5 single column model in order to identify the model's ability to realistically reproduce the effects of clouds on the climate system.

    An extensive database of radiative and atmospheric measurements has been established along five meridional cruises of the German research icebreaker Polarstern. Besides pyranometer and pyrgeometer for downward broadband solar and thermal radiative fluxes, a sky imager and a microwave radiometer have been utilized to determine cloud fraction and cloud type on the one hand and temperature and humidity profiles as well as liquid water path for warm non-precipitating clouds on the other hand.

    Averaged over all cruise tracks, we obtain a total net (solar + thermal radiative flux of 144 W m−2 that is dominated by the solar component. In general, the solar contribution is large for cirrus clouds and small for stratus clouds. No significant meridional dependencies were found for the surface radiation budgets and cloud effects. The strongest surface longwave cloud effects were shown in the presence of low level clouds. Clouds with a high optical density induce strong negative solar radiative effects under high solar altitudes. The mean surface net cloud radiative effect is −33 W m−2.

    For the purpose of quickly estimating the mean surface longwave, shortwave and net cloud effects in moderate, subtropical and tropical climate regimes, a new parameterisation was created, considering the total cloud amount and the solar zenith angle.

    The ECHAM5 single column model provides a surface net cloud effect that is more

  13. Aerosol microphysical and radiative effects on continental cloud ensembles

    Science.gov (United States)

    Wang, Yuan; Vogel, Jonathan M.; Lin, Yun; Pan, Bowen; Hu, Jiaxi; Liu, Yangang; Dong, Xiquan; Jiang, Jonathan H.; Yung, Yuk L.; Zhang, Renyi

    2018-02-01

    Aerosol-cloud-radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations. Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity (typically less than 2%) to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type.

  14. Cloud Computing

    CERN Document Server

    Baun, Christian; Nimis, Jens; Tai, Stefan

    2011-01-01

    Cloud computing is a buzz-word in today's information technology (IT) that nobody can escape. But what is really behind it? There are many interpretations of this term, but no standardized or even uniform definition. Instead, as a result of the multi-faceted viewpoints and the diverse interests expressed by the various stakeholders, cloud computing is perceived as a rather fuzzy concept. With this book, the authors deliver an overview of cloud computing architecture, services, and applications. Their aim is to bring readers up to date on this technology and thus to provide a common basis for d

  15. Technical progress report: Completion of spectral rotating shadowband radiometers and analysis of atmospheric radiation measurement spectral shortwave data

    Energy Technology Data Exchange (ETDEWEB)

    Michalsky, J.; Harrison, L. [State Univ. of New York, Albany, NY (United States)

    1996-04-01

    Our goal in the Atmospheric Radiation Measurement (ARM) Program is the improvement of radiation models used in general circulation models (GCMs), especially in the shortwave, (1) by providing improved shortwave radiometric measurements for the testing of models and (2) by developing methods for retrieving climatologically sensitive parameters that serve as input to shortwave and longwave models. At the Atmospheric Sciences Research Center (ASRC) in Albany, New York, we are acquiring downwelling direct and diffuse spectral irradiance, at six wavelengths, plus downwelling broadband longwave, and upwelling and downwelling broadband shortwave irradiances that we combine with National Weather Service surface and upper air data from the Albany airport as a test data set for ARM modelers. We have also developed algorithms to improve shortwave measurements made at the Southern Great Plains (SGP) ARM site by standard thermopile instruments and by the multifilter rotating shadowband radiometer (MFRSR) based on these Albany data sets. Much time has been spent developing techniques to retrieve column aerosol, water vapor, and ozone from the direct beam spectral measurements of the MFRSR. Additionally, we have had success in calculating shortwave surface albedo and aerosol optical depth from the ratio of direct to diffuse spectral reflectance.

  16. Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

    Science.gov (United States)

    Meyer, Kerry; Yang, Yuekui; Platnick, Steven

    2018-01-01

    This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (clouds the error is mostly limited to within 10%, although for thin clouds (COT cloud masking and cloud temperature retrievals are not considered in this study. PMID:29619116

  17. Radiative effects of global MODIS cloud regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji

    2018-01-01

    We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations. PMID:29619289

  18. Radiative Effects of Global MODIS Cloud Regimes

    Science.gov (United States)

    Oraiopoulos, Lazaros; Cho, Nayeong; Lee, Dong Min; Kato, Seiji

    2016-01-01

    We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.

  19. Cloud Computing

    DEFF Research Database (Denmark)

    Krogh, Simon

    2013-01-01

    with technological changes, the paradigmatic pendulum has swung between increased centralization on one side and a focus on distributed computing that pushes IT power out to end users on the other. With the introduction of outsourcing and cloud computing, centralization in large data centers is again dominating...... the IT scene. In line with the views presented by Nicolas Carr in 2003 (Carr, 2003), it is a popular assumption that cloud computing will be the next utility (like water, electricity and gas) (Buyya, Yeo, Venugopal, Broberg, & Brandic, 2009). However, this assumption disregards the fact that most IT production......), for instance, in establishing and maintaining trust between the involved parties (Sabherwal, 1999). So far, research in cloud computing has neglected this perspective and focused entirely on aspects relating to technology, economy, security and legal questions. While the core technologies of cloud computing (e...

  20. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    A mobile cloud is a cooperative arrangement of dynamically connected communication nodes sharing opportunistic resources. In this book, authors provide a comprehensive and motivating overview of this rapidly emerging technology. The book explores how distributed resources can be shared by mobile...... users in very different ways and for various purposes. The book provides many stimulating examples of resource-sharing applications. Enabling technologies for mobile clouds are also discussed, highlighting the key role of network coding. Mobile clouds have the potential to enhance communications...... performance, improve utilization of resources and create flexible platforms to share resources in very novel ways. Energy efficient aspects of mobile clouds are discussed in detail, showing how being cooperative can bring mobile users significant energy saving. The book presents and discusses multiple...

  1. Radiative effect differences between multi-layered and single-layer clouds derived from CERES, CALIPSO, and CloudSat data

    International Nuclear Information System (INIS)

    Li Jiming; Yi Yuhong; Minnis, Patrick; Huang Jianping; Yan Hongru; Ma Yuejie; Wang Wencai; Kirk Ayers, J.

    2011-01-01

    Clouds alter general circulation through modification of the radiative heating profile within the atmosphere. Their effects are complex and depend on height, vertical structure, and phase. The instantaneous cloud radiative effect (CRE) induced by multi-layered (ML) and single-layer (SL) clouds is estimated by analyzing data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, and Clouds and Earth's Radiation Energy Budget System (CERES) missions from March 2007 through February 2008. The CRE differences between ML and SL clouds at the top of the atmosphere (TOA) and at the surface were also examined. The zonal mean shortwave (SW) CRE differences between the ML and SL clouds at the TOA and surface were positive at most latitudes, peaking at 120 W m -2 in the tropics and dropping to -30 W m -2 at higher latitudes. This indicated that the ML clouds usually reflected less sunlight at the TOA and transmitted more to the surface than the SL clouds, due to their higher cloud top heights. The zonal mean longwave (LW) CRE differences between ML and SL clouds at the TOA and surface were relatively small, ranging from -30 to 30 W m -2 . This showed that the ML clouds only increased the amount of thermal radiation at the TOA relative to the SL clouds in the tropics, decreasing it elsewhere. In other words, ML clouds tended to cool the atmosphere in the tropics and warm it elsewhere when compared to SL clouds. The zonal mean net CRE differences were positive at most latitudes and dominated by the SW CRE differences.

  2. Macquarie Island Cloud and Radiation Experiment (MICRE) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, RT [University of Washington; Protat, A [Australian Bureau of Meterology; Alexander, SP [Australian Antarctic Division

    2015-12-01

    Clouds over the Southern Ocean are poorly represented in present day reanalysis products and global climate model simulations. Errors in top-of-atmosphere (TOA) broadband radiative fluxes in this region are among the largest globally, with large implications for modeling both regional and global scale climate responses (e.g., Trenberth and Fasullo 2010, Ceppi et al. 2012). Recent analyses of model simulations suggest that model radiative errors in the Southern Ocean are due to a lack of low-level postfrontal clouds (including clouds well behind the front) and perhaps a lack of supercooled liquid water that contribute most to the model biases (Bodas-Salcedo et al. 2013, Huang et al. 2014). These assessments of model performance, as well as our knowledge of cloud and aerosol properties over the Southern Ocean, rely heavily on satellite data sets. Satellite data sets are incomplete in that the observations are not continuous (i.e., they are acquired only when the satellite passes nearby), generally do not sample the diurnal cycle, and view primarily the tops of cloud systems (especially for the passive instruments). This is especially problematic for retrievals of aerosol, low-cloud properties, and layers of supercooled water embedded within (rather than at the top of) clouds, as well as estimates of surface shortwave and longwave fluxes based on these properties.

  3. Sensitivity of tropical climate to low-level clouds in the NCEP climate forecast system

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Zeng-Zhen [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); NCEP/NWS/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Huang, Bohua; Schneider, Edwin K. [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); George Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Hou, Yu-Tai; Yang, Fanglin [NCEP/NWS/NOAA, Environmental Modeling Center, Camp Springs, MD (United States); Wang, Wanqiu [NCEP/NWS/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Stan, Cristiana [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States)

    2011-05-15

    In this work, we examine the sensitivity of tropical mean climate and seasonal cycle to low clouds and cloud liquid water path (CLWP) by prescribing them in the NCEP climate forecast system (CFS). It is found that the change of low cloud cover alone has a minor influence on the amount of net shortwave radiation reaching the surface and on the warm biases in the southeastern Atlantic. In experiments where CLWP is prescribed using observations, the mean climate in the tropics is improved significantly, implying that shortwave radiation absorption by CLWP is mainly responsible for reducing the excessive surface net shortwave radiation over the southern oceans in the CFS. Corresponding to large CLWP values in the southeastern oceans, the model generates large low cloud amounts. That results in a reduction of net shortwave radiation at the ocean surface and the warm biases in the sea surface temperature in the southeastern oceans. Meanwhile, the cold tongue and associated surface wind stress in the eastern oceans become stronger and more realistic. As a consequence of the overall improvement of the tropical mean climate, the seasonal cycle in the tropical Atlantic is also improved. Based on the results from these sensitivity experiments, we propose a model bias correction approach, in which CLWP is prescribed only in the southeastern Atlantic by using observed annual mean climatology of CLWP. It is shown that the warm biases in the southeastern Atlantic are largely eliminated, and the seasonal cycle in the tropical Atlantic Ocean is significantly improved. Prescribing CLWP in the CFS is then an effective interim technique to reduce model biases and to improve the simulation of seasonal cycle in the tropics. (orig.)

  4. Thermodynamics and Cloud Radiative Effect from the First Year of GoAmazon

    Science.gov (United States)

    Collow, Allie Marquardt; Miller, Mark; Trabachino, Lynne

    2015-01-01

    Deforestation is an ongoing concern for the Amazon Rainforest of Brazil and associated changes to the land surface have been hypothesized to alter the climate in the region. A comprehensive set of meteorological observations at the surface and within the lower troposphere above Manacapuru, Brazil and data from the Modern Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) are used to evaluate the seasonal cycle of cloudiness, thermodynamics, and the radiation budget. While ample moisture is present in the Amazon Rainforest year round, the northward progression of the Hadley circulation during the dry season contributes to a drying of the middle troposphere and inhibits the formation of deep convection. This results in a reduction in cloudiness and precipitation as well as an increase in the height of the lifting condensation level, which is shown to have a negative correlation to the fraction of low clouds. Frequent cloudiness prevents solar radiation from reaching the surface and clouds are often reflective with high values of shortwave cloud radiative effect at the surface and top of the atmosphere. Cloud radiative effect is reduced during the dry season however the dry season surface shortwave cloud radiative effect is still double what is observed during the wet season in other tropical locations. Within the column, the impact of clouds on the radiation budget is more prevalent in the longwave part of the spectrum, with a net warming in the wet season.

  5. Particles from a Diesel ship engine: Mixing state on the nano scale and cloud condensation abilities

    Science.gov (United States)

    Lieke, K. I.; Rosenørn, T.; Fuglsang, K.; Frederiksen, T.; Butcher, A. C.; King, S. M.; Bilde, M.

    2012-04-01

    Transport by ship plays an important role in global logistics. Current international policy initiatives by the International Maritime Organization (IMO) are taken to reduce emissions from ship propulsion systems (NO and SO, primarily). However, particulate emissions (e.g. soot) from ships are yet not regulated by legislations. To date, there is still a lack of knowledge regarding the global and local effects of the particulate matter emitted from ships at sea. Particles may influence the climate through their direct effects (scattering and absorption of long and shortwave radiation) and indirectly through formation of clouds. Many studies have been carried out estimating the mass and particle number from ship emissions (e.g. Petzold et al. 2008), many of them in test rig studies (e.g. Kasper et al. 2007). It is shown that particulate emissions vary with engine load and chemical composition of fuels. Only a few studies have been carried out to characterize the chemical composition and cloud-nucleating ability of the particulate matter (e.g. Corbett et al. 1997). In most cases, the cloud-nucleating ability of emission particles is estimated from number size distribution. We applied measurements to characterize particulate emissions from a MAN B&W Low Speed engine on test bed. A unique data set was obtained through the use of a scanning mobility particle sizing system (SMPS), combined with a cloud condensation nucleus (CCN) counter and a thermodenuder - all behind a dilution system. In addition, impactor samples were taken on nickel grids with carbon foil for use in an electron microscope (EM) to characterize the mineral phase and mixing state of the particles. The engine was operated at a series of different load conditions and an exhaust gas recirculation (EGR) system was applied. Measurements were carried out before and after the EGR system respectively. Our observations show significant changes in number size distribution and CCN activity with varying conditions

  6. Spectral composition of shortwave radiation reflected and deep penetrating into snow near the Barentsburg settlement (Svalbard

    Directory of Open Access Journals (Sweden)

    P. N. Svyashchennikov

    2015-01-01

    Full Text Available Data on spectral composition of shortwave radiation that is reflected from snow and penetrates deep into the snow cover obtained near the Barentsburg settlement (Svalbard are discussed in the paper. Measurements were made by the use of the spectral radiometer TriOS Ramses within the wavelength range of 280–950 nm. The results will allow more proper taking account of the anthropogenic pollution effects on the radiative properties of snow cover under conditions of industrial activity related to the coal extraction and burning in Barentsburg.

  7. The influence of scrotonin on survival of Candida guillermondii, irradiated by short-wave ultraviolet

    International Nuclear Information System (INIS)

    Strakhovskaya, M.G.; Frajkin, G.Ya.; Goncharenko, E.N.

    1982-01-01

    A study was made on the influence of serotonin on survival of Candida quilliermondu yeast irradiated by 254 nm short-wave ultraviolet. It was established that incubation with serotonin, leading to its penetration inside cells causes two opposite effects - protection from ultraviolet inactivation in preliminary incubation and intensification of cells death in postradiation incubation. Serotonin action is similar to the effects induced in C. guillermondii yeast by 334 nm long-wave ultraviolet light, that is serotonin possesses photomimetic effect. The data obtained are considered as conformaition of participation of serotonin photoinduced synthesis in manifestation of effects of long-wave ultraviolet light action on yeast

  8. Impacts of solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    Directory of Open Access Journals (Sweden)

    X. Zhou

    2017-10-01

    Full Text Available The effects of an initially overlying layer of solar-absorbing aerosol on the transition of stratocumulus to trade cumulus clouds are examined using large-eddy simulations. For lightly drizzling cloud the transition is generally hastened, resulting mainly from increased cloud droplet number concentration (Nc induced by entrained aerosol. The increased Nc slows sedimentation of cloud droplets and shortens their relaxation time for diffusional growth, both of which accelerate entrainment of overlying air and thereby stratocumulus breakup. However, the decrease in albedo from cloud breakup is more than offset by redistributing cloud water over a greater number of droplets, such that the diurnal-average shortwave forcing at the top of the atmosphere is negative. The negative radiative forcing is enhanced by sizable longwave contributions, which result from the greater cloud breakup and a reduced boundary layer height associated with aerosol heating. A perturbation of moisture instead of aerosol aloft leads to a greater liquid water path and a more gradual transition. Adding absorbing aerosol to that atmosphere results in substantial reductions in liquid water path (LWP and cloud cover that lead to positive shortwave and negative longwave forcings on average canceling each other. Only for heavily drizzling clouds is the breakup delayed, as inhibition of precipitation overcomes cloud water loss from enhanced entrainment. Considering these simulations as an imperfect proxy for biomass burning plumes influencing Namibian stratocumulus, we expect regional indirect plus semi-direct forcings to be substantially negative to negligible at the top of the atmosphere, with its magnitude sensitive to background and perturbation properties.

  9. Using ISCCP Weather States to Decompose Cloud Radiative Effects

    Science.gov (United States)

    Oreopoulos, L.; Rossow, W. B.

    2012-01-01

    The presentation will examine the shortwave (SW) and longwave (LW) cloud radiative effect CRE (aka "cloud radiative forcing") at the top-of-the-atmosphere and surface of ISCCP weather states (aka "cloud regimes") in three distinct geographical zones, one tropical and two mid-latitude. Our goal is to understand and quantify the contribution of the different cloud regimes to the planetary radiation budget. In the tropics we find that the three most convectively active states are the ones with largest SW, LW and net TOA CRE contributions to the overall daytime tropical CRE budget. They account for 59%, 71% and 55% of the total CRE, respectively. The boundary layer-dominated weather states account for only 34% of the total SW CRE and 41% of the total net CRE, so to focus only on them in cloud feedback studies may be imprudent. We also find that in both the northern and southern midlatitude zones only two weather states, the first and third most convectively active with large amounts of nimbostratus-type clouds, contribute ",40% to both the SW and net TOA CRE budgets, highlighting the fact that cloud regimes associated with frontal systems are not only important for weather (precipitation) but also for climate (radiation budget). While all cloud regimes in all geographical zones have a slightly larger SFC than TOA SW CRE, implying cooling of the surface and slight warming of the atmosphere, their LW radiative effects are more subtle: in the tropics the weather states with plentiful high clouds warm the atmosphere while those with copious amounts of low clouds cool the atmosphere. In both midlatitude zones only the weather states with peak cloud fractions at levels above 440 mbar warm the atmosphere while all the rest cool it. These results make the connection of the contrasting CRE effects to the atmospheric dynamics more explicit - "storms" tend to warm the atmosphere whereas fair weather clouds cool it, suggesting a positive feedback of clouds on weather systems. The

  10. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound...... archiving. The Soft Clouding Project is part of LARM - a major infrastructure combining research in and access to sound and radio archives in Denmark. In 2012 the LARM infrastructure will consist of more than 1 million hours of radio, combined with metadata who describes the content. The idea is to analyse...... the concept of ‘infrastructure’ and ‘interface’ on a creative play with the fundamentals of LARM (and any sound archive situation combining many kinds and layers of data and sources). This paper will present and discuss the Soft clouding project from the perspective of the three practices and competencies...

  11. Cloud Chamber

    DEFF Research Database (Denmark)

    Gfader, Verina

    Cloud Chamber takes its roots in a performance project, titled The Guests 做东, devised by Verina Gfader for the 11th Shanghai Biennale, ‘Why Not Ask Again: Arguments, Counter-arguments, and Stories’. Departing from the inclusion of the biennale audience to write a future folk tale, Cloud Chamber......: fiction and translation and translation through time; post literacy; world picturing-world typing; and cartographic entanglements and expressions of subjectivity; through the lens a social imaginary of worlding or cosmological quest. Art at its core? Contributions by Nikos Papastergiadis, Rebecca Carson...

  12. A study of Monte Carlo radiative transfer through fractal clouds

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, C.; Lavallec, D.; O`Hirok, W.; Ricchiazzi, P. [Univ. of California, Santa Barbara, CA (United States)] [and others

    1996-04-01

    An understanding of radiation transport (RT) through clouds is fundamental to studies of the earth`s radiation budget and climate dynamics. The transmission through horizontally homogeneous clouds has been studied thoroughly using accurate, discreet ordinates radiative transfer models. However, the applicability of these results to general problems of global radiation budget is limited by the plane parallel assumption and the fact that real clouds fields show variability, both vertically and horizontally, on all size scales. To understand how radiation interacts with realistic clouds, we have used a Monte Carlo radiative transfer model to compute the details of the photon-cloud interaction on synthetic cloud fields. Synthetic cloud fields, generated by a cascade model, reproduce the scaling behavior, as well as the cloud variability observed and estimated from cloud satellite data.

  13. Variety identification of brown sugar using short-wave near infrared spectroscopy and multivariate calibration

    Science.gov (United States)

    Yang, Haiqing; Wu, Di; He, Yong

    2007-11-01

    Near-infrared spectroscopy (NIRS) with the characteristics of high speed, non-destructiveness, high precision and reliable detection data, etc. is a pollution-free, rapid, quantitative and qualitative analysis method. A new approach for variety discrimination of brown sugars using short-wave NIR spectroscopy (800-1050nm) was developed in this work. The relationship between the absorbance spectra and brown sugar varieties was established. The spectral data were compressed by the principal component analysis (PCA). The resulting features can be visualized in principal component (PC) space, which can lead to discovery of structures correlative with the different class of spectral samples. It appears to provide a reasonable variety clustering of brown sugars. The 2-D PCs plot obtained using the first two PCs can be used for the pattern recognition. Least-squares support vector machines (LS-SVM) was applied to solve the multivariate calibration problems in a relatively fast way. The work has shown that short-wave NIR spectroscopy technique is available for the brand identification of brown sugar, and LS-SVM has the better identification ability than PLS when the calibration set is small.

  14. Sub-grid-scale effects on short-wave instability in magnetized hall-MHD plasma

    International Nuclear Information System (INIS)

    Miura, H.; Nakajima, N.

    2010-11-01

    Aiming to clarify effects of short-wave modes on nonlinear evolution/saturation of the ballooning instability in the Large Helical Device, fully three-dimensional simulations of the single-fluid MHD and the Hall MHD equations are carried out. A moderate parallel heat conductivity plays an important role both in the two kinds of simulations. In the single-fluid MHD simulations, the parallel heat conduction effectively suppresses short-wave ballooning modes but it turns out that the suppression is insufficient in comparison to an experimental result. In the Hall MHD simulations, the parallel heat conduction triggers a rapid growth of the parallel flow and enhance nonlinear couplings. A comparison between single-fluid and the Hall MHD simulations reveals that the Hall MHD model does not necessarily improve the saturated pressure profile, and that we may need a further extension of the model. We also find by a comparison between two Hall MHD simulations with different numerical resolutions that sub-grid-scales of the Hall term should be modeled to mimic an inverse energy transfer in the wave number space. (author)

  15. The global influence of dust mineralogical composition on heterogeneous ice nucleation in mixed-phase clouds

    International Nuclear Information System (INIS)

    Hoose, C; Lohmann, U; Erdin, R; Tegen, I

    2008-01-01

    Mineral dust is the dominant natural ice nucleating aerosol. Its ice nucleation efficiency depends on the mineralogical composition. We show the first sensitivity studies with a global climate model and a three-dimensional dust mineralogy. Results show that, depending on the dust mineralogical composition, coating with soluble material from anthropogenic sources can lead to quasi-deactivation of natural dust ice nuclei. This effect counteracts the increased cloud glaciation by anthropogenic black carbon particles. The resulting aerosol indirect effect through the glaciation of mixed-phase clouds by black carbon particles is small (+0.1 W m -2 in the shortwave top-of-the-atmosphere radiation in the northern hemisphere)

  16. Cloud computing.

    Science.gov (United States)

    Wink, Diane M

    2012-01-01

    In this bimonthly series, the author examines how nurse educators can use Internet and Web-based technologies such as search, communication, and collaborative writing tools; social networking and social bookmarking sites; virtual worlds; and Web-based teaching and learning programs. This article describes how cloud computing can be used in nursing education.

  17. Cloud Computing

    Indian Academy of Sciences (India)

    IAS Admin

    2014-03-01

    Mar 1, 2014 ... There are several types of services available on a cloud. We describe .... CPU speed has been doubling every 18 months at constant cost. Besides this ... Plain text (e.g., email) may be read by anyone who is able to access it.

  18. New approaches to quantifying aerosol influence on the cloud radiative effect.

    Science.gov (United States)

    Feingold, Graham; McComiskey, Allison; Yamaguchi, Takanobu; Johnson, Jill S; Carslaw, Kenneth S; Schmidt, K Sebastian

    2016-05-24

    The topic of cloud radiative forcing associated with the atmospheric aerosol has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand aspects such as aerosol composition, optical properties, cloud condensation, and ice nucleation potential, along with the global distribution of these properties, controlled by emissions, transport, transformation, and sinks. Equally daunting is that clouds themselves are complex, turbulent, microphysical entities and, by their very nature, ephemeral and hard to predict. Atmospheric general circulation models represent aerosol-cloud interactions at ever-increasing levels of detail, but these models lack the resolution to represent clouds and aerosol-cloud interactions adequately. There is a dearth of observational constraints on aerosol-cloud interactions. We develop a conceptual approach to systematically constrain the aerosol-cloud radiative effect in shallow clouds through a combination of routine process modeling and satellite and surface-based shortwave radiation measurements. We heed the call to merge Darwinian and Newtonian strategies by balancing microphysical detail with scaling and emergent properties of the aerosol-cloud radiation system.

  19. Reconciling Ground-Based and Space-Based Estimates of the Frequency of Occurrence and Radiative Effect of Clouds around Darwin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Protat, Alain; Young, Stuart; McFarlane, Sally A.; L' Ecuyer, Tristan; Mace, Gerald G.; Comstock, Jennifer M.; Long, Charles N.; Berry, Elizabeth; Delanoe, Julien

    2014-02-01

    The objective of this paper is to investigate whether estimates of the cloud frequency of occurrence and associated cloud radiative forcing as derived from ground-based and satellite active remote sensing and radiative transfer calculations can be reconciled over a well instrumented active remote sensing site located in Darwin, Australia, despite the very different viewing geometry and instrument characteristics. It is found that the ground-based radar-lidar combination at Darwin does not detect most of the cirrus clouds above 10 km (due to limited lidar detection capability and signal obscuration by low-level clouds) and that the CloudSat radar - Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) combination underreports the hydrometeor frequency of occurrence below 2 km height, due to instrument limitations at these heights. The radiative impact associated with these differences in cloud frequency of occurrence is large on the surface downwelling shortwave fluxes (ground and satellite) and the top-of atmosphere upwelling shortwave and longwave fluxes (ground). Good agreement is found for other radiative fluxes. Large differences in radiative heating rate as derived from ground and satellite radar-lidar instruments and RT calculations are also found above 10 km (up to 0.35 Kday-1 for the shortwave and 0.8 Kday-1 for the longwave). Given that the ground-based and satellite estimates of cloud frequency of occurrence and radiative impact cannot be fully reconciled over Darwin, caution should be exercised when evaluating the representation of clouds and cloud-radiation interactions in large-scale models and limitations of each set of instrumentation should be considered when interpreting model-observations differences.

  20. Cloud retrievals from satellite data using optimal estimation: evaluation and application to ATSR

    Directory of Open Access Journals (Sweden)

    C. A. Poulsen

    2012-08-01

    Full Text Available Clouds play an important role in balancing the Earth's radiation budget. Hence, it is vital that cloud climatologies are produced that quantify cloud macro and micro physical parameters and the associated uncertainty. In this paper, we present an algorithm ORAC (Oxford-RAL retrieval of Aerosol and Cloud which is based on fitting a physically consistent cloud model to satellite observations simultaneously from the visible to the mid-infrared, thereby ensuring that the resulting cloud properties provide both a good representation of the short-wave and long-wave radiative effects of the observed cloud. The advantages of the optimal estimation method are that it enables rigorous error propagation and the inclusion of all measurements and any a priori information and associated errors in a rigorous mathematical framework. The algorithm provides a measure of the consistency between retrieval representation of cloud and satellite radiances. The cloud parameters retrieved are the cloud top pressure, cloud optical depth, cloud effective radius, cloud fraction and cloud phase.

    The algorithm can be applied to most visible/infrared satellite instruments. In this paper, we demonstrate the applicability to the Along-Track Scanning Radiometers ATSR-2 and AATSR. Examples of applying the algorithm to ATSR-2 flight data are presented and the sensitivity of the retrievals assessed, in particular the algorithm is evaluated for a number of simulated single-layer and multi-layer conditions. The algorithm was found to perform well for single-layer cloud except when the cloud was very thin; i.e., less than 1 optical depths. For the multi-layer cloud, the algorithm was robust except when the upper ice cloud layer is less than five optical depths. In these cases the retrieved cloud top pressure and cloud effective radius become a weighted average of the 2 layers. The sum of optical depth of multi-layer cloud is retrieved well until the cloud becomes thick

  1. Background estimation in short-wave region during determination of total sample composition by x-ray fluorescence method

    International Nuclear Information System (INIS)

    Simakov, V.A.; Kordyukov, S.V.; Petrov, E.N.

    1988-01-01

    Method of background estimation in short-wave spectral region during determination of total sample composition by X-ray fluorescence method is described. 13 types of different rocks with considerable variations of base composition and Zr, Nb, Th, U content below 7x10 -3 % are investigated. The suggested method of background accounting provides for a less statistical error of the background estimation than direct isolated measurement and reliability of its determination in a short-wave region independent on the sample base. Possibilities of suggested method for artificial mixtures conforming by the content of main component to technological concemtrates - niobium, zirconium, tantalum are estimated

  2. Cloud management and security

    CERN Document Server

    Abbadi, Imad M

    2014-01-01

    Written by an expert with over 15 years' experience in the field, this book establishes the foundations of Cloud computing, building an in-depth and diverse understanding of the technologies behind Cloud computing. In this book, the author begins with an introduction to Cloud computing, presenting fundamental concepts such as analyzing Cloud definitions, Cloud evolution, Cloud services, Cloud deployment types and highlighting the main challenges. Following on from the introduction, the book is divided into three parts: Cloud management, Cloud security, and practical examples. Part one presents the main components constituting the Cloud and federated Cloud infrastructure(e.g., interactions and deployment), discusses management platforms (resources and services), identifies and analyzes the main properties of the Cloud infrastructure, and presents Cloud automated management services: virtual and application resource management services. Part two analyzes the problem of establishing trustworthy Cloud, discuss...

  3. Preliminary Results from the First Deployment of a Tethered-Balloon Cloud Particle Imager Instrument Package in Arctic Stratus Clouds at Ny-Alesund

    Science.gov (United States)

    Lawson, P.; Stamnes, K.; Stamnes, J.; Zmarzly, P.; O'Connor, D.; Koskulics, J.; Hamre, B.

    2008-12-01

    A tethered balloon system specifically designed to collect microphysical data in mixed-phase clouds was deployed in Arctic stratus clouds during May 2008 near Ny-Alesund, Svalbard, at 79 degrees North Latitude. This is the first time a tethered balloon system with a cloud particle imager (CPI) that records high-resolution digital images of cloud drops and ice particles has been operated in cloud. The custom tether supplies electrical power to the instrument package, which in addition to the CPI houses a 4-pi short-wavelength radiometer and a met package that measures temperature, humidity, pressure, GPS position, wind speed and direction. The instrument package was profiled vertically through cloud up to altitudes of 1.6 km. Since power was supplied to the instrument package from the ground, it was possible to keep the balloon package aloft for extended periods of time, up to 9 hours at Ny- Ålesund, which was limited only by crew fatigue. CPI images of cloud drops and the sizes, shapes and degree of riming of ice particles are shown throughout vertical profiles of Arctic stratus clouds. The images show large regions of mixed-phase cloud from -8 to -2 C. The predominant ice crystal habits in these regions are needles and aggregates of needles. The amount of ice in the mixed-phase clouds varied considerably and did not appear to be a function of temperature. On some occasions, ice was observed near cloud base at -2 C with supercooled cloud above to - 8 C that was devoid of ice. Measurements of shortwave radiation are also presented. Correlations between particle distributions and radiative measurements will be analyzed to determine the effect of these Arctic stratus clouds on radiative forcing.

  4. Cloud time

    CERN Document Server

    Lockwood, Dean

    2012-01-01

    The ‘Cloud’, hailed as a new digital commons, a utopia of collaborative expression and constant connection, actually constitutes a strategy of vitalist post-hegemonic power, which moves to dominate immanently and intensively, organizing our affective political involvements, instituting new modes of enclosure, and, crucially, colonizing the future through a new temporality of control. The virtual is often claimed as a realm of invention through which capitalism might be cracked, but it is precisely here that power now thrives. Cloud time, in service of security and profit, assumes all is knowable. We bear witness to the collapse of both past and future virtuals into a present dedicated to the exploitation of the spectres of both.

  5. A Climatology of Midlatitude Continental Clouds from the ARM SGP Central Facility. Part II; Cloud Fraction and Radiative Forcing

    Science.gov (United States)

    Dong, Xiquan; Xi, Baike; Minnis, Patrick

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) central facility are analyzed for determining the variability of cloud fraction and radiative forcing at several temporal scales between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layer low (0-3 km), middle (3-6 km), and high clouds (greater than 6 km) using ARM SGP ground-based paired lidar-radar measurements. Shortwave (SW), longwave (LW), and net cloud radiative forcings (CRF) are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements. The annual averages of total, and single-layer, nonoverlapped low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Total and low cloud amounts were greatest from December through March and least during July and August. The monthly variation of high cloud amount is relatively small with a broad maximum from May to August. During winter, total cloud cover varies diurnally with a small amplitude, mid-morning maximum and early evening minimum, and during summer it changes by more than 0.14 over the daily cycle with a pronounced early evening minimum. The diurnal variations of mean single-layer cloud cover change with season and cloud height. Annual averages of all-sky, total, and single-layer high, middle, and low LW CRFs are 21.4, 40.2, 16.7, 27.2, and 55.0 Wm(sup -2), respectively; and their SW CRFs are -41.5, -77.2, -37.0, -47.0, and -90.5 Wm(sup -2). Their net CRFs range from -20 to -37 Wm(sup -2). For all-sky, total, and low clouds, the maximum negative net CRFs of -40.1, -70, and -69.5 Wm(sup -2), occur during April; while the respective minimum values of -3.9, -5.7, and -4.6 Wm(sup -2), are found during December. July is the month having maximum negative net CRF of -46.2 Wm(sup -2) for middle clouds, and May has the maximum value of -45.9 Wm(sup -2) for high clouds. An

  6. SUNYA Regional Climate Model Simulations of East Asia Summer Monsoon: Effects of Cloud Vertical Structure on the Surface Energy Balance

    Directory of Open Access Journals (Sweden)

    Wei Gong and Wei-Chyung Wang

    2007-01-01

    Full Text Available We used the State University of New York at Albany (SUNYA regional climate model to study the effect of cloud vertical distribution in affecting the surface energy balance of the East Asia summer monsoon (EASM. Simulations were conducted for the summers of 1988 and 1989, during which large contrast in the intra-seasonal cloud radiative forcing (CRF was observed at the top of the atmosphere. The model results indicate that both the high and low clouds are persistent throughout the summer months in both years. Because of large cloud water, low clouds significantly reduce the solar radiation flux reaching the surface, which nevertheless still dominate the surface energy balance, accounting for more than 50% of the surface heating. The low clouds also contribute significantly the downward longwave radiation to the surface with values strongly dependent on the cloud base temperature. The presence of low clouds effectively decreases the temperature and moisture gradients near surface, resulting in a substantial decrease in the sensible and latent heat fluxes from surface, which partially compensate the decrease of the net radiative cooling of the surface. For example, in the two days, May 8 and July 11 of 1988, the total cloud cover of 80% is simulated, but the respective low cloud cover (water was 63% (114 gm-2 and 22% (21 gm-2. As a result, the downward solar radiation is smaller by 161 Wm-2 in May 8. On the other hand, the cloud temperature was _ lower, yielding 56 Wm-2 smaller downward longwave radiation. The near surface temperature and gradient is more than _ smaller (and moisture gradient, leading to 21 and 81 Wm-2 smaller sensible heat and latent heat fluxes. It is also demonstrated that the model is capable to reproduce the intraseasonal variation of shortwave CRF, and catches the relationship between total cloud cover and SW CRF. The model results show the dominance of high cloud on the regional mean longwave CRF and low cloud on the intra

  7. The radiation budget of stratocumulus clouds measured by tethered balloon instrumentation: Variability of flux measurements

    Science.gov (United States)

    Duda, David P.; Stephens, Graeme L.; Cox, Stephen K.

    1990-01-01

    Measurements of longwave and shortwave radiation were made using an instrument package on the NASA tethered balloon during the FIRE Marine Stratocumulus experiment. Radiation data from two pairs of pyranometers were used to obtain vertical profiles of the near-infrared and total solar fluxes through the boundary layer, while a pair of pyrgeometers supplied measurements of the longwave fluxes in the cloud layer. The radiation observations were analyzed to determine heating rates and to measure the radiative energy budget inside the stratocumulus clouds during several tethered balloon flights. The radiation fields in the cloud layer were also simulated by a two-stream radiative transfer model, which used cloud optical properties derived from microphysical measurements and Mie scattering theory.

  8. Robot Towed Shortwave Infrared Camera for Specific Surface Area Retrieval of Surface Snow

    Science.gov (United States)

    Elliott, J.; Lines, A.; Ray, L.; Albert, M. R.

    2017-12-01

    Optical grain size and specific surface area are key parameters for measuring the atmospheric interactions of snow, as well as tracking metamorphosis and allowing for the ground truthing of remote sensing data. We describe a device using a shortwave infrared camera with changeable optical bandpass filters (centered at 1300 nm and 1550 nm) that can be used to quickly measure the average SSA over an area of 0.25 m^2. The device and method are compared with calculations made from measurements taken with a field spectral radiometer. The instrument is designed to be towed by a small autonomous ground vehicle, and therefore rides above the snow surface on ultra high molecular weight polyethylene (UHMW) skis.

  9. Nonlinear effects in the propagation of shortwave transverse sound in pure superconductors

    International Nuclear Information System (INIS)

    Gal'perin, Y.

    1982-01-01

    Various mechanisms are analyzed which lead to nonlinear phenomena (e.g., the dependence of the absorption coefficient and of the velocity of sound on its intensity) in the propagation of transverse shortwave sound in pure superconductors (the wavelength of the sound being much less than the mean free path of the quasiparticles). It is shown that the basic mechanism, over a wide range of superconductor parameters and of the sound intensity, is the so-called momentum nonlinearity. The latter is due to the distortion (induced by the sound wave) of the quasimomentum distribution of resonant electrons interacting with the wave. The dependences of the absorption coefficient and of the sound velocity on its intensity and on the temperature are analyzed in the vicinity of the superconducting transition point. The feasibility of an experimental study of nonlinear acoustic phenomena in the case of transverse sound is considered

  10. Developments of sausages in a z-pinch with short-wave perturbation of a boundary

    International Nuclear Information System (INIS)

    Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

    1989-01-01

    A numeric simulation of sausage evolution in z-pinch during short-wave excitation of the boundary of plasma column pinch is carried out. The simulation has shown that due to nonlinear development of sausages in a pinch plasma colomn the cavities filled with a magnetic field in a rarefied pinch plasma are formed. Simultaneously compact column of tense plasma whose temperature is much higher than the average temperature of pinch plasma column are formed on the pinch axis. In the region of inlet in the cavity plasma is radially directed due to ponderomotoric force 1/2 x jB up to velocities greatly increasing the thermal velocity of ions in a plasma column

  11. Energy and carbon balances in cheatgrass, an essay in autecology. [Shortwave radiation, radiowave radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hinds, W.T.

    1975-01-01

    An experiment to determine the fates of energy and carbon in cheatgrass (Bromus tectorum L.) was carried out on steep (40/sup 0/) north- and south-facing slopes on a small earth mound, using many small lysimeters to emulate swards of cheatgrass. Meteorological conditions and energy fluxes that were measured included air and soil temperatures, relative humidity, wind speed, incoming shortwave radiation, net all-wave radiation, heat flux to the soil, and evaporation and transpiration separately. The fate of photosynthetically fixed carbon during spring growth was determined by analysis of the plant tissues into mineral nutrients, crude protein, crude fat, crude fiber, and nitrogen-free extract (NFE) for roots, shoots, and seeds separately. (auth)

  12. Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Younkin, K; Long, CN

    2003-11-01

    Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

  13. A practical approach to compute short-wave irradiance interacting with subgrid-scale buildings

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Uwe; Frueh, Barbara [Deutscher Wetterdienst, Offenbach am Main (Germany)

    2012-08-15

    A numerical approach for the calculation of short-wave irradiances at the ground as well as the walls and roofs of buildings in an environment with unresolved built-up is presented. In this radiative parameterization scheme the properties of the unresolved built-up are assigned to settlement types which are characterized by mean values of the volume density of the buildings and their wall area density. Therefore it is named wall area approach. In the vertical direction the range of building heights may be subdivided into several layers. In the case of non-uniform building heights the shadowing of the lower roofs by the taller buildings is taken into account. The method includes the approximate calculation of sky view and sun view factors. For an idealized building arrangement it is shown that the obtained approximate factors are in good agreement with exact calculations just as for the comparison of the calculated and measured effective albedo values. For arrangements with isolated single buildings the presented wall area approach yields a better agreement with the observations than similar methods where the unresolved built-up is characterized by the aspect ratio of a representative street canyon (aspect ratio approach). In the limiting case where the built-up is well represented by an ensemble of idealized street canyons both approaches become equivalent. The presented short-wave radiation scheme is part of the microscale atmospheric model MUKLIMO 3 where it contributes to the calculation of surface temperatures on the basis of energy-flux equilibrium conditions. (orig.)

  14. Statistical retrieval of thin liquid cloud microphysical properties using ground-based infrared and microwave observations

    Science.gov (United States)

    Marke, Tobias; Ebell, Kerstin; Löhnert, Ulrich; Turner, David D.

    2016-12-01

    In this article, liquid water cloud microphysical properties are retrieved by a combination of microwave and infrared ground-based observations. Clouds containing liquid water are frequently occurring in most climate regimes and play a significant role in terms of interaction with radiation. Small perturbations in the amount of liquid water contained in the cloud can cause large variations in the radiative fluxes. This effect is enhanced for thin clouds (liquid water path, LWP cloud properties crucial. Due to large relative errors in retrieving low LWP values from observations in the microwave domain and a high sensitivity for infrared methods when the LWP is low, a synergistic retrieval based on a neural network approach is built to estimate both LWP and cloud effective radius (reff). These statistical retrievals can be applied without high computational demand but imply constraints like prior information on cloud phase and cloud layering. The neural network retrievals are able to retrieve LWP and reff for thin clouds with a mean relative error of 9% and 17%, respectively. This is demonstrated using synthetic observations of a microwave radiometer (MWR) and a spectrally highly resolved infrared interferometer. The accuracy and robustness of the synergistic retrievals is confirmed by a low bias in a radiative closure study for the downwelling shortwave flux, even for marginally invalid scenes. Also, broadband infrared radiance observations, in combination with the MWR, have the potential to retrieve LWP with a higher accuracy than a MWR-only retrieval.

  15. A Climatology of Surface Cloud Radiative Effects at the ARM Tropical Western Pacific Sites

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Long, Charles N.; Flaherty, Julia E.

    2013-04-01

    Cloud radiative effects on surface downwelling fluxes are investigated using long-term datasets from the three Atmospheric Radiation Measurement (ARM) sites in the Tropical Western Pacific (TWP) region. The Nauru and Darwin sites show significant variability in sky cover, downwelling radiative fluxes, and surface cloud radiative effect (CRE) due to El Niño and the Australian monsoon, respectively, while the Manus site shows little intra-seasonal or interannual variability. Cloud radar measurement of cloud base and top heights are used to define cloud types so that the effect of cloud type on the surface CRE can be examined. Clouds with low bases contribute 71-75% of the surface shortwave (SW) CRE and 66-74% of the surface longwave (LW) CRE at the three TWP sites, while clouds with mid-level bases contribute 8-9% of the SW CRE and 12-14% of the LW CRE, and clouds with high bases contribute 16-19% of the SW CRE and 15-21% of the LW CRE.

  16. The effect of cloud shape on radiative characteristics

    International Nuclear Information System (INIS)

    Welch, R.M.; Zdunkowski, W.G.

    1981-01-01

    Cumulus cloud radiative characteristics are calculated using Monte-Carlo codes as a function of solar zenith angle for clouds approximated by hemispherical, cylindrical and combination-type geometries. Values of cloud reflectivity, transmissivity and absorptivity are compared with values computed from assuming cubic and rectangular geometries, the basis for most previous finite cloud calculations. Poor agreement is obtained at large cloud sizes and only marginal agreement is obtained at small cloud sizes. Two approximations based upon various scalings of cloud optical depth (extinction parameters) are also constructed, but with limited success in reproducing the values produced by the convex shaped clouds. Reasonable agreement among the various approximations occurs at large solar zenith angles, but extremely poor agreement may occur at small angles. (orig./WB) [de

  17. Stationary spectra of short-wave convective and magnetostatic fluctuations in a finite-pressure plasma and anomalous heat conductivity

    International Nuclear Information System (INIS)

    Vakulenko, M.O.

    1992-01-01

    Within the general renormalized statistical approach, the low-frequency short-wave stationary spectra of potential and magnetic perturbations in a finite-pressure plasma, are obtained. Anomalous heat conductivity considerably enhances due to non-linear interaction between magnetic excitations. 11 refs. (author)

  18. Direct shortwave forcing of climate by anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Nemesure, S.; Wagener, R.; Schwartz, S.E. [Brookhaven National Lab., Upton, New York (United States)

    1996-04-01

    Recent estimates of global or hemispheric average forcing of climate by anthropogenic sulfate aerosol due to scattering of shortwave radiation are uncertain by more than a factor of 2. This paper examines the sensitivity of forcing to these microphysical properties for the purposes of obtaining a better understanding of the properties required to reduce the uncertainty in the forcing.

  19. The multispectral reflectance of shortwave radiation by agricultural crops in relation with their morphological and optical properties

    NARCIS (Netherlands)

    Bunnik, N.J.J.

    1978-01-01

    Relations between morphological properties of uniform canopies. optical properties of the leaves and reflection of shortwave radiation, in the visible light region and the near infrared, by crops are the subject of this thesis.

    The aim of the study was a further investigation of

  20. Essentials of cloud computing

    CERN Document Server

    Chandrasekaran, K

    2014-01-01

    ForewordPrefaceComputing ParadigmsLearning ObjectivesPreambleHigh-Performance ComputingParallel ComputingDistributed ComputingCluster ComputingGrid ComputingCloud ComputingBiocomputingMobile ComputingQuantum ComputingOptical ComputingNanocomputingNetwork ComputingSummaryReview PointsReview QuestionsFurther ReadingCloud Computing FundamentalsLearning ObjectivesPreambleMotivation for Cloud ComputingThe Need for Cloud ComputingDefining Cloud ComputingNIST Definition of Cloud ComputingCloud Computing Is a ServiceCloud Computing Is a Platform5-4-3 Principles of Cloud computingFive Essential Charact

  1. Cloud Feedbacks on Greenhouse Warming in a Multi-Scale Modeling Framework with a Higher-Order Turbulence Closure

    Science.gov (United States)

    Cheng, Anning; Xu, Kuan-Man

    2015-01-01

    Five-year simulation experiments with a multi-scale modeling Framework (MMF) with a advanced intermediately prognostic higher-order turbulence closure (IPHOC) in its cloud resolving model (CRM) component, also known as SPCAM-IPHOC (super parameterized Community Atmospheric Model), are performed to understand the fast tropical (30S-30N) cloud response to an instantaneous doubling of CO2 concentration with SST held fixed at present-day values. SPCAM-IPHOC has substantially improved the low-level representation compared with SPCAM. It is expected that the cloud responses to greenhouse warming in SPCAM-IPHOC is more realistic. The change of rising motion, surface precipitation, cloud cover, and shortwave and longwave cloud radiative forcing in SPCAM-IPHOC from the greenhouse warming will be presented in the presentation.

  2. Neuroglial Transmission

    DEFF Research Database (Denmark)

    Gundersen, Vidar; Storm-Mathisen, Jon; Bergersen, Linda Hildegard

    2015-01-01

    as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates...... synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies....

  3. Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

    KAUST Repository

    Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

    2015-01-01

    Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL's High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

  4. Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

    KAUST Repository

    Bangalath, Hamza Kunhu

    2015-04-01

    Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL\\'s High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

  5. Cloud Computing, Tieto Cloud Server Model

    OpenAIRE

    Suikkanen, Saara

    2013-01-01

    The purpose of this study is to find out what is cloud computing. To be able to make wise decisions when moving to cloud or considering it, companies need to understand what cloud is consists of. Which model suits best to they company, what should be taken into account before moving to cloud, what is the cloud broker role and also SWOT analysis of cloud? To be able to answer customer requirements and business demands, IT companies should develop and produce new service models. IT house T...

  6. Blue skies for CLOUD

    CERN Multimedia

    2006-01-01

    Through the recently approved CLOUD experiment, CERN will soon be contributing to climate research. Tests are being performed on the first prototype of CLOUD, an experiment designed to assess cosmic radiation influence on cloud formation.

  7. Mapping the Distribution of Cloud Forests Using MODIS Imagery

    Science.gov (United States)

    Douglas, M. W.; Mejia, J.; Murillo, J.; Orozco, R.

    2007-05-01

    Tropical cloud forests - those forests that are frequently immersed in clouds or otherwise very humid, are extremely difficult to map from the ground, and are not easily distinguished in satellite imagery from other forest types, but they have a very different flora and fauna than lowland rainforest. Cloud forests, although found in many parts of the tropics, have a very restricted vertical extent and thus are also restricted horizontally. As a result, they are subject to both human disturbance (coffee growing for example) and the effects of possible climate change. Motivated by a desire to seek meteorological explanations for the distribution of cloud forests, we have begun to map cloudiness using MODIS Terra and Aqua visible imagery. This imagery, at ~1030 LT and 1330 LT, is an approximation for mid-day cloudiness. In tropical regions the amount of mid-day cloudiness strongly controls the shortwave radiation and thus the potential for evaporation (and aridity). We have mapped cloudiness using a simple algorithm that distinguishes between the cloud-free background brightness and the generally more reflective clouds to separate clouds from the underlying background. A major advantage of MODIS imagery over many other sources of satellite imagery is its high spatial resolution (~250m). This, coupled with precisely navigated images, means that detailed maps of cloudiness can be produced. The cloudiness maps can then be related to the underlying topography to further refine the location of the cloud forests. An advantage of this technique is that we are mapping the potential cloud forest, based on cloudiness, rather than the actual cloud forest, which are commonly based on forest estimates from satellite and digital elevation data. We do not derive precipitation, only estimates of daytime cloudiness. Although only a few years of MODIS imagery has been used in our studies, we will show that this is sufficient to describe the climatology of cloudiness with acceptable

  8. Improving Estimates of Cloud Radiative Forcing over Greenland

    Science.gov (United States)

    Wang, W.; Zender, C. S.

    2014-12-01

    Multiple driving mechanisms conspire to increase melt extent and extreme melt events frequency in the Arctic: changing heat transport, shortwave radiation (SW), and longwave radiation (LW). Cloud Radiative Forcing (CRF) of Greenland's surface is amplified by a dry atmosphere and by albedo feedback, making its contribution to surface melt even more variable in time and space. Unfortunately accurate cloud observations and thus CRF estimates are hindered by Greenland's remoteness, harsh conditions, and low contrast between surface and cloud reflectance. In this study, cloud observations from satellites and reanalyses are ingested into and evaluated within a column radiative transfer model. An improved CRF dataset is obtained by correcting systematic discrepancies derived from sensitivity experiments. First, we compare the surface radiation budgets from the Column Radiation Model (CRM) driven by different cloud datasets, with surface observations from Greenland Climate Network (GC-Net). In clear skies, CRM-estimated surface radiation driven by water vapor profiles from both AIRS and MODIS during May-Sept 2010-2012 are similar, stable, and reliable. For example, although AIRS water vapor path exceeds MODIS by 1.4 kg/m2 on a daily average, the overall absolute difference in downwelling SW is CRM estimates are within 20 W/m2 range of GC-Net downwelling SW. After calibrating CRM in clear skies, the remaining differences between CRM and observed surface radiation are primarily attributable to differences in cloud observations. We estimate CRF using cloud products from MODIS and from MERRA. The SW radiative forcing of thin clouds is mainly controlled by cloud water path (CWP). As CWP increases from near 0 to 200 g/m2, the net surface SW drops from over 100 W/m2 to 30 W/m2 almost linearly, beyond which it becomes relatively insensitive to CWP. The LW is dominated by cloud height. For clouds at all altitudes, the lower the clouds, the greater the LW forcing. By applying

  9. The Dependence of Cloud Property Trend Detection on Absolute Calibration Accuracy of Passive Satellite Sensors

    Science.gov (United States)

    Shea, Y.; Wielicki, B. A.; Sun-Mack, S.; Minnis, P.; Zelinka, M. D.

    2016-12-01

    Detecting trends in climate variables on global, decadal scales requires highly accurate, stable measurements and retrieval algorithms. Trend uncertainty depends on its magnitude, natural variability, and instrument and retrieval algorithm accuracy and stability. We applied a climate accuracy framework to quantify the impact of absolute calibration on cloud property trend uncertainty. The cloud properties studied were cloud fraction, effective temperature, optical thickness, and effective radius retrieved using the Clouds and the Earth's Radiant Energy System (CERES) Cloud Property Retrieval System, which uses Moderate-resolution Imaging Spectroradiometer measurements (MODIS). Modeling experiments from the fifth phase of the Climate Model Intercomparison Project (CMIP5) agree that net cloud feedback is likely positive but disagree regarding its magnitude, mainly due to uncertainty in shortwave cloud feedback. With the climate accuracy framework we determined the time to detect trends for instruments with various calibration accuracies. We estimated a relationship between cloud property trend uncertainty, cloud feedback, and Equilibrium Climate Sensitivity and also between effective radius trend uncertainty and aerosol indirect effect trends. The direct relationship between instrument accuracy requirements and climate model output provides the level of instrument absolute accuracy needed to reduce climate model projection uncertainty. Different cloud types have varied radiative impacts on the climate system depending on several attributes, such as their thermodynamic phase, altitude, and optical thickness. Therefore, we also conducted these studies by cloud types for a clearer understanding of instrument accuracy requirements needed to detect changes in their cloud properties. Combining this information with the radiative impact of different cloud types helps to prioritize among requirements for future satellite sensors and understanding the climate detection

  10. Relative spectral absorption of solar radiation by water vapor and cloud droplets

    Science.gov (United States)

    Davies, R.; Ridgway, W. L.

    1983-01-01

    A moderate (20/cm) spectral resolution model which accounts for both the highly variable spectral transmission of solar radiation through water vapor within and above cloud, as well as the more slowly varying features of absorption and anisotropic multiple scattering by the cloud droplets, is presented. Results from this model as applied to the case of a typical 1 km thick stratus cloud in a standard atmosphere, with cloud top altitude of 2 km and overhead sun, are discussed, showing the relative importance of water vapor above the cloud, water vapor within the cloud, and cloud droplets on the spectral absorption of solar radiation.

  11. Moving towards Cloud Security

    OpenAIRE

    Edit Szilvia Rubóczki; Zoltán Rajnai

    2015-01-01

    Cloud computing hosts and delivers many different services via Internet. There are a lot of reasons why people opt for using cloud resources. Cloud development is increasing fast while a lot of related services drop behind, for example the mass awareness of cloud security. However the new generation upload videos and pictures without reason to a cloud storage, but only few know about data privacy, data management and the proprietary of stored data in the cloud. In an enterprise environment th...

  12. Cloud-Top Entrainment in Stratocumulus Clouds

    Science.gov (United States)

    Mellado, Juan Pedro

    2017-01-01

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

  13. Cloud Infrastructure & Applications - CloudIA

    Science.gov (United States)

    Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

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

  14. A Characterization of Cirrus Cloud Properties That Affect Laser Propagation

    National Research Council Canada - National Science Library

    Norquist, Donald C; Desrochers, Paul R; McNicholl, Patrick J; Roadcap, John R

    2008-01-01

    Future high-altitude laser systems may be affected by cirrus clouds. Laser transmission models were applied to measured and retrieved cirrus properties to determine cirrus impact on power incident on a target or receiver...

  15. Silicon Photonics Cloud (SiCloud)

    DEFF Research Database (Denmark)

    DeVore, P. T. S.; Jiang, Y.; Lynch, M.

    2015-01-01

    Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

  16. Diurnal, Seasonal, and Interannual Variations of Cloud Properties Derived for CERES From Imager Data

    Science.gov (United States)

    Minnis, Patrick; Young, David F.; Sun-Mack, Sunny; Trepte, Qing Z.; Chen, Yan; Brown, Richard R.; Gibson, Sharon; Heck, Patrick W.

    2004-01-01

    Simultaneous measurement of the radiation and cloud fields on a global basis is a key component in the effort to understand and model the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project, begun in 1998, is meeting this need. Broadband shortwave (SW) and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth OD from the TRMM Visible Infrared Scanner (VIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Besides aiding the interpretation of the broadband radiances, the CERES cloud properties are valuable for understanding cloud variations at a variety of scales. In this paper, the resulting CERES cloud data taken to date are averaged at several temporal scales to examine the temporal and spatial variability of the cloud properties on a global scale at a 1 resolution.

  17. A novel method for surface defect inspection of optic cable with short-wave infrared illuminance

    Science.gov (United States)

    Chen, Xiaohong; Liu, Ning; You, Bo; Xiao, Bin

    2016-07-01

    Intelligent on-line detection of cable quality is a crucial issue in optic cable factory, and defects on the surface of optic cable can dramatically depress cable grade. Manual inspection in optic cable quality cannot catch up with the development of optic cable industry due to its low detection efficiency and huge human cost. Therefore, real-time is highly demanded by industry in order to replace the subjective and repetitive process of manual inspection. For this reason, automatic cable defect inspection has been a trend. In this paper, a novel method for surface defect inspection of optic cable with short-wave infrared illuminance is presented. The special condition of short-wave infrared cannot only provide illumination compensation for the weak illumination environment, but also can avoid the problem of exposure when using visible light illuminance, which affects the accuracy of inspection algorithm. A series of image processing algorithms are set up to analyze cable image for the verification of real-time and veracity of the detection method. Unlike some existing detection algorithms which concentrate on the characteristics of defects with an active search way, the proposed method removes the non-defective areas of the image passively at the same time of image processing, which reduces a large amount of computation. OTSU algorithm is used to convert the gray image to the binary image. Furthermore, a threshold window is designed to eliminate the fake defects, and the threshold represents the considered minimum size of defects ε . Besides, a new regional suppression method is proposed to deal with the edge burrs of the cable, which shows the superior performance compared with that of Open-Close operation of mathematical morphological in the boundary processing. Experimental results of 10,000 samples show that the rates of miss detection and false detection are 2.35% and 0.78% respectively when ε equals to 0.5 mm, and the average processing period of one frame

  18. Leaf temperature and transpiration of rice plants in relation to short-wave radiation and wind speed

    International Nuclear Information System (INIS)

    Ito, D.; Haseba, T.

    1984-01-01

    Leaf temperature and transpiration amount of rice plants were measured in a steady environment in a laboratory and in field situations. The plants set in Wagner pots were used. Experiments were carried out at the tillering and booting stages, and on the date of maturity. Measured leaf temperatures and transpiration rates were analyzed in connection with incident short-wave radiation on a leaf and wind speed measured simultaneously.Instantaneous supplying and turning-off of steady artificial light caused cyclic changes in leaf temperature and transpiration. Leaf temperature dropped in feeble illumination compared with the steady temperature in the preceeding dark.On the date of maturity, a rice plant leaf was warmer than the air, even in feeble light. Then, the leaf-air temperature difference and transpiration rate showed approximately linear increases with short-wave radiation intensity. On the same date, an increase in wind speed produced a decrease in leaf-air temperature difference, i.e., leaf temperature dropped, and an increase in transpiration rate. The rates of both changes in leaf temperature and transpiration rate were fairly large in a range of wind speed below about 1m/s.For rice plants growing favorably from the tillering stage through the booting stage, the leaves were considerably cooler than the air, even in an intense light and/or solar radiation. The leaf temperature showed the lowest value at short-wave radiations between 0.15 and 0.20ly/min, at above which the leaf temperature rised with an increase in short-wave radiation until it approached the air temperature. Transpiration rate of rice plants increased rapidly with an increase in short-wave radiation ranging below 0.2 or 0.3ly/min, at above which the increase in transpiration rate slowed.The relationships between leaf temperature and/or transpiration rate and wind speed and/or incident short-wave radiation (solar radiation) which were obtained experimentally, supported the relationships

  19. Monte Carlo-based subgrid parameterization of vertical velocity and stratiform cloud microphysics in ECHAM5.5-HAM2

    Directory of Open Access Journals (Sweden)

    J. Tonttila

    2013-08-01

    Full Text Available A new method for parameterizing the subgrid variations of vertical velocity and cloud droplet number concentration (CDNC is presented for general circulation models (GCMs. These parameterizations build on top of existing parameterizations that create stochastic subgrid cloud columns inside the GCM grid cells, which can be employed by the Monte Carlo independent column approximation approach for radiative transfer. The new model version adds a description for vertical velocity in individual subgrid columns, which can be used to compute cloud activation and the subgrid distribution of the number of cloud droplets explicitly. Autoconversion is also treated explicitly in the subcolumn space. This provides a consistent way of simulating the cloud radiative effects with two-moment cloud microphysical properties defined at subgrid scale. The primary impact of the new parameterizations is to decrease the CDNC over polluted continents, while over the oceans the impact is smaller. Moreover, the lower CDNC induces a stronger autoconversion of cloud water to rain. The strongest reduction in CDNC and cloud water content over the continental areas promotes weaker shortwave cloud radiative effects (SW CREs even after retuning the model. However, compared to the reference simulation, a slightly stronger SW CRE is seen e.g. over mid-latitude oceans, where CDNC remains similar to the reference simulation, and the in-cloud liquid water content is slightly increased after retuning the model.

  20. 3D Cloud Radiative Effects on Polarized Reflectances

    Science.gov (United States)

    Cornet, C.; Matar, C.; C-Labonnote, L.; Szczap, F.; Waquet, F.; Parol, F.; Riedi, J.

    2017-12-01

    As recognized in the last IPCC report, clouds have a major importance in the climate budget and need to be better characterized. Remote sensing observations are a way to obtain either global observations of cloud from satellites or a very fine description of clouds from airborne measurements. An increasing numbers of radiometers plan to measure polarized reflectances in addition to total reflectances, since this information is very helpful to obtain aerosol or cloud properties. In a near future, for example, the Multi-viewing, Multi-channel, Multi-polarization Imager (3MI) will be part the EPS-SG Eumetsat-ESA mission. It will achieve multi-angular polarimetric measurements from visible to shortwave infrared wavelengths. An airborne prototype, OSIRIS (Observing System Including Polarization in the Solar Infrared Spectrum), is also presently developed at the Laboratoire d'Optique Atmospherique and had already participated to several measurements campaigns. In order to analyze suitably the measured signal, it it necessary to have realistic and accurate models able to simulate polarized reflectances. The 3DCLOUD model (Szczap et al., 2014) was used to generate three-dimensional synthetic cloud and the 3D radiative transfer model, 3DMCPOL (Cornet et al., 2010) to compute realistic polarized reflectances. From these simulations, we investigate the effects of 3D cloud structures and heterogeneity on the polarized angular signature often used to retrieve cloud or aerosol properties. We show that 3D effects are weak for flat clouds but become quite significant for fractional clouds above ocean. The 3D effects are quite different according to the observation scale. For the airborne scale (few tens of meter), solar illumination effects can lead to polarized cloud reflectance values higher than the saturation limit predicted by the homogeneous cloud assumption. In the cloud gaps, corresponding to shadowed areas of the total reflectances, polarized signal can also be enhanced

  1. Transmission issues

    International Nuclear Information System (INIS)

    Bradford, J.; Wilson, L.; Thon, S.; Millar, N.

    2005-01-01

    This session on transmission issues focused on the role that transmission plays in electricity markets and the importance of getting the market structure right in terms of generation divestiture with buy back contracts, demand side responsive programs, transmission upgrades and long term contracts. The difficulties of distinguishing between market power and scarcity were examined along with some of the complications that ensue if transmission experiences congestion, as exemplified by the August 2003 blackout in eastern North America. The presentations described the best ways to handle transmission issues, and debated whether transmission should be deregulated or follow market forces. Issues of interconnections and reliability of connections were also debated along with the attempt to integrate renewables into the grid. Some presentations identified what new transmission must be built and what must be done to ensure that transmission gets built. The challenges and business opportunities for transmission in Alberta were discussed with reference to plans to invest in new infrastructure, where it is going outside of the province and how it works with other jurisdictions. Manitoba's Conawapa Hydro Project and its 2000 MW tie line to Ontario was also discussed. Some examples of non-optimal use of interconnections in Europe were also discussed in an effort to learn from these mistakes and avoid them in Canada. tabs., figs

  2. The MODIS cloud optical and microphysical products: Collection 6 updates and examples from Terra and Aqua

    Science.gov (United States)

    Platnick, Steven; Meyer, Kerry G.; King, Michael D.; Wind, Galina; Amarasinghe, Nandana; Marchant, Benjamin; Arnold, G. Thomas; Zhang, Zhibo; Hubanks, Paul A.; Holz, Robert E.; Yang, Ping; Ridgway, William L.; Riedi, Jérôme

    2018-01-01

    The MODIS Level-2 cloud product (Earth Science Data Set names MOD06 and MYD06 for Terra and Aqua MODIS, respectively) provides pixel-level retrievals of cloud-top properties (day and night pressure, temperature, and height) and cloud optical properties (optical thickness, effective particle radius, and water path for both liquid water and ice cloud thermodynamic phases–daytime only). Collection 6 (C6) reprocessing of the product was completed in May 2014 and March 2015 for MODIS Aqua and Terra, respectively. Here we provide an overview of major C6 optical property algorithm changes relative to the previous Collection 5 (C5) product. Notable C6 optical and microphysical algorithm changes include: (i) new ice cloud optical property models and a more extensive cloud radiative transfer code lookup table (LUT) approach, (ii) improvement in the skill of the shortwave-derived cloud thermodynamic phase, (iii) separate cloud effective radius retrieval datasets for each spectral combination used in previous collections, (iv) separate retrievals for partly cloudy pixels and those associated with cloud edges, (v) failure metrics that provide diagnostic information for pixels having observations that fall outside the LUT solution space, and (vi) enhanced pixel-level retrieval uncertainty calculations. The C6 algorithm changes collectively can result in significant changes relative to C5, though the magnitude depends on the dataset and the pixel’s retrieval location in the cloud parameter space. Example Level-2 granule and Level-3 gridded dataset differences between the two collections are shown. While the emphasis is on the suite of cloud optical property datasets, other MODIS cloud datasets are discussed when relevant. PMID:29657349

  3. Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC).

    Science.gov (United States)

    Meyer, Kerry; Yang, Yuekui; Platnick, Steven

    2016-01-01

    This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

  4. [Bare Soil Moisture Inversion Model Based on Visible-Shortwave Infrared Reflectance].

    Science.gov (United States)

    Zheng, Xiao-po; Sun, Yue-jun; Qin, Qi-ming; Ren, Hua-zhong; Gao, Zhong-ling; Wu, Ling; Meng, Qing-ye; Wang, Jin-liang; Wang, Jian-hua

    2015-08-01

    Soil is the loose solum of land surface that can support plants. It consists of minerals, organics, atmosphere, moisture, microbes, et al. Among its complex compositions, soil moisture varies greatly. Therefore, the fast and accurate inversion of soil moisture by using remote sensing is very crucial. In order to reduce the influence of soil type on the retrieval of soil moisture, this paper proposed a normalized spectral slope and absorption index named NSSAI to estimate soil moisture. The modeling of the new index contains several key steps: Firstly, soil samples with different moisture level were artificially prepared, and soil reflectance spectra was consequently measured using spectroradiometer produced by ASD Company. Secondly, the moisture absorption spectral feature located at shortwave wavelengths and the spectral slope of visible wavelengths were calculated after analyzing the regular spectral feature change patterns of different soil at different moisture conditions. Then advantages of the two features at reducing soil types' effects was synthesized to build the NSSAI. Thirdly, a linear relationship between NSSAI and soil moisture was established. The result showed that NSSAI worked better (correlation coefficient is 0.93) than most of other traditional methods in soil moisture extraction. It can weaken the influences caused by soil types at different moisture levels and improve the bare soil moisture inversion accuracy.

  5. Nitrogen deficiency detection using reflected shortwave radiation from irrigated corn canopies

    International Nuclear Information System (INIS)

    Blackmer, T.M.; Schepers, J.S.; Varvel, G.E.; Walter-Shea, E.A.

    1996-01-01

    Techniques that measure the N status of corn (Zea mays L.) can aid in management decisions that have economic and environmental implications. This study was conducted to identify reflected electromagnetic wavelengths most sensitive to detecting N deficiencies in a corn canopy with the possibility for use as a management tool. Reflected shortwave radiation was measured from an irrigated corn N response trial with four hybrids and five N rates at 0, 40, 80, 120, and 160 kg N ha -1 in 1992 and 0, 50, 100, 150, and 200 kg N ha -1 in 1993. A portable spectroradiometer was used to measure reflected radiation (400-1100 nm in 1992, 350-1050 nm in 1993) from corn canopies at approximately the R5 growth stage. Regression analyses revealed that reflected radiation near 550 and 710 nm was superior to reflected radiation near 450 or 650 nm for detecting N deficiencies. The ratio of light reflectance between 550 and 600 nm to light reflectance between 800 and 900 nm also provided sensitive detection of N stress. In 1993, an inexpensive photometric cell, which has peak sensitivity to light centered at 550 nm, was also used to measure reflected radiation from a corn canopy. Photometric cell readings correlated with relative grain yield (P < 0.001, r 2 = 0.74), but more research will be required to develop procedures to account for varying daylight conditions. These results provide information needed for the development of variable-rate fertilizer N application technology. (author)

  6. Explicit validation of a surface shortwave radiation balance model over snow-covered complex terrain

    Science.gov (United States)

    Helbig, N.; Löwe, H.; Mayer, B.; Lehning, M.

    2010-09-01

    A model that computes the surface radiation balance for all sky conditions in complex terrain is presented. The spatial distribution of direct and diffuse sky radiation is determined from observations of incident global radiation, air temperature, and relative humidity at a single measurement location. Incident radiation under cloudless sky is spatially derived from a parameterization of the atmospheric transmittance. Direct and diffuse sky radiation for all sky conditions are obtained by decomposing the measured global radiation value. Spatial incident radiation values under all atmospheric conditions are computed by adjusting the spatial radiation values obtained from the parametric model with the radiation components obtained from the decomposition model at the measurement site. Topographic influences such as shading are accounted for. The radiosity approach is used to compute anisotropic terrain reflected radiation. Validations of the shortwave radiation balance model are presented in detail for a day with cloudless sky. For a day with overcast sky a first validation is presented. Validation of a section of the horizon line as well as of individual radiation components is performed with high-quality measurements. A new measurement setup was designed to determine terrain reflected radiation. There is good agreement between the measurements and the modeled terrain reflected radiation values as well as with incident radiation values. A comparison of the model with a fully three-dimensional radiative transfer Monte Carlo model is presented. That validation reveals a good agreement between modeled radiation values.

  7. Penetrating Shortwave Radiation and Sea Ice Algae feedbacks using the Community Earth System Model

    Science.gov (United States)

    Arntsen, A. E.; Perovich, D. K.; Bailey, D. A.; Holland, M. M.

    2017-12-01

    Transmittance of solar radiation through the sea ice cover determines energy transfer to the upper ocean in the form of heat as well as photosynthetically active radiation (PAR) available for the growth of under ice phytoplankton and bottom ice algal communities. A thinning ice cover, increased pond coverage, and earlier melt onset has increased light availability to the upper ocean in contemporary Arctic ice-covered waters. To investigate seasonal and spatial variability of solar shortwave irradiance penetrating the ice cover in the Beaufort and Chukchi Sea regions, we use the fully coupled Community Earth System Model (CESM) in conjunction with a multistream radiative transfer model constrained and initiated by in situ observations. Results inform the importance of light attenuation by ice-based algal pigments within large scale global climate models. We demonstrate the presence of bio-optical feedbacks related to a younger ice cover and examine how these relationships are impacting the trajectory of under ice blooms and the energy budget of the ice-ocean system.

  8. Short-Wave Near-Infrared Spectrometer for Alcohol Determination and Temperature Correction

    Directory of Open Access Journals (Sweden)

    Qingbo Fu

    2012-01-01

    Full Text Available A multichannel short-wave near-infrared (SW-NIR spectrometer module based on charge-coupled device (CCD detection was designed. The design relied on a tungsten lamp enhanced by light emitting diodes, a fixed grating monochromator and a linear CCD array. The main advantages were high optical resolution and an optimized signal-to-noise ratio (0.24 nm and 500, resp. in the whole wavelength range of 650 to 1100 nm. An application to alcohol determination using partial least squares calibration and the temperature correction was presented. It was found that the direct transfer method had significant systematic prediction errors due to temperature effect. Generalized least squares weighting (GLSW method was utilized for temperature correction. After recalibration, the RMSEP found for the 25°C model was 0.53% v/v and errors of the same order of magnitude were obtained at other temperatures (15, 35 and 40°C. And an 2 better than 0.99 was achieved for each validation set. The possibility and accuracy of using the miniature SW-NIR spectrometer and GLSW transfer calibration method for alcohol determination at different temperatures were proven. And the analysis procedure was simple and fast, allowing a strict control of alcohol content in the wine industry.

  9. Analytic Approximations for Soliton Solutions of Short-Wave Models for Camassa-Holm and Degasperis-Procesi Equations

    International Nuclear Information System (INIS)

    Yang Pei; Li Zhibin; Chen Yong

    2010-01-01

    In this paper, the short-wave model equations are investigated, which are associated with the Camassa-Holm (CH) and Degasperis-Procesi (DP) shallow-water wave equations. Firstly, by means of the transformation of the independent variables and the travelling wave transformation, the partial differential equation is reduced to an ordinary differential equation. Secondly, the equation is solved by homotopy analysis method. Lastly, by the transformations back to the original independent variables, the solution of the original partial differential equation is obtained. The two types of solutions of the short-wave models are obtained in parametric form, one is one-cusp soliton for the CH equation while the other one is one-loop soliton for the DP equation. The approximate analytic solutions expressed by a series of exponential functions agree well with the exact solutions. It demonstrates the validity and great potential of homotopy analysis method for complicated nonlinear solitary wave problems. (general)

  10. Spectral cumulus parameterization based on cloud-resolving model

    Science.gov (United States)

    Baba, Yuya

    2018-02-01

    We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.

  11. Transmission eigenvalues

    Science.gov (United States)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  12. The CLOUD experiment

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    The Cosmics Leaving Outdoor Droplets (CLOUD) experiment as shown by Jasper Kirkby (spokesperson). Kirkby shows a sketch to illustrate the possible link between galactic cosmic rays and cloud formations. The CLOUD experiment uses beams from the PS accelerator at CERN to simulate the effect of cosmic rays on cloud formations in the Earth's atmosphere. It is thought that cosmic ray intensity is linked to the amount of low cloud cover due to the formation of aerosols, which induce condensation.

  13. BUSINESS INTELLIGENCE IN CLOUD

    OpenAIRE

    Celina M. Olszak

    2014-01-01

    . The paper reviews and critiques current research on Business Intelligence (BI) in cloud. This review highlights that organizations face various challenges using BI cloud. The research objectives for this study are a conceptualization of the BI cloud issue, as well as an investigation of some benefits and risks from BI cloud. The study was based mainly on a critical analysis of literature and some reports on BI cloud using. The results of this research can be used by IT and business leaders ...

  14. Cloud Robotics Platforms

    Directory of Open Access Journals (Sweden)

    Busra Koken

    2015-01-01

    Full Text Available Cloud robotics is a rapidly evolving field that allows robots to offload computation-intensive and storage-intensive jobs into the cloud. Robots are limited in terms of computational capacity, memory and storage. Cloud provides unlimited computation power, memory, storage and especially collaboration opportunity. Cloud-enabled robots are divided into two categories as standalone and networked robots. This article surveys cloud robotic platforms, standalone and networked robotic works such as grasping, simultaneous localization and mapping (SLAM and monitoring.

  15. Cloud Processed CCN Suppress Stratus Cloud Drizzle

    Science.gov (United States)

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

    2017-12-01

    Conversion of sulfur dioxide to sulfate within cloud droplets increases the sizes and decreases the critical supersaturation, Sc, of cloud residual particles that had nucleated the droplets. Since other particles remain at the same sizes and Sc a size and Sc gap is often observed. Hudson et al. (2015) showed higher cloud droplet concentrations (Nc) in stratus clouds associated with bimodal high-resolution CCN spectra from the DRI CCN spectrometer compared to clouds associated with unimodal CCN spectra (not cloud processed). Here we show that CCN spectral shape (bimodal or unimodal) affects all aspects of stratus cloud microphysics and drizzle. Panel A shows mean differential cloud droplet spectra that have been divided according to traditional slopes, k, of the 131 measured CCN spectra in the Marine Stratus/Stratocumulus Experiment (MASE) off the Central California coast. K is generally high within the supersaturation, S, range of stratus clouds (< 0.5%). Because cloud processing decreases Sc of some particles, it reduces k. Panel A shows higher concentrations of small cloud droplets apparently grown on lower k CCN than clouds grown on higher k CCN. At small droplet sizes the concentrations follow the k order of the legend, black, red, green, blue (lowest to highest k). Above 13 µm diameter the lines cross and the hierarchy reverses so that blue (highest k) has the highest concentrations followed by green, red and black (lowest k). This reversed hierarchy continues into the drizzle size range (panel B) where the most drizzle drops, Nd, are in clouds grown on the least cloud-processed CCN (blue), while clouds grown on the most processed CCN (black) have the lowest Nd. Suppression of stratus cloud drizzle by cloud processing is an additional 2nd indirect aerosol effect (IAE) that along with the enhancement of 1st IAE by higher Nc (panel A) are above and beyond original IAE. However, further similar analysis is needed in other cloud regimes to determine if MASE was

  16. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part II; Cloud Fraction and Surface Radiative Forcing

    Science.gov (United States)

    Xi, B.; Minnis, P.

    2006-01-01

    Data collected at the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Central Facility (SCF) are analyzed to determine the monthly and hourly variations of cloud fraction and radiative forcing between January 1997 and December 2002. Cloud fractions are estimated for total cloud cover and for single-layered low (0-3 km), middle (3-6 km), and high clouds (more than 6 km) using ARM SCG ground-based paired lidar-radar measurements. Shortwave (SW) and longwave (LW) fluxes are derived from up- and down-looking standard precision spectral pyranometers and precision infrared radiometer measurements with uncertainties of approximately 10 Wm(exp -2). The annual averages of total, and single-layered low, middle and high cloud fractions are 0.49, 0.11, 0.03, and 0.17, respectively. Both total and low cloud amounts peak during January and February and reach a minimum during July and August, high clouds occur more frequently than other types of clouds with a peak in summer. The average annual downwelling surface SW fluxes for total and low clouds (151 and 138 Wm(exp-2), respectively) are less than those under middle and high clouds (188 and 201 Wm(exp -2), respectively), but the downwelling LW fluxes (349 and 356 Wm(exp -2)) underneath total and low clouds are greater than those from middle and high clouds (337 and 333 Wm(exp -2)). Low clouds produce the largest LW warming (55 Wm(exp -2) and SW cooling (-91 Wm(exp -2)) effects with maximum and minimum absolute values in spring and summer, respectively. High clouds have the smallest LW warming (17 Wm(exp -2)) and SW cooling (-37 Wm(exp -2)) effects at the surface. All-sky SW CRF decreases and LW CRF increases with increasing cloud fraction with mean slopes of -0.984 and 0.616 Wm(exp -2)%(exp -1), respectively. Over the entire diurnal cycle, clouds deplete the amount of surface insolation more than they add to the downwelling LW flux. The calculated CRFs do not appear to be significantly

  17. Quantifying Transmission.

    Science.gov (United States)

    Woolhouse, Mark

    2017-07-01

    Transmissibility is the defining characteristic of infectious diseases. Quantifying transmission matters for understanding infectious disease epidemiology and designing evidence-based disease control programs. Tracing individual transmission events can be achieved by epidemiological investigation coupled with pathogen typing or genome sequencing. Individual infectiousness can be estimated by measuring pathogen loads, but few studies have directly estimated the ability of infected hosts to transmit to uninfected hosts. Individuals' opportunities to transmit infection are dependent on behavioral and other risk factors relevant given the transmission route of the pathogen concerned. Transmission at the population level can be quantified through knowledge of risk factors in the population or phylogeographic analysis of pathogen sequence data. Mathematical model-based approaches require estimation of the per capita transmission rate and basic reproduction number, obtained by fitting models to case data and/or analysis of pathogen sequence data. Heterogeneities in infectiousness, contact behavior, and susceptibility can have substantial effects on the epidemiology of an infectious disease, so estimates of only mean values may be insufficient. For some pathogens, super-shedders (infected individuals who are highly infectious) and super-spreaders (individuals with more opportunities to transmit infection) may be important. Future work on quantifying transmission should involve integrated analyses of multiple data sources.

  18. Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate

    Science.gov (United States)

    Palm, Stephen P.; Strey, Sara T.; Spinhirne, James; Markus, Thorsten

    2010-01-01

    Recent satellite lidar measurements of cloud properties spanning a period of 5 years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anticorrelation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice!free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7% and 10%, respectively, as year average sea ice extent has decreased by 5% 7%. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Because longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

  19. The Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate

    Science.gov (United States)

    Palm, Stephen P.; Strey, Sara T.; Spinhirne, James; Markus, Thorsten

    2010-01-01

    Recent satellite lidar measurements of cloud properties spanning a period of five years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anti-correlation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7 and 10 percent, respectively, as year average sea ice extent has decreased by 5 to 7 percent. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Since longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

  20. Global model comparison of heterogeneous ice nucleation parameterizations in mixed phase clouds

    Science.gov (United States)

    Yun, Yuxing; Penner, Joyce E.

    2012-04-01

    A new aerosol-dependent mixed phase cloud parameterization for deposition/condensation/immersion (DCI) ice nucleation and one for contact freezing are compared to the original formulations in a coupled general circulation model and aerosol transport model. The present-day cloud liquid and ice water fields and cloud radiative forcing are analyzed and compared to observations. The new DCI freezing parameterization changes the spatial distribution of the cloud water field. Significant changes are found in the cloud ice water fraction and in the middle cloud fractions. The new DCI freezing parameterization predicts less ice water path (IWP) than the original formulation, especially in the Southern Hemisphere. The smaller IWP leads to a less efficient Bergeron-Findeisen process resulting in a larger liquid water path, shortwave cloud forcing, and longwave cloud forcing. It is found that contact freezing parameterizations have a greater impact on the cloud water field and radiative forcing than the two DCI freezing parameterizations that we compared. The net solar flux at top of atmosphere and net longwave flux at the top of the atmosphere change by up to 8.73 and 3.52 W m-2, respectively, due to the use of different DCI and contact freezing parameterizations in mixed phase clouds. The total climate forcing from anthropogenic black carbon/organic matter in mixed phase clouds is estimated to be 0.16-0.93 W m-2using the aerosol-dependent parameterizations. A sensitivity test with contact ice nuclei concentration in the original parameterization fit to that recommended by Young (1974) gives results that are closer to the new contact freezing parameterization.

  1. Bias correction of surface downwelling longwave and shortwave radiation for the EWEMBI dataset

    Science.gov (United States)

    Lange, Stefan

    2018-05-01

    Many meteorological forcing datasets include bias-corrected surface downwelling longwave and shortwave radiation (rlds and rsds). Methods used for such bias corrections range from multi-year monthly mean value scaling to quantile mapping at the daily timescale. An additional downscaling is necessary if the data to be corrected have a higher spatial resolution than the observational data used to determine the biases. This was the case when EartH2Observe (E2OBS; Calton et al., 2016) rlds and rsds were bias-corrected using more coarsely resolved Surface Radiation Budget (SRB; Stackhouse Jr. et al., 2011) data for the production of the meteorological forcing dataset EWEMBI (Lange, 2016). This article systematically compares various parametric quantile mapping methods designed specifically for this purpose, including those used for the production of EWEMBI rlds and rsds. The methods vary in the timescale at which they operate, in their way of accounting for physical upper radiation limits, and in their approach to bridging the spatial resolution gap between E2OBS and SRB. It is shown how temporal and spatial variability deflation related to bilinear interpolation and other deterministic downscaling approaches can be overcome by downscaling the target statistics of quantile mapping from the SRB to the E2OBS grid such that the sub-SRB-grid-scale spatial variability present in the original E2OBS data is retained. Cross validations at the daily and monthly timescales reveal that it is worthwhile to take empirical estimates of physical upper limits into account when adjusting either radiation component and that, overall, bias correction at the daily timescale is more effective than bias correction at the monthly timescale if sampling errors are taken into account.

  2. Estimating Surface Downward Shortwave Radiation over China Based on the Gradient Boosting Decision Tree Method

    Directory of Open Access Journals (Sweden)

    Lu Yang

    2018-01-01

    Full Text Available Downward shortwave radiation (DSR is an essential parameter in the terrestrial radiation budget and a necessary input for models of land-surface processes. Although several radiation products using satellite observations have been released, coarse spatial resolution and low accuracy limited their application. It is important to develop robust and accurate retrieval methods with higher spatial resolution. Machine learning methods may be powerful candidates for estimating the DSR from remotely sensed data because of their ability to perform adaptive, nonlinear data fitting. In this study, the gradient boosting regression tree (GBRT was employed to retrieve DSR measurements with the ground observation data in China collected from the China Meteorological Administration (CMA Meteorological Information Center and the satellite observations from the Advanced Very High Resolution Radiometer (AVHRR at a spatial resolution of 5 km. The validation results of the DSR estimates based on the GBRT method in China at a daily time scale for clear sky conditions show an R2 value of 0.82 and a root mean square error (RMSE value of 27.71 W·m−2 (38.38%. These values are 0.64 and 42.97 W·m−2 (34.57%, respectively, for cloudy sky conditions. The monthly DSR estimates were also evaluated using ground measurements. The monthly DSR estimates have an overall R2 value of 0.92 and an RMSE of 15.40 W·m−2 (12.93%. Comparison of the DSR estimates with the reanalyzed and retrieved DSR measurements from satellite observations showed that the estimated DSR is reasonably accurate but has a higher spatial resolution. Moreover, the proposed GBRT method has good scalability and is easy to apply to other parameter inversion problems by changing the parameters and training data.

  3. Application of short-wave infrared (SWIR) spectroscopy in quantitative estimation of clay mineral contents

    International Nuclear Information System (INIS)

    You, Jinfeng; Xing, Lixin; Pan, Jun; Meng, Tao; Liang, Liheng

    2014-01-01

    Clay minerals are significant constituents of soil which are necessary for life. This paper studied three types of clay minerals, kaolinite, illite, and montmorillonite, for they are not only the most common soil forming materials, but also important indicators of soil expansion and shrinkage potential. These clay minerals showed diagnostic absorption bands resulting from vibrations of hydroxyl groups and structural water molecules in the SWIR wavelength region. The short-wave infrared reflectance spectra of the soil was obtained from a Portable Near Infrared Spectrometer (PNIS, spectrum range: 1300∼2500 nm, interval: 2 nm). Due to the simplicity, quickness, and the non-destructiveness analysis, SWIR spectroscopy has been widely used in geological prospecting, chemical engineering and many other fields. The aim of this study was to use multiple linear regression (MLR) and partial least squares (PLS) regression to establish the optimizing quantitative estimation models of the kaolinite, illite and montmorillonite contents from soil reflectance spectra. Here, the soil reflectance spectra mainly refers to the spectral reflectivity of soil (SRS) corresponding to the absorption-band position (AP) of kaolinite, illite, and montmorillonite representative spectra from USGS spectral library, the SRS corresponding to the AP of soil spectral and soil overall spectrum reflectance values. The optimal estimation models of three kinds of clay mineral contents showed that the retrieval accuracy was satisfactory (Kaolinite content: a Root Mean Square Error of Calibration (RMSEC) of 1.671 with a coefficient of determination (R 2 ) of 0.791; Illite content: a RMSEC of 1.126 with a R 2 of 0.616; Montmorillonite content: a RMSEC of 1.814 with a R 2 of 0.707). Thus, the reflectance spectra of soil obtained form PNIS could be used for quantitative estimation of kaolinite, illite and montmorillonite contents in soil

  4. Spatiotemporal variation of surface shortwave forcing from fire-induced albedo change in interior Alaska

    Science.gov (United States)

    Huang, Shengli; Dahal, Devendra; Liu, Heping; Jin, Suming; Young, Claudia J.; Liu, Shuang; Liu, Shu-Guang

    2015-01-01

    The albedo change caused by both fires and subsequent succession is spatially heterogeneous, leading to the need to assess the spatiotemporal variation of surface shortwave forcing (SSF) as a component to quantify the climate impacts of high-latitude fires. We used an image reconstruction approach to compare postfire albedo with the albedo assuming fires had not occurred. Combining the fire-caused albedo change from the 2001-2010 fires in interior Alaska and the monthly surface incoming solar radiation, we examined the spatiotemporal variation of SSF in the early successional stage of around 10 years. Our results showed that while postfire albedo generally increased in fall, winter, and spring, some burned areas could show an albedo decrease during these seasons. In summer, the albedo increased for several years and then declined again. The spring SSF distribution did not show a latitudinal decrease from south to north as previously reported. The results also indicated that although the SSF is usually largely negative in the early successional years, it may not be significant during the first postfire year. The annual 2005-2010 SSF for the 2004 fire scars was -1.30, -4.40, -3.31, -4.00, -3.42, and -2.47 Wm-2. The integrated annual SSF map showed significant spatial variation with a mean of -3.15 Wm-2 and a standard deviation of 3.26 Wm-2, 16% of burned areas having positive SSF. Our results suggest that boreal deciduous fires would be less positive for climate change than boreal evergreen fires. Future research is needed to comprehensively investigate the spatiotemporal radiative and non-radiative forcings to determine the effect of boreal fires on climate.

  5. Evaluation of Shortwave Infrared Atmospheric Correction for Ocean Color Remote Sensing of Chesapeake Bay

    Science.gov (United States)

    Werdell, P. Jeremy; Franz, Bryan A.; Bailey, Sean W.

    2010-01-01

    The NASA Moderate Resolution Imaging Spectroradiometer onboard the Aqua platform (MODIS-Aqua) provides a viable data stream for operational water quality monitoring of Chesapeake Bay. Marine geophysical products from MODIS-Aqua depend on the efficacy of the atmospheric correction process, which can be problematic in coastal environments. The operational atmospheric correction algorithm for MODIS-Aqua requires an assumption of negligible near-infrared water-leaving radiance, nL(sub w)(NIR). This assumption progressively degrades with increasing turbidity and, as such, methods exist to account for non-negligible nL(sub w)(NIR) within the atmospheric correction process or to use alternate radiometric bands where the assumption is satisfied, such as those positioned within shortwave infrared (SWIR) region of the spectrum. We evaluated a decade-long time-series of nL(sub w)(lambda) from MODIS-Aqua in Chesapeake Bay derived using NIR and SWIR bands for atmospheric correction. Low signal-to-noise ratios (SNR) for the SWIR bands of MODIS-Aqua added noise errors to the derived radiances, which produced broad, flat frequency distributions of nL(sub w)(lambda) relative to those produced using the NIR bands. The SWIR approach produced an increased number of negative nL(sub w)(lambda) and decreased sample size relative to the NIR approach. Revised vicarious calibration and regional tuning of the scheme to switch between the NIR and SWIR approaches may improve retrievals in Chesapeake Bay, however, poor SNR values for the MODIS-Aqua SWIR bands remain the primary deficiency of the SWIR-based atmospheric correction approach.

  6. Advanced shortwave infrared and Raman hyperspectral sensors for homeland security and law enforcement operations

    Science.gov (United States)

    Klueva, Oksana; Nelson, Matthew P.; Gardner, Charles W.; Gomer, Nathaniel R.

    2015-05-01

    Proliferation of chemical and explosive threats as well as illicit drugs continues to be an escalating danger to civilian and military personnel. Conventional means of detecting and identifying hazardous materials often require the use of reagents and/or physical sampling, which is a time-consuming, costly and often dangerous process. Stand-off detection allows the operator to detect threat residues from a safer distance minimizing danger to people and equipment. Current fielded technologies for standoff detection of chemical and explosive threats are challenged by low area search rates, poor targeting efficiency, lack of sensitivity and specificity or use of costly and potentially unsafe equipment such as lasers. A demand exists for stand-off systems that are fast, safe, reliable and user-friendly. To address this need, ChemImage Sensor Systems™ (CISS) has developed reagent-less, non-contact, non-destructive sensors for the real-time detection of hazardous materials based on widefield shortwave infrared (SWIR) and Raman hyperspectral imaging (HSI). Hyperspectral imaging enables automated target detection displayed in the form of image making result analysis intuitive and user-friendly. Application of the CISS' SWIR-HSI and Raman sensing technologies to Homeland Security and Law Enforcement for standoff detection of homemade explosives and illicit drugs and their precursors in vehicle and personnel checkpoints is discussed. Sensing technologies include a portable, robot-mounted and standalone variants of the technology. Test data is shown that supports the use of SWIR and Raman HSI for explosive and drug screening at checkpoints as well as screening for explosives and drugs at suspected clandestine manufacturing facilities.

  7. On the Use of Shortwave Infrared for Tree Species Discrimination in Tropical Semideciduous Forest

    Science.gov (United States)

    Ferreira, M. P.; Zortea, M.; Zanotta, D. C.; Féret, J. B.; Shimabukuro, Y. E.; Souza Filho, C. R.

    2015-08-01

    Tree species mapping in tropical forests provides valuable insights for forest managers. Keystone species can be located for collection of seeds for forest restoration, reducing fieldwork costs. However, mapping of tree species in tropical forests using remote sensing data is a challenge due to high floristic and spectral diversity. Little is known about the use of different spectral regions as most of studies performed so far used visible/near-infrared (390-1000 nm) features. In this paper we show the contribution of shortwave infrared (SWIR, 1045-2395 nm) for tree species discrimination in a tropical semideciduous forest. Using high-resolution hyperspectral data we also simulated WorldView-3 (WV-3) multispectral bands for classification purposes. Three machine learning methods were tested to discriminate species at the pixel-level: Linear Discriminant Analysis (LDA), Support Vector Machines with Linear (L-SVM) and Radial Basis Function (RBF-SVM) kernels, and Random Forest (RF). Experiments were performed using all and selected features from the VNIR individually and combined with SWIR. Feature selection was applied to evaluate the effects of dimensionality reduction and identify potential wavelengths that may optimize species discrimination. Using VNIR hyperspectral bands, RBF-SVM achieved the highest average accuracy (77.4%). Inclusion of the SWIR increased accuracy to 85% with LDA. The same pattern was also observed when WV-3 simulated channels were used to classify the species. The VNIR bands provided and accuracy of 64.2% for LDA, which was increased to 79.8 % using the new SWIR bands that are operationally available in this platform. Results show that incorporating SWIR bands increased significantly average accuracy for both the hyperspectral data and WorldView-3 simulated bands.

  8. Bias correction of surface downwelling longwave and shortwave radiation for the EWEMBI dataset

    Directory of Open Access Journals (Sweden)

    S. Lange

    2018-05-01

    Full Text Available Many meteorological forcing datasets include bias-corrected surface downwelling longwave and shortwave radiation (rlds and rsds. Methods used for such bias corrections range from multi-year monthly mean value scaling to quantile mapping at the daily timescale. An additional downscaling is necessary if the data to be corrected have a higher spatial resolution than the observational data used to determine the biases. This was the case when EartH2Observe (E2OBS; Calton et al., 2016 rlds and rsds were bias-corrected using more coarsely resolved Surface Radiation Budget (SRB; Stackhouse Jr. et al., 2011 data for the production of the meteorological forcing dataset EWEMBI (Lange, 2016. This article systematically compares various parametric quantile mapping methods designed specifically for this purpose, including those used for the production of EWEMBI rlds and rsds. The methods vary in the timescale at which they operate, in their way of accounting for physical upper radiation limits, and in their approach to bridging the spatial resolution gap between E2OBS and SRB. It is shown how temporal and spatial variability deflation related to bilinear interpolation and other deterministic downscaling approaches can be overcome by downscaling the target statistics of quantile mapping from the SRB to the E2OBS grid such that the sub-SRB-grid-scale spatial variability present in the original E2OBS data is retained. Cross validations at the daily and monthly timescales reveal that it is worthwhile to take empirical estimates of physical upper limits into account when adjusting either radiation component and that, overall, bias correction at the daily timescale is more effective than bias correction at the monthly timescale if sampling errors are taken into account.

  9. Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation

    International Nuclear Information System (INIS)

    Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.

    1993-01-01

    Changes in the composition of trace gases in the earth's atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth's climate that may be caused by radiatively active gases introduced into the earth's atmosphere by man's activities. Radiatively active trace gases produce temperature changes in the earth's atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992

  10. Spectralon BRDF and DHR Measurements in Support of Satellite Instruments Operating Through Shortwave Infrared

    Science.gov (United States)

    Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

    2016-01-01

    Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laboratory and onorbit flight diffusers. A new measurement setup for BRDF measurements from 900 nm to 2500 nm located at NASA Goddard Space Flight Center (GSFC) is described. The GSFC setup employs an extended indium gallium arsenide detector, bandpass filters, and a supercontinuum light source. Comparisons of the GSFC BRDF measurements in the ShortWave InfraRed (SWIR) with those made by the NIST Spectral Trifunction Automated Reference Reflectometer (STARR) are presented. The Spectralon sample used in this study was 2 inch diameter, 99% white pressed and sintered Polytetrafluoroethylene (PTFE) target. The NASA/NIST BRDF comparison measurements were made at an incident angle of 0 deg and viewing angle of 45 deg. Additional BRDF data not compared to NIST were measured at additional incident and viewing angle geometries and are not presented here The total combined uncertainty for the measurement of BRDF in the SWIR range made by the GSFC scatterometer is less than 1% (k=1). This study is in support of the calibration of the Joint Polar Satellite System (JPSS) Radiation Budget Instrument (RBI) and Visible Infrared Imaging Radiometer Suite (VIIRS) of and other current and future NASA remote sensing missions operating across the reflected solar wavelength region.

  11. An energy balance model exploration of the impacts of interactions between surface albedo, cloud cover and water vapor on polar amplification

    Science.gov (United States)

    Södergren, A. Helena; McDonald, Adrian J.; Bodeker, Gregory E.

    2017-11-01

    We examine the effects of non-linear interactions between surface albedo, water vapor and cloud cover (referred to as climate variables) on amplified warming of the polar regions, using a new energy balance model. Our simulations show that the sum of the contributions to surface temperature changes due to any variable considered in isolation is smaller than the temperature changes from coupled feedback simulations. This non-linearity is strongest when all three climate variables are allowed to interact. Surface albedo appears to be the strongest driver of this non-linear behavior, followed by water vapor and clouds. This is because increases in longwave radiation absorbed by the surface, related to increases in water vapor and clouds, and increases in surface absorbed shortwave radiation caused by a decrease in surface albedo, amplify each other. Furthermore, our results corroborate previous findings that while increases in cloud cover and water vapor, along with the greenhouse effect itself, warm the polar regions, water vapor also significantly warms equatorial regions, which reduces polar amplification. Changes in surface albedo drive large changes in absorption of incoming shortwave radiation, thereby enhancing surface warming. Unlike high latitudes, surface albedo change at low latitudes are more constrained. Interactions between surface albedo, water vapor and clouds drive larger increases in temperatures in the polar regions compared to low latitudes. This is in spite of the fact that, due to a forcing, cloud cover increases at high latitudes and decreases in low latitudes, and that water vapor significantly enhances warming at low latitudes.

  12. Cloud CCN feedback

    International Nuclear Information System (INIS)

    Hudson, J.G.

    1992-01-01

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

  13. Force transmissibility versus displacement transmissibility

    Science.gov (United States)

    Lage, Y. E.; Neves, M. M.; Maia, N. M. M.; Tcherniak, D.

    2014-10-01

    It is well-known that when a single-degree-of-freedom (sdof) system is excited by a continuous motion of the foundation, the force transmissibility, relating the force transmitted to the foundation to the applied force, equals the displacement transmissibility. Recent developments in the generalization of the transmissibility to multiple-degree-of-freedom (mdof) systems have shown that similar simple and direct relations between both types of transmissibility do not appear naturally from the definitions, as happens in the sdof case. In this paper, the authors present their studies on the conditions under which it is possible to establish a relation between force transmissibility and displacement transmissibility for mdof systems. As far as the authors are aware, such a relation is not currently found in the literature, which is justified by being based on recent developments in the transmissibility concept for mdof systems. Indeed, it does not appear naturally, but the authors observed that the needed link is present when the displacement transmissibility is obtained between the same coordinates where the applied and reaction forces are considered in the force transmissibility case; this implies that the boundary conditions are not exactly the same and instead follow some rules. This work presents a formal derivation of the explicit relation between the force and displacement transmissibilities for mdof systems, and discusses its potential and limitations. The authors show that it is possible to obtain the displacement transmissibility from measured forces, and the force transmissibility from measured displacements, opening new perspectives, for example, in the identification of applied or transmitted forces. With this novel relation, it becomes possible, for example, to estimate the force transmissibility matrix with the structure off its supports, in free boundary conditions, and without measuring the forces. As far as force identification is concerned, this

  14. Data transmission

    National Research Council Canada - National Science Library

    Tugal, Dogan A; Tugal, Osman

    1989-01-01

    This updated second edition provides working answers to today's critical questions about designing and managing all types of data transmission systems and features a new chapter on local area networks (LANs...

  15. Hybrid cloud for dummies

    CERN Document Server

    Hurwitz, Judith; Halper, Fern; Kirsch, Dan

    2012-01-01

    Understand the cloud and implement a cloud strategy for your business Cloud computing enables companies to save money by leasing storage space and accessing technology services through the Internet instead of buying and maintaining equipment and support services. Because it has its own unique set of challenges, cloud computing requires careful explanation. This easy-to-follow guide shows IT managers and support staff just what cloud computing is, how to deliver and manage cloud computing services, how to choose a service provider, and how to go about implementation. It also covers security and

  16. Secure cloud computing

    CERN Document Server

    Jajodia, Sushil; Samarati, Pierangela; Singhal, Anoop; Swarup, Vipin; Wang, Cliff

    2014-01-01

    This book presents a range of cloud computing security challenges and promising solution paths. The first two chapters focus on practical considerations of cloud computing. In Chapter 1, Chandramouli, Iorga, and Chokani describe the evolution of cloud computing and the current state of practice, followed by the challenges of cryptographic key management in the cloud. In Chapter 2, Chen and Sion present a dollar cost model of cloud computing and explore the economic viability of cloud computing with and without security mechanisms involving cryptographic mechanisms. The next two chapters addres

  17. Clouds of Venus

    Energy Technology Data Exchange (ETDEWEB)

    Knollenberg, R G [Particle Measuring Systems, Inc., 1855 South 57th Court, Boulder, Colorado 80301, U.S.A.; Hansen, J [National Aeronautics and Space Administration, New York (USA). Goddard Inst. for Space Studies; Ragent, B [National Aeronautics and Space Administration, Moffett Field, Calif. (USA). Ames Research Center; Martonchik, J [Jet Propulsion Lab., Pasadena, Calif. (USA); Tomasko, M [Arizona Univ., Tucson (USA)

    1977-05-01

    The current state of knowledge of the Venusian clouds is reviewed. The visible clouds of Venus are shown to be quite similar to low level terrestrial hazes of strong anthropogenic influence. Possible nucleation and particle growth mechanisms are presented. The Pioneer Venus experiments that emphasize cloud measurements are described and their expected findings are discussed in detail. The results of these experiments should define the cloud particle composition, microphysics, thermal and radiative heat budget, rough dynamical features and horizontal and vertical variations in these and other parameters. This information should be sufficient to initialize cloud models which can be used to explain the cloud formation, decay, and particle life cycle.

  18. Aircraft-measured indirect cloud effects from biomass burning smoke in the Arctic and subarctic

    Directory of Open Access Journals (Sweden)

    L. M. Zamora

    2016-01-01

    Full Text Available The incidence of wildfires in the Arctic and subarctic is increasing; in boreal North America, for example, the burned area is expected to increase by 200–300 % over the next 50–100 years, which previous studies suggest could have a large effect on cloud microphysics, lifetime, albedo, and precipitation. However, the interactions between smoke particles and clouds remain poorly quantified due to confounding meteorological influences and remote sensing limitations. Here, we use data from several aircraft campaigns in the Arctic and subarctic to explore cloud microphysics in liquid-phase clouds influenced by biomass burning. Median cloud droplet radii in smoky clouds were  ∼  40–60 % smaller than in background clouds. Based on the relationship between cloud droplet number (Nliq and various biomass burning tracers (BBt across the multi-campaign data set, we calculated the magnitude of subarctic and Arctic smoke aerosol–cloud interactions (ACIs, where ACI  =  (1∕3 × dln(Nliq∕dln(BBt to be  ∼  0.16 out of a maximum possible value of 0.33 that would be obtained if all aerosols were to nucleate cloud droplets. Interestingly, in a separate subarctic case study with low liquid water content ( ∼  0.02 g m−3 and very high aerosol concentrations (2000–3000 cm−3 in the most polluted clouds, the estimated ACI value was only 0.05. In this case, competition for water vapor by the high concentration of cloud condensation nuclei (CCN strongly limited the formation of droplets and reduced the cloud albedo effect, which highlights the importance of cloud feedbacks across scales. Using our calculated ACI values, we estimate that the smoke-driven cloud albedo effect may decrease local summertime short-wave radiative flux by between 2 and 4 W m−2 or more under some low and homogeneous cloud cover conditions in the subarctic, although the changes should be smaller in high surface albedo regions of the

  19. A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Kazumasa; Okuzumi, Satoshi [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)

    2017-02-01

    A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our model by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation–coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.

  20. A Condensation–coalescence Cloud Model for Exoplanetary Atmospheres: Formulation and Test Applications to Terrestrial and Jovian Clouds

    International Nuclear Information System (INIS)

    Ohno, Kazumasa; Okuzumi, Satoshi

    2017-01-01

    A number of transiting exoplanets have featureless transmission spectra that might suggest the presence of clouds at high altitudes. A realistic cloud model is necessary to understand the atmospheric conditions under which such high-altitude clouds can form. In this study, we present a new cloud model that takes into account the microphysics of both condensation and coalescence. Our model provides the vertical profiles of the size and density of cloud and rain particles in an updraft for a given set of physical parameters, including the updraft velocity and the number density of cloud condensation nuclei (CCNs). We test our model by comparing with observations of trade-wind cumuli on Earth and ammonia ice clouds in Jupiter. For trade-wind cumuli, the model including both condensation and coalescence gives predictions that are consistent with observations, while the model including only condensation overestimates the mass density of cloud droplets by up to an order of magnitude. For Jovian ammonia clouds, the condensation–coalescence model simultaneously reproduces the effective particle radius, cloud optical thickness, and cloud geometric thickness inferred from Voyager observations if the updraft velocity and CCN number density are taken to be consistent with the results of moist convection simulations and Galileo probe measurements, respectively. These results suggest that the coalescence of condensate particles is important not only in terrestrial water clouds but also in Jovian ice clouds. Our model will be useful to understand how the dynamics, compositions, and nucleation processes in exoplanetary atmospheres affect the vertical extent and optical thickness of exoplanetary clouds via cloud microphysics.

  1. Climatology analysis of cirrus cloud in ARM site: South Great Plain

    Science.gov (United States)

    Olayinka, K.

    2017-12-01

    Cirrus cloud play an important role in the atmospheric energy balance and hence in the earth's climate system. The properties of optically thin clouds can be determined from measurements of transmission of the direct solar beam. The accuracy of cloud optical properties determined in this way is compromised by contamination of the direct transmission by light that is scattered into the sensors field of view. With the forward scattering correction method developed by Min et al., (2004), the accuracy of thin cloud retrievals from MFRSR has been improved. Our result shows over 30% of cirrus cloud present in the atmosphere are within optical depth between (1-2). In this study, we do statistics studies on cirrus clouds properties based on multi-years cirrus cloud measurements from MFRSR at ARM site from the South Great Plain (SGP) site due to its relatively easy accessibility, wide variability of climate cloud types and surface flux properties, large seasonal variation in temperature and specific humidity. Through the statistic studies, temporal and spatial variations of cirrus clouds are investigated. Since the presence of cirrus cloud increases the effect of greenhouse gases, we will retrieve the aerosol optical depth in all the cirrus cloud regions using a radiative transfer model for atmospheric correction. Calculate thin clouds optical depth (COD), and aerosol optical depth (AOD) using a radiative transfer model algorithm, e.g.: MODTRAN (MODerate resolution atmospheric TRANsmission)

  2. A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Sedlar, Joseph; Tjernstroem, Michael; Leck, Caroline [Stockholm University, Department of Meteorology, Stockholm (Sweden); Mauritsen, Thorsten [Max-Planck-Institute for Meteorology, Hamburg (Germany); Shupe, Matthew D.; Persson, P.O.G. [University of Colorado, NOAA-ESRL-PSD, Boulder, CO (United States); Brooks, Ian M.; Birch, Cathryn E. [University of Leeds, School of Earth and Environment, Leeds (United Kingdom); Sirevaag, Anders [University of Bergen, Bjerknes Center for Climate Research, Bergen (Norway); Nicolaus, Marcel [Norwegian Polar Institute, Tromsoe (Norway); Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)

    2011-10-15

    Snow surface and sea-ice energy budgets were measured near 87.5 N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to -7 C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between -50 W m{sup -2} and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m{sup -2}, except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area. (orig.)

  3. Moving towards Cloud Security

    Directory of Open Access Journals (Sweden)

    Edit Szilvia Rubóczki

    2015-01-01

    Full Text Available Cloud computing hosts and delivers many different services via Internet. There are a lot of reasons why people opt for using cloud resources. Cloud development is increasing fast while a lot of related services drop behind, for example the mass awareness of cloud security. However the new generation upload videos and pictures without reason to a cloud storage, but only few know about data privacy, data management and the proprietary of stored data in the cloud. In an enterprise environment the users have to know the rule of cloud usage, however they have little knowledge about traditional IT security. It is important to measure the level of their knowledge, and evolve the training system to develop the security awareness. The article proves the importance of suggesting new metrics and algorithms for measuring security awareness of corporate users and employees to include the requirements of emerging cloud security.

  4. Cloud Computing for radiologists.

    Science.gov (United States)

    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.

  5. Cloud Computing for radiologists

    International Nuclear Information System (INIS)

    Kharat, Amit T; Safvi, Amjad; Thind, SS; Singh, Amarjit

    2012-01-01

    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

  6. Cloud computing for radiologists

    Directory of Open Access Journals (Sweden)

    Amit T Kharat

    2012-01-01

    Full Text Available 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. Overview of CERES Cloud Properties Derived From VIRS AND MODIS DATA

    Science.gov (United States)

    Minis, Patrick; Geier, Erika; Wielicki, Bruce A.; Sun-Mack, Sunny; Chen, Yan; Trepte, Qing Z.; Dong, Xiquan; Doelling, David R.; Ayers, J. Kirk; Khaiyer, Mandana M.

    2006-01-01

    Simultaneous measurement of radiation and cloud fields on a global basis is recognized as a key component in understanding and modeling the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project (Wielicki et al., 1998) began addressing this issue in 1998 with its first broadband shortwave and longwave scanner on the Tropical Rainfall Measuring Mission (TRMM). This was followed by the launch of two CERES scanners each on Terra and Aqua during late 1999 and early 2002, respectively. When combined, these satellites should provide the most comprehensive global characterization of clouds and radiation to date. Unfortunately, the TRMM scanner failed during late 1998. The Terra and Aqua scanners continue to operate, however, providing measurements at a minimum of 4 local times each day. CERES was designed to scan in tandem with high resolution imagers so that the cloud conditions could be evaluated for every CERES measurement. The cloud properties are essential for converting CERES radiances shortwave albedo and longwave fluxes needed to define the radiation budget (ERB). They are also needed to unravel the impact of clouds on the ERB. The 5-channel, 2-km Visible Infrared Scanner (VIRS) on the TRMM and the 36-channel 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua are analyzed to define the cloud properties for each CERES footprint. To minimize inter-satellite differences and aid the development of useful climate-scale measurements, it was necessary to ensure that each satellite imager is calibrated in a fashion consistent with its counterpart on the other CERES satellites (Minnis et al., 2006) and that the algorithms are as similar as possible for all of the imagers. Thus, a set of cloud detection and retrieval algorithms were developed that could be applied to all three imagers utilizing as few channels as possible

  8. Plane-parallel biases computed from inhomogeneous Arctic clouds and sea ice

    Science.gov (United States)

    Rozwadowska, Anna; Cahalan, Robert F.

    2002-10-01

    Monte Carlo simulations of the expected influence of nonuniformity in cloud structure and surface albedo on shortwave radiative fluxes in the Arctic atmosphere are presented. In particular, plane-parallel biases in cloud albedo and transmittance are studied for nonabsorbing, low-level, all-liquid stratus clouds over sea ice. The "absolute bias" is defined as the difference between the cloud albedo or transmittance for the uniform or plane-parallel case, and the albedo or transmittance for nonuniform conditions with the same mean cloud optical thickness and the same mean surface albedo, averaged over a given area (i.e., bias > 0 means plane-parallel overestimates). Ranges of means and standard deviations of input parameters typical of Arctic conditions are determined from the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment Artic Cloud Experiment (FIRE/ACE)/Surface Heat Budget of the Arctic Ocean (SHEBA)/Atmospheric Radiation Measurement Program (ARM) experiment, a cooperative effort of the Department of Energy, NASA, NSF, the National Oceanic and Atmospheric Administration, the Office of Naval Research, and the Atmospheric Environment Service. We determine the sensitivity of the bias with respect to the following: domain averaged means and spatial variances of cloud optical thickness and surface albedo, shape of the surface reflectance function, presence of a scattering layer under the clouds, and solar zenith angle. The simulations show that the biases in Arctic conditions are generally lower than in subtropical stratocumulus. The magnitudes of the absolute biases are unlikely to exceed 0.02 for albedo and 0.05 for transmittance. The "relative bias" expresses the absolute bias as a percentage of the actual cloud albedo or transmittance. The magnitude of the relative bias in albedo is typically below 2% over the reflective Arctic surface, while the magnitude of the relative bias in transmittance can exceed 10%.

  9. Progress towards NASA MODIS and Suomi NPP Cloud Property Data Record Continuity

    Science.gov (United States)

    Platnick, S.; Meyer, K.; Holz, R.; Ackerman, S. A.; Heidinger, A.; Wind, G.; Platnick, S. E.; Wang, C.; Marchant, B.; Frey, R.

    2017-12-01

    The Suomi NPP VIIRS imager provides an opportunity to extend the 17+ year EOS MODIS climate data record into the next generation operational era. Similar to MODIS, VIIRS provides visible through IR observations at moderate spatial resolution with a 1330 LT equatorial crossing consistent with the MODIS on the Aqua platform. However, unlike MODIS, VIIRS lacks key water vapor and CO2 absorbing channels used for high cloud detection and cloud-top property retrievals. In addition, there is a significant mismatch in the spectral location of the 2.2 μm shortwave-infrared channels used for cloud optical/microphysical retrievals and cloud thermodynamic phase. Given these instrument differences between MODIS EOS and VIIRS S-NPP/JPSS, a merged MODIS-VIIRS cloud record to serve the science community in the coming decades requires different algorithm approaches than those used for MODIS alone. This new approach includes two parallel efforts: (1) Imager-only algorithms with only spectral channels common to VIIRS and MODIS (i.e., eliminate use of MODIS CO2 and NIR/IR water vapor channels). Since the algorithms are run with similar spectral observations, they provide a basis for establishing a continuous cloud data record across the two imagers. (2) Merged imager and sounder measurements (i.e.., MODIS-AIRS, VIIRS-CrIS) in lieu of higher-spatial resolution MODIS absorption channels absent on VIIRS. The MODIS-VIIRS continuity algorithm for cloud optical property retrievals leverages heritage algorithms that produce the existing MODIS cloud mask (MOD35), optical and microphysical properties product (MOD06), and the NOAA AWG Cloud Height Algorithm (ACHA). We discuss our progress towards merging the MODIS observational record with VIIRS in order to generate cloud optical property climate data record continuity across the observing systems. In addition, we summarize efforts to reconcile apparent radiometric biases between analogous imager channels, a critical consideration for

  10. A Comparison of Cloud Microphysical and Optical Properties during TOGA-COARE

    Science.gov (United States)

    Strawa, A. W.; Pueschel, R. F.; Pilewskie, P.; Valero, F. P. J.; Gore, Warren J. (Technical Monitor)

    1996-01-01

    The impact of cirrus clouds on climate is an issue of research interest currently. Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the cloud shortwave albedo and infrared reflectance and absorptance. These in turn are determined by the size distribution, phase, and composition of particles in the clouds. The TOGA-COARE campaign presented an excellent opportunity to study cirrus clouds and their influence on climate. In this campaign, a microphysics instrument package was flown aboard the DC-8 aircraft at medium altitudes in cirrus clouds. This package included a 2D Greyscale Cloud Particle Probe, a Forward Scattering Spectrometer Aerosol Probe, and an ice crystal replicator. At the same time the ER-2 equipped with a radiation measurement system flew coordinated flight tracks above the DC-8 at very high altitude. The radiation measurement made were short and long wave fluxes, as well as narrowband fluxes, both upwelling and downwelling. In addition LIDAR data is available. The existence of these data sets allows for a the comparison of radiation measurement with microphysical measurements. For example, the optical depth and effective radius retrieved from the ER-2 radiation measurements can be compared to the microphysical data. Conversely, the optical properties and fluxes produced by the clouds can be calculated from the microphysical measurements and compared to those measured aboard the ER-2. The assumptions required to make these comparisons are discussed. Typical microphysical results show a prevalence of micron-sized particles, in addition to the cloud particles that exceed 100 mm. The large number of small particles or "haze" cause the effective cloud radii to shift to smaller sizes, leading to changes in optical parameters.

  11. Detector with internal gain for short-wave infrared ranging applications

    Science.gov (United States)

    Fathipour, Vala; Mohseni, Hooman

    2017-09-01

    Abstarct.Highly sensitive photon detectors are regarded as the key enabling elements in many applications. Due to the low photon energy at the short-wave infrared (SWIR), photon detection and imaging at this band are very challenging. As such, many efforts in photon detector research are directed toward improving the performance of the photon detectors operating in this wavelength range. To solve these problems, we have developed an electron-injection (EI) technique. The significance of this detection mechanism is that it can provide both high efficiency and high sensitivity at room temperature, a condition that is very difficult to achieve in conventional SWIR detectors. An EI detector offers an overall system-level sensitivity enhancement due to a feedback stabilized internal avalanche-free gain. Devices exhibit an excess noise of unity, operate in linear mode, require bias voltage of a few volts, and have a cutoff wavelength of 1700 nm. We review the material system, operating principle, and development of EI detectors. The shortcomings of the first-generation devices were addressed in the second-generation detectors. Measurement on second-generation devices showed a high-speed response of ˜6 ns rise time, low jitter of less than 20 ps, high amplification of more than 2000 (at optical power levels larger than a few nW), unity excess noise factor, and low leakage current (amplified dark current ˜10 nA at a bias voltage of -3 V and at room temperature. These characteristics make EI detectors a good candidate for high-resolution flash light detection and ranging (LiDAR) applications with millimeter scale depth resolution at longer ranges compared with conventional p-i-n diodes. Based on our experimentally measured device characteristics, we compare the performance of the EI detector with commercially available linear mode InGaAs avalanche photodiode (APD) as well as a p-i-n diode using a theoretical model. Flash LiDAR images obtained by our model show that the EI

  12. Shortwave radiative forcing and efficiency of key aerosol types using AERONET data

    Directory of Open Access Journals (Sweden)

    O. E. García

    2012-06-01

    Full Text Available The shortwave radiative forcing (ΔF and the radiative forcing efficiency (ΔFeff of natural and anthropogenic aerosols have been analyzed using estimates of radiation both at the Top (TOA and at the Bottom Of Atmosphere (BOA modeled based on AERONET aerosol retrievals. Six main types of atmospheric aerosols have been compared (desert mineral dust, biomass burning, urban-industrial, continental background, oceanic and free troposphere in similar observational conditions (i.e., for solar zenith angles between 55° and 65° in order to compare the nearly same solar geometry. The instantaneous ΔF averages obtained vary from −122 ± 37 Wm−2 (aerosol optical depth, AOD, at 0.55 μm, 0.85 ± 0.45 at the BOA for the mixture of desert mineral dust and biomass burning aerosols in West Africa and −42 ± 22 Wm−2 (AOD = 0.9 ± 0.5 at the TOA for the pure mineral dust also in this region up to −6 ± 3 Wm−2 and −4 ± 2 Wm−2 (AOD = 0.03 ± 0.02 at the BOA and the TOA, respectively, for free troposphere conditions. This last result may be taken as reference on a global scale. Furthermore, we observe that the more absorbing aerosols are overall more efficient at the BOA in contrast to at the TOA, where they backscatter less solar energy into the space. The analysis of the radiative balance at the TOA shows that, together with the amount of aerosols and their absorptive capacity, it is essential to consider the surface albedo of the region on which they are. Thus, we document that in regions with high surface reflectivity (deserts and snow conditions atmospheric aerosols lead to a warming of the Earth-atmosphere system.

  13. Marine cloud brightening

    OpenAIRE

    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

    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 identi...

  14. Cloud computing strategies

    CERN Document Server

    Chorafas, Dimitris N

    2011-01-01

    A guide to managing cloud projects, Cloud Computing Strategies provides the understanding required to evaluate the technology and determine how it can be best applied to improve business and enhance your overall corporate strategy. Based on extensive research, it examines the opportunities and challenges that loom in the cloud. It explains exactly what cloud computing is, what it has to offer, and calls attention to the important issues management needs to consider before passing the point of no return regarding financial commitments.

  15. Towards Indonesian Cloud Campus

    OpenAIRE

    Thamrin, Taqwan; Lukman, Iing; Wahyuningsih, Dina Ika

    2013-01-01

    Nowadays, Cloud Computing is most discussed term in business and academic environment.Cloud campus has many benefits such as accessing the file storages, e-mails, databases,educational resources, research applications and tools anywhere for faculty, administrators,staff, students and other users in university, on demand. Furthermore, cloud campus reduces universities’ IT complexity and cost.This paper discuss the implementation of Indonesian cloud campus and various opportunies and benefits...

  16. Cloud Infrastructure Security

    OpenAIRE

    Velev , Dimiter; Zlateva , Plamena

    2010-01-01

    Part 4: Security for Clouds; International audience; Cloud computing can help companies accomplish more by eliminating the physical bonds between an IT infrastructure and its users. Users can purchase services from a cloud environment that could allow them to save money and focus on their core business. At the same time certain concerns have emerged as potential barriers to rapid adoption of cloud services such as security, privacy and reliability. Usually the information security professiona...

  17. Cloud services in organization

    OpenAIRE

    FUXA, Jan

    2013-01-01

    The work deals with the definition of the word cloud computing, cloud computing models, types, advantages, disadvantages, and comparing SaaS solutions such as: Google Apps and Office 365 in the area of electronic communications. The work deals with the use of cloud computing in the corporate practice, both good and bad practice. The following section describes the methodology for choosing the appropriate cloud service organization. Another part deals with analyzing the possibilities of SaaS i...

  18. Orchestrating Your Cloud Orchestra

    OpenAIRE

    Hindle, Abram

    2015-01-01

    Cloud computing potentially ushers in a new era of computer music performance with exceptionally large computer music instruments consisting of 10s to 100s of virtual machines which we propose to call a `cloud-orchestra'. Cloud computing allows for the rapid provisioning of resources, but to deploy such a complicated and interconnected network of software synthesizers in the cloud requires a lot of manual work, system administration knowledge, and developer/operator skills. This is a barrier ...

  19. Cloud security mechanisms

    OpenAIRE

    2014-01-01

    Cloud computing has brought great benefits in cost and flexibility for provisioning services. The greatest challenge of cloud computing remains however the question of security. The current standard tools in access control mechanisms and cryptography can only partly solve the security challenges of cloud infrastructures. In the recent years of research in security and cryptography, novel mechanisms, protocols and algorithms have emerged that offer new ways to create secure services atop cloud...

  20. Cloud computing for radiologists

    OpenAIRE

    Amit T Kharat; Amjad Safvi; S S Thind; Amarjit Singh

    2012-01-01

    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...

  1. Cloud Robotics Model

    OpenAIRE

    Mester, Gyula

    2015-01-01

    Cloud Robotics was born from the merger of service robotics and cloud technologies. It allows robots to benefit from the powerful computational, storage, and communications resources of modern data centres. Cloud robotics allows robots to take advantage of the rapid increase in data transfer rates to offload tasks without hard real time requirements. Cloud Robotics has rapidly gained momentum with initiatives by companies such as Google, Willow Garage and Gostai as well as more than a dozen a...

  2. Genomics With Cloud Computing

    OpenAIRE

    Sukhamrit Kaur; Sandeep Kaur

    2015-01-01

    Abstract Genomics is study of genome which provides large amount of data for which large storage and computation power is needed. These issues are solved by cloud computing that provides various cloud platforms for genomics. These platforms provides many services to user like easy access to data easy sharing and transfer providing storage in hundreds of terabytes more computational power. Some cloud platforms are Google genomics DNAnexus and Globus genomics. Various features of cloud computin...

  3. Chargeback for cloud services.

    NARCIS (Netherlands)

    Baars, T.; Khadka, R.; Stefanov, H.; Jansen, S.; Batenburg, R.; Heusden, E. van

    2014-01-01

    With pay-per-use pricing models, elastic scaling of resources, and the use of shared virtualized infrastructures, cloud computing offers more efficient use of capital and agility. To leverage the advantages of cloud computing, organizations have to introduce cloud-specific chargeback practices.

  4. On CLOUD nine

    CERN Multimedia

    2009-01-01

    The team from the CLOUD experiment - the world’s first experiment using a high-energy particle accelerator to study the climate - were on cloud nine after the arrival of their new three-metre diameter cloud chamber. This marks the end of three years’ R&D and design, and the start of preparations for data taking later this year.

  5. Cloud Computing Explained

    Science.gov (United States)

    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…

  6. Greening the Cloud

    NARCIS (Netherlands)

    van den Hoed, Robert; Hoekstra, Eric; Procaccianti, G.; Lago, P.; Grosso, Paola; Taal, Arie; Grosskop, Kay; van Bergen, Esther

    The cloud has become an essential part of our daily lives. We use it to store our documents (Dropbox), to stream our music and lms (Spotify and Net ix) and without giving it any thought, we use it to work on documents in the cloud (Google Docs). The cloud forms a massive storage and processing

  7. Security in the cloud.

    Science.gov (United States)

    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.

  8. Polar winter cloud depolarization measurements with the CANDAC Rayleigh-Mie-Raman Lidar

    Science.gov (United States)

    McCullough, E. M.; Nott, G. J.; Duck, T. J.; Sica, R. J.; Doyle, J. G.; Pike-thackray, C.; Drummond, J. R.

    2011-12-01

    Clouds introduce a significant positive forcing to the Arctic radiation budget and this is strongest during the polar winter when shortwave radiation is absent (Intrieri et al., 2002). The amount of forcing depends on the occurrence probability and optical depth of the clouds as well as the cloud particle phase (Ebert and Curry 1992). Mixed-phase clouds are particularly complex as they involve interactions between three phases of water (vapour, liquid and ice) coexisting in the same cloud. Although significant progress has been made in characterizing wintertime Arctic clouds (de Boer et al., 2009 and 2011), there is considerable variability in the relative abundance of particles of each phase, in the morphology of solid particles, and in precipitation rates depending on the meteorology at the time. The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman Lidar (CRL) was installed in the Canadian High Arctic at Eureka, Nunavut (80°N, 86°W) in 2008-2009. The remotely-operated system began with measurement capabilities for multi-wavelength aerosol extinction, water vapour mixing ratio, and tropospheric temperature profiles, as well as backscatter cross section coefficient and colour ratio. In 2010, a new depolarization channel was added. The capability to measure the polarization state of the return signal allows the characterization of the cloud in terms of liquid and ice water content, enabling the lidar to probe all three phases of water in these clouds. Lidar depolarization results from 2010 and 2011 winter clouds at Eureka will be presented, with a focus on differences in downwelling radiation between mixed phase clouds and ice clouds. de Boer, G., E.W. Eloranta, and M.D. Shupe (2009), Arctic mixed-phase stratiform cloud properties from multiple years of surface-based measurements at two high-latitude locations, Journal of Atmospheric Sciences, 66 (9), 2874-2887. de Boer, G., H. Morrison, M. D. Shupe, and R. Hildner (2011

  9. Electrical transmission

    Energy Technology Data Exchange (ETDEWEB)

    Sayers, D P

    1960-05-01

    After briefly tracing the history of electricity transmission, trends in high voltage transmission and experiments being conducted on 650 kV are discussed. 5000 miles of the U.K. grid are operated at 132 kV and 1000 at 275 kV, ultimately to provide a super grid at 380 kV. Problems are insulation, radio interference and the cost of underground lines (16 times that of overhead lines). Also considered are the economics of the grid as a means of transporting energy and as a means of spreading the peak load over the power stations in the most efficient manner. Finally, the question of amenities is discussed.

  10. Evaluation of reproductive function of female rats exposed to radiofrequency fields (27. 12 MHz) near a shortwave diathermy device

    Energy Technology Data Exchange (ETDEWEB)

    Brown-Woodman, P.D.; Hadley, J.A.; Richardson, L.; Bright, D.; Porter, D.

    1989-04-01

    In recent years, there has been increased concern regarding effects of operator exposure to the electromagnetic (EM) field associated with shortwave diathermy devices. The present study was designed to investigate the effects, on rats, of repeated exposure to such an EM field. Following repeated exposure for 5 wk, a reduction in fertility occurred as indicated by a reduced number of matings in exposed rats compared to sham-irradiated rats and a reduction in the number of rats that conceived after mating. The data suggest that female operators could experience reduced fertility, if they remained close to the console for prolonged periods. This has particular significant for the physiotherapy profession.

  11. Cloud-radiation-precipitation associations over the Asian monsoon region: an observational analysis

    Science.gov (United States)

    Li, Jiandong; Wang, Wei-Chyung; Dong, Xiquan; Mao, Jiangyu

    2017-11-01

    This study uses 2001-2014 satellite observations and reanalyses to investigate the seasonal characteristics of Cloud Radiative Effects (CREs) and their associations with cloud fraction (CF) and precipitation over the Asian monsoon region (AMR) covering Eastern China (EC) and South Asia (SA). The CREs exhibit strong seasonal variations but show distinctly different relationships with CFs and precipitation over the two regions. For EC, the CREs is dominated by shortwave (SW) cooling, with an annual mean value of - 40 W m- 2 for net CRE, and peak in summer while the presence of extensive and opaque low-level clouds contributes to large Top-Of-Atmosphere (TOA) albedo (>0.5) in winter. For SA, a weak net CRE exists throughout the year due to in-phase compensation of SWCRE by longwave (LW) CRE associated with the frequent occurrence of high clouds. For the entire AMR, SWCRE strongly correlates with the dominant types of CFs, although the cloud vertical structure plays important role particularly in summer. The relationships between CREs and precipitation are stronger in SA than in EC, indicating the dominant effect of monsoon circulation in the former region. SWCRE over EC is only partly related to precipitation and shows distinctive regional variations. Further studies need to pay more attention to vertical distributions of cloud micro- and macro-physical properties, and associated precipitation systems over the AMR.

  12. Comparison of three ice cloud optical schemes in climate simulations with community atmospheric model version 5

    Science.gov (United States)

    Zhao, Wenjie; Peng, Yiran; Wang, Bin; Yi, Bingqi; Lin, Yanluan; Li, Jiangnan

    2018-05-01

    A newly implemented Baum-Yang scheme for simulating ice cloud optical properties is compared with existing schemes (Mitchell and Fu schemes) in a standalone radiative transfer model and in the global climate model (GCM) Community Atmospheric Model Version 5 (CAM5). This study systematically analyzes the effect of different ice cloud optical schemes on global radiation and climate by a series of simulations with a simplified standalone radiative transfer model, atmospheric GCM CAM5, and a comprehensive coupled climate model. Results from the standalone radiative model show that Baum-Yang scheme yields generally weaker effects of ice cloud on temperature profiles both in shortwave and longwave spectrum. CAM5 simulations indicate that Baum-Yang scheme in place of Mitchell/Fu scheme tends to cool the upper atmosphere and strengthen the thermodynamic instability in low- and mid-latitudes, which could intensify the Hadley circulation and dehydrate the subtropics. When CAM5 is coupled with a slab ocean model to include simplified air-sea interaction, reduced downward longwave flux to surface in Baum-Yang scheme mitigates ice-albedo feedback in the Arctic as well as water vapor and cloud feedbacks in low- and mid-latitudes, resulting in an overall temperature decrease by 3.0/1.4 °C globally compared with Mitchell/Fu schemes. Radiative effect and climate feedback of the three ice cloud optical schemes documented in this study can be referred for future improvements on ice cloud simulation in CAM5.

  13. Seasonal Bias of Retrieved Ice Cloud Optical Properties Based on MISR and MODIS Measurements

    Science.gov (United States)

    Wang, Y.; Hioki, S.; Yang, P.; Di Girolamo, L.; Fu, D.

    2017-12-01

    The precise estimation of two important cloud optical and microphysical properties, cloud particle optical thickness and cloud particle effective radius, is fundamental in the study of radiative energy budget and hydrological cycle. In retrieving these two properties, an appropriate selection of ice particle surface roughness is important because it substantially affects the single-scattering properties. At present, using a predetermined ice particle shape without spatial and temporal variations is a common practice in satellite-based retrieval. This approach leads to substantial uncertainties in retrievals. The cloud radiances measured by each of the cameras of the Multi-angle Imaging SpectroRadiometer (MISR) instrument are used to estimate spherical albedo values at different scattering angles. By analyzing the directional distribution of estimated spherical albedo values, the degree of ice particle surface roughness is estimated. With an optimal degree of ice particle roughness, cloud optical thickness and effective radius are retrieved based on a bi-spectral shortwave technique in conjunction with two Moderate Resolution Imaging Spectroradiometer (MODIS) bands centered at 0.86 and 2.13 μm. The seasonal biases of retrieved cloud optical and microphysical properties, caused by the uncertainties in ice particle roughness, are investigated by using one year of MISR-MODIS fused data.

  14. The highs and lows of cloud radiative feedback: Comparing observational data and CMIP5 models

    Science.gov (United States)

    Jenney, A.; Randall, D. A.

    2014-12-01

    Clouds play a complex role in the climate system, and remain one of the more difficult aspects of the future climate to predict. Over subtropical eastern ocean basins, particularly next to California, Peru, and Southwest Africa, low marine stratocumulus clouds (MSC) help to reduce the amount of solar radiation that reaches the surface by reflecting incident sunlight. The climate feedback associated with these clouds is thought to be positive. This project looks at CMIP5 models and compares them to observational data from CERES and ERA-Interim to try and find observational evidence and model agreement for low, marine stratocumulus cloud feedback. Although current evidence suggests that the low cloud feedback is positive (IPCC, 2014), an analysis of the simulated relationship between July lower tropospheric stability (LTS) and shortwave cloud forcing in MSC regions suggests that this feedback is not due to changes in LTS. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

  15. Cognitive Privacy for Personal Clouds

    Directory of Open Access Journals (Sweden)

    Milena Radenkovic

    2016-01-01

    Full Text Available This paper proposes a novel Cognitive Privacy (CogPriv framework that improves privacy of data sharing between Personal Clouds for different application types and across heterogeneous networks. Depending on the behaviour of neighbouring network nodes, their estimated privacy levels, resource availability, and social network connectivity, each Personal Cloud may decide to use different transmission network for different types of data and privacy requirements. CogPriv is fully distributed, uses complex graph contacts analytics and multiple implicit novel heuristics, and combines these with smart probing to identify presence and behaviour of privacy compromising nodes in the network. Based on sensed local context and through cooperation with remote nodes in the network, CogPriv is able to transparently and on-the-fly change the network in order to avoid transmissions when privacy may be compromised. We show that CogPriv achieves higher end-to-end privacy levels compared to both noncognitive cellular network communication and state-of-the-art strategies based on privacy-aware adaptive social mobile networks routing for a range of experiment scenarios based on real-world user and network traces. CogPriv is able to adapt to varying network connectivity and maintain high quality of service while managing to keep low data exposure for a wide range of privacy leakage levels in the infrastructure.

  16. CLOUD STORAGE SERVICES

    OpenAIRE

    Yan, Cheng

    2017-01-01

    Cloud computing is a hot topic in recent research and applications. Because it is widely used in various fields. Up to now, Google, Microsoft, IBM, Amazon and other famous co partnership have proposed their cloud computing application. Look upon cloud computing as one of the most important strategy in the future. Cloud storage is the lower layer of cloud computing system which supports the service of the other layers above it. At the same time, it is an effective way to store and manage heavy...

  17. Cloud Computing Quality

    Directory of Open Access Journals (Sweden)

    Anamaria Şiclovan

    2013-02-01

    Full Text Available Cloud computing was and it will be a new way of providing Internet services and computers. This calculation approach is based on many existing services, such as the Internet, grid computing, Web services. Cloud computing as a system aims to provide on demand services more acceptable as price and infrastructure. It is exactly the transition from computer to a service offered to the consumers as a product delivered online. This paper is meant to describe the quality of cloud computing services, analyzing the advantages and characteristics offered by it. It is a theoretical paper.Keywords: Cloud computing, QoS, quality of cloud computing

  18. Benchmarking Cloud Storage Systems

    OpenAIRE

    Wang, Xing

    2014-01-01

    With the rise of cloud computing, many cloud storage systems like Dropbox, Google Drive and Mega have been built to provide decentralized and reliable file storage. It is thus of prime importance to know their features, performance, and the best way to make use of them. In this context, we introduce BenchCloud, a tool designed as part of this thesis to conveniently and efficiently benchmark any cloud storage system. First, we provide a study of six commonly-used cloud storage systems to ident...

  19. The Magellanic clouds

    International Nuclear Information System (INIS)

    1989-01-01

    As the two galaxies nearest to our own, the Magellanic Clouds hold a special place in studies of the extragalactic distance scale, of stellar evolution and the structure of galaxies. In recent years, results from the South African Astronomical Observatory (SAAO) and elsewhere have shown that it is possible to begin understanding the three dimensional structure of the Clouds. Studies of Magellanic Cloud Cepheids have continued, both to investigate the three-dimensional structure of the Clouds and to learn more about Cepheids and their use as extragalactic distance indicators. Other research undertaken at SAAO includes studies on Nova LMC 1988 no 2 and red variables in the Magellanic Clouds

  20. Cloud Computing Bible

    CERN Document Server

    Sosinsky, Barrie

    2010-01-01

    The complete reference guide to the hot technology of cloud computingIts potential for lowering IT costs makes cloud computing a major force for both IT vendors and users; it is expected to gain momentum rapidly with the launch of Office Web Apps later this year. Because cloud computing involves various technologies, protocols, platforms, and infrastructure elements, this comprehensive reference is just what you need if you'll be using or implementing cloud computing.Cloud computing offers significant cost savings by eliminating upfront expenses for hardware and software; its growing popularit

  1. Tropical and Subtropical Cloud Transitions in Weather and Climate Prediction Models: The GCSS/WGNE Pacific Cross-Section Intercomparison (GPCI)

    Science.gov (United States)

    Teixeira, J.; Cardoso, S.; Bonazzola, M.; Cole, J.; DeGenio, A.; DeMott, C.; Franklin, C.; Hannay, C.; Jakob, C.; Jiao, Y.; hide

    2011-01-01

    A model evaluation approach is proposed in which weather and climate prediction models are analyzed along a Pacific Ocean cross section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade winds, to the deep convection regions of the ITCZ the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/ WGNE) Pacific Cross-Section Intercomparison (GPCI). The main goal of GPCI is to evaluate and help understand and improve the representation of tropical and subtropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross section from the subtropics to the tropics for the season June July August of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the 40-yr ECMWF Re-Analysis (ERA-40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical cross sections of cloud properties (in particular), vertical velocity, and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA-40 in the stratocumulus regions [as compared to the first International Satellite Cloud Climatology Project (ISCCP)] is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too

  2. The MODIS Cloud Optical and Microphysical Products: Collection 6 Up-dates and Examples From Terra and Aqua

    Science.gov (United States)

    Platnick, Steven; Meyer, Kerry G.; King, Michael D.; Wind, Galina; Amarasinghe, Nandana; Marchant, Benjamin G.; Arnold, G. Thomas; Zhang, Zhibo; Hubanks, Paul A.; Holz, Robert E.; hide

    2016-01-01

    The MODIS Level-2 cloud product (Earth Science Data Set names MOD06 and MYD06 for Terra and Aqua MODIS, respectively) provides pixel-level retrievals of cloud-top properties (day and night pressure, temperature, and height) and cloud optical properties(optical thickness, effective particle radius, and water path for both liquid water and ice cloud thermodynamic phases daytime only). Collection 6 (C6) reprocessing of the product was completed in May 2014 and March 2015 for MODIS Aqua and Terra, respectively. Here we provide an overview of major C6 optical property algorithm changes relative to the previous Collection 5 (C5) product. Notable C6 optical and microphysical algorithm changes include: (i) new ice cloud optical property models and a more extensive cloud radiative transfer code lookup table (LUT) approach, (ii) improvement in the skill of the shortwave-derived cloud thermodynamic phase, (iii) separate cloud effective radius retrieval datasets for each spectral combination used in previous collections, (iv) separate retrievals for partly cloudy pixels and those associated with cloud edges, (v) failure metrics that provide diagnostic information for pixels having observations that fall outside the LUT solution space, and (vi) enhanced pixel-level retrieval uncertainty calculations.The C6 algorithm changes collectively can result in significant changes relative to C5,though the magnitude depends on the dataset and the pixels retrieval location in the cloud parameter space. Example Level-2 granule and Level-3 gridded dataset differences between the two collections are shown. While the emphasis is on the suite of cloud opticalproperty datasets, other MODIS cloud datasets are discussed when relevant.

  3. Absorbing Aerosols Above Cloud: Detection, Quantitative Retrieval, and Radiative Forcing from Satellite-based Passive Sensors

    Science.gov (United States)

    Jethva, H.; Torres, O.; Remer, L. A.; Bhartia, P. K.

    2012-12-01

    Light absorbing particles such as carbonaceous aerosols generated from biomass burning activities and windblown dust particles can exert a net warming effect on climate; the strength of which depends on the absorption capacity of the particles and brightness of the underlying reflecting background. When advected over low-level bright clouds, these aerosols absorb the cloud reflected radiation from ultra-violet (UV) to shortwave-IR (SWIR) and makes cloud scene darker-a phenomenon commonly known as "cloud darkening". The apparent "darkening" effect can be seen by eyes in satellite images as well as quantitatively in the spectral reflectance measurements made by space borne sensors over regions where light absorbing carbonaceous and dust aerosols overlay low-level cloud decks. Theoretical radiative transfer simulations support the observational evidence, and further reveal that the strength of the cloud darkening and its spectral signature (or color ratio) between measurements at two wavelengths are a bi-function of aerosol and cloud optical thickness (AOT and COT); both are measures of the total amount of light extinction caused by aerosols and cloud, respectively. Here, we developed a retrieval technique, named as the "color ratio method" that uses the satellite measurements at two channels, one at shorter wavelength in the visible and one at longer wavelength in the shortwave-IR for the simultaneous retrieval of AOT and COT. The present technique requires assumptions on the aerosol single-scattering albedo and aerosol-cloud separation which are supplemented by the Aerosol Robotic Network (AERONET) and space borne CALIOP lidar measurements. The retrieval technique has been tested making use of the near-UV and visible reflectance observations made by the Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS) for distinct above-cloud smoke and dust aerosol events observed seasonally over the southeast and tropical Atlantic Ocean

  4. CLOUD COMPUTING SECURITY

    Directory of Open Access Journals (Sweden)

    Ştefan IOVAN

    2016-05-01

    Full Text Available Cloud computing reprentes the software applications offered as a service online, but also the software and hardware components from the data center.In the case of wide offerd services for any type of client, we are dealing with a public cloud. In the other case, in wich a cloud is exclusively available for an organization and is not available to the open public, this is consider a private cloud [1]. There is also a third type, called hibrid in which case an user or an organization might use both services available in the public and private cloud. One of the main challenges of cloud computing are to build the trust and ofer information privacy in every aspect of service offerd by cloud computingle. The variety of existing standards, just like the lack of clarity in sustenability certificationis not a real help in building trust. Also appear some questions marks regarding the efficiency of traditionsecurity means that are applied in the cloud domain. Beside the economic and technology advantages offered by cloud, also are some advantages in security area if the information is migrated to cloud. Shared resources available in cloud includes the survey, use of the "best practices" and technology for advance security level, above all the solutions offered by the majority of medium and small businesses, big companies and even some guvermental organizations [2].

  5. Impacts of cloud overlap assumptions on radiative budgets and heating fields in convective regions

    Science.gov (United States)

    Wang, XiaoCong; Liu, YiMin; Bao, Qing

    2016-01-01

    Impacts of cloud overlap assumptions on radiative budgets and heating fields are explored with the aid of a cloud-resolving model (CRM), which provided cloud geometry as well as cloud micro and macro properties. Large-scale forcing data to drive the CRM are from TRMM Kwajalein Experiment and the Global Atmospheric Research Program's Atlantic Tropical Experiment field campaigns during which abundant convective systems were observed. The investigated overlap assumptions include those that were traditional and widely used in the past and the one that was recently addressed by Hogan and Illingworth (2000), in which the vertically projected cloud fraction is expressed by a linear combination of maximum and random overlap, with the weighting coefficient depending on the so-called decorrelation length Lcf. Results show that both shortwave and longwave cloud radiative forcings (SWCF/LWCF) are significantly underestimated under maximum (MO) and maximum-random (MRO) overlap assumptions, whereas remarkably overestimated under the random overlap (RO) assumption in comparison with that using CRM inherent cloud geometry. These biases can reach as high as 100 Wm- 2 for SWCF and 60 Wm- 2 for LWCF. By its very nature, the general overlap (GenO) assumption exhibits an encouraging performance on both SWCF and LWCF simulations, with the biases almost reduced by 3-fold compared with traditional overlap assumptions. The superiority of GenO assumption is also manifested in the simulation of shortwave and longwave radiative heating fields, which are either significantly overestimated or underestimated under traditional overlap assumptions. The study also pointed out the deficiency of constant assumption on Lcf in GenO assumption. Further examinations indicate that the CRM diagnostic Lcf varies among different cloud types and tends to be stratified in the vertical. The new parameterization that takes into account variation of Lcf in the vertical well reproduces such a relationship and

  6. Temporal variation of aerosol optical depth and associated shortwave radiative forcing over a coastal site along the west coast of India.

    Science.gov (United States)

    Menon, Harilal B; Shirodkar, Shilpa; Kedia, Sumita; S, Ramachandran; Babu, Suresh; Moorthy, K Krishna

    2014-01-15

    Optical characterization of aerosol was performed by assessing the columnar aerosol optical depth (AOD) and angstrom wavelength exponent (α) using data from the Microtops II Sunphotometer. The data were collected on cloud free days over Goa, a coastal site along the west coast of India, from January to December 2008. Along with the composite aerosol, the black carbon (BC) mass concentration from the Aethalometer was also analyzed. The AOD0.500 μm and angstrom wavelength exponent (α) were in the range of 0.26 to 0.7 and 0.52 to 1.33, respectively, indicative of a significant seasonal shift in aerosol characteristics during the study period. The monthly mean AOD0.500 μm exhibited a bi-modal distribution, with a primary peak in April (0.7) and a secondary peak in October (0.54), whereas the minimum of 0.26 was observed in May. The monthly mean BC mass concentration varied between 0.31 μg/m(3) and 4.5 μg/m(3), and the single scattering albedo (SSA), estimated using the OPAC model, ranged from 0.87 to 0.97. Modeled aerosol optical properties were used to estimate the direct aerosol shortwave radiative forcing (DASRF) in the wavelength range 0.25 μm4.0 μm. The monthly mean forcing at the surface, at the top of the atmosphere (TOA) and in the atmosphere varied between -14.1 Wm(-2) and -35.6 Wm(-2), -6.7 Wm(-2) and -13.4 Wm(-2) and 5.5 Wm(-2) to 22.5 Wm(-2), respectively. These results indicate that the annual SSA cycle in the atmosphere is regulated by BC (absorbing aerosol), resulting in a positive forcing; however, the surface forcing was governed by the natural aerosol scattering, which yielded a negative forcing. These two conditions neutralized, resulting in a negative forcing at the TOA that remains nearly constant throughout the year. © 2013.

  7. Observational characteristics of cloud radiative effects over three arid regions in the Northern Hemisphere

    Science.gov (United States)

    Li, Jiandong; Wang, Tianhe; Habib, Ammara

    2017-08-01

    Cloud-radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects (CREs) are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia (CA), East Asia (EA), and North America (NA), based on recent satellite datasets. Our results show that the annual mean shortwave (SW) and net CREs (SWCRE and NCRE) over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months (November-March), the longwave (LW) CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere-land surface system. The cold-season mean NCRE at the top of the atmosphere (TOA) averaged over EA is 4.1 W m-2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud-radiation processes over arid regions of the Northern Hemisphere.

  8. Analysis and assessment of Shortwave Angle and Slope Index for monitoring rice phenology and hydroperiod.

    Science.gov (United States)

    Tornos, Lucía; Moyano, María Carmen; Huesca, Margarita; Cicuendez, Victor; Recuero, Laura; Domínguez, Jose Antonio; Palacios-Orueta, Alicia

    2014-05-01

    According to the United Nations, more than 50 percent of the world population depends on rice for about 80 percent of its food requirements. Besides, rice fields are important aquatic ecosystems, hosting a great variety of aquatic species. However, environmental issues such as water consumption and the emission of greenhouse gases, as well as the effects of climate change in crops, may endanger their sustainability. In this context, the determination of rice hydroperiod and phenology is necessary for rice monitoring and impact management, and is expected to become more relevant in the near future. The present study has explored the potential of Shortwave Angle Slope Index (SASI), based on the spectral data contained in Moderate Resolution Imaging Spectroradiometer, to monitoring rice paddy fields under different water management practices. SASI is a spectral shape index (SSI), based on the angle formed in SWIR1 vertex with NIR and SWIR2 in the spectrum, and the slope of the line linking NIR and SWIR2 vertices. This index was developed to distinguish between dry soil, wet soil, dry vegetation and green vegetation. It takes large, positive values for dry soil and large, negative values for green vegetation. Two case studies in Spain, the Ebro Delta and Orellana are presented. The behaviour of the index in each zone for the period 2001-2012 has been evaluated to characterize the response of SASI index to phenological and flooding events in rice. The average values and standard deviation of the index for the period 2001-2012 were calculated to identify the significant points of SASI in coincidence with phenological and flooding field data. An algorithm for the detection of significant points was also applied to determine phenological metrics, based on the information obtained. SASI presented similar values for both zones during the rice growing period. Differences arose during the non-growing period when the Delta was flooded for environmental reasons (i

  9. An Evaluation of Marine Boundary Layer Cloud Property Simulations in the Community Atmosphere Model Using Satellite Observations: Conventional Subgrid Parameterization versus CLUBB

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hua [Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, Maryland; Zhang, Zhibo [Joint Center for Earth Systems Technology, and Physics Department, University of Maryland, Baltimore County, Baltimore, Maryland; Ma, Po-Lun [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Ghan, Steven J. [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington; Wang, Minghuai [Institute for Climate and Global Change Research, and School of Atmospheric Sciences, Nanjing University, Nanjing, China

    2018-03-01

    This paper presents a two-step evaluation of the marine boundary layer (MBL) cloud properties from two Community Atmospheric Model (version 5.3, CAM5) simulations, one based on the CAM5 standard parameterization schemes (CAM5-Base), and the other on the Cloud Layers Unified By Binormals (CLUBB) scheme (CAM5-CLUBB). In the first step, we compare the cloud properties directly from model outputs between the two simulations. We find that the CAM5-CLUBB run produces more MBL clouds in the tropical and subtropical large-scale descending regions. Moreover, the stratocumulus (Sc) to cumulus (Cu) cloud regime transition is much smoother in CAM5-CLUBB than in CAM5-Base. In addition, in CAM5-Base we find some grid cells with very small low cloud fraction (<20%) to have very high in-cloud water content (mixing ratio up to 400mg/kg). We find no such grid cells in the CAM5-CLUBB run. However, we also note that both simulations, especially CAM5-CLUBB, produce a significant amount of “empty” low cloud cells with significant cloud fraction (up to 70%) and near-zero in-cloud water content. In the second step, we use satellite observations from CERES, MODIS and CloudSat to evaluate the simulated MBL cloud properties by employing the COSP satellite simulators. We note that a feature of the COSP-MODIS simulator to mimic the minimum detection threshold of MODIS cloud masking removes much more low clouds from CAM5-CLUBB than it does from CAM5-Base. This leads to a surprising result — in the large-scale descending regions CAM5-CLUBB has a smaller COSP-MODIS cloud fraction and weaker shortwave cloud radiative forcing than CAM5-Base. A sensitivity study suggests that this is because CAM5-CLUBB suffers more from the above-mentioned “empty” clouds issue than CAM5-Base. The COSP-MODIS cloud droplet effective radius in CAM5-CLUBB shows a spatial increase from coastal St toward Cu, which is in qualitative agreement with MODIS observations. In contrast, COSP-MODIS cloud droplet

  10. Searchable Encryption in Cloud Storage

    OpenAIRE

    Ren-Junn Hwang; Chung-Chien Lu; Jain-Shing Wu

    2014-01-01

    Cloud outsource storage is one of important services in cloud computing. Cloud users upload data to cloud servers to reduce the cost of managing data and maintaining hardware and software. To ensure data confidentiality, users can encrypt their files before uploading them to a cloud system. However, retrieving the target file from the encrypted files exactly is difficult for cloud server. This study proposes a protocol for performing multikeyword searches for encrypted cloud data by applying ...

  11. Enterprise Cloud Adoption - Cloud Maturity Assessment Model

    OpenAIRE

    Conway, Gerry; Doherty, Eileen; Carcary, Marian; Crowley, Catherine

    2017-01-01

    The introduction and use of cloud computing by an organization has the promise of significant benefits that include reduced costs, improved services, and a pay-per-use model. Organizations that successfully harness these benefits will potentially have a distinct competitive edge, due to their increased agility and flexibility to rapidly respond to an ever changing and complex business environment. However, as cloud technology is a relatively new ph...

  12. Clouds and Earth Radiant Energy System (CERES), a Review: Past, Present and Future

    Science.gov (United States)

    Smith, G. L.; Priestley, K. J.; Loeb, N. G.; Wielicki, B. A.; Charlock, T. P.; Minnis, P.; Doelling, D. R.; Rutan, D. A.

    2011-01-01

    The Clouds and Earth Radiant Energy System (CERES) project s objectives are to measure the reflected solar radiance (shortwave) and Earth-emitted (longwave) radiances and from these measurements to compute the shortwave and longwave radiation fluxes at the top of the atmosphere (TOA) and the surface and radiation divergence within the atmosphere. The fluxes at TOA are to be retrieved to an accuracy of 2%. Improved bidirectional reflectance distribution functions (BRDFs) have been developed to compute the fluxes at TOA from the measured radiances with errors reduced from ERBE by a factor of two or more. Instruments aboard the Terra and Aqua spacecraft provide sampling at four local times. In order to further reduce temporal sampling errors, data are used from the geostationary meteorological satellites to account for changes of scenes between observations by the CERES radiometers. A validation protocol including in-flight calibrations and comparisons of measurements has reduced the instrument errors to less than 1%. The data are processed through three editions. The first edition provides a timely flow of data to investigators and the third edition provides data products as accurate as possible with resources available. A suite of cloud properties retrieved from the MODerate-resolution Imaging Spectroradiometer (MODIS) by the CERES team is used to identify the cloud properties for each pixel in order to select the BRDF for each pixel so as to compute radiation fluxes from radiances. Also, the cloud information is used to compute radiation at the surface and through the atmosphere and to facilitate study of the relationship between clouds and the radiation budget. The data products from CERES include, in addition to the reflected solar radiation and Earth emitted radiation fluxes at TOA, the upward and downward shortwave and longwave radiation fluxes at the surface and at various levels in the atmosphere. Also at the surface the photosynthetically active radiation

  13. Star clouds of Magellan

    International Nuclear Information System (INIS)

    Tucker, W.

    1981-01-01

    The Magellanic Clouds are two irregular galaxies belonging to the local group which the Milky Way belongs to. By studying the Clouds, astronomers hope to gain insight into the origin and composition of the Milky Way. The overall structure and dynamics of the Clouds are clearest when studied in radio region of the spectrum. One benefit of directly observing stellar luminosities in the Clouds has been the discovery of the period-luminosity relation. Also, the Clouds are a splendid laboratory for studying stellar evolution. It is believed that both Clouds may be in the very early stage in the development of a regular, symmetric galaxy. This raises a paradox because some of the stars in the star clusters of the Clouds are as old as the oldest stars in our galaxy. An explanation for this is given. The low velocity of the Clouds with respect to the center of the Milky Way shows they must be bound to it by gravity. Theories are given on how the Magellanic Clouds became associated with the galaxy. According to current ideas the Clouds orbits will decay and they will spiral into the Galaxy

  14. Cloud Computing Governance Lifecycle

    Directory of Open Access Journals (Sweden)

    Soňa Karkošková

    2016-06-01

    Full Text Available Externally provisioned cloud services enable flexible and on-demand sourcing of IT resources. Cloud computing introduces new challenges such as need of business process redefinition, establishment of specialized governance and management, organizational structures and relationships with external providers and managing new types of risk arising from dependency on external providers. There is a general consensus that cloud computing in addition to challenges brings many benefits but it is unclear how to achieve them. Cloud computing governance helps to create business value through obtain benefits from use of cloud computing services while optimizing investment and risk. Challenge, which organizations are facing in relation to governing of cloud services, is how to design and implement cloud computing governance to gain expected benefits. This paper aims to provide guidance on implementation activities of proposed Cloud computing governance lifecycle from cloud consumer perspective. Proposed model is based on SOA Governance Framework and consists of lifecycle for implementation and continuous improvement of cloud computing governance model.

  15. First Transmitted Hyperspectral Light Measurements and Cloud Properties from Recent Field Campaign Sampling Clouds Under Biomass Burning Aerosol

    Science.gov (United States)

    Leblanc, S.; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor J.; Segal Rozenhaimer, Michal; Kacenelenbogen, Meloe Shenandoah; Pistone, Kristina Marie Myers; Schmidt, Sebastian; Cochrane, Sabrina

    2016-01-01

    We present a first view of data collected during a recent field campaign aimed at measuring biomass burning aerosol above clouds from airborne platforms. The NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) field campaign recently concluded its first deployment sampling clouds and overlying aerosol layer from the airborne platform NASA P3. We present results from the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), in conjunction with the Solar Spectral Flux Radiometers (SSFR). During this deployment, 4STAR sampled transmitted solar light either via direct solar beam measurements and scattered light measurements, enabling the measurement of aerosol optical thickness and the retrieval of information on aerosol particles in addition to overlying cloud properties. We focus on the zenith-viewing scattered light measurements, which are used to retrieve cloud optical thickness, effective radius, and thermodynamic phase of clouds under a biomass burning layer. The biomass burning aerosol layer present above the clouds is the cause of potential bias in retrieved cloud optical depth and effective radius from satellites. We contrast the typical reflection based approach used by satellites to the transmission based approach used by 4STAR during ORACLES for retrieving cloud properties. It is suspected that these differing approaches will yield a change in retrieved properties since light transmitted through clouds is sensitive to a different cloud volume than reflected light at cloud top. We offer a preliminary view of the implications of these differences in sampling volumes to the calculation of cloud radiative effects (CRE).

  16. THE CALIFORNIA MOLECULAR CLOUD

    International Nuclear Information System (INIS)

    Lada, Charles J.; Lombardi, Marco; Alves, Joao F.

    2009-01-01

    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 ∼ 10 5 M 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 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 2 ) ∼ a few x 10 4 cm -3 .

  17. Validation of Cloud Optical Parameters from Passive Remote Sensing in the Arctic by using the Aircraft Measurements

    Science.gov (United States)

    Chen, H.; Schmidt, S.; Coddington, O.; Wind, G.; Bucholtz, A.; Segal-Rosenhaimer, M.; LeBlanc, S. E.

    2017-12-01

    Cloud Optical Parameters (COPs: e.g., cloud optical thickness and cloud effective radius) and surface albedo are the most important inputs for determining the Cloud Radiative Effect (CRE) at the surface. In the Arctic, the COPs derived from passive remote sensing such as from the Moderate Resolution Imaging Spectroradiometer (MODIS) are difficult to obtain with adequate accuracy owing mainly to insufficient knowledge about the snow/ice surface, but also because of the low solar zenith angle. This study aims to validate COPs derived from passive remote sensing in the Arctic by using aircraft measurements collected during two field campaigns based in Fairbanks, Alaska. During both experiments, ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) and ARISE (Arctic Radiation-IceBridge Sea and Ice Experiment), the Solar Spectral Flux Radiometer (SSFR) measured upwelling and downwelling shortwave spectral irradiances, which can be used to derive surface and cloud albedo, as well as the irradiance transmitted by clouds. We assess the variability of the Arctic sea ice/snow surfaces albedo through these aircraft measurements and incorporate this variability into cloud retrievals for SSFR. We then compare COPs as derived from SSFR and MODIS for all suitable aircraft underpasses of the satellites. Finally, the sensitivities of the COPs to surface albedo and solar zenith angle are investigated.

  18. Bacterial ice nuclei impact cloud lifetime and radiative properties and reduce atmospheric heat loss in the BRAMS simulation model

    International Nuclear Information System (INIS)

    Costa, Tassio S; Gonçalves, Fábio L T; Yamasoe, Marcia A; Martins, Jorge A; Morris, Cindy E

    2014-01-01

    This study examines the effect of the bacterial species Pseudomonas syringae acting as ice nuclei (IN) on cloud properties to understand its impact on local radiative budget and heating rates. These bacteria may become active IN at temperatures as warm as −2 °C. Numerical simulations were developed using the Brazilian Regional Atmospheric Model System (BRAMS). To investigate the isolated effect of bacterial IN, four scenarios were created considering only homogeneous and bacterial ice nucleation, with 1, 10 and 100 IN per cubic meter of cloud volume and one with no bacteria. Moreover, two other scenarios were generated: the BRAMS default parameterization and its combination with bacterial IN. The model reproduced a strong convective cell over São Paulo on 3 March 2003. Results showed that bacterial IN may change cloud evolution as well as its microphysical properties, which in turn influence cloud radiative properties. For example, the reflected shortwave irradiance over an averaged domain in a scenario considering bacterial IN added to the BRAMS default parameterization was 14% lower than if bacteria were not considered. Heating rates can also be impacted, especially due to differences in cloud lifetime. Results suggest that the omission of bacterial IN in numerical models, including global cloud models, could neglect relevant ice nucleation processes that potentially influence cloud radiative properties. (letter)

  19. The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)

    Energy Technology Data Exchange (ETDEWEB)

    May, Peter T.; Long, Charles N.; Protat, Alain

    2012-08-01

    The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.

  20. Development of Multi-Sensor Global Cloud and Radiance Composites for DSCOVR EPIC Imager with Subpixel Definition

    Science.gov (United States)

    Khlopenkov, K. V.; Duda, D. P.; Thieman, M. M.; Sun-Mack, S.; Su, W.; Minnis, P.; Bedka, K. M.

    2017-12-01

    The Deep Space Climate Observatory (DSCOVR) is designed to study the daytime Earth radiation budget by means of onboard Earth Polychromatic Imaging Camera (EPIC) and National Institute of Standards and Technology Advanced Radiometer (NISTAR). EPIC imager observes in several shortwave bands (317-780 nm), while NISTAR measures the top-of-atmosphere (TOA) whole-disk radiance in shortwave and total broadband windows. Calculation of albedo and outgoing longwave flux requires a high-resolution scene identification such as the radiance observations and cloud property retrievals from low earth orbit and geostationary satellite imagers. These properties have to be co-located with EPIC imager pixels to provide scene identification and to select anisotropic directional models, which are then used to adjust the NISTAR-measured radiance and subsequently obtain the global daytime shortwave and longwave fluxes. This work presents an algorithm for optimal merging of selected radiances and cloud properties derived from multiple satellite imagers to obtain seamless global hourly composites at 5-km resolution. The highest quality observation is selected by means of an aggregated rating which incorporates several factors such as the nearest time relative to EPIC observation, lowest viewing zenith angle, and others. This process provides a smoother transition and avoids abrupt changes in the merged composite data. Higher spatial accuracy in the composite product is achieved by using the inverse mapping with gradient search during reprojection and bicubic interpolation for pixel resampling. The composite data are subsequently remapped into the EPIC-view domain by convolving composite pixels with the EPIC point spread function (PSF) defined with a half-pixel accuracy. Within every EPIC footprint, the PSF-weighted average radiances and cloud properties are computed for each cloud phase and then stored within five data subsets (clear-sky, water cloud, ice cloud, total cloud, and no

  1. Expansion of magnetic clouds

    International Nuclear Information System (INIS)

    Suess, S.T.

    1987-01-01

    Magnetic clouds are a carefully defined subclass of all interplanetary signatures of coronal mass ejections whose geometry is thought to be that of a cylinder embedded in a plane. It has been found that the total magnetic pressure inside the clouds is higher than the ion pressure outside, and that the clouds are expanding at 1 AU at about half the local Alfven speed. The geometry of the clouds is such that even though the magnetic pressure inside is larger than the total pressure outside, expansion will not occur because the pressure is balanced by magnetic tension - the pinch effect. The evidence for expansion of clouds at 1 AU is nevertheless quite strong so another reason for its existence must be found. It is demonstrated that the observations can be reproduced by taking into account the effects of geometrical distortion of the low plasma beta clouds as they move away from the Sun

  2. Encyclopedia of cloud computing

    CERN Document Server

    Bojanova, Irena

    2016-01-01

    The Encyclopedia of Cloud Computing provides IT professionals, educators, researchers and students with a compendium of cloud computing knowledge. Authored by a spectrum of subject matter experts in industry and academia, this unique publication, in a single volume, covers a wide range of cloud computing topics, including technological trends and developments, research opportunities, best practices, standards, and cloud adoption. Providing multiple perspectives, it also addresses questions that stakeholders might have in the context of development, operation, management, and use of clouds. Furthermore, it examines cloud computing's impact now and in the future. The encyclopedia presents 56 chapters logically organized into 10 sections. Each chapter covers a major topic/area with cross-references to other chapters and contains tables, illustrations, side-bars as appropriate. Furthermore, each chapter presents its summary at the beginning and backend material, references and additional resources for further i...

  3. Effectiveness and limitations of parameter tuning in reducing biases of top-of-atmosphere radiation and clouds in MIROC version 5

    Science.gov (United States)

    Ogura, Tomoo; Shiogama, Hideo; Watanabe, Masahiro; Yoshimori, Masakazu; Yokohata, Tokuta; Annan, James D.; Hargreaves, Julia C.; Ushigami, Naoto; Hirota, Kazuya; Someya, Yu; Kamae, Youichi; Tatebe, Hiroaki; Kimoto, Masahide

    2017-12-01

    This study discusses how much of the biases in top-of-atmosphere (TOA) radiation and clouds can be removed by parameter tuning in the present-day simulation of a climate model in the Coupled Model Inter-comparison Project phase 5 (CMIP5) generation. We used output of a perturbed parameter ensemble (PPE) experiment conducted with an atmosphere-ocean general circulation model (AOGCM) without flux adjustment. The Model for Interdisciplinary Research on Climate version 5 (MIROC5) was used for the PPE experiment. Output of the PPE was compared with satellite observation data to evaluate the model biases and the parametric uncertainty of the biases with respect to TOA radiation and clouds. The results indicate that removing or changing the sign of the biases by parameter tuning alone is difficult. In particular, the cooling bias of the shortwave cloud radiative effect at low latitudes could not be removed, neither in the zonal mean nor at each latitude-longitude grid point. The bias was related to the overestimation of both cloud amount and cloud optical thickness, which could not be removed by the parameter tuning either. However, they could be alleviated by tuning parameters such as the maximum cumulus updraft velocity at the cloud base. On the other hand, the bias of the shortwave cloud radiative effect in the Arctic was sensitive to parameter tuning. It could be removed by tuning such parameters as albedo of ice and snow both in the zonal mean and at each grid point. The obtained results illustrate the benefit of PPE experiments which provide useful information regarding effectiveness and limitations of parameter tuning. Implementing a shallow convection parameterization is suggested as a potential measure to alleviate the biases in radiation and clouds.

  4. Effectiveness and limitations of parameter tuning in reducing biases of top-of-atmosphere radiation and clouds in MIROC version 5

    Directory of Open Access Journals (Sweden)

    T. Ogura

    2017-12-01

    Full Text Available This study discusses how much of the biases in top-of-atmosphere (TOA radiation and clouds can be removed by parameter tuning in the present-day simulation of a climate model in the Coupled Model Inter-comparison Project phase 5 (CMIP5 generation. We used output of a perturbed parameter ensemble (PPE experiment conducted with an atmosphere–ocean general circulation model (AOGCM without flux adjustment. The Model for Interdisciplinary Research on Climate version 5 (MIROC5 was used for the PPE experiment. Output of the PPE was compared with satellite observation data to evaluate the model biases and the parametric uncertainty of the biases with respect to TOA radiation and clouds. The results indicate that removing or changing the sign of the biases by parameter tuning alone is difficult. In particular, the cooling bias of the shortwave cloud radiative effect at low latitudes could not be removed, neither in the zonal mean nor at each latitude–longitude grid point. The bias was related to the overestimation of both cloud amount and cloud optical thickness, which could not be removed by the parameter tuning either. However, they could be alleviated by tuning parameters such as the maximum cumulus updraft velocity at the cloud base. On the other hand, the bias of the shortwave cloud radiative effect in the Arctic was sensitive to parameter tuning. It could be removed by tuning such parameters as albedo of ice and snow both in the zonal mean and at each grid point. The obtained results illustrate the benefit of PPE experiments which provide useful information regarding effectiveness and limitations of parameter tuning. Implementing a shallow convection parameterization is suggested as a potential measure to alleviate the biases in radiation and clouds.

  5. Online Cloud Offloading Using Heterogeneous Enhanced Remote Radio Heads

    KAUST Repository

    Shnaiwer, Yousef N.

    2018-02-12

    This paper studies the cloud offloading gains of using heterogeneous enhanced remote radio heads (eRRHs) and dual-interface clients in fog radio access networks (F-RANs). First, the cloud offloading problem is formulated as a collection of independent sets selection problem over a network coding graph, and its NP-hardness is shown. Therefore, a computationally simple online heuristic algorithm is proposed, that maximizes cloud offloading by finding an efficient schedule of coded file transmissions from the eRRHs and the cloud base station (CBS). Furthermore, a lower bound on the average number of required CBS channels to serve all clients is derived. Simulation results show that our proposed framework that uses both network coding and a heterogeneous F-RAN setting enhances cloud offloading as compared to conventional homogeneous F-RANs with network coding.

  6. Saharan Dust Event Impacts on Cloud Formation and Radiation over Western Europe

    Science.gov (United States)

    Bangert, M.; Nenes, A.; Vogel, B.; Vogel, H.; Barahona, D.; Karydis, V. A.; Kumar, P.; Kottmeier, C.; Blahak, U.

    2013-01-01

    We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle-microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties. The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l-1 during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds. Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected). This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to -75Wm-2. Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80Wm-2, and the incoming long-wave radiation at the surface was increased significantly in the order of +10Wm-2. The strong radiative forcings associated with dust caused a reduction in surface temperature in the order of -0

  7. Saharan dust event impacts on cloud formation and radiation over Western Europe

    Directory of Open Access Journals (Sweden)

    M. Bangert

    2012-05-01

    Full Text Available We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties.

    The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l−1 during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds.

    Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected. This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to −75 W m−2. Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80 W m−2, and the incoming long-wave radiation at the surface was increased significantly in the order of +10 W m−2.

    The

  8. Considerations for Cloud Security Operations

    OpenAIRE

    Cusick, James

    2016-01-01

    Information Security in Cloud Computing environments is explored. Cloud Computing is presented, security needs are discussed, and mitigation approaches are listed. Topics covered include Information Security, Cloud Computing, Private Cloud, Public Cloud, SaaS, PaaS, IaaS, ISO 27001, OWASP, Secure SDLC.

  9. Evaluating statistical cloud schemes

    OpenAIRE

    Grützun, Verena; Quaas, Johannes; Morcrette , Cyril J.; Ament, Felix

    2015-01-01

    Statistical cloud schemes with prognostic probability distribution functions have become more important in atmospheric modeling, especially since they are in principle scale adaptive and capture cloud physics in more detail. While in theory the schemes have a great potential, their accuracy is still questionable. High-resolution three-dimensional observational data of water vapor and cloud water, which could be used for testing them, are missing. We explore the potential of ground-based re...

  10. Cloud Computing Governance Lifecycle

    OpenAIRE

    Soňa Karkošková; George Feuerlicht

    2016-01-01

    Externally provisioned cloud services enable flexible and on-demand sourcing of IT resources. Cloud computing introduces new challenges such as need of business process redefinition, establishment of specialized governance and management, organizational structures and relationships with external providers and managing new types of risk arising from dependency on external providers. There is a general consensus that cloud computing in addition to challenges brings many benefits but it is uncle...

  11. Security in cloud computing

    OpenAIRE

    Moreno Martín, Oriol

    2016-01-01

    Security in Cloud Computing is becoming a challenge for next generation Data Centers. This project will focus on investigating new security strategies for Cloud Computing systems. Cloud Computingisarecent paradigmto deliver services over Internet. Businesses grow drastically because of it. Researchers focus their work on it. The rapid access to exible and low cost IT resources on an on-demand fashion, allows the users to avoid planning ahead for provisioning, and enterprises to save money ...

  12. Simulation of cloud/radiation interaction using a second-order turbulence radiative-convective model

    International Nuclear Information System (INIS)

    Kao, C.Y.; Smith, W.S.

    1994-01-01

    Extended sheets of low-level stratus and stratocumulus clouds are a persistent feature over the eastern parts of the major ocean basins associated with the quasi-permanent subtropical high-pressure systems. These clouds exert a strong influence on climate through their high albedo, compared with the underlying surface, and their low altitude. The former leads to a reduction of the net shortwave flux entering the atmosphere, and the latter leads to an infrared loss in a way essentially the same as the cloud-free conditions. This paper is a modeling study with the current understanding of the important physical processes associated with a cloud-capped boundary layer. The numerical model is a high-resolution one-dimensional version of the second-order turbulence convective/radiative model developed at the Los Alamos National Laboratory. Future work includes sensitivity tests to ascertain the model validity as well as to systematically include all the possible ambient atmospheric and surface conditions. Detailed budget analyses are also useful in categorizing the cloud-capped boundary layers into a few classes

  13. CLOUD TECHNOLOGY IN EDUCATION

    Directory of Open Access Journals (Sweden)

    Alexander N. Dukkardt

    2014-01-01

    Full Text Available This article is devoted to the review of main features of cloud computing that can be used in education. Particular attention is paid to those learning and supportive tasks, that can be greatly improved in the case of the using of cloud services. Several ways to implement this approach are proposed, based on widely accepted models of providing cloud services. Nevertheless, the authors have not ignored currently existing problems of cloud technologies , identifying the most dangerous risks and their impact on the core business processes of the university. 

  14. Cloud Computing: An Overview

    Science.gov (United States)

    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.

  15. Genomics With Cloud Computing

    Directory of Open Access Journals (Sweden)

    Sukhamrit Kaur

    2015-04-01

    Full Text Available Abstract Genomics is study of genome which provides large amount of data for which large storage and computation power is needed. These issues are solved by cloud computing that provides various cloud platforms for genomics. These platforms provides many services to user like easy access to data easy sharing and transfer providing storage in hundreds of terabytes more computational power. Some cloud platforms are Google genomics DNAnexus and Globus genomics. Various features of cloud computing to genomics are like easy access and sharing of data security of data less cost to pay for resources but still there are some demerits like large time needed to transfer data less network bandwidth.

  16. Electric field measuring and display system. [for cloud formations

    Science.gov (United States)

    Wojtasinski, R. J.; Lovall, D. D. (Inventor)

    1974-01-01

    An apparatus is described for monitoring the electric fields of cloud formations within a particular area. It utilizes capacitor plates that are alternately shielded from the clouds for generating an alternating signal corresponding to the intensity of the electric field of the clouds. A synchronizing signal is produced for controlling sampling of the alternating signal. Such samplings are fed through a filter and converted by an analogue to digital converter into digital form and subsequently fed to a transmitter for transmission to the control station for recording.

  17. Review of Cloud Computing and existing Frameworks for Cloud adoption

    OpenAIRE

    Chang, Victor; Walters, Robert John; Wills, Gary

    2014-01-01

    This paper presents a selected review for Cloud Computing and explains the benefits and risks of adopting Cloud Computing in a business environment. Although all the risks identified may be associated with two major Cloud adoption challenges, a framework is required to support organisations as they begin to use Cloud and minimise risks of Cloud adoption. Eleven Cloud Computing frameworks are investigated and a comparison of their strengths and limitations is made; the result of the comparison...

  18. +Cloud: An Agent-Based Cloud Computing Platform

    OpenAIRE

    González, Roberto; Hernández de la Iglesia, Daniel; de la Prieta Pintado, Fernando; Gil González, Ana Belén

    2017-01-01

    Cloud computing is revolutionizing the services provided through the Internet, and is continually adapting itself in order to maintain the quality of its services. This study presents the platform +Cloud, which proposes a cloud environment for storing information and files by following the cloud paradigm. This study also presents Warehouse 3.0, a cloud-based application that has been developed to validate the services provided by +Cloud.

  19. Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models

    Science.gov (United States)

    Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In

    2017-07-01

    Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.

  20. Relationships between radiation, clouds, and convection during DYNAMO

    Science.gov (United States)

    Ciesielski, Paul E.; Johnson, Richard H.; Jiang, Xianan; Zhang, Yunyan; Xie, Shaocheng

    2017-03-01

    The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden-Julian Oscillation (MJO) field campaign. Specifically, column-net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large-scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region. Longwave (LW) and shortwave radiative heating rates exhibit tilted structures, reflecting radiative effects associated with the prevalence of shallow cumulus during the dry, suppressed MJO phase followed by increasing deep convection leading into the active phase. As the convection builds going into the MJO active phase, there are increasingly top-heavy anomalous radiative heating rates while the column-net radiative cooling rate progressively decreases. Temporal fluctuations in the cloud radiative forcing, being quite sensitive to changes in high cloudiness, are dominated by LW effects with an intraseasonal variation of 0.4-0.6 K/d. While both the water vapor and cloud fields are inextricably linked, it appears that the tilted radiative structures are more related to water vapor effects. The intraseasonal variation of column-net radiative heating enhances the convective signal in the mean by 20% with a minimum in this enhancement 10 days prior to peak MJO rainfall and maximum 7 days after. This suggests that as MJO convective envelope weakens over the central IO, cloud-radiative feedbacks help maintain the mature MJO as it moves eastward.

  1. Strategies for cloud-top phase determination: differentiation between thin cirrus clouds and snow in manual (ground truth) analyses

    Science.gov (United States)

    Hutchison, Keith D.; Etherton, Brian J.; Topping, Phillip C.

    1996-12-01

    Quantitative assessments on the performance of automated cloud analysis algorithms require the creation of highly accurate, manual cloud, no cloud (CNC) images from multispectral meteorological satellite data. In general, the methodology to create ground truth analyses for the evaluation of cloud detection algorithms is relatively straightforward. However, when focus shifts toward quantifying the performance of automated cloud classification algorithms, the task of creating ground truth images becomes much more complicated since these CNC analyses must differentiate between water and ice cloud tops while ensuring that inaccuracies in automated cloud detection are not propagated into the results of the cloud classification algorithm. The process of creating these ground truth CNC analyses may become particularly difficult when little or no spectral signature is evident between a cloud and its background, as appears to be the case when thin cirrus is present over snow-covered surfaces. In this paper, procedures are described that enhance the researcher's ability to manually interpret and differentiate between thin cirrus clouds and snow-covered surfaces in daytime AVHRR imagery. The methodology uses data in up to six AVHRR spectral bands, including an additional band derived from the daytime 3.7 micron channel, which has proven invaluable for the manual discrimination between thin cirrus clouds and snow. It is concluded that while the 1.6 micron channel remains essential to differentiate between thin ice clouds and snow. However, this capability that may be lost if the 3.7 micron data switches to a nighttime-only transmission with the launch of future NOAA satellites.

  2. Lost in Cloud

    Science.gov (United States)

    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.

  3. [Determination of fat, protein and DM in raw milk by portable short-wave near infrared spectrometer].

    Science.gov (United States)

    Li, Xiao-yun; Wang, Jia-hua; Huang, Ya-wei; Han, Dong-hai

    2011-03-01

    Near infrared diffuse reflectance spectroscopy calibrations of fat, protein and DM in raw milk were studied with partial least-squares (PLS) regression using portable short-wave near infrared spectrometer. The results indicated that good calibrations of fat and DM were found, the correlation coefficients were all 0.98, the RMSEC were 0.187 and 0.217, RMSEP were 0.187 and 0.296, the RPDs were 5.02 and 3.20 respectively; the calibration of protein needed to be improved but can be used for practice, the correlation coefficient was 0.95, RMSEC was 0.105, RMSEP was 0.120, and RPD was 2.60. Furthermore, the measuring accuracy was improved by analyzing the correction relation of fat and DM in raw milk This study will probably provide a new on-site method for nondestructive and rapid measurement of milk.

  4. Relation between seasonally detrended shortwave infrared reflectance data and land surface moisture in semi-arid Sahel

    DEFF Research Database (Denmark)

    Olsen, Jørgen Lundegaard; Ceccato, Pietro; Proud, Simon Richard

    2013-01-01

    in vegetation moisture status, and is compared to detrended time series of the Normalized Difference Vegetation Index (NDVI). It was found that when plant available water is low, the SIWSI anomalies increase over time, while the NDVI anomalies decrease over time, but less systematically. Therefore SIWSI may......In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue...... Second Generation (MSG) satellite. We focused on responses in surface reflectance to soil- and surface moisture for bare soil and early to mid- growing season. A method for implementing detrended time series of the Shortwave Infrared Water Stress Index (SIWSI) is examined for detecting variations...

  5. Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

    Energy Technology Data Exchange (ETDEWEB)

    Craig, A. P.; Percy, B.; Marshall, A. R. J. [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Jain, M. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Wicks, G.; Hossain, K. [Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); Golding, T. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); McEwan, K.; Howle, C. [Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ (United Kingdom)

    2015-05-18

    Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In{sub 0.28}Ga{sub 0.72}As{sub 0.25}Sb{sub 0.75} allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×10{sup 10} Jones and 1×10{sup 10} Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures.

  6. Water vapor radiative effects on short-wave radiation in Spain

    Science.gov (United States)

    Vaquero-Martínez, Javier; Antón, Manuel; Ortiz de Galisteo, José Pablo; Román, Roberto; Cachorro, Victoria E.

    2018-06-01

    In this work, water vapor radiative effect (WVRE) is studied by means of the Santa Barbara's Disort Radiative Transfer (SBDART) model, fed with integrated water vapor (IWV) data from 20 ground-based GPS stations in Spain. Only IWV data recorded during cloud-free days (selected using daily insolation data) were used in this study. Typically, for SZA = 60.0 ± 0.5° WVRE values are around - 82 and - 66 Wm-2 (first and third quartile), although it can reach up - 100 Wm-2 or decrease to - 39 Wm-2. A power dependence of WVRE on IWV and cosine of solar zenith angle (SZA) was found by an empirical fit. This relation is used to determine the water vapor radiative efficiency (WVEFF = ∂WVRE/∂IWV). Obtained WVEFF values range from - 9 and 0 Wm-2 mm-1 (- 2.2 and 0% mm-1 in relative terms). It is observed that WVEFF decreases as IWV increases, but also as SZA increases. On the other hand, when relative WVEFF is calculated from normalized WVRE, an increase of SZA results in an increase of relative WVEFF. Heating rates were also calculated, ranging from 0.2 Kday-1 to 1.7 Kday-1. WVRE was also calculated at top of atmosphere, where values ranged from 4 Wm-2 to 37 Wm-2.

  7. Research on cloud computing solutions

    OpenAIRE

    Liudvikas Kaklauskas; Vaida Zdanytė

    2015-01-01

    Cloud computing can be defined as a new style of computing in which dynamically scala-ble and often virtualized resources are provided as a services over the Internet. Advantages of the cloud computing technology include cost savings, high availability, and easy scalability. Voas and Zhang adapted six phases of computing paradigms, from dummy termi-nals/mainframes, to PCs, networking computing, to grid and cloud computing. There are four types of cloud computing: public cloud, private cloud, ...

  8. VMware vCloud security

    CERN Document Server

    Sarkar, Prasenjit

    2013-01-01

    VMware vCloud Security provides the reader with in depth knowledge and practical exercises sufficient to implement a secured private cloud using VMware vCloud Director and vCloud Networking and Security.This book is primarily for technical professionals with system administration and security administration skills with significant VMware vCloud experience who want to learn about advanced concepts of vCloud security and compliance.

  9. Security in hybrid cloud computing

    OpenAIRE

    Koudelka, Ondřej

    2016-01-01

    This bachelor thesis deals with the area of hybrid cloud computing, specifically with its security. The major aim of the thesis is to analyze and compare the chosen hybrid cloud providers. For the minor aim this thesis compares the security challenges of hybrid cloud as opponent to other deployment models. In order to accomplish said aims, this thesis defines the terms cloud computing and hybrid cloud computing in its theoretical part. Furthermore the security challenges for cloud computing a...

  10. Transcending Transmission

    DEFF Research Database (Denmark)

    Schoeneborn, Dennis; Trittin, Hannah

    2013-01-01

    Purpose – Extant research on corporate social responsibility (CSR) communication primarily relies on a transmission model of communication that treats organizations and communication as distinct phenomena. This approach has been criticized for neglecting the formative role of communication...... in the emergence of organizations. This paper seeks to propose to reconceptualize CSR communication by drawing on the “communication constitutes organizations” (CCO) perspective. Design/methodology/approach – This is a conceptual paper that explores the implications of switching from an instrumental...... to a constitutive notion of communication. Findings – The study brings forth four main findings: from the CCO view, organizations are constituted by several, partly dissonant, and potentially contradictory communicative practices. From that viewpoint, the potential impact of CSR communication becomes a matter...

  11. Cloud security in vogelvlucht

    NARCIS (Netherlands)

    Pieters, Wolter

    2011-01-01

    Cloud computing is dé hype in IT op het moment, en hoewel veel aspecten niet nieuw zijn, leidt het concept wel tot de noodzaak voor nieuwe vormen van beveiliging. Het idee van cloud computing biedt echter ook juist kansen om hierover na te denken: wat is de rol van informatiebeveiliging in een

  12. CLOUD SERVICES IN EDUCATION

    Directory of Open Access Journals (Sweden)

    Z.S. Seydametova

    2011-05-01

    Full Text Available We present the on-line services based on cloud computing, provided by Google to educational institutions. We describe the own experience of the implementing the Google Apps Education Edition in the educational process. We analyzed and compared the other universities experience of using cloud technologies.

  13. Cloud MicroAtlas

    Indian Academy of Sciences (India)

    We begin by outlining the life cycle of a tall cloud, and thenbriefly discuss cloud systems. We choose one aspect of thislife cycle, namely, the rapid growth of water droplets in ice freeclouds, to then discuss in greater detail. Taking a singlevortex to be a building block of turbulence, we demonstrateone mechanism by which ...

  14. Greening the cloud

    NARCIS (Netherlands)

    van den Hoed, Robert; Hoekstra, Eric; Procaccianti, Giuseppe; Lago, Patricia; Grosso, Paolo; Taal, Arie; Grosskop, Kay; van Bergen, Esther

    The cloud has become an essential part of our daily lives. We use it to store our documents (Dropbox), to stream our music and films (Spotify and Netflix) and without giving it any thought, we use it to work on documents in the cloud (Google Docs).

  15. Learning in the Clouds?

    Science.gov (United States)

    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.…

  16. Kernel structures for Clouds

    Science.gov (United States)

    Spafford, Eugene H.; Mckendry, Martin S.

    1986-01-01

    An overview of the internal structure of the Clouds kernel was presented. An indication of how these structures will interact in the prototype Clouds implementation is given. Many specific details have yet to be determined and await experimentation with an actual working system.

  17. Observation of the Spectrally Invariant Properties of Clouds in Cloudy-to-Clear Transition Zones During the MAGIC Field Campaign

    Science.gov (United States)

    Yang, Weidong; Marshak, Alexander; McBride, Patrick; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

    2016-01-01

    We use the spectrally invariant method to study the variability of cloud optical thickness tau and droplet effective radius r(sub eff) in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness t while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius r(sub eff)even without the exact knowledge of tau; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

  18. Microphysical Modeling of Mineral Clouds in GJ1214 b and GJ436 b: Predicting Upper Limits on the Cloud-top Height

    Science.gov (United States)

    Ohno, Kazumasa; Okuzumi, Satoshi

    2018-05-01

    The ubiquity of clouds in the atmospheres of exoplanets, especially of super-Earths, is one of the outstanding issues for the transmission spectra survey. Understanding the formation process of clouds in super-Earths is necessary to interpret the observed spectra correctly. In this study, we investigate the vertical distributions of particle size and mass density of mineral clouds in super-Earths using a microphysical model that takes into account the vertical transport and growth of cloud particles in a self-consistent manner. We demonstrate that the vertical profiles of mineral clouds significantly vary with the concentration of cloud condensation nuclei and atmospheric metallicity. We find that the height of the cloud top increases with increasing metallicity as long as the metallicity is lower than the threshold. If the metallicity is larger than the threshold, the cloud-top height no longer increases appreciably with metallicity because coalescence yields larger particles of higher settling velocities. We apply our cloud model to GJ1214 b and GJ436 b, for which recent transmission observations suggest the presence of high-altitude opaque clouds. For GJ436 b, we show that KCl particles can ascend high enough to explain the observation. For GJ1214 b, by contrast, the height of KCl clouds predicted from our model is too low to explain its flat transmission spectrum. Clouds made of highly porous KCl particles could explain the observations if the atmosphere is highly metal-rich, and hence the particle microstructure might be a key to interpret the flat spectrum of GJ1214 b.

  19. Cloud computing basics

    CERN Document Server

    Srinivasan, S

    2014-01-01

    Cloud Computing Basics covers the main aspects of this fast moving technology so that both practitioners and students will be able to understand cloud computing. The author highlights the key aspects of this technology that a potential user might want to investigate before deciding to adopt this service. This book explains how cloud services can be used to augment existing services such as storage, backup and recovery. Addressing the details on how cloud security works and what the users must be prepared for when they move their data to the cloud. Also this book discusses how businesses could prepare for compliance with the laws as well as industry standards such as the Payment Card Industry.

  20. Solar variability and clouds

    CERN Document Server

    Kirkby, Jasper

    2000-01-01

    Satellite observations have revealed a surprising imprint of the 11- year solar cycle on global low cloud cover. The cloud data suggest a correlation with the intensity of Galactic cosmic rays. If this apparent connection between cosmic rays and clouds is real, variations of the cosmic ray flux caused by long-term changes in the solar wind could have a significant influence on the global energy radiation budget and the climate. However a direct link between cosmic rays and clouds has not been unambiguously established and, moreover, the microphysical mechanism is poorly understood. New experiments are being planned to find out whether cosmic rays can affect cloud formation, and if so how. (37 refs).

  1. Energy efficiency for cloud-radio access networks with imperfect channel state information

    KAUST Repository

    Al-Oquibi, Bayan; Amin, Osama; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2016-01-01

    metric in next generation wireless systems (5G). Cloud radio access network (C-RAN), a promising 5G network architecture, provides an efficient framework for improving the EE performance, by means of coordinating the transmission across the network

  2. Laboratory and Cloud Chamber Studies of Formation Processes and Properties of Atmospheric Ice Particles

    Science.gov (United States)

    Leisner, T.; Abdelmonem, A.; Benz, S.; Brinkmann, M.; Möhler, O.; Rzesanke, D.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2009-04-01

    The formation of ice in tropospheric clouds controls the evolution of precipitation and thereby influences climate and weather via a complex network of dynamical and microphysical processes. At higher altitudes, ice particles in cirrus clouds or contrails modify the radiative energy budget by direct interaction with the shortwave and longwave radiation. In order to improve the parameterisation of the complex microphysical and dynamical processes leading to and controlling the evolution of tropospheric ice, laboratory experiments are performed at the IMK Karlsruhe both on a single particle level and in the aerosol and cloud chamber AIDA. Single particle experiments in electrodynamic levitation lend themselves to the study of the interaction between cloud droplets and aerosol particles under extremely well characterized and static conditions in order to obtain microphysical parameters as freezing nucleation rates for homogeneous and heterogeneous ice formation. They also allow the observation of the freezing dynamics and of secondary ice formation and multiplication processes under controlled conditions and with very high spatial and temporal resolution. The inherent droplet charge in these experiments can be varied over a wide range in order to assess the influence of the electrical state of the cloud on its microphysics. In the AIDA chamber on the other hand, these processes are observable under the realistic dynamic conditions of an expanding and cooling cloud- parcel with interacting particles and are probed simultaneously by a comprehensive set of analytical instruments. By this means, microphysical processes can be studied in their complex interplay with dynamical processes as for example coagulation or particle evaporation and growth via the Bergeron - Findeisen process. Shortwave scattering and longwave absorption properties of the nucleating and growing ice crystals are probed by in situ polarised laser light scattering measurements and infrared extinction

  3. The impact of meteorology on smoke and low-level clouds over the southeast Atlantic

    Science.gov (United States)

    Adebiyi, Adeyemi A.

    In this dissertation, we use radiosondes and satellite observation, reanalysis datasets, as well as radiative and trajectory models to document the relationship between the low-level clouds, smoke and meteorology over the southeast Atlantic. The southeast Atlantic presents a natural environment with one of the world's largest marine low-level clouds, occurring along with the largest consumption of biomass fire over the adjacent southern African continent. This combination results in an extensive region of above-cloud biomass burning aerosols (predominantly smoke) over the marine low-level clouds, whereby the elevated smoke could lead to the stabilization of the lower troposphere, reduction of the cloud-top entrainment, and the build-up of water vapor within the boundary layer, which may eventually lead to increases in cloud fraction and decreases in cloud-top heights, in a process called semi-direct aerosol effect. The smokes are transported at a preferred altitude (˜750h Pa - 550hPa) by a background easterly winds between July and October. During the same period, strong surface winds and ocean-influenced cold surface temperature characterize the meteorology within the boundary layer. The marine low-level cloud region is also associated with strong climatological subsidence above it, and cloud-top temperature inversion layer. The meteorological variations occurring above and below the low-level clouds are capable of influencing the cloud properties, and therefore may confound with the aerosol effects, making the separation of the aerosol and meteorological influences, on the low-level cloud, a very difficult challenge. We address this problem by identifying the dynamical and thermodynamical variations above the low-level clouds during the the peak aerosol months (July-October). Specifically, three areas are explored in this dissertation: the convolution of the dynamical and moisture effects with shortwave-absorbing aerosols over the low-level clouds; the role of

  4. Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision

    OpenAIRE

    Inoue, Tsuyoshi; Fukui, Yasuo

    2013-01-01

    Recent observations of molecular clouds around rich massive star clusters including NGC3603, 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 the cloud-cloud collision. We find that the massive mol...

  5. Zonal Aerosol Direct and Indirect Radiative Forcing using Combined CALIOP, CERES, CloudSat, and CERES Data

    Science.gov (United States)

    Miller, W. F.; Kato, S.; Rose, F. G.; Sun-Mack, S.

    2009-12-01

    Under the NASA Energy and Water Cycle System (NEWS) program, cloud and aerosol properties derived from CALIPSO, CloudSat, and MODIS data then matched to the CERES footprint are used for irradiance profile computations. Irradiance profiles are included in the publicly available product, CCCM. In addition to the MODIS and CALIPSO generated aerosol, aerosol optical thickness is calculated over ocean by processing MODIS radiance through the Stowe-Ignatov algorithm. The CERES cloud mask and properties algorithm are use with MODIS radiance to provide additional cloud information to accompany the actively sensed data. The passively sensed data is the only input to the standard CERES radiative flux products. The combined information is used as input to the NASA Langley Fu-Liou radiative transfer model to determine vertical profiles and Top of Atmosphere shortwave and longwave flux for pristine, all-sky, and aerosol conditions for the special data product. In this study, the three sources of aerosol optical thickness will be compared directly and their influence on the calculated and measured TOA fluxes. Earlier studies indicate that the largest uncertainty in estimating direct aerosol forcing using aerosol optical thickness derived from passive sensors is caused by cloud contamination. With collocated CALIPSO data, we are able to estimate frequency of occurrence of cloud contamination, effect on the aerosol optical thickness and direct radiative effect estimates.

  6. Cloud residues and interstitial aerosols from non-precipitating clouds over an industrial and urban area in northern China

    Science.gov (United States)

    Li, Weijun; Li, Peiren; Sun, Guode; Zhou, Shengzhen; Yuan, Qi; Wang, Wenxing

    2011-05-01

    Most studies of aerosol-cloud interactions have been conducted in remote locations; few have investigated the characterization of cloud condensation nuclei (CCN) over highly polluted urban and industrial areas. The present work, based on samples collected at Mt. Tai, a site in northern China affected by nearby urban and industrial air pollutant emissions, illuminates CCN properties in a polluted atmosphere. High-resolution transmission electron microscopy (TEM) was used to obtain the size, composition, and mixing state of individual cloud residues and interstitial aerosols. Most of the cloud residues displayed distinct rims which were found to consist of soluble organic matter (OM). Nearly all (91.7%) cloud residues were attributed to sulfate-related salts (the remainder was mostly coarse crustal dust particles with nitrate coatings). Half the salt particles were internally mixed with two or more refractory particles (e.g., soot, fly ash, crustal dust, CaSO 4, and OM). A comparison between cloud residues and interstitial particles shows that the former contained more salts and were of larger particle size than the latter. In addition, a somewhat high number scavenging ratio of 0.54 was observed during cloud formation. Therefore, the mixtures of salts with OMs account for most of the cloud-nucleating ability of the entire aerosol population in the polluted air of northern China. We advocate that both size and composition - the two influential, controlling factors for aerosol activation - should be built into all regional climate models of China.

  7. Influence of Ice Cloud Microphysics on Imager-Based Estimates of Earth's Radiation Budget

    Science.gov (United States)

    Loeb, N. G.; Kato, S.; Minnis, P.; Yang, P.; Sun-Mack, S.; Rose, F. G.; Hong, G.; Ham, S. H.

    2016-12-01

    A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget from the TOA down to the surface along with the associated atmospheric and surface properties that influence it. CERES relies on a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, high-resolution spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. While the TOA radiation budget is largely determined directly from accurate broadband radiometer measurements, the surface radiation budget is derived indirectly through radiative transfer model calculations initialized using imager-based cloud and aerosol retrievals and meteorological assimilation data. Because ice cloud particles exhibit a wide range of shapes, sizes and habits that cannot be independently retrieved a priori from passive visible/infrared imager measurements, assumptions about the scattering properties of ice clouds are necessary in order to retrieve ice cloud optical properties (e.g., optical depth) from imager radiances and to compute broadband radiative fluxes. This presentation will examine how the choice of an ice cloud particle model impacts computed shortwave (SW) radiative fluxes at the top-of-atmosphere (TOA) and surface. The ice cloud particle models considered correspond to those from prior, current and future CERES data product versions. During the CERES Edition2 (and Edition3) processing, ice cloud particles were assumed to be smooth hexagonal columns. In the Edition4, roughened hexagonal columns are assumed. The CERES team is now working on implementing in a future version an ice cloud particle model comprised of a two-habit ice cloud model consisting of roughened hexagonal columns and aggregates of roughened columnar elements. In each case, we use the same ice particle model in both the

  8. Making and Breaking Clouds

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Molecular clouds which youre likely familiar with from stunning popular astronomy imagery lead complicated, tumultuous lives. A recent study has now found that these features must be rapidly built and destroyed.Star-Forming CollapseA Hubble view of a molecular cloud, roughly two light-years long, that has broken off of the Carina Nebula. [NASA/ESA, N. Smith (University of California, Berkeley)/The Hubble Heritage Team (STScI/AURA)]Molecular gas can be found throughout our galaxy in the form of eminently photogenic clouds (as featured throughout this post). Dense, cold molecular gas makes up more than 20% of the Milky Ways total gas mass, and gravitational instabilities within these clouds lead them to collapse under their own weight, resulting in the formation of our galaxys stars.How does this collapse occur? The simplest explanation is that the clouds simply collapse in free fall, with no source of support to counter their contraction. But if all the molecular gas we observe collapsed on free-fall timescales, star formation in our galaxy would churn a rate thats at least an order of magnitude higher than the observed 12 solar masses per year in the Milky Way.Destruction by FeedbackAstronomers have theorized that there may be some mechanism that supports these clouds against gravity, slowing their collapse. But both theoretical studies and observations of the clouds have ruled out most of these potential mechanisms, and mounting evidence supports the original interpretation that molecular clouds are simply gravitationally collapsing.A sub-mm image from ESOs APEX telescope of part of the Taurus molecular cloud, roughly ten light-years long, superimposed on a visible-light image of the region. [ESO/APEX (MPIfR/ESO/OSO)/A. Hacar et al./Digitized Sky Survey 2. Acknowledgment: Davide De Martin]If this is indeed the case, then one explanation for our low observed star formation rate could be that molecular clouds are rapidly destroyed by feedback from the very stars

  9. Cloud Computing: An Overview

    Directory of Open Access Journals (Sweden)

    Libor Sarga

    2012-10-01

    Full Text Available As cloud computing is gaining acclaim as a cost-effective alternative to acquiring processing resources for corporations, scientific applications and individuals, various challenges are rapidly coming to the fore. While academia struggles to procure a concise definition, corporations are more interested in competitive advantages it may generate and individuals view it as a way of speeding up data access times or a convenient backup solution. Properties of the cloud architecture largely preclude usage of existing practices while achieving end-users’ and companies’ compliance requires considering multiple infrastructural as well as commercial factors, such as sustainability in case of cloud-side interruptions, identity management and off-site corporate data handling policies. The article overviews recent attempts at formal definitions of cloud computing, summarizes and critically evaluates proposed delimitations, and specifies challenges associated with its further proliferation. Based on the conclusions, future directions in the field of cloud computing are also briefly hypothesized to include deeper focus on community clouds and bolstering innovative cloud-enabled platforms and devices such as tablets, smart phones, as well as entertainment applications.

  10. Cloud Computing Law

    CERN Document Server

    Millard, Christopher

    2013-01-01

    This book is about the legal implications of cloud computing. In essence, ‘the cloud’ is a way of delivering computing resources as a utility service via the internet. It is evolving very rapidly with substantial investments being made in infrastructure, platforms and applications, all delivered ‘as a service’. The demand for cloud resources is enormous, driven by such developments as the deployment on a vast scale of mobile apps and the rapid emergence of ‘Big Data’. Part I of this book explains what cloud computing is and how it works. Part II analyses contractual relationships between cloud service providers and their customers, as well as the complex roles of intermediaries. Drawing on primary research conducted by the Cloud Legal Project at Queen Mary University of London, cloud contracts are analysed in detail, including the appropriateness and enforceability of ‘take it or leave it’ terms of service, as well as the scope for negotiating cloud deals. Specific arrangements for public sect...

  11. Community Cloud Computing

    Science.gov (United States)

    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.

  12. A Global Survey of Cloud Thermodynamic Phase using High Spatial Resolution VSWIR Spectroscopy, 2005-2015

    Science.gov (United States)

    Thompson, D. R.; Kahn, B. H.; Green, R. O.; Chien, S.; Middleton, E.; Tran, D. Q.

    2017-12-01

    Clouds' variable ice and liquid content significantly influences their optical properties, evolution, and radiative forcing potential (Tan and Storelvmo, J. Atmos. Sci, 73, 2016). However, most remote measurements of thermodynamic phase have spatial resolutions of 1 km or more and are insensitive to mixed phases. This under-constrains important processes, such as spatial partitioning within mixed phase clouds, that carry outsize radiative forcing impacts. These uncertainties could shift Global Climate Model (GCM) predictions of future warming by over 1 degree Celsius (Tan et al., Science 352:6282, 2016). Imaging spectroscopy of reflected solar energy from the 1.4 - 1.8 μm shortwave infrared (SWIR) spectral range can address this observational gap. These observations can distinguish ice and water absorption, providing a robust and sensitive measurement of cloud top thermodynamic phase including mixed phases. Imaging spectrometers can resolve variations at scales of tens to hundreds of meters (Thompson et al., JGR-Atmospheres 121, 2016). We report the first such global high spatial resolution (30 m) survey, based on data from 2005-2015 acquired by the Hyperion imaging spectrometer onboard NASA's EO-1 spacecraft (Pearlman et al., Proc. SPIE 4135, 2001). Estimated seasonal and latitudinal distributions of cloud thermodynamic phase generally agree with observations made by other satellites such as the Atmospheric Infrared Sounder (AIRS). Variogram analyses reveal variability at different spatial scales. Our results corroborate previously observed zonal distributions, while adding insight into the spatial scales of processes governing cloud top thermodynamic phase. Figure: Thermodynamic phase retrievals. Top: Example of a cloud top thermodynamic phase map from the EO-1/Hyperion. Bottom: Latitudinal distributions of pure and mixed phase clouds, 2005-2015, showing Liquid Thickness Fraction (LTF). LTF=0 corresponds to pure ice absorption, while LTF=1 is pure liquid. The

  13. Diffuse interstellar clouds

    International Nuclear Information System (INIS)

    Black, J.H.

    1987-01-01

    The author defines and discusses the nature of diffuse interstellar clouds. He discusses how they contribute to the general extinction of starlight. The atomic and molecular species that have been identified in the ultraviolet, visible, and near infrared regions of the spectrum of a diffuse cloud are presented. The author illustrates some of the practical considerations that affect absorption line observations of interstellar atoms and molecules. Various aspects of the theoretical description of diffuse clouds required for a full interpretation of the observations are discussed

  14. Cloud Computing Security

    OpenAIRE

    Ngongang, Guy

    2011-01-01

    This project aimed to show how possible it is to use a network intrusion detection system in the cloud. The security in the cloud is a concern nowadays and security professionals are still finding means to make cloud computing more secure. First of all the installation of the ESX4.0, vCenter Server and vCenter lab manager in server hardware was successful in building the platform. This allowed the creation and deployment of many virtual servers. Those servers have operating systems and a...

  15. Trusted cloud computing

    CERN Document Server

    Krcmar, Helmut; Rumpe, Bernhard

    2014-01-01

    This book documents the scientific results of the projects related to the Trusted Cloud Program, covering fundamental aspects of trust, security, and quality of service for cloud-based services and applications. These results aim to allow trustworthy IT applications in the cloud by providing a reliable and secure technical and legal framework. In this domain, business models, legislative circumstances, technical possibilities, and realizable security are closely interwoven and thus are addressed jointly. The book is organized in four parts on "Security and Privacy", "Software Engineering and

  16. COMPARATIVE STUDY OF CLOUD COMPUTING AND MOBILE CLOUD COMPUTING

    OpenAIRE

    Nidhi Rajak*, Diwakar Shukla

    2018-01-01

    Present era is of Information and Communication Technology (ICT) and there are number of researches are going on Cloud Computing and Mobile Cloud Computing such security issues, data management, load balancing and so on. Cloud computing provides the services to the end user over Internet and the primary objectives of this computing are resource sharing and pooling among the end users. Mobile Cloud Computing is a combination of Cloud Computing and Mobile Computing. Here, data is stored in...

  17. Molecular clouds near supernova remnants

    International Nuclear Information System (INIS)

    Wootten, H.A.

    1978-01-01

    The physical properties of molecular clouds near supernova remnants were investigated. Various properties of the structure and kinematics of these clouds are used to establish their physical association with well-known remmnants. An infrared survey of the most massive clouds revealed embedded objects, probably stars whose formation was induced by the supernova blast wave. In order to understand the relationship between these and other molecular clouds, a control group of clouds was also observed. Excitation models for dense regions of all the clouds are constructed to evaluate molecular abundances in these regions. Those clouds that have embedded stars have lower molecular abundances than the clouds that do not. A cloud near the W28 supernova remnant also has low abundances. Molecular abundances are used to measure an important parameter, the electron density, which is not directly observable. In some clouds extensive deuterium fractionation is observed which confirms electron density measurements in those clouds. Where large deuterium fractionation is observed, the ionization rate in the cloud interior can also be measured. The electron density and ionization rate in the cloud near W28 are higher than in most clouds. The molecular abundances and electron densities are functions of the chemical and dynamical state of evolution of the cloud. Those clouds with lowest abundances are probably the youngest clouds. As low-abundance clouds, some clouds near supernova remnants may have been recently swept from the local interstellar material. Supernova remnants provide sites for star formation in ambient clouds by compressing them, and they sweep new clouds from more diffuse local matter

  18. Taxonomy of cloud computing services

    NARCIS (Netherlands)

    Hoefer, C.N.; Karagiannis, Georgios

    2010-01-01

    Cloud computing is a highly discussed topic, and many big players of the software industry are entering the development of cloud services. Several companies want to explore the possibilities and benefits of cloud computing, but with the amount of cloud computing services increasing quickly, the need

  19. Decreasing cloud cover drives the recent mass loss on the Greenland Ice Sheet.

    Science.gov (United States)

    Hofer, Stefan; Tedstone, Andrew J; Fettweis, Xavier; Bamber, Jonathan L

    2017-06-01

    The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate since the mid-1990s. This has been due to both increased ice discharge into the ocean and melting at the surface, with the latter being the dominant contribution. This change in state has been attributed to rising temperatures and a decrease in surface albedo. We show, using satellite data and climate model output, that the abrupt reduction in surface mass balance since about 1995 can be attributed largely to a coincident trend of decreasing summer cloud cover enhancing the melt-albedo feedback. Satellite observations show that, from 1995 to 2009, summer cloud cover decreased by 0.9 ± 0.3% per year. Model output indicates that the GrIS summer melt increases by 27 ± 13 gigatons (Gt) per percent reduction in summer cloud cover, principally because of the impact of increased shortwave radiation over the low albedo ablation zone. The observed reduction in cloud cover is strongly correlated with a state shift in the North Atlantic Oscillation promoting anticyclonic conditions in summer and suggests that the enhanced surface mass loss from the GrIS is driven by synoptic-scale changes in Arctic-wide atmospheric circulation.

  20. Cloud Computing (1/2)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Cloud computing, the recent years buzzword for distributed computing, continues to attract and keep the interest of both the computing and business world. These lectures aim at explaining "What is Cloud Computing?" identifying and analyzing it's characteristics, models, and applications. The lectures will explore different "Cloud definitions" given by different authors and use them to introduce the particular concepts. The main cloud models (SaaS, PaaS, IaaS), cloud types (public, private, hybrid), cloud standards and security concerns will be presented. The borders between Cloud Computing and Grid Computing, Server Virtualization, Utility Computing will be discussed and analyzed.

  1. Cloud Computing (2/2)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Cloud computing, the recent years buzzword for distributed computing, continues to attract and keep the interest of both the computing and business world. These lectures aim at explaining "What is Cloud Computing?" identifying and analyzing it's characteristics, models, and applications. The lectures will explore different "Cloud definitions" given by different authors and use them to introduce the particular concepts. The main cloud models (SaaS, PaaS, IaaS), cloud types (public, private, hybrid), cloud standards and security concerns will be presented. The borders between Cloud Computing and Grid Computing, Server Virtualization, Utility Computing will be discussed and analyzed.

  2. IBM SmartCloud essentials

    CERN Document Server

    Schouten, Edwin

    2013-01-01

    A practical, user-friendly guide that provides an introduction to cloud computing using IBM SmartCloud, along with a thorough understanding of resource management in a cloud environment.This book is great for anyone who wants to get a grasp of what cloud computing is and what IBM SmartCloud has to offer. If you are an IT specialist, IT architect, system administrator, or a developer who wants to thoroughly understand the cloud computing resource model, this book is ideal for you. No prior knowledge of cloud computing is expected.

  3. Data distribution method of workflow in the cloud environment

    Science.gov (United States)

    Wang, Yong; Wu, Junjuan; Wang, Ying

    2017-08-01

    Cloud computing for workflow applications provides the required high efficiency calculation and large storage capacity and it also brings challenges to the protection of trade secrets and other privacy data. Because of privacy data will cause the increase of the data transmission time, this paper presents a new data allocation algorithm based on data collaborative damage degree, to improve the existing data allocation strategy? Safety and public cloud computer algorithm depends on the private cloud; the static allocation method in the initial stage only to the non-confidential data division to improve the original data, in the operational phase will continue to generate data to dynamically adjust the data distribution scheme. The experimental results show that the improved method is effective in reducing the data transmission time.

  4. Cloud MicroAtlas∗

    Indian Academy of Sciences (India)

    ∗Any resemblance to the title of David Mitchell's book is purely intentional! RESONANCE | March 2017. 269 .... The most comprehensive reference we know of on the subject of cloud microphysics is the book .... Economic and. Political Weekly ...

  5. Experimental project - Cloud chamber

    International Nuclear Information System (INIS)

    Nour, Elena; Quinchard, Gregory; Soudon, Paul

    2015-01-01

    This document reports an academic experimental project dealing with the general concepts of radioactivity and their application to the cloud room experiment. The author first recalls the history of the design and development of a cloud room, and some definitions and characteristics of cosmic radiation, and proposes a description of the principle and physics of a cloud room. The second part is a theoretical one, and addresses the involved particles, the origins of electrons, and issues related to the transfer of energy (Bremsstrahlung effect, Bragg peak). The third part reports the experimental work with the assessment of a cloud droplet radius, the identification of a trace for each particle (alphas and electrons), and the study of the magnetic field deviation

  6. Green symbiotic cloud communications

    CERN Document Server

    Mustafa, H D; Desai, Uday B; Baveja, Brij Mohan

    2017-01-01

    This book intends to change the perception of modern day telecommunications. Communication systems, usually perceived as “dumb pipes”, carrying information / data from one point to another, are evolved into intelligently communicating smart systems. The book introduces a new field of cloud communications. The concept, theory, and architecture of this new field of cloud communications are discussed. The book lays down nine design postulates that form the basis of the development of a first of its kind cloud communication paradigm entitled Green Symbiotic Cloud Communications or GSCC. The proposed design postulates are formulated in a generic way to form the backbone for development of systems and technologies of the future. The book can be used to develop courses that serve as an essential part of graduate curriculum in computer science and electrical engineering. Such courses can be independent or part of high-level research courses. The book will also be of interest to a wide range of readers including b...

  7. Entangled Cloud Storage

    DEFF Research Database (Denmark)

    Ateniese, Giuseppe; Dagdelen, Özgür; Damgård, Ivan Bjerre

    2012-01-01

    keeps the files in it private but still lets each client P_i recover his own data by interacting with S; no cooperation from other clients is needed. At the same time, the cloud provider is discouraged from altering or overwriting any significant part of c as this will imply that none of the clients can......Entangled cloud storage enables a set of clients {P_i} to “entangle” their files {f_i} into a single clew c to be stored by a (potentially malicious) cloud provider S. The entanglement makes it impossible to modify or delete significant part of the clew without affecting all files in c. A clew...... recover their files. We provide theoretical foundations for entangled cloud storage, introducing the notion of an entangled encoding scheme that guarantees strong security requirements capturing the properties above. We also give a concrete construction based on privacy-preserving polynomial interpolation...

  8. Marine Cloud Brightening

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. CLOUD COMPUTING SECURITY ISSUES

    OpenAIRE

    Florin OGIGAU-NEAMTIU

    2012-01-01

    The term “cloud computing” has been in the spotlights of IT specialists the last years because of its potential to transform this industry. The promised benefits have determined companies to invest great sums of money in researching and developing this domain and great steps have been made towards implementing this technology. Managers have traditionally viewed IT as difficult and expensive and the promise of cloud computing leads many to think that IT will now be easy and cheap. The reality ...

  10. Marine cloud brightening.

    Science.gov (United States)

    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.

  11. Cloud benchmarking for performance

    OpenAIRE

    Varghese, Blesson; Akgun, Ozgur; Miguel, Ian; Thai, Long; Barker, Adam

    2014-01-01

    Date of Acceptance: 20/09/2014 How can applications be deployed on the cloud to achieve maximum performance? This question has become significant and challenging with the availability of a wide variety of Virtual Machines (VMs) with different performance capabilities in the cloud. The above question is addressed by proposing a six step benchmarking methodology in which a user provides a set of four weights that indicate how important each of the following groups: memory, processor, computa...

  12. Toward Cloud Computing Evolution

    OpenAIRE

    Susanto, Heru; Almunawar, Mohammad Nabil; Kang, Chen Chin

    2012-01-01

    -Information Technology (IT) shaped the success of organizations, giving them a solid foundation that increases both their level of efficiency as well as productivity. The computing industry is witnessing a paradigm shift in the way computing is performed worldwide. There is a growing awareness among consumers and enterprises to access their IT resources extensively through a "utility" model known as "cloud computing." Cloud computing was initially rooted in distributed grid-based computing. ...

  13. A TRUSTWORTHY CLOUD FORENSICS ENVIRONMENT

    OpenAIRE

    Zawoad , Shams; Hasan , Ragib

    2015-01-01

    Part 5: CLOUD FORENSICS; International audience; The rapid migration from traditional computing and storage models to cloud computing environments has made it necessary to support reliable forensic investigations in the cloud. However, current cloud computing environments often lack support for forensic investigations and the trustworthiness of evidence is often questionable because of the possibility of collusion between dishonest cloud providers, users and forensic investigators. This chapt...

  14. On Cloud-based Oversubscription

    OpenAIRE

    Householder, Rachel; Arnold, Scott; Green, Robert

    2014-01-01

    Rising trends in the number of customers turning to the cloud for their computing needs has made effective resource allocation imperative for cloud service providers. In order to maximize profits and reduce waste, providers have started to explore the role of oversubscribing cloud resources. However, the benefits of cloud-based oversubscription are not without inherent risks. This paper attempts to unveil the incentives, risks, and techniques behind oversubscription in a cloud infrastructure....

  15. SOME CONSIDERATIONS ON CLOUD ACCOUNTING

    OpenAIRE

    Doina Pacurari; Elena Nechita

    2013-01-01

    Cloud technologies have developed intensively during the last years. Cloud computing allows the customers to interact with their data and applications at any time, from any location, while the providers host these resources. A client company may choose to run in the cloud a part of its business (sales by agents, payroll, etc.), or even the entire business. The company can get access to a large category of cloud-based software, including accounting software. Cloud solutions are especially reco...

  16. CLOUD COMPUTING TECHNOLOGY TRENDS

    Directory of Open Access Journals (Sweden)

    Cristian IVANUS

    2014-05-01

    Full Text Available Cloud computing has been a tremendous innovation, through which applications became available online, accessible through an Internet connection and using any computing device (computer, smartphone or tablet. According to one of the most recent studies conducted in 2012 by Everest Group and Cloud Connect, 57% of companies said they already use SaaS application (Software as a Service, and 38% reported using standard tools PaaS (Platform as a Service. However, in the most cases, the users of these solutions highlighted the fact that one of the main obstacles in the development of this technology is the fact that, in cloud, the application is not available without an Internet connection. The new challenge of the cloud system has become now the offline, specifically accessing SaaS applications without being connected to the Internet. This topic is directly related to user productivity within companies as productivity growth is one of the key promises of cloud computing system applications transformation. The aim of this paper is the presentation of some important aspects related to the offline cloud system and regulatory trends in the European Union (EU.

  17. Coupling between marine boundary layer clouds and summer-to-summer sea surface temperature variability over the North Atlantic and Pacific

    Science.gov (United States)

    Myers, Timothy A.; Mechoso, Carlos R.; DeFlorio, Michael J.

    2018-02-01

    Climate modes of variability over the Atlantic and Pacific may be amplified by a positive feedback between sea-surface temperature (SST) and marine boundary layer clouds. However, it is well known that climate models poorly simulate this feedback. Does this deficiency contribute to model-to-model differences in the representation of climate modes of variability? Over both the North Atlantic and Pacific, typical summertime interannual to interdecadal SST variability exhibits horseshoe-like patterns of co-located anomalies of shortwave cloud radiative effect (CRE), low-level cloud fraction, SST, and estimated inversion strength over the subtropics and midlatitudes that are consistent with a positive cloud feedback. During winter over the midlatitudes, this feedback appears to be diminished. Models participating in the Coupled Model Intercomparison Project phase 5 that simulate a weak feedback between subtropical SST and shortwave CRE produce smaller and less realistic amplitudes of summertime SST and CRE variability over the northern oceans compared to models with a stronger feedback. The change in SST amplitude per unit change in CRE amplitude among the models and observations may be understood as the temperature response of the ocean mixed layer to a unit change in radiative flux over the course of a season. These results highlight the importance of boundary layer clouds in interannual to interdecadal atmosphere-ocean variability over the northern oceans during summer. The results also suggest that deficiencies in the simulation of these clouds in coupled climate models contribute to underestimation in their simulation of summer-to-summer SST variability.

  18. Using a second-order turbulence radiative-convective model to study the cloud/radiation interaction with the FIRE data

    International Nuclear Information System (INIS)

    Kao, C.Y.J.

    1992-01-01

    It is well recognized that extended sheets of low-level stratus and stratocumulus clouds are a persistent feature over the eastern parts of the major ocean basins associated with the quasipermanent subtropical high-pressure systems. These clouds exert a strong influence on climate through their high albedo, compared with the underlying surface, and their low altitude. The former leads to a reduction of the net incoming shortwave flux into the atmosphere and the latter leads to an infrared loss in a way essentially the same as the cloud-free conditions. Randall et al.[1984] estimated that an increase of a few percent of global low-level stratiform clouds may offset the warming caused by a doubling of the atmos-pheric CO 2 . The Atmospheric Radiation Measure-ment (ARM) Program, sponsored by the US Department of Energy, is envisioning a locale in the Eastern North Pacific for extensive measure-ments of stratiform boundary-layer clouds and their interaction with atmospheric radiation. Thus, a physically-based parameterization sheme for marine low-level stratiform clouds can be developed for general circulation models (GCMs). This paper is a modeling study with the current understanding of the important physical processes associated with a cloud-capped boundary layer. The numerical model is a high-resolution one-dimensional version of the second-order turbulence convective/radiative model developed at the Los Alamos National Laboratory

  19. How Difficult is it to Reduce Low-Level Cloud Biases With the Higher-Order Turbulence Closure Approach in Climate Models?

    Science.gov (United States)

    Xu, Kuan-Man

    2015-01-01

    is that cloud water content is much higher than in CAM5, which is combined with higher low-cloud coverage to produce larger shortwave CREs in some low-cloud prevailing regions. Thus, the cloud-radiative feedbacks are exaggerated there. The turning exercise is focused on microphysical parameters, which are also commonly used for tuning in climate models. The results will be discussed in this presentation.

  20. Optimizing the updated Goddard shortwave radiation Weather Research and Forecasting (WRF) scheme for Intel Many Integrated Core (MIC) architecture

    Science.gov (United States)

    Mielikainen, Jarno; Huang, Bormin; Huang, Allen H.-L.

    2015-05-01

    Intel Many Integrated Core (MIC) ushers in a new era of supercomputing speed, performance, and compatibility. It allows the developers to run code at trillions of calculations per second using the familiar programming model. In this paper, we present our results of optimizing the updated Goddard shortwave radiation Weather Research and Forecasting (WRF) scheme on Intel Many Integrated Core Architecture (MIC) hardware. The Intel Xeon Phi coprocessor is the first product based on Intel MIC architecture, and it consists of up to 61 cores connected by a high performance on-die bidirectional interconnect. The co-processor supports all important Intel development tools. Thus, the development environment is familiar one to a vast number of CPU developers. Although, getting a maximum performance out of Xeon Phi will require using some novel optimization techniques. Those optimization techniques are discusses in this paper. The results show that the optimizations improved performance of the original code on Xeon Phi 7120P by a factor of 1.3x.

  1. Infrared autofluorescence, short-wave autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytomas

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2016-05-01

    Full Text Available AIM: To investigate the findings of infrared fundus autofluorescence (IR-AF and spectral-domain optical coherence tomography (SD-OCT in eyes with optic disc melanocytoma (ODM. METHODS: IR-AF findings and those of other ophthalmologic imaging examinations, including short-wave autofluorescence (SW-AF, fluorescein angiography (FA, fundus color photography, and SD-OCT of 8 eyes of 8 consecutive cases with ODM were assessed. RESULTS: The ODMs in all cases (100% presented similar IR-AF, SW-AF, and FA findings. On IR-AF images, ODMs showed outstanding hyper-AF with well-defined outline. On SW-AF images, the area of ODMs presented as hypo-AF. FA images revealed the leaking retinal telangiectasia on the surface of the ODMs. On SD-OCT images in 8 cases (100%, the ODMs were sloped with highly reflective surface, which were disorganized retina and optic nerve layers. In 7 cases (87.5%, peripapillary choroids were involved. The melanocytomas of 8 cases (100% presented as optically empty spaces. Vitreous seeds were found in one case (12.5%. CONCLUSION: IR-AF imaging may provide a new modality to evaluate the pathologic features of ODMs, and together with SW-AF imaging, offers a new tool to study biological characteristics associated with ODMs. SD-OCT is a valuable tool in delimitating the tumor extension and providing morphological information about the adjacent retinal tissue.

  2. Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.).

    Science.gov (United States)

    Dogu-Baykut, Esra; Gunes, Gurbuz; Decker, Eric Andrew

    2014-08-15

    Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64 min. UV-C treatment led to 1.04 and 1.38 log CFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a(∗) value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3 μmol GAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14 days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Does variation in mineral composition alter the short-wave light scattering properties of desert dust aerosol?

    International Nuclear Information System (INIS)

    Smith, Andrew J.A.; Grainger, Roy G.

    2014-01-01

    Mineral dust aerosol is a major component of natural airborne particulates. Using satellite measurements from the visible and near-infrared, there is insufficient information to retrieve a full microphysical and chemical description of an aerosol distribution. As such, refractive index is one of many parameters that must be implicitly assumed in order to obtain an optical depth retrieval. This is essentially a proxy for the dust mineralogy. Using a global soil map, it is shown that as long as a reasonable refractive index for dust is assumed, global dust variability is unlikely to cause significant variation in the optical properties of a dust aerosol distribution in the short-wave, and so should not greatly affect retrievals of mineral dust aerosol from space by visible and near-infrared radiometers. Errors in aerosol optical depth due to this variation are expected to be ≲1%. The work is framed around the ORAC AATSR aerosol retrieval, but is equally applicable to similar satellite retrievals. In this case, variations in the top-of-atmosphere reflectance caused by mineral variation are within the noise limits of the instrument. -- Highlights: • Global variation in dust aerosol refractive index is quantified using soil maps. • Resulting visible light scattering properties have limited variability. • Satellite aerosol retrievals do not need to account for varying dust refractive indices

  4. Coupling aerosol-cloud-radiative processes in the WRF-Chem model: Investigating the radiative impact of elevated point sources

    Directory of Open Access Journals (Sweden)

    E. G. Chapman

    2009-02-01

    resolution model domain (the extent of which corresponds to the typical size of a single global climate model grid cell and temporally over a three day analysis period, total rainfall in the sensitivity simulation increased by 31% over that in the baseline simulation. Fewer optically thin clouds, arbitrarily defined as a cloud exhibiting an optical depth less than 1, formed in the sensitivity simulation. Domain-averaged AODs dropped from 0.46 in the baseline simulation to 0.38 in the sensitivity simulation. The overall net effect of additional aerosols attributable to primary particulates and aerosol precursors from point source emissions above the surface was a domain-averaged reduction of 5 W m−2 in mean daytime downwelling shortwave radiation.

  5. Cloud networking understanding cloud-based data center networks

    CERN Document Server

    Lee, Gary

    2014-01-01

    Cloud Networking: Understanding Cloud-Based Data Center Networks explains the evolution of established networking technologies into distributed, cloud-based networks. Starting with an overview of cloud technologies, the book explains how cloud data center networks leverage distributed systems for network virtualization, storage networking, and software-defined networking. The author offers insider perspective to key components that make a cloud network possible such as switch fabric technology and data center networking standards. The final chapters look ahead to developments in architectures

  6. Sensitivity of regional meteorology and atmospheric composition during the DISCOVER-AQ period to subgrid-scale cloud-radiation interactions

    Science.gov (United States)

    Huang, X.; Allen, D. J.; Herwehe, J. A.; Alapaty, K. V.; Loughner, C.; Pickering, K. E.

    2014-12-01

    Subgrid-scale cloudiness directly influences global and regional atmospheric radiation budgets by attenuating shortwave radiation, leading to suppressed convection, decreased surface precipitation as well as other meteorological parameter changes. We use the latest version of WRF (v3.6, Apr 2014), which incorporates the Kain-Fritsch (KF) convective parameterization to provide subgrid-scale cloud fraction and condensate feedback to the rapid radiative transfer model-global (RRTMG) shortwave and longwave radiation schemes. We apply the KF scheme to simulate the DISCOVER-AQ Maryland field campaign (July 2011), and compare the sensitivity of meteorological parameters to the control run that does not include subgrid cloudiness. Furthermore, we will examine the chemical impact from subgrid cloudiness using a regional chemical transport model (CMAQ). There are several meteorological parameters influenced by subgrid cumulus clouds that are very important to air quality modeling, including changes in surface temperature that impact biogenic emission rates; changes in PBL depth that affect pollutant concentrations; and changes in surface humidity levels that impact peroxide-related reactions. Additionally, subgrid cumulus clouds directly impact air pollutant concentrations by modulating photochemistry and vertical mixing. Finally, we will compare with DISCOVER-AQ flight observation data and evaluate how well this off-line CMAQ simulation driven by WRF with the KF scheme simulates the effects of regional convection on atmospheric composition.

  7. Marine cloud brightening

    Science.gov (United States)

    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

  8. USGEO DMWG Cloud Computing Recommendations

    Science.gov (United States)

    de la Beaujardiere, J.; McInerney, M.; Frame, M. T.; Summers, C.

    2017-12-01

    The US Group on Earth Observations (USGEO) Data Management Working Group (DMWG) has been developing Cloud Computing Recommendations for Earth Observations. This inter-agency report is currently in draft form; DMWG hopes to have released the report as a public Request for Information (RFI) by the time of AGU. The recommendations are geared toward organizations that have already decided to use the Cloud for some of their activities (i.e., the focus is not on "why you should use the Cloud," but rather "If you plan to use the Cloud, consider these suggestions.") The report comprises Introductory Material, including Definitions, Potential Cloud Benefits, and Potential Cloud Disadvantages, followed by Recommendations in several areas: Assessing When to Use the Cloud, Transferring Data to the Cloud, Data and Metadata Contents, Developing Applications in the Cloud, Cost Minimization, Security Considerations, Monitoring and Metrics, Agency Support, and Earth Observations-specific recommendations. This talk will summarize the recommendations and invite comment on the RFI.

  9. Cloud GIS Based Watershed Management

    Science.gov (United States)

    Bediroğlu, G.; Colak, H. E.

    2017-11-01

    In this study, we generated a Cloud GIS based watershed management system with using Cloud Computing architecture. Cloud GIS is used as SAAS (Software as a Service) and DAAS (Data as a Service). We applied GIS analysis on cloud in terms of testing SAAS and deployed GIS datasets on cloud in terms of DAAS. We used Hybrid cloud computing model in manner of using ready web based mapping services hosted on cloud (World Topology, Satellite Imageries). We uploaded to system after creating geodatabases including Hydrology (Rivers, Lakes), Soil Maps, Climate Maps, Rain Maps, Geology and Land Use. Watershed of study area has been determined on cloud using ready-hosted topology maps. After uploading all the datasets to systems, we have applied various GIS analysis and queries. Results shown that Cloud GIS technology brings velocity and efficiency for watershed management studies. Besides this, system can be easily implemented for similar land analysis and management studies.

  10. Security Problems in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Rola Motawie

    2016-12-01

    Full Text Available Cloud is a pool of computing resources which are distributed among cloud users. Cloud computing has many benefits like scalability, flexibility, cost savings, reliability, maintenance and mobile accessibility. Since cloud-computing technology is growing day by day, it comes with many security problems. Securing the data in the cloud environment is most critical challenges which act as a barrier when implementing the cloud. There are many new concepts that cloud introduces, such as resource sharing, multi-tenancy, and outsourcing, create new challenges for the security community. In this work, we provide a comparable study of cloud computing privacy and security concerns. We identify and classify known security threats, cloud vulnerabilities, and attacks.

  11. Compositional Variations in Sands of the Bagnold Dunes, Gale Crater, Mars, from Visible-Shortwave Infrared Spectroscopy and Comparison to Ground-Truth from the Curiosity Rover

    OpenAIRE

    Lapotre, M. G. A.; Ehlmann, B. L.; Minson, S. E.; Arvidson, R. E.; Ayoub, F.; Fraeman, A. A.; Ewing, R. C.; Bridges, N. T.

    2017-01-01

    During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single-scattering albedo spectra and a Markov chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity ...

  12. Coastal fog and low cloud spatial patterns: do they indicate potential biodiversity refugia?

    Science.gov (United States)

    Torregrosa, A.

    2016-12-01

    Marine fog and low clouds transfer water and nutrients to coastal ecosystems through advection from the ocean and reduce heat effects by reflecting incoming shortwave radiation. These effects are known to benefit many species, vegetation communities, and habitats such as coastal redwood trees and their understory, maritime chaparral, and coastal streams harboring endangered salmon species. The California floristic region is the highest ranked hotspot in the U.S. and ranked 7th of 35 biodiversity hotspots worldwide in terms of the percent of its plant species that are found nowhere else (endemic). Many environmental drivers have been identified as contributing to California's remarkably high endemism and biodiversity, however, coastal low clouds have not typically been included. This could be due to the lack of data such as high resolution maps of coastal low cloud occurrence or the lack of long term records. Using a recent analysis of hourly National Weather Service satellite data, a stability index (SI) for coastal fog and low cloud cover was derived using two measures of variation and average summertime cloud cover to quantify long term spatial stability trends. Several discrete spatial clumps were identified that had both high temporal stability and high coastal low cloud cover. These areas show a strong correlation with a specific topographic landscape configuration with respect to wind direction. Point occurrence distribution maps of endemic coastal species were overlain with the SI to explore spatial correlation. The federally endangered species that showed very high spatial correlation included Yadon's Rein-orchid (Piperia yadonii), Monterey Spineflower (Chorizanthe pungens var. pungens), and Seaside Bird's-beak (Cordylanthus rigidus ssp. littoralis). Current estimated range maps are not consistent with the SI results suggesting a need to update estimated ranges. Biodiversity measures are being investigated in these areas to explore the hypothesis that they

  13. Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

    Science.gov (United States)

    Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

    2013-01-01

    Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

  14. A Location-Based Interactive Model of Internet of Things and Cloud (IoT-Cloud) for Mobile Cloud Computing Applications.

    Science.gov (United States)

    Dinh, Thanh; Kim, Younghan; Lee, Hyukjoon

    2017-03-01

    This paper presents a location-based interactive model of Internet of Things (IoT) and cloud integration (IoT-cloud) for mobile cloud computing applications, in comparison with the periodic sensing model. In the latter, sensing collections are performed without awareness of sensing demands. Sensors are required to report their sensing data periodically regardless of whether or not there are demands for their sensing services. This leads to unnecessary energy loss due to redundant transmission. In the proposed model, IoT-cloud provides sensing services on demand based on interest and location of mobile users. By taking advantages of the cloud as a coordinator, sensing scheduling of sensors is controlled by the cloud, which knows when and where mobile users request for sensing services. Therefore, when there is no demand, sensors are put into an inactive mode to save energy. Through extensive analysis and experimental results, we show that the location-based model achieves a significant improvement in terms of network lifetime compared to the periodic model.

  15. A Location-Based Interactive Model of Internet of Things and Cloud (IoT-Cloud for Mobile Cloud Computing Applications

    Directory of Open Access Journals (Sweden)

    Thanh Dinh

    2017-03-01

    Full Text Available This paper presents a location-based interactive model of Internet of Things (IoT and cloud integration (IoT-cloud for mobile cloud computing applications, in comparison with the periodic sensing model. In the latter, sensing collections are performed without awareness of sensing demands. Sensors are required to report their sensing data periodically regardless of whether or not there are demands for their sensing services. This leads to unnecessary energy loss due to redundant transmission. In the proposed model, IoT-cloud provides sensing services on demand based on interest and location of mobile users. By taking advantages of the cloud as a coordinator, sensing scheduling of sensors is controlled by the cloud, which knows when and where mobile users request for sensing services. Therefore, when there is no demand, sensors are put into an inactive mode to save energy. Through extensive analysis and experimental results, we show that the location-based model achieves a significant improvement in terms of network lifetime compared to the periodic model.

  16. A Location-Based Interactive Model of Internet of Things and Cloud (IoT-Cloud) for Mobile Cloud Computing Applications †

    Science.gov (United States)

    Dinh, Thanh; Kim, Younghan; Lee, Hyukjoon

    2017-01-01

    This paper presents a location-based interactive model of Internet of Things (IoT) and cloud integration (IoT-cloud) for mobile cloud computing applications, in comparison with the periodic sensing model. In the latter, sensing collections are performed without awareness of sensing demands. Sensors are required to report their sensing data periodically regardless of whether or not there are demands for their sensing services. This leads to unnecessary energy loss due to redundant transmission. In the proposed model, IoT-cloud provides sensing services on demand based on interest and location of mobile users. By taking advantages of the cloud as a coordinator, sensing scheduling of sensors is controlled by the cloud, which knows when and where mobile users request for sensing services. Therefore, when there is no demand, sensors are put into an inactive mode to save energy. Through extensive analysis and experimental results, we show that the location-based model achieves a significant improvement in terms of network lifetime compared to the periodic model. PMID:28257067

  17. Cloud type comparisons of AIRS, CloudSat, and CALIPSO cloud height and amount

    Directory of Open Access Journals (Sweden)

    B. H. Kahn

    2008-03-01

    Full Text Available The precision of the two-layer cloud height fields derived from the Atmospheric Infrared Sounder (AIRS is explored and quantified for a five-day set of observations. Coincident profiles of vertical cloud structure by CloudSat, a 94 GHz profiling radar, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO, are compared to AIRS for a wide range of cloud types. Bias and variability in cloud height differences are shown to have dependence on cloud type, height, and amount, as well as whether CloudSat or CALIPSO is used as the comparison standard. The CloudSat-AIRS biases and variability range from −4.3 to 0.5±1.2–3.6 km for all cloud types. Likewise, the CALIPSO-AIRS biases range from 0.6–3.0±1.2–3.6 km (−5.8 to −0.2±0.5–2.7 km for clouds ≥7 km (<7 km. The upper layer of AIRS has the greatest sensitivity to Altocumulus, Altostratus, Cirrus, Cumulonimbus, and Nimbostratus, whereas the lower layer has the greatest sensitivity to Cumulus and Stratocumulus. Although the bias and variability generally decrease with increasing cloud amount, the ability of AIRS to constrain cloud occurrence, height, and amount is demonstrated across all cloud types for many geophysical conditions. In particular, skill is demonstrated for thin Cirrus, as well as some Cumulus and Stratocumulus, cloud types infrared sounders typically struggle to quantify. Furthermore, some improvements in the AIRS Version 5 operational retrieval algorithm are demonstrated. However, limitations in AIRS cloud retrievals are also revealed, including the existence of spurious Cirrus near the tropopause and low cloud layers within Cumulonimbus and Nimbostratus clouds. Likely causes of spurious clouds are identified and the potential for further improvement is discussed.

  18. Survey of Transmission Cost Allocation Methodologies for Regional Transmission Organizations

    Energy Technology Data Exchange (ETDEWEB)

    Fink, S.; Porter, K.; Mudd, C.; Rogers, J.

    2011-02-01

    The report presents transmission cost allocation methodologies for reliability transmission projects, generation interconnection, and economic transmission projects for all Regional Transmission Organizations.

  19. Counting the clouds

    International Nuclear Information System (INIS)

    Randall, David A

    2005-01-01

    Cloud processes are very important for the global circulation of the atmosphere. It is now possible, though very expensive, to simulate the global circulation of the atmosphere using a model with resolution fine enough to explicitly represent the larger individual clouds. An impressive preliminary calculation of this type has already been performed by Japanese scientists, using the Earth Simulator. Within the next few years, such global cloud-resolving models (GCRMs) will be applied to weather prediction, and later they will be used in climatechange simulations. The tremendous advantage of GCRMs, relative to conventional lowerresolution global models, is that GCRMs can avoid many of the questionable 'parameterizations' used to represent cloud effects in lower-resolution global models. Although cloud microphysics, turbulence, and radiation must still be parameterized in GCRMs, the high resolution of a GCRM simplifies these problems considerably, relative to conventional models. The United States currently has no project to develop a GCRM, although we have both the computer power and the expertise to do it. A research program aimed at development and applications of GCRMs is outlined

  20. Trust management in cloud services

    CERN Document Server

    Noor, Talal H; Bouguettaya, Athman

    2014-01-01

    This book describes the design and implementation of Cloud Armor, a novel approach for credibility-based trust management and automatic discovery of cloud services in distributed and highly dynamic environments. This book also helps cloud users to understand the difficulties of establishing trust in cloud computing and the best criteria for selecting a service cloud. The techniques have been validated by a prototype system implementation and experimental studies using a collection of real world trust feedbacks on cloud services.The authors present the design and implementation of a novel pro

  1. Scale analysis of convective clouds

    Directory of Open Access Journals (Sweden)

    Micha Gryschka

    2008-12-01

    Full Text Available The size distribution of cumulus clouds due to shallow and deep convection is analyzed using satellite pictures, LES model results and data from the German rain radar network. The size distributions found can be described by simple power laws as has also been proposed for other cloud data in the literature. As the observed precipitation at ground stations is finally determined by cloud numbers in an area and individual sizes and rain rates of single clouds, the cloud size distributions might be used for developing empirical precipitation forecasts or for validating results from cloud resolving models being introduced to routine weather forecasts.

  2. Two-moment bulk stratiform cloud microphysics in the GFDL AM3 GCM: description, evaluation, and sensitivity tests

    Directory of Open Access Journals (Sweden)

    M. Salzmann

    2010-08-01

    Full Text Available A new stratiform cloud scheme including a two-moment bulk microphysics module, a cloud cover parameterization allowing ice supersaturation, and an ice nucleation parameterization has been implemented into the recently developed GFDL AM3 general circulation model (GCM as part of an effort to treat aerosol-cloud-radiation interactions more realistically. Unlike the original scheme, the new scheme facilitates the study of cloud-ice-aerosol interactions via influences of dust and sulfate on ice nucleation. While liquid and cloud ice water path associated with stratiform clouds are similar for the new and the original scheme, column integrated droplet numbers and global frequency distributions (PDFs of droplet effective radii differ significantly. This difference is in part due to a difference in the implementation of the Wegener-Bergeron-Findeisen (WBF mechanism, which leads to a larger contribution from super-cooled droplets in the original scheme. Clouds are more likely to be either completely glaciated or liquid due to the WBF mechanism in the new scheme. Super-saturations over ice simulated with the new scheme are in qualitative agreement with observations, and PDFs of ice numbers and effective radii appear reasonable in the light of observations. Especially, the temperature dependence of ice numbers qualitatively agrees with in-situ observations. The global average long-wave cloud forcing decreases in comparison to the original scheme as expected when super-saturation over ice is allowed. Anthropogenic aerosols lead to a larger decrease in short-wave absorption (SWABS in the new model setup, but outgoing long-wave radiation (OLR decreases as well, so that the net effect of including anthropogenic aerosols on the net radiation at the top of the atmosphere (netradTOA = SWABS-OLR is of similar magnitude for the new and the original scheme.

  3. Two-moment bulk stratiform cloud microphysics in the GFDL AM3 GCM: description, evaluation, and sensitivity tests

    Science.gov (United States)

    Salzmann, M.; Ming, Y.; Golaz, J.-C.; Ginoux, P. A.; Morrison, H.; Gettelman, A.; Krämer, M.; Donner, L. J.

    2010-08-01

    A new stratiform cloud scheme including a two-moment bulk microphysics module, a cloud cover parameterization allowing ice supersaturation, and an ice nucleation parameterization has been implemented into the recently developed GFDL AM3 general circulation model (GCM) as part of an effort to treat aerosol-cloud-radiation interactions more realistically. Unlike the original scheme, the new scheme facilitates the study of cloud-ice-aerosol interactions via influences of dust and sulfate on ice nucleation. While liquid and cloud ice water path associated with stratiform clouds are similar for the new and the original scheme, column integrated droplet numbers and global frequency distributions (PDFs) of droplet effective radii differ significantly. This difference is in part due to a difference in the implementation of the Wegener-Bergeron-Findeisen (WBF) mechanism, which leads to a larger contribution from super-cooled droplets in the original scheme. Clouds are more likely to be either completely glaciated or liquid due to the WBF mechanism in the new scheme. Super-saturations over ice simulated with the new scheme are in qualitative agreement with observations, and PDFs of ice numbers and effective radii appear reasonable in the light of observations. Especially, the temperature dependence of ice numbers qualitatively agrees with in-situ observations. The global average long-wave cloud forcing decreases in comparison to the original scheme as expected when super-saturation over ice is allowed. Anthropogenic aerosols lead to a larger decrease in short-wave absorption (SWABS) in the new model setup, but outgoing long-wave radiation (OLR) decreases as well, so that the net effect of including anthropogenic aerosols on the net radiation at the top of the atmosphere (netradTOA = SWABS-OLR) is of similar magnitude for the new and the original scheme.

  4. Moving HammerCloud to CERN's private cloud

    CERN Document Server

    Barrand, Quentin

    2013-01-01

    HammerCloud is a testing framework for the Worldwide LHC Computing Grid. Currently deployed on about 20 hand-managed machines, it was desirable to move it to the Agile Infrastructure, CERN's OpenStack-based private cloud.

  5. Modeling of Cloud/Radiation Processes for Cirrus Cloud Formation

    National Research Council Canada - National Science Library

    Liou, K

    1997-01-01

    This technical report includes five reprints and pre-prints of papers associated with the modeling of cirrus cloud and radiation processes as well as remote sensing of cloud optical and microphysical...

  6. Tharsis Limb Cloud

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Annotated image of Tharsis Limb Cloud 7 September 2005 This composite of red and blue Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired on 6 July 2005 shows an isolated water ice cloud extending more than 30 kilometers (more than 18 miles) above the martian surface. Clouds such as this are common in late spring over the terrain located southwest of the Arsia Mons volcano. Arsia Mons is the dark, oval feature near the limb, just to the left of the 'T' in the 'Tharsis Montes' label. The dark, nearly circular feature above the 'S' in 'Tharsis' is the volcano, Pavonis Mons, and the other dark circular feature, above and to the right of 's' in 'Montes,' is Ascraeus Mons. Illumination is from the left/lower left. Season: Northern Autumn/Southern Spring

  7. Transition to the Cloud

    DEFF Research Database (Denmark)

    Hedman, Jonas; Xiao, Xiao

    2016-01-01

    The rising of cloud computing has dramatically changed the way software companies provide and distribute their IT product and related services over the last decades. Today, most software is bought offthe-shelf and distributed over the Internet. This transition is greatly influencing how software...... companies operate. In this paper, we present a case study of an ERP vendor for SMB (small and mediumsize business) in making a transition towards a cloud-based business model. Through the theoretical lens of ecosystem, we are able to analyze the evolution of the vendor and its business network as a whole......, and find that the relationship between vendor and Value-added-Reseller (VAR) is greatly affected. We conclude by presenting critical issues and challenges for managing such cloud transition....

  8. The photoevaporation of interstellar clouds

    International Nuclear Information System (INIS)

    Bertoldi, F.

    1989-01-01

    The dynamics of the photoevaporation of interstellar clouds and its consequences for the structure and evolution of H II regions are studied. An approximate analytical solution for the evolution of photoevaporating clouds is derived under the realistic assumption of axisymmetry. The effects of magnetic fields are taken into account in an approximate way. The evolution of a neutral cloud subjected to the ionizing radiation of an OB star has two distinct stages. When a cloud is first exposed to the radiation, the increase in pressure due to the ionization at the surface of the cloud leads to a radiation-driven implosion: an ionization front drives a shock into the cloud, ionizes part of it and compresses the remaining into a dense globule. The initial implosion is followed by an equilibrium cometary stage, in which the cloud maintains a semistationary comet-shaped configuration; it slowly evaporates while accelerating away from the ionizing star until the cloud has been completely ionized, reaches the edge of the H II region, or dies. Expressions are derived for the cloud mass-loss rate and acceleration. To investigate the effect of the cloud photoevaporation on the structure of H II regions, the evolution of an ensemble of clouds of a given mass distribution is studied. It is shown that the compressive effect of the ionizing radiation can induce star formation in clouds that were initially gravitationally stable, both for thermally and magnetically supported clouds

  9. Cloud Computing: A study of cloud architecture and its patterns

    OpenAIRE

    Mandeep Handa,; Shriya Sharma

    2015-01-01

    Cloud computing is a general term for anything that involves delivering hosted services over the Internet. Cloud computing is a paradigm shift following the shift from mainframe to client–server in the early 1980s. Cloud computing can be defined as accessing third party software and services on web and paying as per usage. It facilitates scalability and virtualized resources over Internet as a service providing cost effective and scalable solution to customers. Cloud computing has...

  10. Confidentiality Protection of Digital Health Records in Cloud Computing.

    Science.gov (United States)

    Chen, Shyh-Wei; Chiang, Dai Lun; Liu, Chia-Hui; Chen, Tzer-Shyong; Lai, Feipei; Wang, Huihui; Wei, Wei

    2016-05-01

    Electronic medical records containing confidential information were uploaded to the cloud. The cloud allows medical crews to access and manage the data and integration of medical records easily. This data system provides relevant information to medical personnel and facilitates and improve electronic medical record management and data transmission. A structure of cloud-based and patient-centered personal health record (PHR) is proposed in this study. This technique helps patients to manage their health information, such as appointment date with doctor, health reports, and a completed understanding of their own health conditions. It will create patients a positive attitudes to maintain the health. The patients make decision on their own for those whom has access to their records over a specific span of time specified by the patients. Storing data in the cloud environment can reduce costs and enhance the share of information, but the potential threat of information security should be taken into consideration. This study is proposing the cloud-based secure transmission mechanism is suitable for multiple users (like nurse aides, patients, and family members).

  11. Ash cloud aviation advisories

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, T.J.; Ellis, J.S. [Lawrence Livermore National Lab., CA (United States); Schalk, W.W.; Nasstrom, J.S. [EG and G, Inc., Pleasanton, CA (United States)

    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. Cloud Collaboration: Cloud-Based Instruction for Business Writing Class

    Science.gov (United States)

    Lin, Charlie; Yu, Wei-Chieh Wayne; Wang, Jenny

    2014-01-01

    Cloud computing technologies, such as Google Docs, Adobe Creative Cloud, Dropbox, and Microsoft Windows Live, have become increasingly appreciated to the next generation digital learning tools. Cloud computing technologies encourage students' active engagement, collaboration, and participation in their learning, facilitate group work, and support…

  13. Cloud blueprints for integrating and managing cloud federations

    NARCIS (Netherlands)

    Papazoglou, M.; Heisel, M.

    2012-01-01

    Contemporary cloud technologies face insurmountable obstacles. They follow a pull-based, producer-centric trajectory to development where cloud consumers have to ‘squeeze and bolt’ applications onto cloud APIs. They also introduce a monolithic SaaS/PaaS/IaaS stack where a one-size-fits-all mentality

  14. Opaque cloud detection

    Science.gov (United States)

    Roskovensky, John K [Albuquerque, NM

    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. Storm and cloud dynamics

    CERN Document Server

    Cotton, William R

    1992-01-01

    This book focuses on the dynamics of clouds and of precipitating mesoscale meteorological systems. Clouds and precipitating mesoscale systems represent some of the most important and scientifically exciting weather systems in the world. These are the systems that produce torrential rains, severe winds including downburst and tornadoes, hail, thunder and lightning, and major snow storms. Forecasting such storms represents a major challenge since they are too small to be adequately resolved by conventional observing networks and numerical prediction models.Key Features* Key Highlight

  16. Detailed Information Security in Cloud Computing

    OpenAIRE

    Pavel Valerievich Ivonin

    2013-01-01

    The object of research in this article is technology of public clouds, structure and security system of clouds. Problems of information security in clouds are considered, elements of security system in public clouds are described.

  17. Cloud Based Applications and Platforms (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

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

    Science.gov (United States)

    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.

  19. Clouds and the Earth's Radiant Energy System (CERES) Data Products for Climate Research

    Science.gov (United States)

    Kato, Seiji; Loeb, Norman G.; Rutan, David A.; Rose, Fred G.

    2015-01-01

    NASA's Clouds and the Earth's Radiant Energy System (CERES) project integrates CERES, Moderate Resolution Imaging Spectroradiometer (MODIS), and geostationary satellite observations to provide top-of-atmosphere (TOA) irradiances derived from broadband radiance observations by CERES instruments. It also uses snow cover and sea ice extent retrieved from microwave instruments as well as thermodynamic variables from reanalysis. In addition, these variables are used for surface and atmospheric irradiance computations. The CERES project provides TOA, surface, and atmospheric irradiances in various spatial and temporal resolutions. These data sets are for climate research and evaluation of climate models. Long-term observations are required to understand how the Earth system responds to radiative forcing. A simple model is used to estimate the time to detect trends in TOA reflected shortwave and emitted longwave irradiances.

  20. Securing virtual and cloud environments

    CSIR Research Space (South Africa)

    Carroll, M

    2012-01-01

    Full Text Available targets such as reduced costs, scalability, flexibility, capacity utilisation, higher efficiencies and mobility. Many of these benefits are achieved through the utilisation of technologies such as cloud computing and virtualisation. In many instances cloud...

  1. An evaluation of safety guidelines to restrict exposure to stray radiofrequency radiation from short-wave diathermy units

    Energy Technology Data Exchange (ETDEWEB)

    Shields, Nora [School of Physiotherapy, La Trobe University, Victoria 3086 (Australia); O' Hare, Neil [Department of Medical Physics and Bioengineering, St James' s Hospital, Dublin 8 (Ireland); Gormley, John [School of Physiotherapy, Trinity College Dublin, Trinity Centre for Health Sciences, St James' s Hospital, Dublin 8 (Ireland)

    2004-07-07

    Short-wave diathermy (SWD), a form of radiofrequency radiation used therapeutically by physiotherapists, may be applied in continuous (CSWD) or pulsed (PSWD) mode using either capacitive or inductive methods. Stray radiation emitted by these units may exceed exposure guidelines close to the equipment. Discrepant guidelines exist on a safe distance from an operating unit for operators and other personnel. Stray electric (E-field) and magnetic (H-field) field strengths from 10 SWD units in six departments were examined using a PMM 8053 meter and two isotropic probes (EP-330, HP-032). A 5 l saline phantom completed the patient circuit. Measurements were recorded in eight directions between 0.5 m and 2 m at hip and eye levels while the units operated at maximum output and data compared to current guidelines. Results found stray fields from capacitive CSWD fell below operator limits at 2 m (E-field 4.8-39.8 V/m; H-field 0.015-0.072 A/m) and at 1 m for inductive CSWD (E-field 0-36 V/m; H-field 0.01-0.065 A/m). Capacitive PSWD fields fell below the limits at 1.5 m (E-field 1.2-19.9 V/m; H-field 0.002-0.045 A/m) and at 1m for inductive PSWD (E-field 0.7-4.0 V/m; H-field 0.009-0.03 A/m). An extra 0.5 m was required before fields fell below the guidelines for other personnel. These results demonstrate, under a worst case scenario, emissions from SWD exceed the guidelines for operators at distances currently recommended as safe. Future guidelines should include recommendations for personnel other than physiotherapists.

  2. An evaluation of safety guidelines to restrict exposure to stray radiofrequency radiation from short-wave diathermy units

    International Nuclear Information System (INIS)

    Shields, Nora; O'Hare, Neil; Gormley, John

    2004-01-01

    Short-wave diathermy (SWD), a form of radiofrequency radiation used therapeutically by physiotherapists, may be applied in continuous (CSWD) or pulsed (PSWD) mode using either capacitive or inductive methods. Stray radiation emitted by these units may exceed exposure guidelines close to the equipment. Discrepant guidelines exist on a safe distance from an operating unit for operators and other personnel. Stray electric (E-field) and magnetic (H-field) field strengths from 10 SWD units in six departments were examined using a PMM 8053 meter and two isotropic probes (EP-330, HP-032). A 5 l saline phantom completed the patient circuit. Measurements were recorded in eight directions between 0.5 m and 2 m at hip and eye levels while the units operated at maximum output and data compared to current guidelines. Results found stray fields from capacitive CSWD fell below operator limits at 2 m (E-field 4.8-39.8 V/m; H-field 0.015-0.072 A/m) and at 1 m for inductive CSWD (E-field 0-36 V/m; H-field 0.01-0.065 A/m). Capacitive PSWD fields fell below the limits at 1.5 m (E-field 1.2-19.9 V/m; H-field 0.002-0.045 A/m) and at 1m for inductive PSWD (E-field 0.7-4.0 V/m; H-field 0.009-0.03 A/m). An extra 0.5 m was required before fields fell below the guidelines for other personnel. These results demonstrate, under a worst case scenario, emissions from SWD exceed the guidelines for operators at distances currently recommended as safe. Future guidelines should include recommendations for personnel other than physiotherapists

  3. Laboratory estimate of the regional shortwave refractive index and single scattering albedo of mineral dust from major sources worldwide

    Science.gov (United States)

    Di Biagio, C.; Formenti, P.; Caponi, L.; Cazaunau, M.; Pangui, E.; Journet, E.; Nowak, S.; Caquineau, S.; Andreae, M. O.; Kandler, K.; Saeed, T.; Piketh, S.; Seibert, D.; Williams, E.; Balkanski, Y.; Doussin, J. F.

    2017-12-01

    Mineral dust is one of the most abundant aerosol species in the atmosphere and strongly contributes to the global and regional direct radiative effect. Still large uncertainties persist on the magnitude and overall sign of the dust direct effect, where indeed one of the main unknowns is how much mineral dust absorbs light in the shortwave (SW) spectral range. Aerosol absorption is represented both by the imaginary part (k) of the complex refractive index or the single scattering albedo (SSA, i.e. the ratio of the scattering to extinction coefficient). In this study we present a new dataset of SW complex refractive indices and SSA for mineral dust aerosols obtained from in situ measurements in the 4.2 m3 CESAM simulation chamber at LISA (Laboratoire Interuniversitaire des Systemes Atmospheriques) in Créteil, France. Investigated dust aerosol samples were issued from major desert sources worldwide, including the African Sahara and Sahel, Eastern Asia, the Middle East, Southern Africa, Australia, and the Americas, with differing iron oxides content. Results from the present study provide a regional mapping of the SW absorption by dust and show that the imaginary part of the refractive index largely varies (by up to a factor 6, 0.003-0.02 at 370 nm and 0.001-0.003 at 950 nm) for the different source areas due to the change in the particle iron oxide content. The SSA for dust varies between 0.75-0.90 at 370 nm and 0.95-0.99 at 950 nm, with the largest absorption observed for Sahelian and Australian dust aerosols. Our range of variability for k and SSA is well bracketed by already published literature estimates, but suggests that regional‒dependent values should be used in models. The possible relationship between k and the dust iron oxides content is investigated with the aim of providing a parameterization of the regional‒dependent dust absorption to include in climate models.

  4. Cloud Droplet Size and Liquid Water Path Retrievals From Zenith Radiance Measurements: Examples From the Atmospheric Radiation Measurement Program and the Aerosol Robotic Network

    Science.gov (United States)

    Chiu, J. C.; Marshak, A.; Huang, C.-H.; Varnai, T.; Hogan, R. J.; Giles, D. M.; Holben, B. N.; Knyazikhin, Y.; O'Connor, E. J.; Wiscombe, W. J.

    2012-01-01

    The ground-based Atmospheric Radiation Measurement Program (ARM) and NASA Aerosol Robotic Network (AERONET) routinely monitor clouds using zenith radiances at visible and near-infrared wavelengths. Using the transmittance calculated from such measurements, we have developed a new retrieval method for cloud effective droplet size and conducted extensive tests for non-precipitating liquid water clouds. The underlying principle is to combine a water-absorbing wavelength (i.e. 1640 nm) with a nonwater-absorbing wavelength for acquiring information on cloud droplet size and optical depth. For simulated stratocumulus clouds with liquid water path less than 300 g/sq m and horizontal resolution of 201m, the retrieval method underestimates the mean effective radius by 0.8 m, with a root-mean-squared error of 1.7 m and a relative deviation of 13 %. For actual observations with a liquid water path less than 450 gm.2 at the ARM Oklahoma site during 2007-2008, our 1.5 min-averaged retrievals are generally larger by around 1 m than those from combined ground-based cloud radar and microwave radiometer at a 5min temporal resolution. We also compared our retrievals to those from combined shortwave flux and microwave observations for relatively homogeneous clouds, showing that the bias between these two retrieval sets is negligible, but the error of 2.6 m and the relative deviation of 22% are larger than those found in our simulation case. Finally, the transmittance-based cloud effective droplet radii agree to better than 11% with satellite observations and have a negative bias of 1 m. Overall, the retrieval method provides reasonable cloud effective radius estimates, which can enhance the cloud products of both ARM and AERONET.

  5. Efficient Resource Management in Cloud Computing

    OpenAIRE

    Rushikesh Shingade; Amit Patil; Shivam Suryawanshi; M. Venkatesan

    2015-01-01

    Cloud computing, one of the widely used technology to provide cloud services for users who are charged for receiving services. In the aspect of a maximum number of resources, evaluating the performance of Cloud resource management policies are difficult to optimize efficiently. There are different simulation toolkits available for simulation and modelling the Cloud computing environment like GridSim CloudAnalyst, CloudSim, GreenCloud, CloudAuction etc. In proposed Efficient Resource Manage...

  6. Cloud computing basics for librarians.

    Science.gov (United States)

    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. Copyright © Taylor & Francis Group, LLC

  7. Cloud Computing Security: A Survey

    OpenAIRE

    Khalil, Issa; Khreishah, Abdallah; Azeem, Muhammad

    2014-01-01

    Cloud computing is an emerging technology paradigm that migrates current technological and computing concepts into utility-like solutions similar to electricity and water systems. Clouds bring out a wide range of benefits including configurable computing resources, economic savings, and service flexibility. However, security and privacy concerns are shown to be the primary obstacles to a wide adoption of clouds. The new concepts that clouds introduce, such as multi-tenancy, resource sharing a...

  8. Database security in the cloud

    OpenAIRE

    Sakhi, Imal

    2012-01-01

    The aim of the thesis is to get an overview of the database services available in cloud computing environment, investigate the security risks associated with it and propose the possible countermeasures to minimize the risks. The thesis also analyzes two cloud database service providers namely; Amazon RDS and Xeround. The reason behind choosing these two providers is because they are currently amongst the leading cloud database providers and both provide relational cloud databases which makes ...

  9. QUALITY ASSURANCE FOR CLOUD COMPUTING

    OpenAIRE

    Sumaira Aslam; Hina Shahid

    2016-01-01

    Cloud computing is a greatest and latest thing. Marketers for lots of big companies are all using cloud computing terms in their marketing campaign to make them seem them impressive so, that they can get clients and customers. Cloud computing is overall the philosophy and design concept and it is much more complicated and yet much simpler. The basic underlined thing that cloud computing do is to separate the applications from operating systems from the software from the hardware that runs eve...

  10. Cloud services, networking, and management

    CERN Document Server

    da Fonseca, Nelson L S

    2015-01-01

    Cloud Services, Networking and Management provides a comprehensive overview of the cloud infrastructure and services, as well as their underlying management mechanisms, including data center virtualization and networking, cloud security and reliability, big data analytics, scientific and commercial applications. Special features of the book include: State-of-the-art content. Self-contained chapters for readers with specific interests. Includes commercial applications on Cloud (video services and games).

  11. Security Dynamics of Cloud Computing

    OpenAIRE

    Khan, Khaled M.

    2009-01-01

    This paper explores various dimensions of cloud computing security. It argues that security concerns of cloud computing need to be addressed from the perspective of individual stakeholder. Security focuses of cloud computing are essentially different in terms of its characteristics and business model. Conventional way of viewing as well as addressing security such as ‘bolting-in’ on the top of cloud computing may not work well. The paper attempts to portray the security spectrum necessary for...

  12. Green Cloud on the Horizon

    Science.gov (United States)

    Ali, Mufajjul

    This paper proposes a Green Cloud model for mobile Cloud computing. The proposed model leverage on the current trend of IaaS (Infrastructure as a Service), PaaS (Platform as a Service) and SaaS (Software as a Service), and look at new paradigm called "Network as a Service" (NaaS). The Green Cloud model proposes various Telco's revenue generating streams and services with the CaaS (Cloud as a Service) for the near future.

  13. Reusability Framework for Cloud Computing

    OpenAIRE

    Singh, Sukhpal; Singh, Rishideep

    2012-01-01

    Cloud based development is a challenging task for several software engineering projects, especially for those which needs development with reusability. Present time of cloud computing is allowing new professional models for using the software development. The expected upcoming trend of computing is assumed to be this cloud computing because of speed of application deployment, shorter time to market, and lower cost of operation. Until Cloud Co mputing Reusability Model is considered a fundamen...

  14. Determination of the influence of high clouds on the radiation field and on climate by analyzing NOAA AVHRR data. Die Bestimmung des Einflusses von hohen Wolken auf das Strahlungsfeld und auf das Klima durch Analyse von NOAA AVHRR-Daten

    Energy Technology Data Exchange (ETDEWEB)

    Berger, F H

    1991-11-01

    The influence of clouds on the radiation field and on climate is investigated over the North Sea by analyzing NOAA AVHRR data. The derived information was applied to calculate the cloud-climate efficiency at the top of atmosphere and at the surface. The cloud-climate efficiencies in the shortwave spectrum show a cooling effect of the earth/atmosphere system for all clouds and a strong dependence on the solar insolation. For the cloud-climate efficiency in the longwave region always heating of the earth/atmosphere system was observed. Because of the solar zenith angle effect thick high clouds with the same optical properties may lead to different effects in the earth/atmosphere system. A first approach of a comparison of the increasing cloud forcing (heating of the earth-atmosphere system) and an analysis of the relative topography 300/850 hPa shows that the increase of the cloud forcing is well correlated with an increase of the temperature in this layer. The deviation from the long-term mean of the pressure or temperature shows the same behaviour. (orig.).

  15. iCloud standard guide

    CERN Document Server

    Alfi, Fauzan

    2013-01-01

    An easy-to-use guide, filled with tutorials that will teach you how to set up and use iCloud, and profit from all of its marvellous features.This book is for anyone with basic knowledge of computers and mobile operations. Prior knowledge of cloud computing or iCloud is not expected.

  16. Coherent Radiation of Electron Cloud

    International Nuclear Information System (INIS)

    Heifets, S.

    2004-01-01

    The electron cloud in positron storage rings is pinched when a bunch passes by. For short bunches, the radiation due to acceleration of electrons of the cloud is coherent. Detection of such radiation can be used to measure the density of the cloud. The estimate of the power and the time structure of the radiated signal is given in this paper

  17. Understanding and Monitoring Cloud Services

    NARCIS (Netherlands)

    Drago, Idilio

    2013-01-01

    Cloud services have changed the way computing power is delivered to customers. The advantages of the cloud model have fast resulted in powerful providers. However, this success has not come without problems. Cloud providers have been related to major failures, including outages and performance

  18. Research on cloud computing solutions

    Directory of Open Access Journals (Sweden)

    Liudvikas Kaklauskas

    2015-07-01

    Full Text Available Cloud computing can be defined as a new style of computing in which dynamically scala-ble and often virtualized resources are provided as a services over the Internet. Advantages of the cloud computing technology include cost savings, high availability, and easy scalability. Voas and Zhang adapted six phases of computing paradigms, from dummy termi-nals/mainframes, to PCs, networking computing, to grid and cloud computing. There are four types of cloud computing: public cloud, private cloud, hybrid cloud and community. The most common and well-known deployment model is Public Cloud. A Private Cloud is suited for sensitive data, where the customer is dependent on a certain degree of security.According to the different types of services offered, cloud computing can be considered to consist of three layers (services models: IaaS (infrastructure as a service, PaaS (platform as a service, SaaS (software as a service. Main cloud computing solutions: web applications, data hosting, virtualization, database clusters and terminal services. The advantage of cloud com-puting is the ability to virtualize and share resources among different applications with the objective for better server utilization and without a clustering solution, a service may fail at the moment the server crashes.DOI: 10.15181/csat.v2i2.914

  19. GEWEX cloud assessment: A review

    Science.gov (United States)

    Stubenrauch, Claudia; Rossow, William B.; Kinne, Stefan; Ackerman, Steve; Cesana, Gregory; Chepfer, Hélène; Di Girolamo, Larry; Getzewich, Brian; Guignard, Anthony; Heidinger, Andy; Maddux, Brent; Menzel, Paul; Minnis, Patrick; Pearl, Cindy; Platnick, Steven; Poulsen, Caroline; Riedi, Jérôme; Sayer, Andrew; Sun-Mack, Sunny; Walther, Andi; Winker, Dave; Zeng, Shen; Zhao, Guangyu

    2013-05-01

    Clouds cover about 70% of the Earth's surface and play a dominant role in the energy and water cycle of our planet. Only satellite observations provide a continuous survey of the state of the atmosphere over the entire globe and across the wide range of spatial and temporal scales that comprise weather and climate variability. Satellite cloud data records now exceed more than 25 years; however, climatologies compiled from different satellite datasets can exhibit systematic biases. Questions therefore arise as to the accuracy and limitations of the various sensors. The Global Energy and Water cycle Experiment (GEWEX) Cloud Assessment, initiated in 2005 by the GEWEX Radiation Panel, provides the first coordinated intercomparison of publicly available, global cloud products (gridded, monthly statistics) retrieved from measurements of multi-spectral imagers (some with multi-angle view and polarization capabilities), IR sounders and lidar. Cloud properties under study include cloud amount, cloud height (in terms of pressure, temperature or altitude), cloud radiative properties (optical depth or emissivity), cloud thermodynamic phase and bulk microphysical properties (effective particle size and water path). Differences in average cloud properties, especially in the amount of high-level clouds, are mostly explained by the inherent instrument measurement capability for detecting and/or identifying optically thin cirrus, especially when overlying low-level clouds. The study of long-term variations with these datasets requires consideration of many factors. The monthly, gridded database presented here facilitates further assessments, climate studies, and the evaluation of climate models.

  20. The Basics of Cloud Computing

    Science.gov (United States)

    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…

  1. Towards trustworthy health platform cloud

    NARCIS (Netherlands)

    Deng, M.; Nalin, M.; Petkovic, M.; Baroni, I.; Marco, A.; Jonker, W.; Petkovic, M.

    2012-01-01

    To address today’s major concerns of health service providers regarding security, resilience and data protection when moving on the cloud, we propose an approach to build a trustworthy healthcare platform cloud, based on a trustworthy cloud infrastructure. This paper first highlights the main

  2. A View from the Clouds

    Science.gov (United States)

    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…

  3. Trusting Privacy in the Cloud

    NARCIS (Netherlands)

    Prüfer, J.O.

    2014-01-01

    Cloud computing technologies have the potential to increase innovation and economic growth considerably. But many users worry that data in the cloud can be accessed by others, thereby damaging the data owner. Consequently, they do not use cloud technologies up to the efficient level. I design an

  4. Securing the Cloud Cloud Computer Security Techniques and Tactics

    CERN Document Server

    Winkler, Vic (JR)

    2011-01-01

    As companies turn to cloud computing technology to streamline and save money, security is a fundamental concern. Loss of certain control and lack of trust make this transition difficult unless you know how to handle it. Securing the Cloud discusses making the move to the cloud while securing your peice of it! The cloud offers felxibility, adaptability, scalability, and in the case of security-resilience. This book details the strengths and weaknesses of securing your company's information with different cloud approaches. Attacks can focus on your infrastructure, communications network, data, o

  5. AceCloud: Molecular Dynamics Simulations in the Cloud.

    Science.gov (United States)

    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.

  6. VMware private cloud computing with vCloud director

    CERN Document Server

    Gallagher, Simon

    2013-01-01

    It's All About Delivering Service with vCloud Director Empowered by virtualization, companies are not just moving into the cloud, they're moving into private clouds for greater security, flexibility, and cost savings. However, this move involves more than just infrastructure. It also represents a different business model and a new way to provide services. In this detailed book, VMware vExpert Simon Gallagher makes sense of private cloud computing for IT administrators. From basic cloud theory and strategies for adoption to practical implementation, he covers all the issues. You'll lea

  7. Benchmarking personal cloud storage

    NARCIS (Netherlands)

    Drago, Idilio; Bocchi, Enrico; Mellia, Marco; Slatman, Herman; Pras, Aiko

    2013-01-01

    Personal cloud storage services are data-intensive applications already producing a significant share of Internet traffic. Several solutions offered by different companies attract more and more people. However, little is known about each service capabilities, architecture and - most of all -

  8. CLOUD COMPUTING SECURITY ISSUES

    Directory of Open Access Journals (Sweden)

    Florin OGIGAU-NEAMTIU

    2012-01-01

    Full Text Available The term “cloud computing” has been in the spotlights of IT specialists the last years because of its potential to transform this industry. The promised benefits have determined companies to invest great sums of money in researching and developing this domain and great steps have been made towards implementing this technology. Managers have traditionally viewed IT as difficult and expensive and the promise of cloud computing leads many to think that IT will now be easy and cheap. The reality is that cloud computing has simplified some technical aspects of building computer systems, but the myriad challenges facing IT environment still remain. Organizations which consider adopting cloud based services must also understand the many major problems of information policy, including issues of privacy, security, reliability, access, and regulation. The goal of this article is to identify the main security issues and to draw the attention of both decision makers and users to the potential risks of moving data into “the cloud”.

  9. Computing in the Clouds

    Science.gov (United States)

    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…

  10. CloudETL

    DEFF Research Database (Denmark)

    Liu, Xiufeng; Thomsen, Christian; Pedersen, Torben Bach

    2014-01-01

    Extract-Transform-Load (ETL) programs process data into data warehouses (DWs). Rapidly growing data volumes demand systems that scale out. Recently, much attention has been given to MapReduce for parallel handling of massive data sets in cloud environments. Hive is the most widely used RDBMS...

  11. Predictable cloud computing

    NARCIS (Netherlands)

    Mullender, Sape J.

    The standard tools for cloud computing—processor and network virtualization—make it difficult to achieve dependability, both in terms of real time operations and fault tolerance. Virtualization multiplexes virtual resources onto physical ones, typically by time division or statistical multiplexing.

  12. SiCloud

    DEFF Research Database (Denmark)

    Jiang, Cathy Y.; Devore, Peter T.S.; Lonappan, Cejo Konuparamban

    2017-01-01

    The silicon photonics industry is projected to be a multibillion dollar industry driven by the growth of data centers. In this work, we present an interactive online tool for silicon photonics. Silicon Photonics Cloud (SiCCloud.org) is an easy to use instructional tool for optical properties...

  13. Towards autonomous vehicular clouds

    Directory of Open Access Journals (Sweden)

    Stephan Olariu

    2011-09-01

    Full Text Available The dawn of the 21st century has seen a growing interest in vehicular networking and its myriad potential applications. The initial view of practitioners and researchers was that radio-equipped vehicles could keep the drivers informed about potential safety risks and increase their awareness of road conditions. The view then expanded to include access to the Internet and associated services. This position paper proposes and promotes a novel and more comprehensive vision namely, that advances in vehicular networks, embedded devices and cloud computing will enable the formation of autonomous clouds of vehicular computing, communication, sensing, power and physical resources. Hence, we coin the term, autonomous vehicular clouds (AVCs. A key feature distinguishing AVCs from conventional cloud computing is that mobile AVC resources can be pooled dynamically to serve authorized users and to enable autonomy in real-time service sharing and management on terrestrial, aerial, or aquatic pathways or theaters of operations. In addition to general-purpose AVCs, we also envision the emergence of specialized AVCs such as mobile analytics laboratories. Furthermore, we envision that the integration of AVCs with ubiquitous smart infrastructures including intelligent transportation systems, smart cities and smart electric power grids will have an enormous societal impact enabling ubiquitous utility cyber-physical services at the right place, right time and with right-sized resources.

  14. Seeding the Cloud

    Science.gov (United States)

    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.

  15. Data in the Cloud

    Science.gov (United States)

    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…

  16. Sensitivity of the Palaeocene-Eocene Thermal Maximum climate to cloud properties.

    Science.gov (United States)

    Kiehl, Jeffrey T; Shields, Christine A

    2013-10-28

    The Palaeocene-Eocene Thermal Maximum (PETM) was a significant global warming event in the Earth's history (approx. 55 Ma). The cause for this warming event has been linked to increases in greenhouse gases, specifically carbon dioxide and methane. This rapid warming took place in the presence of the existing Early Eocene warm climate. Given that projected business-as-usual levels of atmospheric carbon dioxide reach concentrations of 800-1100 ppmv by 2100, it is of interest to study past climates where atmospheric carbon dioxide was higher than present. This is especially the case given the difficulty of climate models in simulating past warm climates. This study explores the sensitivity of the simulated pre-PETM and PETM periods to change in cloud condensation nuclei (CCN) and microphysical properties of liquid water clouds. Assuming lower levels of CCN for both of these periods leads to significant warming, especially at high latitudes. The study indicates that past differences in cloud properties may be an important factor in accurately simulating past warm climates. Importantly, additional shortwave warming from such a mechanism would imply lower required atmospheric CO2 concentrations for simulated surface temperatures to be in reasonable agreement with proxy data for the Eocene.

  17. AIRS-CloudSat cloud mask, radar reflectivities, and cloud classification matchups V3.2

    Data.gov (United States)

    National Aeronautics and Space Administration — This is AIRS-CloudSat collocated subset, in NetCDF 4 format. These data contain collocated: AIRS Level 1b radiances spectra, CloudSat radar reflectivities, and MODIS...

  18. Arsia Mons Spiral Cloud

    Science.gov (United States)

    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.

  19. A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

    Science.gov (United States)

    Goldsmith, K. J. A.; Pittard, J. M.

    2018-05-01

    The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

  20. Cloud Computing Security Issue: Survey

    Science.gov (United States)

    Kamal, Shailza; Kaur, Rajpreet

    2011-12-01

    Cloud computing is the growing field in IT industry since 2007 proposed by IBM. Another company like Google, Amazon, and Microsoft provides further products to cloud computing. The cloud computing is the internet based computing that shared recourses, information on demand. It provides the services like SaaS, IaaS and PaaS. The services and recourses are shared by virtualization that run multiple operation applications on cloud computing. This discussion gives the survey on the challenges on security issues during cloud computing and describes some standards and protocols that presents how security can be managed.

  1. Security for cloud storage systems

    CERN Document Server

    Yang, Kan

    2014-01-01

    Cloud storage is an important service of cloud computing, which offers service for data owners to host their data in the cloud. This new paradigm of data hosting and data access services introduces two major security concerns. The first is the protection of data integrity. Data owners may not fully trust the cloud server and worry that data stored in the cloud could be corrupted or even removed. The second is data access control. Data owners may worry that some dishonest servers provide data access to users that are not permitted for profit gain and thus they can no longer rely on the servers

  2. Cloud database development and management

    CERN Document Server

    Chao, Lee

    2013-01-01

    Nowadays, cloud computing is almost everywhere. However, one can hardly find a textbook that utilizes cloud computing for teaching database and application development. This cloud-based database development book teaches both the theory and practice with step-by-step instructions and examples. This book helps readers to set up a cloud computing environment for teaching and learning database systems. The book will cover adequate conceptual content for students and IT professionals to gain necessary knowledge and hands-on skills to set up cloud based database systems.

  3. The Diversity of Cloud Responses to Twentieth-Century Sea Surface Temperatures

    Science.gov (United States)

    Silvers, L. G.; Paynter, D.; Zhao, M.

    2017-12-01

    Clouds play a crucial role in determining the magnitude of the global temperature response to forcing. Previous work has shown strong connections between cloud feedbacks and climate change, and between these feedbacks and changing patterns of surface temperature. We show that strong variability of the climate feedback parameter is present in three GFDL atmospheric general circulation models (AM2.1, AM3, AM4) over the twentieth century. This variability is highly correlated with the global mean cloud radiative effect (CRE) and low-cloud cover (LCC) anomalies. The decadal variability is characterized by a period of high climate sensitivity (1925-1955) and a period of low climate sensitivity (1975-2005). Observed trends of surface temperature also show distinct differences over these two periods. Although it is the SST that drives the atmospheric response, the estimated inversion strength (EIS) is necessary to reproduce the changing LCC field. During both periods, trends of EIS are shown to closely mirror trends of LCC over much of the globe, not only in the typical stratocumulus regions. Trends of the shortwave CRE (SWCRE), LCC, and the EIS are analyzed in particular geographic regions. All of these regions show a consistent relationship between LCC, SWCRE, and EIS, as well as significant differences between the two time periods. This study uses a 15 member ensemble of amip-piForcing simulations from 1870 -2005. These experiments are driven by observed SST patterns and hold greenhouse gases and other atmospheric forcing agents fixed at constant pre-industrial levels. This allows for a clean analysis of how clouds respond to changing patterns of SST and the resulting influence on the climate feedback parameter. The cloudy response of the atmosphere to changing SST patterns is critical in driving the variability of the climate feedback parameter during periods of both high and low climate sensitivity.

  4. Response to marine cloud brightening in a multi-model ensemble

    Directory of Open Access Journals (Sweden)

    C. W. Stjern

    2018-01-01

    Full Text Available Here we show results from Earth system model simulations from the marine cloud brightening experiment G4cdnc of the Geoengineering Model Intercomparison Project (GeoMIP. The nine contributing models prescribe a 50 % increase in the cloud droplet number concentration (CDNC of low clouds over the global oceans in an experiment dubbed G4cdnc, with the purpose of counteracting the radiative forcing due to anthropogenic greenhouse gases under the RCP4.5 scenario. The model ensemble median effective radiative forcing (ERF amounts to −1.9 W m−2, with a substantial inter-model spread of −0.6 to −2.5 W m−2. The large spread is partly related to the considerable differences in clouds and their representation between the models, with an underestimation of low clouds in several of the models. All models predict a statistically significant temperature decrease with a median of (for years 2020–2069 −0.96 [−0.17 to −1.21] K relative to the RCP4.5 scenario, with particularly strong cooling over low-latitude continents. Globally averaged there is a weak but significant precipitation decrease of −2.35 [−0.57 to −2.96] % due to a colder climate, but at low latitudes there is a 1.19 % increase over land. This increase is part of a circulation change where a strong negative top-of-atmosphere (TOA shortwave forcing over subtropical oceans, caused by increased albedo associated with the increasing CDNC, is compensated for by rising motion and positive TOA longwave signals over adjacent land regions.

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

    International Nuclear Information System (INIS)

    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

  6. Atmospheric diffusion of large clouds

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T. V. [Univ. of California, Lawrence Radiation Lab., Livermore, California (United States)

    1967-07-01

    Clouds of pollutants travel within a coordinate system that is fixed to the earth's surface, and they diffuse and grow within a coordinate system fixed to the cloud's center. This paper discusses an approach to predicting the cloud's properties, within the latter coordinate system, on space scales of a few hundred meters to a few hundred kilometers and for time periods of a few days. A numerical cloud diffusion model is presented which starts with a cloud placed arbitrarily within the troposphere. Similarity theories of atmospheric turbulence are used to predict the horizontal diffusivity as a function of initial cloud size, turbulent atmospheric dissipation, and time. Vertical diffusivity is input as a function of time and height. Therefore, diurnal variations of turbulent diffusion in the boundary layer and effects of temperature inversions, etc. can be modeled. Nondiffusive cloud depletion mechanisms, such as dry deposition, washout, and radioactive decay, are also a part of this numerical model. An effluent cloud, produced by a reactor run at the Nuclear Rocket Development Station, Nevada, is discussed in this paper. Measurements on this cloud, for a period of two days, are compared to calculations with the above numerical cloud diffusion model. In general, there is agreement. within a factor of two, for airborne concentrations, cloud horizontal area, surface air concentrations, and dry deposition as airborne concentration decreased by seven orders of magnitude during the two-day period. (author)

  7. Sahara Dust Cloud

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24 A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean. These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward. In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005. In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the AIRS retrieved total water

  8. A Framework to Improve Communication and Reliability Between Cloud Consumer and Provider in the Cloud

    OpenAIRE

    Vivek Sridhar

    2014-01-01

    Cloud services consumers demand reliable methods for choosing appropriate cloud service provider for their requirements. Number of cloud consumer is increasing day by day and so cloud providers, hence requirement for a common platform for interacting between cloud provider and cloud consumer is also on the raise. This paper introduces Cloud Providers Market Platform Dashboard. This will act as not only just cloud provider discoverability but also provide timely report to consumer on cloud ser...

  9. Lean computing for the cloud

    CERN Document Server

    Bauer, Eric

    2016-01-01

    Applies lean manufacturing principles across the cloud service delivery chain to enable application and infrastructure service providers to sustainably achieve the shortest lead time, best quality, and value This book focuses on lean in the context of cloud computing capacity management of applications and the physical and virtual cloud resources that support them. Lean Computing for the Cloud considers business, architectural and operational aspects of efficiently delivering valuable services to end users via cloud-based applications hosted on shared cloud infrastructure. The work also focuses on overall optimization of the service delivery chain to enable both application service and infrastructure service providers to adopt leaner, demand driven operations to serve end users more efficiently. The book’s early chapters analyze how capacity management morphs with cloud computing into interlocked physical infrastructure capacity management, virtual resou ce capacity management, and application capacity ma...

  10. A Climatology of Midlatitude Continental Clouds from the ARM SGP Site. Part I; Low-Level Cloud Macrophysical, Microphysical, and Radiative Properties

    Science.gov (United States)

    Dong, Xiquan; Minnis, Patrick; Xi, Baike

    2005-01-01

    A record of single-layer and overcast low cloud (stratus) properties has been generated using approximately 4000 hours of data collected from January 1997 to December 2002 at the Atmospheric Radiation Measurement (ARM) Southern Great Plains Central Facility (SCF). The cloud properties include liquid-phase and liquid-dominant, mixed-phase, low cloud macrophysical, microphysical, and radiative properties including cloud-base and -top heights and temperatures, and cloud physical thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding; cloud liquid water path (LWP) and content (LWC), and cloud-droplet effective radius (r(sub e)) and number concentration (N) derived from the macrophysical properties and radiometer data; and cloud optical depth (tau), effective solar transmission (gamma), and cloud/top-of-atmosphere albedos (R(sub cldy)/R(sub TOA)) derived from Eppley precision spectral pyranometer measurements. The cloud properties were analyzed in terms of their seasonal, monthly, and hourly variations. In general, more stratus clouds occur during winter and spring than in summer. Cloud-layer altitudes and physical thicknesses were higher and greater in summer than in winter with averaged physical thicknesses of 0.85 km and 0.73 km for day and night, respectively. The seasonal variations of LWP, LWC, N. tau, R(sub cldy), and R(sub TOA) basically follow the same pattern with maxima and minima during winter and summer, respectively. There is no significant variation in mean r(sub e), however, despite a summertime peak in aerosol loading, Although a considerable degree of variability exists, the 6-yr average values of LWP, LWC, r(sub e), N, tau, gamma, R(sub cldy) and R(sub TOA) are 150 gm(exp -2) (138), 0.245 gm(exp -3) (0.268), 8.7 micrometers (8.5), 213 cm(exp -3) (238), 26.8 (24.8), 0.331, 0.672, 0.563 for daytime (nighttime). A new conceptual model of midlatitude continental low clouds at the ARM SGP site has been developed from this study

  11. Individual aerosol particles in and below clouds along a Mt. Fuji slope: Modification of sea-salt-containing particles by in-cloud processing

    Science.gov (United States)

    Ueda, S.; Hirose, Y.; Miura, K.; Okochi, H.

    2014-02-01

    Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776 m a.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2 μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in-cloud

  12. Technical note: Fu-Liou-Gu and Corti-Peter model performance evaluation for radiative retrievals from cirrus clouds

    Science.gov (United States)

    Lolli, Simone; Campbell, James R.; Lewis, Jasper R.; Gu, Yu; Welton, Ellsworth J.

    2017-06-01

    We compare, for the first time, the performance of a simplified atmospheric radiative transfer algorithm package, the Corti-Peter (CP) model, versus the more complex Fu-Liou-Gu (FLG) model, for resolving top-of-the-atmosphere radiative forcing characteristics from single-layer cirrus clouds obtained from the NASA Micro-Pulse Lidar Network database in 2010 and 2011 at Singapore and in Greenbelt, Maryland, USA, in 2012. Specifically, CP simplifies calculation of both clear-sky longwave and shortwave radiation through regression analysis applied to radiative calculations, which contributes significantly to differences between the two. The results of the intercomparison show that differences in annual net top-of-the-atmosphere (TOA) cloud radiative forcing can reach 65 %. This is particularly true when land surface temperatures are warmer than 288 K, where the CP regression analysis becomes less accurate. CP proves useful for first-order estimates of TOA cirrus cloud forcing, but may not be suitable for quantitative accuracy, including the absolute sign of cirrus cloud daytime TOA forcing that can readily oscillate around zero globally.

  13. Development of multi-sensor global cloud and radiance composites for earth radiation budget monitoring from DSCOVR

    Science.gov (United States)

    Khlopenkov, Konstantin; Duda, David; Thieman, Mandana; Minnis, Patrick; Su, Wenying; Bedka, Kristopher

    2017-10-01

    The Deep Space Climate Observatory (DSCOVR) enables analysis of the daytime Earth radiation budget via the onboard Earth Polychromatic Imaging Camera (EPIC) and National Institute of Standards and Technology Advanced Radiometer (NISTAR). Radiance observations and cloud property retrievals from low earth orbit and geostationary satellite imagers have to be co-located with EPIC pixels to provide scene identification in order to select anisotropic directional models needed to calculate shortwave and longwave fluxes. A new algorithm is proposed for optimal merging of selected radiances and cloud properties derived from multiple satellite imagers to obtain seamless global hourly composites at 5-km resolution. An aggregated rating is employed to incorporate several factors and to select the best observation at the time nearest to the EPIC measurement. Spatial accuracy is improved using inverse mapping with gradient search during reprojection and bicubic interpolation for pixel resampling. The composite data are subsequently remapped into EPIC-view domain by convolving composite pixels with the EPIC point spread function defined with a half-pixel accuracy. PSF-weighted average radiances and cloud properties are computed separately for each cloud phase. The algorithm has demonstrated contiguous global coverage for any requested time of day with a temporal lag of under 2 hours in over 95% of the globe.

  14. Cloud vertical profiles derived from CALIPSO and CloudSat and a comparison with MODIS derived clouds

    Science.gov (United States)

    Kato, S.; Sun-Mack, S.; Miller, W. F.; Rose, F. G.; Minnis, P.; Wielicki, B. A.; Winker, D. M.; Stephens, G. L.; Charlock, T. P.; Collins, W. D.; Loeb, N. G.; Stackhouse, P. W.; Xu, K.

    2008-05-01

    CALIPSO and CloudSat from the a-train provide detailed information of vertical distribution of clouds and aerosols. The vertical distribution of cloud occurrence is derived from one month of CALIPSO and CloudSat data as a part of the effort of merging CALIPSO, CloudSat and MODIS with CERES data. This newly derived cloud profile is compared with the distribution of cloud top height derived from MODIS on Aqua from cloud algorithms used in the CERES project. The cloud base from MODIS is also estimated using an empirical formula based on the cloud top height and optical thickness, which is used in CERES processes. While MODIS detects mid and low level clouds over the Arctic in April fairly well when they are the topmost cloud layer, it underestimates high- level clouds. In addition, because the CERES-MODIS cloud algorithm is not able to detect multi-layer clouds and the empirical formula significantly underestimates the depth of high clouds, the occurrence of mid and low-level clouds is underestimated. This comparison does not consider sensitivity difference to thin clouds but we will impose an optical thickness threshold to CALIPSO derived clouds for a further comparison. The effect of such differences in the cloud profile to flux computations will also be discussed. In addition, the effect of cloud cover to the top-of-atmosphere flux over the Arctic using CERES SSF and FLASHFLUX products will be discussed.

  15. NASA/GEWEX Surface Radiation Budget: Integrated Data Product With Reprocessed Radiance, Cloud, and Meteorology Inputs, and New Surface Albedo Treatment

    Science.gov (United States)

    Cox, Stephen J.; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Mikovitz, J. Colleen; Zhang, Taiping

    2016-01-01

    The NASA/GEWEX Surface Radiation Budget (SRB) project produces shortwave and longwave surface and top of atmosphere radiative fluxes for the 1983-near present time period. Spatial resolution is 1 degree. The current release 3.0 (available at gewex-srb.larc.nasa.gov) uses the International Satellite Cloud Climatology Project (ISCCP) DX product for pixel level radiance and cloud information. This product is subsampled to 30 km. ISCCP is currently recalibrating and recomputing their entire data series, to be released as the H product, at 10km resolution. The ninefold increase in pixel number will allow SRB a higher resolution gridded product (e.g. 0.5 degree), as well as the production of pixel-level fluxes. In addition to the input data improvements, several important algorithm improvements have been made. Most notable has been the adaptation of Angular Distribution Models (ADMs) from CERES to improve the initial calculation of shortwave TOA fluxes, from which the surface flux calculations follow. Other key input improvements include a detailed aerosol history using the Max Planck Institut Aerosol Climatology (MAC), temperature and moisture profiles from HIRS, and new topography, surface type, and snow/ice. Here we present results for the improved GEWEX Shortwave and Longwave algorithm (GSW and GLW) with new ISCCP data, the various other improved input data sets and the incorporation of many additional internal SRB model improvements. As of the time of abstract submission, results from 2007 have been produced with ISCCP H availability the limiting factor. More SRB data will be produced as ISCCP reprocessing continues. The SRB data produced will be released as part of the Release 4.0 Integrated Product, recognizing the interdependence of the radiative fluxes with other GEWEX products providing estimates of the Earth's global water and energy cycle (I.e., ISCCP, SeaFlux, LandFlux, NVAP, etc.).

  16. CN in dark clouds

    International Nuclear Information System (INIS)

    Churchwell, E.; Bieging, J.H.

    1983-01-01

    We have detected CN (N = 1--0) emission toward six locations in the Taurus dark cloud complex, but not toward L183 or B227. The two hyperfine components, F = 3/2--1/2 and F = 5/2--3/2 (of J = 3/2--1/2), have intensity ratios near unity toward four locations in Taurus, consistent with large line optical depths. CN column densities are found to be > or approx. =6 x 10 13 cm -2 in those directions where the hyperfine ratios are near unity. By comparing CN with NH 3 and C 18 O column densities, we find that the relative abundance of CN in the Taurus cloudlets is at least a factor of 10 greater than in L183. In this respect, CN fits the pattern of enhanced abundances of carbon-bearing molecules (in partricular the cyanopolyynes) in the Taurus cloudlets relative to similar dark clouds outside Taurus

  17. Transmission on Balance 2006

    International Nuclear Information System (INIS)

    2007-02-01

    Every year he Dutch Transmission System Operator (TSO) TenneT issues the title publication 'Transmission on Balance'. This report provides information about the main technical operating results in the past year.

  18. Carbon pellet cloud striations

    International Nuclear Information System (INIS)

    Parks, P.B.

    1989-01-01

    Fine scale striations, with alternating rows of bright and dark zones, have been observed in the ablation clouds of carbon pellets injected into the TEXT tokamak. The striations extend along the magnetic field for about 1 cm with quite regular cross-field variations characterized by a wavelength of a few mm. Their potential as a diagnostic tool for measuring q-profiles in tokamaks provides motivation for investigating the origin of the striations. The authors propose that the striations are not due to a sequence of high and low ablation rates because of the finite thermal magnetic islands localized at rational surfaces, q = m/n, would be responsible for reducing the electron flux to the pellet region; the length of the closed field line which forms the local magnetic axis of the island is too long to prevent a depletion of plasma electrons in a flux tube intercepting the pellet for the duration 2 rp / vp . Instead, they propose that striations are the manifestation of the saturated state of growing fluctuations inside the cloud. The instability is generated by E x B rotation of the ablation cloud. The outward centrifugal force points down the ablation density gradient inducing the Rayleigh-Taylor instability. The instability is not present for wave numbers along the field lines, which may explain why the striations are long and uniform in that direction. The E field develops inside the ablation cloud as a result of cold electron return currents which are induced to cancel the incoming hot plasma electron current streaming along the field lines

  19. Security in cloud computing and virtual environments

    OpenAIRE

    Aarseth, Raymond

    2015-01-01

    Cloud computing is a big buzzwords today. Just watch the commercials on TV and I can promise that you will hear the word cloud service at least once. With the growth of cloud technology steadily rising, and everything from cellphones to cars connected to the cloud, how secure is cloud technology? What are the caveats of using cloud technology? And how does it all work? This thesis will discuss cloud security and the underlying technology called Virtualization to ...

  20. IBM Cloud Computing Powering a Smarter Planet

    Science.gov (United States)

    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.

  1. Grids, Clouds, and Virtualization

    Science.gov (United States)

    Cafaro, Massimo; Aloisio, Giovanni

    This chapter introduces and puts in context Grids, Clouds, and Virtualization. Grids promised to deliver computing power on demand. However, despite a decade of active research, no viable commercial grid computing provider has emerged. On the other hand, it is widely believed - especially in the Business World - that HPC will eventually become a commodity. Just as some commercial consumers of electricity have mission requirements that necessitate they generate their own power, some consumers of computational resources will continue to need to provision their own supercomputers. Clouds are a recent business-oriented development with the potential to render this eventually as rare as organizations that generate their own electricity today, even among institutions who currently consider themselves the unassailable elite of the HPC business. Finally, Virtualization is one of the key technologies enabling many different Clouds. We begin with a brief history in order to put them in context, and recall the basic principles and concepts underlying and clearly differentiating them. A thorough overview and survey of existing technologies provides the basis to delve into details as the reader progresses through the book.

  2. From clouds to stars

    International Nuclear Information System (INIS)

    Elmegreen, B.G.

    1982-01-01

    At the present time, the theory of star formation must be limited to what we know about the lowest density gas, or about the pre-main sequence stars themselves. We would like to understand two basic processes: 1) how star-forming clouds are created from the ambient interstellar gas in the first place, and 2) how small parts of these clouds condense to form individual stars. We are interested also in knowing what pre-main sequence stars are like, and how they can interact with their environment. These topics are reviewed in what follows. In this series of lectures, what we know about the formation of stars is tentatively described. The lectures begin with a description of the interstellar medium, and then they proceed along the same direction that a young star would follow during its creation, namely from clouds through the collapse phase and onto the proto-stellar phase. The evolution of viscous disks and two models for the formation of the solar system are described in the last lectures. The longest lectures, and the topics that are covered in most detail, are not necessarily the ones for which we have the most information. Physically intuitive explanations for the various processes are emphasized, rather then mathematical explanations. In some cases, the mathematical aspects are developed as well, but only when the equations can be used to give important numerical values for comparison with the observations

  3. ATLAS cloud R and D

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 and D working group to investigate the different integration scenarios. The ATLAS Cloud Computing R and 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 and 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 and 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.

  4. Cloud Computing Security: A Survey

    Directory of Open Access Journals (Sweden)

    Issa M. Khalil

    2014-02-01

    Full Text Available Cloud computing is an emerging technology paradigm that migrates current technological and computing concepts into utility-like solutions similar to electricity and water systems. Clouds bring out a wide range of benefits including configurable computing resources, economic savings, and service flexibility. However, security and privacy concerns are shown to be the primary obstacles to a wide adoption of clouds. The new concepts that clouds introduce, such as multi-tenancy, resource sharing and outsourcing, create new challenges to the security community. Addressing these challenges requires, in addition to the ability to cultivate and tune the security measures developed for traditional computing systems, proposing new security policies, models, and protocols to address the unique cloud security challenges. In this work, we provide a comprehensive study of cloud computing security and privacy concerns. We identify cloud vulnerabilities, classify known security threats and attacks, and present the state-of-the-art practices to control the vulnerabilities, neutralize the threats, and calibrate the attacks. Additionally, we investigate and identify the limitations of the current solutions and provide insights of the future security perspectives. Finally, we provide a cloud security framework in which we present the various lines of defense and identify the dependency levels among them. We identify 28 cloud security threats which we classify into five categories. We also present nine general cloud attacks along with various attack incidents, and provide effectiveness analysis of the proposed countermeasures.

  5. ATLAS Cloud R&D

    Science.gov (United States)

    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.

  6. CloudSafetyNet: Detecting Data Leakage between Cloud Tenants

    OpenAIRE

    Pietzuch, PR; Priebe, C; Muthukumaran, D; O'Keeffe, D; Eyers, D; Shand, B; Kapitza, R

    2014-01-01

    01.12.14 KB. Ok to add accepted version to spiral. Copyright ? 2014 by the Association for Computing Machinery, Inc. (ACM).When tenants deploy applications under the control of third-party cloud providers, they must trust the providers security mechanisms for inter-tenant isolation, resource sharing and access control. Despite a providers best efforts, accidental data leakage may occur due to misconfigurations or bugs in the cloud platform. Especially in Platform-as-a-Service (PaaS) clouds...

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

    Science.gov (United States)

    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.

  8. Security prospects through cloud computing by adopting multiple clouds

    DEFF Research Database (Denmark)

    Jensen, Meiko; Schwenk, Jörg; Bohli, Jens Matthias

    2011-01-01

    Clouds impose new security challenges, which are amongst the biggest obstacles when considering the usage of cloud services. This triggered a lot of research activities in this direction, resulting in a quantity of proposals targeting the various security threats. Besides the security issues coming...... with the cloud paradigm, it can also provide a new set of unique features which open the path towards novel security approaches, techniques and architectures. This paper initiates this discussion by contributing a concept which achieves security merits by making use of multiple distinct clouds at the same time....

  9. TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

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

    International Nuclear Information System (INIS)

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

    2002-01-01

    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

  11. The automotive transmission book

    CERN Document Server

    Fischer, Robert; Jürgens, Gunter; Najork, Rolf; Pollak, Burkhard

    2015-01-01

    This book presents essential information on systems and interactions in automotive transmission technology and outlines the methodologies used to analyze and develop transmission concepts and designs. Functions of and interactions between components and subassemblies of transmissions are introduced, providing a basis for designing transmission systems and for determining their potentials and properties in vehicle-specific applications: passenger cars, trucks, buses, tractors, and motorcycles. With these fundamentals the presentation provides universal resources for both state-of-the-art and future transmission technologies, including systems for electric and hybrid electric vehicles.

  12. Decomposing Shortwave Top-of-Atmosphere Radiative Flux Variability in Terms of Surface and Atmospheric Contributions Using CERES Observations

    Science.gov (United States)

    Loeb, N. G.; Wong, T.; Wang, H.

    2017-12-01

    Earth's climate is determined by the exchange of radiant energy between the Sun, Earth and space. The absorbed solar radiation (ASR) fuels the climate system, providing the energy required for atmospheric and oceanic motions, while the system cools by emitting outgoing longwave (LW) radiation to space. A central objective of the Clouds and the Earth's Radiant Energy System (CERES) is to produce a long-term global climate data record of Earth's radiation budget along with the associated atmospheric and surface properties that influence it. CERES data products utilize a number of data sources, including broadband radiometers measuring incoming and reflected solar radiation and OLR, polar orbiting and geostationary spectral imagers, meteorological, aerosol and ozone assimilation data, and snow/sea-ice maps based on microwave radiometer data. Here we use simple diagnostic model of Earth's albedo and CERES Energy Balanced and Filled (EBAF) Ed4.0 data for March 2000-February 2016 to quantify interannual variations in SW TOA flux associated with surface albedo and atmospheric reflectance and transmittance variations. Surface albedo variations account for cloud properties over the Arctic Ocean.

  13. Studi Perbandingan Layanan Cloud Computing

    Directory of Open Access Journals (Sweden)

    Afdhal Afdhal

    2014-03-01

    Full Text Available In the past few years, cloud computing has became a dominant topic in the IT area. Cloud computing offers hardware, infrastructure, platform and applications without requiring end-users knowledge of the physical location and the configuration of providers who deliver the services. It has been a good solution to increase reliability, reduce computing cost, and make opportunities to IT industries to get more advantages. The purpose of this article is to present a better understanding of cloud delivery service, correlation and inter-dependency. This article compares and contrasts the different levels of delivery services and the development models, identify issues, and future directions on cloud computing. The end-users comprehension of cloud computing delivery service classification will equip them with knowledge to determine and decide which business model that will be chosen and adopted securely and comfortably. The last part of this article provides several recommendations for cloud computing service providers and end-users.

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

    Science.gov (United States)

    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.

  15. Pellicle transmission uniformity requirements

    Science.gov (United States)

    Brown, Thomas L.; Ito, Kunihiro

    1998-12-01

    Controlling critical dimensions of devices is a constant battle for the photolithography engineer. Current DUV lithographic process exposure latitude is typically 12 to 15% of the total dose. A third of this exposure latitude budget may be used up by a variable related to masking that has not previously received much attention. The emphasis on pellicle transmission has been focused on increasing the average transmission. Much less, attention has been paid to transmission uniformity. This paper explores the total demand on the photospeed latitude budget, the causes of pellicle transmission nonuniformity and examines reasonable expectations for pellicle performance. Modeling is used to examine how the two primary errors in pellicle manufacturing contribute to nonuniformity in transmission. World-class pellicle transmission uniformity standards are discussed and a comparison made between specifications of other components in the photolithographic process. Specifications for other materials or parameters are used as benchmarks to develop a proposed industry standard for pellicle transmission uniformity.

  16. Estimating cloud field coverage using morphological analysis

    International Nuclear Information System (INIS)

    Bar-Or, Rotem Z; Koren, Ilan; Altaratz, Orit

    2010-01-01

    The apparent cloud-free atmosphere in the vicinity of clouds ('the twilight zone') is often affected by undetectable weak signature clouds and humidified aerosols. It is suggested here to classify the atmosphere into two classes: cloud fields, and cloud-free (away from a cloud field), while detectable clouds are included in the cloud field class as a subset. Since the definition of cloud fields is ambiguous, a robust cloud field masking algorithm is presented here, based on the cloud spatial distribution. The cloud field boundaries are calculated then on the basis of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask products and the total cloud field area is estimated for the Atlantic Ocean (50 deg. S-50 deg. N). The findings show that while the monthly averaged cloud fraction over the Atlantic Ocean during July is 53%, the cloud field fraction may reach 97%, suggesting that cloud field properties should be considered in climate studies. A comparison between aerosol optical depth values inside and outside cloud fields reveals differences in the retrieved radiative properties of aerosols depending on their location. The observed mean aerosol optical depth inside the cloud fields is more than 10% higher than outside it, indicating that such convenient cloud field masking may contribute to better estimations of aerosol direct and indirect forcing.

  17. Cloud Services from Consumer Standpoint

    OpenAIRE

    Koski, Jori

    2016-01-01

    The objective of this thesis is to clarify the use of cloud services and how they are used in practice. This thesis will first cover the history of cloud computing. At the early days of computing, services have been stored on servers locally and could be accessed through direct connections. After this, services have been on the users’ personal computers. Nowadays, services are stored in the cloud. This research paper focuses on four sub topics: communication services, healthcare se...

  18. Cloud Computing: Exploring the scope

    OpenAIRE

    Maurya, Brajesh Kumar

    2010-01-01

    Cloud computing refers to a paradigm shift to overall IT solutions while raising the accessibility, scalability and effectiveness through its enabling technologies. However, migrated cloud platforms and services cost benefits as well as performances are neither clear nor summarized. Globalization and the recessionary economic times have not only raised the bar of a better IT delivery models but also have given access to technology enabled services via internet. Cloud computing has va...

  19. Cloud Computing and Security Issues

    OpenAIRE

    Rohan Jathanna; Dhanamma Jagli

    2017-01-01

    Cloud computing has become one of the most interesting topics in the IT world today. Cloud model of computing as a resource has changed the landscape of computing as it promises of increased greater reliability, massive scalability, and decreased costs have attracted businesses and individuals alike. It adds capabilities to Information Technology’s. Over the last few years, cloud computing has grown considerably in Information Technology. As more and more information of individuals and compan...

  20. Studi Perbandingan Layanan Cloud Computing

    OpenAIRE

    Afdhal, Afdhal

    2013-01-01

    In the past few years, cloud computing has became a dominant topic in the IT area. Cloud computing offers hardware, infrastructure, platform and applications without requiring end-users knowledge of the physical location and the configuration of providers who deliver the services. It has been a good solution to increase reliability, reduce computing cost, and make opportunities to IT industries to get more advantages. The purpose of this article is to present a better understanding of cloud d...