WorldWideScience

Sample records for understand warm cloud

  1. Frequency of Deep Convective Clouds and Global Warming

    Science.gov (United States)

    Aumann, Hartmut H.; Teixeira, Joao

    2008-01-01

    This slide presentation reviews the effect of global warming on the formation of Deep Convective Clouds (DCC). It concludes that nature responds to global warming with an increase in strong convective activity. The frequency of DCC increases with global warming at the rate of 6%/decade. The increased frequency of DCC with global warming alone increases precipitation by 1.7%/decade. It compares the state of the art climate models' response to global warming, and concludes that the parametrization of climate models need to be tuned to more closely emulate the way nature responds to global warming.

  2. From aerosol-limited to invigoration of warm convective clouds.

    Science.gov (United States)

    Koren, Ilan; Dagan, Guy; Altaratz, Orit

    2014-06-06

    Among all cloud-aerosol interactions, the invigoration effect is the most elusive. Most of the studies that do suggest this effect link it to deep convective clouds with a warm base and cold top. Here, we provide evidence from observations and numerical modeling of a dramatic aerosol effect on warm clouds. We propose that convective-cloud invigoration by aerosols can be viewed as an extension of the concept of aerosol-limited clouds, where cloud development is limited by the availability of cloud-condensation nuclei. A transition from pristine to slightly polluted atmosphere yields estimated negative forcing of ~15 watts per square meter (cooling), suggesting that a substantial part of this anthropogenic forcing over the oceans occurred at the beginning of the industrial era, when the marine atmosphere experienced such transformation. Copyright © 2014, American Association for the Advancement of Science.

  3. Warming Ancient Mars with Water Clouds

    Science.gov (United States)

    Hartwick, V. L.; Toon, O. B.

    2017-10-01

    High altitude clouds in the present day Mars atmosphere may form on interplanetary dust particles (IDPs). Paleo fluences of IDPs were likely higher, and similar clouds are expected to influence the Mars paleo-climate.

  4. 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

  5. Cloud clusters and superclusters over the oceanic warm pool

    Science.gov (United States)

    Mapes, Brian E.; Houze, Robert A., Jr.

    1993-01-01

    A study aimed at examining the size distributions of cloud clusters and the temperature distributions within them as functions of location, year, phase of the ISV, and time of day is considered. IR satellite images of tropical convection over the oceanic warm pool were processed to reveal cloud clusters, connected areas with cloud-top temperatures lower than a given threshold value. Results were obtained for a very cold threshold (208 K), corresponding roughly to the radar echo area within Australian monsoon cloud clusters, and for a moderately cold threshold (235 K) frequently used in climatic rainfall estimation.

  6. Rain Initiation Time in Turbulent Warm Clouds

    Science.gov (United States)

    Falkovich, Gregory; Stepanov, Mikhail G.; Vucelja, Marija

    2006-04-01

    A mean field model is presented that describes droplet growth resulting from condensation and collisions and droplet loss resulting from fallout. The model allows for an effective numerical simulation. The numerical scheme that is conservative in water mass and keeps accurate count of the number of droplets is applied, and the way in which the rain initiation time depends on different parameters is studied. In particular, it is shown that the rain initiation time depends nonmonotonically (has a minimum) on the number of cloud condensation nuclei. Also presented is a simple model that allows one to estimate the rain initiation time for turbulent clouds with an inhomogeneous concentration of cloud condensation nuclei. It is argued that by overseeding even a part of a cloud by small hygroscopic nuclei one can substantially delay the onset of precipitation.

  7. Opportunities for understanding of aerosol cloud interactions in the context of Marine Cloud Brightening Experiments

    Science.gov (United States)

    Rasch, Philip J.; Wood, Robert; Ackerman, Thomas P.

    2017-04-01

    Anthropogenic aerosol impacts on clouds constitute the largest source of uncertainty in radiative forcing of climate, confounding estimates of climate sensitivity to increases in greenhouse gases. Projections of future warming are also thus strongly dependent on estimates of aerosol effects on clouds. I will discuss the opportunities for improving estimates of aerosol effects on clouds from controlled field experiments where aerosol with well understood size, composition, amount, and injection altitude could be introduced to deliberately change cloud properties. This would allow scientific investigation to be performed in a manner much closer to a lab environment, and facilitate the use of models to predict cloud responses ahead of time, testing our understanding of aerosol cloud interactions.

  8. 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

  9. The role of clouds and oceans in global greenhouse warming

    International Nuclear Information System (INIS)

    Hoffert, M.I.

    1992-12-01

    During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, ''Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature''. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales

  10. Study of tropical clouds feedback to a climate warming as simulated by climate models

    International Nuclear Information System (INIS)

    Brient, Florent

    2012-01-01

    The last IPCC report affirms the predominant role of low cloud-radiative feedbacks in the inter-model spread of climate sensitivity. Understanding the mechanisms that control the behavior of low-level clouds is thus crucial. However, the complexity of coupled ocean-atmosphere models and the large number of processes potentially involved make the analysis of this response difficult. To simplify the analysis and to identify the most critical controls of cloud feedbacks, we analyze the cloud response to climate change simulated by the IPSL-CM5A model in a hierarchy of configurations. A comparison between three model configurations (coupled, atmospheric and aqua-planet) using the same physical parametrizations shows that the cloud response to global warming is dominated by a decrease of low clouds in regimes of moderate subsidence. Using a Single Column Model, forced by weak subsidence large-scale forcing, allows us to reproduce the vertical cloud profile predicted in the 3D model, as well as its response to climate change (if a stochastic forcing is added on vertical velocity). We analyze the sensitivity of this low-cloud response to external forcing and also to uncertain parameters of physical parameterizations involved on the atmospheric model. Through a moist static energy (MSE) budget, we highlight several mechanisms: (1) Robust: Over weak subsidence regimes, the Clausius-Clapeyron relationship predicts that a warmer atmosphere leads to a increase of the vertical MSE gradient, resulting on a strengthening of the import of low-MSE from the free atmosphere into the cloudy boundary layer. The MSE budget links changes of vertical advection and cloud radiative effects. (2) Physics Model Dependent: The coupling between shallow convection, turbulence and cloud schemes allows the intensification of low-MSE transport so that cloud radiative cooling becomes 'less necessary' to balance the energy budget (Robust positive low cloud-radiative feedback for the model). The

  11. Clouds and the atmospheric circulation response to warming

    Science.gov (United States)

    Ceppi, Paulo; Hartmann, Dennis

    2016-04-01

    We study the effect of clouds on the atmospheric circulation response to CO2 quadrupling in an aquaplanet model with a slab-ocean lower boundary. The cloud effect is isolated by locking the clouds to either the control or 4xCO2 state in the shortwave (SW) or longwave (LW) radiation schemes. In our model, cloud-radiative changes explain more than half of the total poleward expansion of the Hadley cells, midlatitude jets, and storm tracks under CO2 quadrupling, even though they cause only one-fourth of the total global-mean surface warming. The effect of clouds on circulation results mainly from the SW cloud-radiative changes, which strongly enhance the Equator-to-pole temperature gradient at all levels in the troposphere, favoring stronger and poleward-shifted midlatitude eddies. By contrast, quadrupling CO2 while holding the clouds fixed causes strong polar amplification and weakened midlatitude baroclinicity at lower levels, yielding only a small poleward expansion of the circulation. Our results show that (a) the atmospheric circulation responds sensitively to cloud-driven changes in meridional and vertical temperature distribution, and (b) the spatial structure of cloud feedbacks likely plays a dominant role in the circulation response to greenhouse gas forcing. While the magnitude and spatial structure of the cloud feedback are expected to be highly model-dependent, an analysis of 4xCO2 simulations of CMIP5 models shows that the SW cloud feedback likely forces a poleward expansion of the tropospheric circulation in most climate models.

  12. How do changes in warm-phase microphysics affect deep convective clouds?

    Directory of Open Access Journals (Sweden)

    Q. Chen

    2017-08-01

    Full Text Available Understanding aerosol effects on deep convective clouds and the derived effects on the radiation budget and rain patterns can largely contribute to estimations of climate uncertainties. The challenge is difficult in part because key microphysical processes in the mixed and cold phases are still not well understood. For deep convective clouds with a warm base, understanding aerosol effects on the warm processes is extremely important as they set the initial and boundary conditions for the cold processes. Therefore, the focus of this study is the warm phase, which can be better resolved. The main question is: How do aerosol-derived changes in the warm phase affect the properties of deep convective cloud systems? To explore this question, we used a weather research and forecasting (WRF model with spectral bin microphysics to simulate a deep convective cloud system over the Marshall Islands during the Kwajalein Experiment (KWAJEX. The model results were validated against observations, showing similarities in the vertical profile of radar reflectivity and the surface rain rate. Simulations with larger aerosol loading resulted in a larger total cloud mass, a larger cloud fraction in the upper levels, and a larger frequency of strong updrafts and rain rates. Enlarged mass both below and above the zero temperature level (ZTL contributed to the increase in cloud total mass (water and ice in the polluted runs. Increased condensation efficiency of cloud droplets governed the gain in mass below the ZTL, while both enhanced condensational and depositional growth led to increased mass above it. The enhanced mass loading above the ZTL acted to reduce the cloud buoyancy, while the thermal buoyancy (driven by the enhanced latent heat release increased in the polluted runs. The overall effect showed an increased upward transport (across the ZTL of liquid water driven by both larger updrafts and larger droplet mobility. These aerosol effects were reflected in the

  13. Understanding subtropical cloud feedbacks in anthropogenic climate change simulations of CMIP5 models

    Science.gov (United States)

    Myers, T. A.; Norris, J. R.

    2014-12-01

    Subtropical marine boundary layer clouds over the eastern subtropics are poorly simulated by climate models and contribute substantially to inter-model differences in climate sensitivity. The aim of the present study is to better understand inter-model differences in projected cloud changes and to constrain the cloud feedback to warming. To do this, we compute independent relationships of cloud properties (cloud fraction, cloud-top height, and cloud radiative effect) to interannual variations in sea surface temperature, estimated inversion strength, horizontal surface temperature advection, free-tropospheric humidity, and subsidence using observations and as simulated by models participating in the Coupled Model Intercomparison Project phase 5. Each relationship is considered to be independent because it represents the association between some cloud property and a meteorological parameter when the other parameters are held constant. We approximate modelled cloud trends in climate change simulations as the sum of the simulated cloud/meteorology relationships multiplied by the respective meteorological trends. We compare these estimated cloud trends to the sum of the observed cloud/meteorology relationships multiplied by the simulated meteorological trends. This method allows us to better understand the sources of inter-model differences in projected cloud changes, including whether cloud/meteorology relationships or meteorological trends dominate the spread of cloud changes. We approximate the true cloud trend due to climate change as the sum of the observed cloud/meteorology relationships multiplied by the multi-model mean meteorological trends. The results may provide an observational and model constraint on climate sensitivity.

  14. Warming trends in Asia amplified by brown cloud solar absorption.

    Science.gov (United States)

    Ramanathan, Veerabhadran; Ramana, Muvva V; Roberts, Gregory; Kim, Dohyeong; Corrigan, Craig; Chung, Chul; Winker, David

    2007-08-02

    Atmospheric brown clouds are mostly the result of biomass burning and fossil fuel consumption. They consist of a mixture of light-absorbing and light-scattering aerosols and therefore contribute to atmospheric solar heating and surface cooling. The sum of the two climate forcing terms-the net aerosol forcing effect-is thought to be negative and may have masked as much as half of the global warming attributed to the recent rapid rise in greenhouse gases. There is, however, at least a fourfold uncertainty in the aerosol forcing effect. Atmospheric solar heating is a significant source of the uncertainty, because current estimates are largely derived from model studies. Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly. We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers.

  15. Estimating precipitation susceptibility in warm marine clouds using multi-sensor aerosol and cloud products from A-Train satellites

    Directory of Open Access Journals (Sweden)

    H. Bai

    2018-02-01

    Full Text Available Precipitation susceptibility to aerosol perturbation plays a key role in understanding aerosol–cloud interactions and constraining aerosol indirect effects. However, large discrepancies exist in the previous satellite estimates of precipitation susceptibility. In this paper, multi-sensor aerosol and cloud products, including those from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO, CloudSat, Moderate Resolution Imaging Spectroradiometer (MODIS, and Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E from June 2006 to April 2011 are analyzed to estimate precipitation frequency susceptibility SPOP, precipitation intensity susceptibility SI, and precipitation rate susceptibility SR in warm marine clouds. We find that SPOP strongly depends on atmospheric stability, with larger values under more stable environments. Our results show that precipitation susceptibility for drizzle (with a −15 dBZ rainfall threshold is significantly different than that for rain (with a 0 dBZ rainfall threshold. Onset of drizzle is not as readily suppressed in warm clouds as rainfall while precipitation intensity susceptibility is generally smaller for rain than for drizzle. We find that SPOP derived with respect to aerosol index (AI is about one-third of SPOP derived with respect to cloud droplet number concentration (CDNC. Overall, SPOP demonstrates relatively robust features throughout independent liquid water path (LWP products and diverse rain products. In contrast, the behaviors of SI and SR are subject to LWP or rain products used to derive them. Recommendations are further made for how to better use these metrics to quantify aerosol–cloud–precipitation interactions in observations and models.

  16. Precipitation and circulation response to warming shaped by radiative changes of clouds and water vapor

    Science.gov (United States)

    Voigt, Aiko; Shaw, Tiffany

    2015-04-01

    The atmospheric circulation controls how global warming will be expressed regionally, in particular by locally altering the hydrological cycle through changes in moisture transport. While climate models robustly project an increase of global-mean precipitation at a rate of 1-3% per degree warming, there is much less consensus on how the global-mean increase will be distributed regionally, and confidence in long-term projections of regional precipitation changes remains much lower than for temperature. Here, two CMIP5 aquaplanet models, MPI-ESM and IPSL-CM5A, and their response to a uniform 4K increase of sea-surface temperatures are compared to study how radiative changes of clouds and water vapor influence the regional response of precipitation and the circulation to global warming, and to investigate to which extent uncertainty in clouds and water vapor lead to uncertainty in the precipitation and circulation response. Using the cloud and water-vapor locking method it is shown that cloud-radiative changes dominate the response of deep-tropical precipitation and the strength of the Hadley circulation, and lead to disagreement between the two models. In MPI-ESM changes in tropical ice clouds cause a narrowing of the inter-tropical convergence zone (ITCZ) and a strengthening of the Hadley circulation, whereas they lead to a widening of the ITCZ and a weakening of the Hadley circulation in IPSL-CM5A. Radiative changes of clouds and water vapor also impact the subtropics and extratropics. Cloud changes are found to amplify the poleward expansion of the tropical belt and the poleward shift of the extratropical jet, consistent with the fact that they stabilize the tropical atmosphere. In contrast, water vapor changes destabilize the tropical atmosphere and contract the tropical belt and jet towards the equator. Both models show the opposing impacts of cloud and water vapor changes on the jet shift, but the degree of compensation between cloud and water-vapor changes is

  17. Global Warming: Understanding and Teaching the Forecast.

    Science.gov (United States)

    Andrews, Bill

    1994-01-01

    A resource for the teaching of the history and causes of climate change. Discusses evidence of climate change from the Viking era, early ice ages, the most recent ice age, natural causes of climate change, human-made causes of climate change, projections of global warming, and unequal warming. (LZ)

  18. Combining observations and models to reduce uncertainty in the cloud response to global warming

    Science.gov (United States)

    Norris, J. R.; Myers, T.; Chellappan, S.

    2017-12-01

    Currently there is large uncertainty on how subtropical low-level clouds will respond to global warming and whether they will act as a positive feedback or negative feedback. Global climate models substantially agree on what changes in atmospheric structure and circulation will occur with global warming but greatly disagree over how clouds will respond to these changes in structure and circulation. An examination of models with the most realistic simulations of low-level cloudiness indicates that the model cloud response to atmospheric changes associated with global warming is quantitatively similar to the model cloud response to atmospheric changes at interannual time scales. For these models, the cloud response to global warming predicted by multilinear regression using coefficients derived from interannual time scales is quantitatively similar to the cloud response to global warming directly simulated by the model. Since there is a large spread among cloud response coefficients even among models with the most realistic cloud simulations, substitution of coefficients derived from satellite observations reduces the uncertainty range of the low-level cloud feedback. Increased sea surface temperature associated with global warming acts to reduce low-level cloudiness, which is partially offset by increased lower tropospheric stratification that acts to enhance low-level cloudiness. Changes in free-tropospheric relative humidity, subsidence, and horizontal advection have only a small impact on low-level cloud. The net reduction in subtropical low-level cloudiness increases absorption of solar radiation by the climate system, thus resulting in a weak positive feedback.

  19. Analysis of aerosol effects on warm clouds over the Yangtze River Delta from multi-sensor satellite observations

    Science.gov (United States)

    Liu, Yuqin; de Leeuw, Gerrit; Kerminen, Veli-Matti; Zhang, Jiahua; Zhou, Putian; Nie, Wei; Qi, Ximeng; Hong, Juan; Wang, Yonghong; Ding, Aijun; Guo, Huadong; Krüger, Olaf; Kulmala, Markku; Petäjä, Tuukka

    2017-05-01

    Aerosol effects on low warm clouds over the Yangtze River Delta (YRD, eastern China) are examined using co-located MODIS, CALIOP and CloudSat observations. By taking the vertical locations of aerosol and cloud layers into account, we use simultaneously observed aerosol and cloud data to investigate relationships between cloud properties and the amount of aerosol particles (using aerosol optical depth, AOD, as a proxy). Also, we investigate the impact of aerosol types on the variation of cloud properties with AOD. Finally, we explore how meteorological conditions affect these relationships using ERA-Interim reanalysis data. This study shows that the relation between cloud properties and AOD depends on the aerosol abundance, with a different behaviour for low and high AOD (i.e. AOD 0.35). This applies to cloud droplet effective radius (CDR) and cloud fraction (CF), but not to cloud optical thickness (COT) and cloud top pressure (CTP). COT is found to decrease when AOD increases, which may be due to radiative effects and retrieval artefacts caused by absorbing aerosol. Conversely, CTP tends to increase with elevated AOD, indicating that the aerosol is not always prone to expand the vertical extension. It also shows that the COT-CDR and CWP (cloud liquid water path)-CDR relationships are not unique, but affected by atmospheric aerosol loading. Furthermore, separation of cases with either polluted dust or smoke aerosol shows that aerosol-cloud interaction (ACI) is stronger for clouds mixed with smoke aerosol than for clouds mixed with dust, which is ascribed to the higher absorption efficiency of smoke than dust. The variation of cloud properties with AOD is analysed for various relative humidity and boundary layer thermodynamic and dynamic conditions, showing that high relative humidity favours larger cloud droplet particles and increases cloud formation, irrespective of vertical or horizontal level. Stable atmospheric conditions enhance cloud cover horizontally

  20. Modification of cirrus clouds to reduce global warming

    Science.gov (United States)

    Mitchell, D. L.

    2009-12-01

    Since both greenhouse gases and cirrus clouds strongly affect outgoing longwave radiation (OLR) with no affect or less affect on solar radiation, respectively, an attempt to delay global warming to buy time for emission reduction strategies to work might naturally target cirrus clouds. Cirrus having optical depths water vapor and clouds from an initial greenhouse gas forcing, and a recent study indicates water vapor and clouds in the upper troposphere (UT) have the greatest impact on climate sensitivity (the equilibrium response of global-mean surface temperature to a CO2 doubling). Thus altering UT water vapor and cirrus may be a good strategy for climate engineering. Cirrus cloud coverage is predicted to be sensitive to the ice fall speed which depends on ice crystal size. The higher the cirrus, the greater their impact is on OLR. Thus by changing ice crystal size in the coldest cirrus, OLR and climate might be modified. Fortunately the coldest cirrus have the highest ice supersaturation due to the dominance of homogeneous freezing nucleation. Seeding such cirrus with very efficient heterogeneous ice nuclei should produce larger ice crystals due to vapor competition effects, thus increasing OLR and surface cooling. Preliminary estimates of this global net cloud forcing via GCM simulations are more negative than -2.8 W m-2 and could neutralize the radiative forcing due to a CO2 doubling (3.7 W m-2). This cirrus engineered net forcing is due to (1) reduced cirrus coverage and (2) reduced upper tropospheric water vapor, due to enhanced ice sedimentation. The implementation of this climate engineering could use the airline industry to disperse the seeding material. Commercial airliners typically fly at temperatures between -40 and -60 deg. C (where homogeneous freezing nucleation dominates). Weather modification research has developed ice nucleating substances that are extremely effective at these cold temperatures, are non-toxic and are relatively inexpensive. The

  1. The effect of aerosol-derived changes in the warm phase on the properties of deep convective clouds

    Science.gov (United States)

    Chen, Qian; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven; Dagan, Guy

    2017-04-01

    The aerosol impact on deep convective clouds starts in an increased number of cloud droplets in higher aerosol loading environment. This change drives many others, like enhanced condensational growth, delay in collision-coalescence and others. Since the warm processes serve as the initial and boundary conditions for the mixed and cold-phase processes in deep clouds, it is highly important to understand the aerosol effect on them. The weather research and forecasting model (WRF) with spectral bin microphysics was used to study a deep convective system over the Marshall Islands, during the Kwajalein Experiment (KWAJEX). Three simulations were conducted with aerosol concentrations of 100, 500 and 2000 cm-3, to reflect clean, semipolluted, and polluted conditions. The results of the clean run agreed well with the radar profiles and rain rate observations. The more polluted simulations resulted in larger total cloud mass, larger upper level cloud fraction and rain rates. There was an increased mass both below and above the zero temperature level. It indicates of more efficient growth processes both below and above the zero level. In addition the polluted runs showed an increased upward transport (across the zero level) of liquid water due to both stronger updrafts and larger droplet mobility. In this work we discuss the transport of cloud mass crossing the zero temperature level (in both directions) in order to gain a process level understanding of how aerosol effects on the warm processes affect the macro- and micro-properties of deep convective clouds.

  2. Understanding the challenges of global warming

    International Nuclear Information System (INIS)

    Smith, P.

    2003-01-01

    The evolution of the threat of global warming and the chronology of the last half century of efforts to prevent it from overwhelming humanity is chronicled. It was in the 1970s when it was first realized that the cumulative total of atmospheric carbon dioxide from fossil fuel burning had been steadily rising from the pre-industrial 280 ppmv (parts per million by volume) to 325 ppmv, approximately parallel with the rise of industrialization. Nevertheless, the first attempt at a global accord to reduce emissions was not made until 1992, when the Rio de Janeiro Earth Summit tried, but miserably failed to reach agreement, having been prevented from achieving anything of substance by a loose-knit group of nations and commercial interests. Binding agreements were finally reached at the next scheduled international meeting in Kyoto, Japan, in 1997. There is a detailed discussion of the Kyoto Protocols, the measures that Annex One nations such as Canada have to do to achieve the six per cent reductions targets below 1990 levels of emissions by 2010, and estimates of the costs involved. These discussions of proposed actions are balanced by a display of examples of the the growing volume of arguments advanced by opponents who not only disagree about what can be done to reduce emissions, but that there is anything that needs to be done at all. Central to their arguments is the denial that human activities are responsible for global warming, disregarding the overwhelming evidence by 3000+ leading scientists of the Intergovernmental Panel on Climate Change that most of the global warming over the last 50 years is attributable to human activities. The rest of the article details what can and needs to be done to reverse the cumulative impact of greenhouse gas emissions, how we can produce the energy we need at the lowest environmental cost, and the types of energy (solar, wind, biomass, natural gas) that result in the smallest GHG emissions. Familiar arguments are recited to

  3. Competition between core and periphery-based processes in warm convective clouds – from invigoration to suppression

    OpenAIRE

    G. Dagan; I. Koren; O. Altaratz

    2015-01-01

    How do changes in the amount and properties of aerosol affect warm clouds? Recent studies suggest that they have opposing effects. Some suggest that an increase in aerosol loading leads to enhanced evaporation and therefore smaller clouds, whereas other studies suggest clouds' invigoration. In this study, using an axisymmetric bin-microphysics cloud model, we propose a theoretical scheme that analyzes the evolution of key processes in warm clouds, under different aerosol loa...

  4. The basics of cloud computing understanding the fundamentals of cloud computing in theory and practice

    CERN Document Server

    Rountree, Derrick

    2013-01-01

    As part of the Syngress Basics series, The Basics of Cloud Computing provides readers with an overview of the cloud and how to implement cloud computing in their organizations. Cloud computing continues to grow in popularity, and while many people hear the term and use it in conversation, many are confused by it or unaware of what it really means. This book helps readers understand what the cloud is and how to work with it, even if it isn't a part of their day-to-day responsibility. Authors Derrick Rountree and Ileana Castrillo explains the concepts of cloud computing in prac

  5. Inside Dropbox: Understanding Personal Cloud Storage Services

    NARCIS (Netherlands)

    Drago, Idilio; Mellia, Marco; Munafò, Maurizio M.; Sperotto, Anna; Sadre, R.; Pras, Aiko

    2012-01-01

    Personal cloud storage services are gaining popularity. With a rush of providers to enter the market and an increasing offer of cheap storage space, it is to be expected that cloud storage will soon generate a high amount of Internet traffic. Very little is known about the architecture and the

  6. Aerosol Indirect Effect on Warm Clouds over Eastern China Using Combined CALIOP and MODIS Observations

    Science.gov (United States)

    Guo, Jianping; Wang, Fu; Huang, Jingfeng; Li, Xiaowen

    2015-04-01

    Aerosol, one of key components of the climate system, is highly variable, both temporally and spatially. It often exerts great influences on the cloud-precipitation chain processes by serving as CCN/IN, altering cloud microphysics and its life cycle. Yet, the aerosol indirect effect on clouds remains largely unknown, because the initial changes in clouds due to aerosols may be enhanced or dampened by such feedback processes as modified cloud dynamics, or evaporation of the smaller droplets due to the competition for water vapor. In this study, we attempted to quantify the aerosol effects on warm cloud over eastern China, based on near-simultaneous retrievals from MODIS/AQUA, CALIOP/CALIPSO and CPR/CLOUDSAT during the period 2006 to 2010. The seasonality of aerosol from ground-based PM10 is quite different from that estimated from MODIS AOD. This result is corroborated by lower level profile of aerosol occurrence frequency from CALIOP, indicating the significant role CALIOP could play in aerosol-cloud interaction. The combined use of CALIOP and CPR facilitate the process to exactly determine the (vertical) position of warm cloud relative to aerosol, out of six scenarios in terms of aerosol-cloud mixing status in terms of aerosol-cloud mixing status, which shows as follows: AO (Aerosol only), CO (Cloud only), SASC (Single aerosol-single cloud), SADC (single aerosol-double cloud), DASC (double aerosol-single cloud), and others. Results shows that about 54% of all the cases belong to mixed status, among all the collocated aerosol-cloud cases. Under mixed condition, a boomerang shape is observed, i.e., reduced cloud droplet radius (CDR) is associated with increasing aerosol at moderate aerosol pollution (AODthe boomerang shape varies with season. For moderate aerosol loading (AODthe effect on the droplet size for the "Mixed" cases is greater during cold season (denoted by a large slope), as compared with that during warm season. It is likely associated with an increase

  7. Development of a cloud microphysical model and parameterizations to describe the effect of CCN on warm cloud

    Directory of Open Access Journals (Sweden)

    N. Kuba

    2006-01-01

    Full Text Available First, a hybrid cloud microphysical model was developed that incorporates both Lagrangian and Eulerian frameworks to study quantitatively the effect of cloud condensation nuclei (CCN on the precipitation of warm clouds. A parcel model and a grid model comprise the cloud model. The condensation growth of CCN in each parcel is estimated in a Lagrangian framework. Changes in cloud droplet size distribution arising from condensation and coalescence are calculated on grid points using a two-moment bin method in a semi-Lagrangian framework. Sedimentation and advection are estimated in the Eulerian framework between grid points. Results from the cloud model show that an increase in the number of CCN affects both the amount and the area of precipitation. Additionally, results from the hybrid microphysical model and Kessler's parameterization were compared. Second, new parameterizations were developed that estimate the number and size distribution of cloud droplets given the updraft velocity and the number of CCN. The parameterizations were derived from the results of numerous numerical experiments that used the cloud microphysical parcel model. The input information of CCN for these parameterizations is only several values of CCN spectrum (they are given by CCN counter for example. It is more convenient than conventional parameterizations those need values concerned with CCN spectrum, C and k in the equation of N=CSk, or, breadth, total number and median radius, for example. The new parameterizations' predictions of initial cloud droplet size distribution for the bin method were verified by using the aforesaid hybrid microphysical model. The newly developed parameterizations will save computing time, and can effectively approximate components of cloud microphysics in a non-hydrostatic cloud model. The parameterizations are useful not only in the bin method in the regional cloud-resolving model but also both for a two-moment bulk microphysical model and

  8. Clouds and the extratropical circulation response to global warming in a hierarchy of global atmosphere models

    Science.gov (United States)

    Voigt, A.

    2017-12-01

    Climate models project that global warming will lead to substantial changes in extratropical jet streams. Yet, many quantitative aspects of warming-induced jet stream changes remain uncertain, and recent work has indicated an important role of clouds and their radiative interactions. Here, I will investigate how cloud-radiative changes impact the zonal-mean extratropical circulation response under global warming using a hierarchy of global atmosphere models. I will first focus on aquaplanet setups with prescribed sea-surface temperatures (SSTs), which reproduce the model spread found in realistic simulations with interactive SSTs. Simulations with two CMIP5 models MPI-ESM and IPSL-CM5A and prescribed clouds show that half of the circulation response can be attributed to cloud changes. The rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry Held-Suarez model, although the latter is too sensitive because of its simplified treatment of diabatic processes. I will then show that the aquaplanet results also hold when the models are used in a realistic setup that includes continents and seasonality. I will further juxtapose these prescribed-SST simulations with interactive-SST simulations and show that atmospheric and surface cloud-radiative interactions impact the jet poleward jet shifts in about equal measure. Finally, I will discuss the cloud impact on regional and seasonal circulation changes.

  9. Tropical Warm Pool International Cloud Experiment TWP-ICE Cloud and rain characteristics in the Australian Monsoon

    Energy Technology Data Exchange (ETDEWEB)

    May, P.T., Jakob, C., and Mather, J.H.

    2004-05-31

    The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them.

  10. Retrieving latent heating vertical structure from cloud and precipitation Profiles—Part I: Warm rain processes

    International Nuclear Information System (INIS)

    Min, Qilong; Li, Rui; Wu, Xiaoqing; Fu, Yunfei

    2013-01-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages of hydrometeor profiles of cloud and precipitation to the major processes related to the phase change of atmospheric water. Specifically, rain events are segregated into three rain types: warm, convective, and stratiform, based on their dynamical and thermodynamical characteristics. As the first of the series, only the warm rain LH algorithm is presented and evaluated here. The major microphysical processes of condensation and evaporation for warm rain are parameterized through traditional rain growth theory, with the aid of Cloud Resolving Model (CRM) simulations. The evaluation or the self-consistency tests indicate that the physical based retrievals capture the fundamental LH processes associated with the warm rain life cycle. There is no significant systematic bias in terms of convection strength, illustrated by the month-long CRM simulation as the mesoscale convective systems (MCSs) experience from initial, mature, to decay stages. The overall monthly-mean LH comparison showed that the total LH, as well as condensation heating and evaporation cooling components, agree with the CRM simulation. -- Highlights: ► An exploratory study on physics-based warm rain latent heat retrieval algorithm. ► Utilize the full information of the vertical structures of cloud and rainfall. ► Directly link water mass measurements to latent heat at instantaneous pixel level. ► Applicable at various stages of cloud system life cycle

  11. Ocean Heat Uptake Slows 21st Century Surface Warming Driven by Extratropical Cloud Feedbacks

    Science.gov (United States)

    Frey, W.; Maroon, E.; Pendergrass, A. G.; Kay, J. E.

    2017-12-01

    Equilibrium climate sensitivity (ECS), the warming in response to instantaneously doubled CO2, has long been used to compare climate models. In many models, ECS is well correlated with warming produced by transient forcing experiments. Modifications to cloud phase at high latitudes in a state-of-the-art climate model, the Community Earth System Model (CESM), produce a large increase in ECS (1.5 K) via extratropical cloud feedbacks. However, only a small surface warming increase occurs in a realistic 21st century simulation including a full-depth dynamic ocean and the "business as usual" RCP8.5 emissions scenario. In fact, the increase in surface warming is only barely above the internal variability-generated range in the CESM Large Ensemble. The small change in 21st century warming is attributed to subpolar ocean heat uptake in both hemispheres. In the Southern Ocean, the mean-state circulation takes up heat while in the North Atlantic a slowdown in circulation acts as a feedback to slow surface warming. These results show the importance of subpolar ocean heat uptake in controlling the pace of warming and demonstrate that ECS cannot be used to reliably infer transient warming when it is driven by extratropical feedbacks.

  12. Understanding Cloud Requirements - A Supply Chain Lifecycle Approach

    OpenAIRE

    Lindner, Mark; McDonald, Fiona; Conway, Gerry; Curry, Edward

    2011-01-01

    Cloud Computing is offering competitive advantages to companies through flexible and, scalable access to computing resources. More and more companies are moving to cloud environments; therefore understanding the requirements for this process is both important and beneficial. The requirements for migrating from a traditional computing environment to a cloud hosting environment are discussed in this paper, considering this migration from a supply chain lifecycle perspective...

  13. Aerosol effect on the evolution of the thermodynamic properties of warm convective cloud fields

    Science.gov (United States)

    Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.

    2016-12-01

    Convective cloud formation and evolution strongly depend on environmental temperature and humidity profiles. The forming clouds change the profiles that created them by redistributing heat and moisture. Here we show that the evolution of the field’s thermodynamic properties depends heavily on the concentration of aerosol, liquid or solid particles suspended in the atmosphere. Under polluted conditions, rain formation is suppressed and the non-precipitating clouds act to warm the lower part of the cloudy layer (where there is net condensation) and cool and moisten the upper part of the cloudy layer (where there is net evaporation), thereby destabilizing the layer. Under clean conditions, precipitation causes net warming of the cloudy layer and net cooling of the sub-cloud layer (driven by rain evaporation), which together act to stabilize the atmosphere with time. Previous studies have examined different aspects of the effects of clouds on their environment. Here, we offer a complete analysis of the cloudy atmosphere, spanning the aerosol effect from instability-consumption to enhancement, below, inside and above warm clouds, showing the temporal evolution of the effects. We propose a direct measure for the magnitude and sign of the aerosol effect on thermodynamic instability.

  14. Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming

    Science.gov (United States)

    Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

    2010-01-01

    The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

  15. Aerosol-induced changes of convective cloud anvils produce strong climate warming

    Directory of Open Access Journals (Sweden)

    I. Koren

    2010-05-01

    Full Text Available The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm−2. Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing.

    We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvil clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming at top-of-atmosphere.

    Furthermore we introduce the cloud optical depth (τ, cloud height (Z forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene.

    Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds, increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

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

    Directory of Open Access Journals (Sweden)

    M. Abe

    2016-11-01

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

  17. Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming.

    Science.gov (United States)

    Cronin, Timothy W; Tziperman, Eli

    2015-09-15

    High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback--consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state--slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼ 10 d for initial maritime surface air temperatures of 20 °C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the "lapse rate feedback" in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates.

  18. Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

    NARCIS (Netherlands)

    Nuijens, Louise; Emanuel, Kerry; Masunaga, Hirohiko; L’Ecuyer, Tristan

    2017-01-01

    Space-borne observations reveal that 20–40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column

  19. Simulation of idealized warm fronts and life cycles of cirrus clouds

    Science.gov (United States)

    Bense, Vera; Spichtinger, Peter

    2013-04-01

    One of the generally accepted formation mechanisms of cirrus clouds is connected to warm fronts. As the warm air glides over the cold air mass, it cools through adiabatic expansion and reaches ice supersaturation that eventually leads to the formation of ice clouds. Within this work, the EULAG model (see e.g. Prusa et al., 2008) was used to study the formation and life cycles of cirrus clouds in idealized 2-dimensional simulations. The microphysical processes were modelled with the double-moment bulk scheme of Spichtinger and Gierens (2009), which describes homogeneous and heterogeneous nucleation. In order to represent the gradual gliding of the air along the front, a ramp was chosen as topography. The sensibility of cloud formation to different environmental conditions such as wind shear, aerosol distribution and slope of the front was analyzed. In case of cirrus cloud formation its persistence after the front was studied as well as the change in microphysical properties such as ice crystal number concentrations. References: Prusa, J.M., P.K. Smolarkiewicz, A.A. Wyszogrodzki, 2008: EULAG, a computational model for multiscale flows. Computers and Fluids, doi:10.1016/j.compfluid.2007.12.001. Spichtinger, P., K. M. Gierens, 2009: Modelling of cirrus clouds - Part 1a: Model description and validation, Atmos. Chem. Phys., 9, 685-706.

  20. Clearing clouds of uncertainty

    Science.gov (United States)

    Zelinka, Mark D.; Randall, David A.; Webb, Mark J.; Klein, Stephen A.

    2017-10-01

    Since 1990, the wide range in model-based estimates of equilibrium climate warming has been attributed to disparate cloud responses to warming. However, major progress in our ability to understand, observe, and simulate clouds has led to the conclusion that global cloud feedback is likely positive.

  1. Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bala, G. [Indian Institute of Science, Divecha Center for Climate Change, Bangalore (India); Indian Institute of Science, Center for Atmospheric and Oceanic Sciences, Bangalore (India); Caldeira, Ken; Cao, Long; Ban-Weiss, George; Shin, Ho-Jeong [Carnegie Institution, Department of Global Ecology, Stanford, CA (United States); Nemani, Rama [NASA Ames Research Center, Moffett Field, CA (United States)

    2011-09-15

    Recent studies have shown that changes in solar radiation affect the hydrological cycle more strongly than equivalent CO{sub 2} changes for the same change in global mean surface temperature. Thus, solar radiation management ''geoengineering'' proposals to completely offset global mean temperature increases by reducing the amount of absorbed sunlight might be expected to slow the global water cycle and reduce runoff over land. However, proposed countering of global warming by increasing the albedo of marine clouds would reduce surface solar radiation only over the oceans. Here, for an idealized scenario, we analyze the response of temperature and the hydrological cycle to increased reflection by clouds over the ocean using an atmospheric general circulation model coupled to a mixed layer ocean model. When cloud droplets are reduced in size over all oceans uniformly to offset the temperature increase from a doubling of atmospheric CO{sub 2}, the global-mean precipitation and evaporation decreases by about 1.3% but runoff over land increases by 7.5% primarily due to increases over tropical land. In the model, more reflective marine clouds cool the atmospheric column over ocean. The result is a sinking motion over oceans and upward motion over land. We attribute the increased runoff over land to this increased upward motion over land when marine clouds are made more reflective. Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale. (orig.)

  2. Tropical Warm Pool International Cloud Experiment (TWP-ICE): Cloud and Rain Characteristics in the Australian Monsoon

    Energy Technology Data Exchange (ETDEWEB)

    PT May; C Jakob; JH Mather

    2004-05-30

    The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool – International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them. The experiment is a collaboration between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program, the Bureau of Meteorology (BoM), the National Aeronautics and Space Administration (NASA), the European Commission DG RTD-1.2, and several United States, Australian, Canadian, and European Universities. This experiment will be undertaken over a 4-week period in early 2006. January and February corresponds to the wet phase of the Australia monsoon. This season has been selected because, despite Darwin’s coastal location, the convection that occurs over and near Darwin at this time is largely of maritime origin with a large fetch over water

  3. Observational Insights into the Factors that Modulate Aerosol Impacts on Warm Clouds

    Science.gov (United States)

    L'Ecuyer, T. S.

    2016-12-01

    A large number of modern satellite datasets provide complementary evidence of aerosol influences on the microphysical, macrophysical, and radiative properties of warm clouds. This presentation will demonstrate that these observations are now sufficiently mature and abundant to qualitatively distinguish a wide range of independent, robust aerosol signatures from transient effects that may be artifacts of the methodology or datasets adopted. In some cases, modeled and observed aerosol influences on cloud properties diverge to such a degree that we can identify model biases with some confidence. More generally, however, quantitative relationships derived from satellite datasets are subject to numerous sources of uncertainty owing to inaccurate retrieval methodologies, a lack of knowledge of aerosol nucleation rate, and the strong covariation of cloud properties, aerosol abundance, and environmental conditions. To establish the significance of new observationally-derived estimates of aerosol effects we will examine their sensitivity to uncertainties in observed aerosol and cloud properties, the source of aerosol proxy adopted, local environmental conditions, and the relative vertical placement of cloud and aerosol layers. The analysis reveals that while some aerosol signatures are robust, others depend on the specific choice of datasets employed or fail to exceed realistic noise levels imposed by uncertainties in current satellite products. For example, many relationships that are robust in specific regions at certain times of year are not universal globally. Common to all observed relationships is the fact that aerosol signatures exhibit profound sensitivity to local meteorology and cloud morphology reinforcing the notion that aerosol-cloud interactions vary significantly between scenes, even over relatively large time and space domains. The results caution against the use of universal relationships to represent aerosol-cloud interactions globally but provide a

  4. The role of clouds and oceans in global greenhouse warming. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hoffert, M.I.

    1996-10-01

    This research focuses on assessing connections between anthropogenic greenhouse gas emissions and global climatic change. it has been supported since the early 1990s in part by the DOE ``Quantitative Links`` Program (QLP). A three-year effort was originally proposed to the QLP to investigate effects f global cloudiness on global climate and its implications for cloud feedback; and to continue the development and application of climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by clouds and oceans. It is well-known that cloud and ocean processes are major sources of uncertainty in the ability to predict climatic change from humankind`s greenhouse gas and aerosol emissions. And it has always been the objective to develop timely and useful analytical tools for addressing real world policy issues stemming from anthropogenic climate change.

  5. A set of experiments to understand global warming

    Science.gov (United States)

    Bouquelle, Veronique; Bauwens, Anne; De Bont, Adele; Kivits, Sandrine; Marbaix, Philippe

    2014-05-01

    We have developed a set of experiments addressed to pupils from the age of 14 to teach the basic causes and effects of global warming. Through ten experiments conducted in turns by the pupils themselves, they will understand the physics, biology and chemistry of the main issues linked to the increase in greenhouse gases in our atmosphere. More specifically, the hand-made, low-cost material, allow the students to discover and experiment the science of the greenhouse effect, sea level rise, ocean circulation, ocean acidification, species relocation and extinction, differential heating according to the albedo, carbon cycle, and photosynthesis. Technical notes give background theory input. All the experiments can easily be reproduced.

  6. Aerosol microphysical effects on warm cloud in Eastern China: impacts of meteorological conditions

    Science.gov (United States)

    Guo, J.; Wang, F.; Li, Z.

    2013-12-01

    Atmospheric aerosol particles can alter the droplet size and number concentration of clouds, thereby changing the Earth's climate system. The aerosol indirect effect has been proved climatically significant after decades of research, albeit uncertain. This is partially due to the frustrating difficulty in decoupling the aerosol effect from meteorology influences on cloud properties. This study attempts to probe into the aerosol indirect effect on the warm clouds of summertime the Yangtze River Delta (YRD) of eastern China and East China Sea (ECS), respectively. It is based on simultaneously observed aerosol and cloud properties from MODIS/Aqua Level 3 datasets, along with meteorological properties from NCEP Final Analyses Operational Global Analysis datasets. Statistic analysis is employed to analyze the aerosol cloud interaction, constrained by multiple meteorological conditions, such as cloud top pressure (CTP), relative humidity (RH), pressure vertical velocity (PVV) and lower tropospheric stability (LTS), expected to minimize meteorological impact. The reduction of cloud droplet radius (CDR) with increasing aerosol optical depth (AOD) is revealed over ECS. In contrast, anti-Twomey effect is detected over YRD. The aerosol effects on cloud fraction (CF) are further investigated, taking CTP and RH into account. CF is found to increase more sharply over YRD than over ECS in response to aerosol enhancement, regardless of RH conditions. In addition, the horizontal extension of cloud is prone to be driven by aerosol rather than RH in the summertime over YRD. Meanwhile, CTP effect on AOD-CF is eliminated, indicating CTP make little contribution to the observed AOD-CF relationship. Also, CDR variation in response to AOD, constrained by LTS and PVV (750hPa) is analyzed. In general, aerosol tends to observe the law of Twomey's effect except for the unstable condition over land. Regarding dynamic effect, the rising atmospheric environment is subject to larger CDR than the

  7. Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations

    Science.gov (United States)

    Nuijens, Louise; Emanuel, Kerry; Masunaga, Hirohiko; L'Ecuyer, Tristan

    2017-11-01

    Space-borne observations reveal that 20-40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative-convective model of hydrostatic, nonlinear flow on a non-rotating sphere, with parameterized convection and radiation, and review ongoing efforts in high-resolution modeling and observations of warm rain. The model experiments investigate the response of convection and circulation to sea surface temperature (SST) gradients between the columns and to changes in a parameter that controls the conversion of cloud condensate to rain. Convection over the cold ocean collapses to a shallow mode with tops near 850 hPa, but a congestus mode with tops near 600 hPa can develop at small SST differences when warm rain formation is more efficient. Here, interactive radiation and the response of the circulation are crucial: along with congestus a deeper moist layer develops, which leads to less low-level radiative cooling, a smaller buoyancy gradient between the columns, and therefore a weaker circulation and less subsidence over the cold ocean. The congestus mode is accompanied with more surface precipitation in the subsiding column and less surface precipitation in the deep convecting column. For the shallow mode over colder oceans, circulations also weaken with more efficient warm rain formation, but only marginally. Here, more warm rain reduces convective tops and the boundary layer depth—similar to Large-Eddy Simulation (LES) studies—which reduces the integrated buoyancy gradient. Elucidating the impact of warm rain can benefit from large-domain high-resolution simulations and observations. Parameterizations of warm rain may be constrained through collocated cloud and rain profiling from ground, and concurrent changes in convection and rain in subsiding and convecting branches of

  8. Humidity trends imply increased sensitivity to clouds in a warming Arctic.

    Science.gov (United States)

    Cox, Christopher J; Walden, Von P; Rowe, Penny M; Shupe, Matthew D

    2015-12-10

    Infrared radiative processes are implicated in Arctic warming and sea-ice decline. The infrared cloud radiative effect (CRE) at the surface is modulated by cloud properties; however, CRE also depends on humidity because clouds emit at wavelengths that are semi-transparent to greenhouse gases, most notably water vapour. Here we show how temperature and humidity control CRE through competing influences between the mid- and far-infrared. At constant relative humidity, CRE does not decrease with increasing temperature/absolute humidity as expected, but rather is found to be approximately constant for temperatures characteristic of the Arctic. This stability is disrupted if relative humidity varies. Our findings explain observed seasonal and regional variability in Arctic CRE of order 10 W m(-2). With the physical properties of Arctic clouds held constant, we calculate recent increases in CRE of 1-5 W m(-2) in autumn and winter, which are projected to reach 5-15 W m(-2) by 2050, implying increased sensitivity of the surface to clouds.

  9. Low Cloud Feedback to Surface Warming in the World's First Global Climate Model with Explicit Embedded Boundary Layer Turbulence

    Science.gov (United States)

    Parishani, H.; Pritchard, M. S.; Bretherton, C. S.; Wyant, M. C.; Khairoutdinov, M.; Singh, B.

    2017-12-01

    Biases and parameterization formulation uncertainties in the representation of boundary layer clouds remain a leading source of possible systematic error in climate projections. Here we show the first results of cloud feedback to +4K SST warming in a new experimental climate model, the ``Ultra-Parameterized (UP)'' Community Atmosphere Model, UPCAM. We have developed UPCAM as an unusually high-resolution implementation of cloud superparameterization (SP) in which a global set of cloud resolving arrays is embedded in a host global climate model. In UP, the cloud-resolving scale includes sufficient internal resolution to explicitly generate the turbulent eddies that form marine stratocumulus and trade cumulus clouds. This is computationally costly but complements other available approaches for studying low clouds and their climate interaction, by avoiding parameterization of the relevant scales. In a recent publication we have shown that UP, while not without its own complexity trade-offs, can produce encouraging improvements in low cloud climatology in multi-month simulations of the present climate and is a promising target for exascale computing (Parishani et al. 2017). Here we show results of its low cloud feedback to warming in multi-year simulations for the first time. References: Parishani, H., M. S. Pritchard, C. S. Bretherton, M. C. Wyant, and M. Khairoutdinov (2017), Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence, J. Adv. Model. Earth Syst., 9, doi:10.1002/2017MS000968.

  10. Cloudy Skies: Assessing Public Understanding of Global Warming

    OpenAIRE

    Sterman, John; Booth Sweeney, Linda

    2003-01-01

    Surveys show most Americans believe global warming is real. But many advocate delaying action until there is more evidence that warming is harmful. The stock and flow structure of the climate, however, means "wait and see" policies guarantee further warming. Atmospheric CO 2 concentration is now higher than any time in the last 420,000 years, and growing faster than any time in the past 20,000 years. The high concentration of CO 2 and other greenhouse gases (GHGs) generates significant radiat...

  11. Time-dependent, non-monotonic response of warm convective cloud fields to changes in aerosol loading

    Science.gov (United States)

    Dagan, Guy; Koren, Ilan; Altaratz, Orit; Heiblum, Reuven H.

    2017-06-01

    Large eddy simulations (LESs) with bin microphysics are used here to study cloud fields' sensitivity to changes in aerosol loading and the time evolution of this response. Similarly to the known response of a single cloud, we show that the mean field properties change in a non-monotonic trend, with an optimum aerosol concentration for which the field reaches its maximal water mass or rain yield. This trend is a result of competition between processes that encourage cloud development versus those that suppress it. However, another layer of complexity is added when considering clouds' impact on the field's thermodynamic properties and how this is dependent on aerosol loading. Under polluted conditions, rain is suppressed and the non-precipitating clouds act to increase atmospheric instability. This results in warming of the lower part of the cloudy layer (in which there is net condensation) and cooling of the upper part (net evaporation). Evaporation at the upper part of the cloudy layer in the polluted simulations raises humidity at these levels and thus amplifies the development of the next generation of clouds (preconditioning effect). On the other hand, under clean conditions, the precipitating clouds drive net warming of the cloudy layer and net cooling of the sub-cloud layer due to rain evaporation. These two effects act to stabilize the atmospheric boundary layer with time (consumption of the instability). The evolution of the field's thermodynamic properties affects the cloud properties in return, as shown by the migration of the optimal aerosol concentration toward higher values.

  12. Tropical cyclogenesis in warm climates simulated by a cloud-system resolving model

    Science.gov (United States)

    Fedorov, Alexey V.; Muir, Les; Boos, William R.; Studholme, Joshua

    2018-03-01

    Here we investigate tropical cyclogenesis in warm climates, focusing on the effect of reduced equator-to-pole temperature gradient relevant to past equable climates and, potentially, to future climate change. Using a cloud-system resolving model that explicitly represents moist convection, we conduct idealized experiments on a zonally periodic equatorial β-plane stretching from nearly pole-to-pole and covering roughly one-fifth of Earth's circumference. To improve the representation of tropical cyclogenesis and mean climate at a horizontal resolution that would otherwise be too coarse for a cloud-system resolving model (15 km), we use the hypohydrostatic rescaling of the equations of motion, also called reduced acceleration in the vertical. The simulations simultaneously represent the Hadley circulation and the intertropical convergence zone, baroclinic waves in mid-latitudes, and a realistic distribution of tropical cyclones (TCs), all without use of a convective parameterization. Using this model, we study the dependence of TCs on the meridional sea surface temperature gradient. When this gradient is significantly reduced, we find a substantial increase in the number of TCs, including a several-fold increase in the strongest storms of Saffir-Simpson categories 4 and 5. This increase occurs as the mid-latitudes become a new active region of TC formation and growth. When the climate warms we also see convergence between the physical properties and genesis locations of tropical and warm-core extra-tropical cyclones. While end-members of these types of storms remain very distinct, a large distribution of cyclones forming in the subtropics and mid-latitudes share properties of the two.

  13. Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

    Directory of Open Access Journals (Sweden)

    A. E. Van Beusekom

    2017-06-01

    Full Text Available The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ∼ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI, and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ∼ 200–600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic

  14. Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

    Science.gov (United States)

    Van Beusekom, Ashley E.; González, Grizelle; Scholl, Martha A.

    2017-01-01

    The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ∼ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ∼ 200–600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns

  15. Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change

    Science.gov (United States)

    Van Beusekom, Ashley E.; González, Grizelle; Scholl, Martha A.

    2017-06-01

    The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100 m altitude in the forest upwind of the TMCF that occupies an altitude range from ˜ 600 m to the peaks at 1100 m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600 m, from 740 to 964 m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ˜ 200-600 m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns that increase frequency

  16. Turkish Prospective Teachers' Understanding and Misunderstanding on Global Warming

    Science.gov (United States)

    Ocal, A.; Kisoglu, M.; Alas, A.; Gurbuz, H.

    2011-01-01

    The key objective of this study is to determine the Turkish elementary prospective teachers' opinions on global warming. It is also aimed to establish prospective teachers' views about the environmental education in Turkish universities. A true-false type scale was administered to 564 prospective teachers from science education, social studies…

  17. First experimental evidence for carbon starvation at warm temperatures in epiphytic orchids of tropical cloud forests

    Science.gov (United States)

    Hoch, Guenter; Roemer, Helena; Fioroni, Tiffany; Olmedo, Inayat; Kahmen, Ansgar

    2017-04-01

    Tropical cloud forests are among the most climate sensitive ecosystems world-wide. The lack of a strong seasonality and the additional dampening of temperature fluctuations by the omnipresence of clouds and fog produce year-round constant climatic conditions. With climate change the presence of clouds and fog is, however, predicted to be reduced. The disappearance of the cooling fog cover will have dramatic consequences for air temperatures, that are predicted to increase locally well over 5 °C by the end of the 21st century. Especially the large number of endemic epiphytic orchids in tropical cloud forests that contribute substantially to the biological diversity of these ecosystems, but are typically adapted to a very narrow climate envelope, are speculated to be very sensitive to the anticipated rise in temperature. In a phytotron experiment we investigated the effect of increasing temperatures on the carbon balance (gas-exchange and the carbon reserve household) of 10 epiphytic orchid species from the genera Dracula, native to tropical, South-American cloud forests. The orchids were exposed to three temperature treatments: i) a constant temperature treatment (23°C/13°C, day/night) simulating natural conditions, ii) a slow temperature ramp of +0.75 K every 10 days, and iii) a fast temperature ramp of +1.5 K every 10 days. CO2 leaf gas-exchanges was determined every 10 days, and concentrations of low molecular weight sugars and starch were analyses from leaf samples throughout the experiment. We found that increasing temperatures had only minor effects on day-time leaf respiration, but led to a moderate increase of respiration during night-time. In contrast to the rather minor effects of higher temperatures on respiration, there was a dramatic decline of net-photosynthesis above day-time temperatures of 29°C, and a complete stop of net-carbon uptake at 33°C in all investigated species. This high sensitivity of photosynthesis to warming was independent of the

  18. The Effect of Aerosol-Cloud-Vegetation Interactions and Intraseasonal Meteorological Variability on Warm Cloud Development during the Amazonian Biomass Burning Season

    Science.gov (United States)

    Ten Hoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

    2009-12-01

    The effect of aerosols on the hydrological cycle remains one of the largest uncertainties in our climate system. Biomass burning, from both deforestation and annual agricultural burning, is the largest anthropogenic source of these aerosols in the Southern Hemisphere. Biomass burning aerosols have competing effects on clouds: Depending on the level of aerosol loading and the background cloud characteristics, biomass burning aerosols have been shown in observational studies to invigorate or inhibit cloud formation and/or growth through microphysical and absorptive pathways, respectively. Many of these previous studies have employed all days during the Amazonian burning season months of August through October to formulate aerosol-cloud correlations, assuming relatively constant meteorological conditions exist throughout these months. This study investigates how intraseasonal trends of precipitable water vapor and aerosol loading between August and October impact these aerosol-cloud correlations. Other factors affecting aerosol-cloud relationships, such as atmospheric stability, are also investigated. This study is focused on a small 3 degree NE x 4 degree WE region in Rondonia, Brazil that encompasses extensive, contiguous areas of both forested and deforested land. High resolution aerosol, cloud, water vapor, and atmospheric profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites, as well as aerosol and water vapor data from the Aerosol Robotic Network (AERONET), are used collectively to explore the effect of aerosols on water vapor loading and warm cloud development over the Amazon. The difference in aerosol effects on the local hydrological cycle over forested and deforested areas is also examined. This final exercise provides insight into the relationship between aerosols, land-atmosphere processes, and warm clouds.

  19. Using Interactive Technology to Support Students' Understanding of the Greenhouse Effect and Global Warming

    Science.gov (United States)

    Varma, Keisha; Linn, Marcia C.

    2012-01-01

    In this work, we examine middle school students' understanding of the greenhouse effect and global warming. We designed and refined a technology-enhanced curriculum module called "Global Warming: Virtual Earth". In the module activities, students conduct virtual experiments with a visualization of the greenhouse effect. They analyze data and draw…

  20. Origin of CH+ in diffuse molecular clouds. Warm H2 and ion-neutral drift

    Science.gov (United States)

    Valdivia, Valeska; Godard, Benjamin; Hennebelle, Patrick; Gerin, Maryvonne; Lesaffre, Pierre; Le Bourlot, Jacques

    2017-04-01

    Context. Molecular clouds are known to be magnetised and to display a turbulent and complex structure where warm and cold phases are interwoven. The turbulent motions within molecular clouds transport molecules, and the presence of magnetic fields induces a relative velocity between neutrals and ions known as the ion-neutral drift (vd). These effects all together can influence the chemical evolution of the clouds. Aims: This paper assesses the roles of two physical phenomena which have previously been invoked to boost the production of CH+ under realistic physical conditions: the presence of warm H2 and the increased formation rate due to the ion-neutral drift. Methods: We performed ideal magnetohydrodynamical (MHD) simulations that include the heating and cooling of the multiphase interstellar medium (ISM), and where we treat dynamically the formation of the H2 molecule. In a post-processing step we compute the abundances of species at chemical equilibrium using a solver that we developed. The solver uses the physical conditions of the gas as input parameters, and can also prescribe the H2 fraction if needed. We validate our approach by showing that the H2 molecule generally has a much longer chemical evolution timescale compared to the other species. Results: We show that CH+ is efficiently formed at the edge of clumps, in regions where the H2 fraction is low (0.3-30%) but nevertheless higher than its equilibrium value, and where the gas temperature is high (≳ 300 K). We show that warm and out of equilibrium H2 increases the integrated column densities of CH+ by one order of magnitude up to values still 3-10 times lower than those observed in the diffuse ISM. We balance the Lorentz force with the ion-neutral drag to estimate the ion-drift velocities from our ideal MHD simulations. We find that the ion-neutral drift velocity distribution peaks around 0.04 km s-1, and that high drift velocities are too rare to have a significant statistical impact on the

  1. Evaluating regional cloud-permitting simulations of the WRF model for the Tropical Warm Pool International Cloud Experiment (TWP-ICE, Darwin 2006)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi; Long, Charles N.; Leung, Lai-Yung R.; Dudhia, Jimy; McFarlane, Sally A.; Mather, James H.; Ghan, Steven J.; Liu, Xiaodong

    2009-11-05

    Data from the Tropical Warm Pool I5 nternational Cloud Experiment (TWPICE) were used to evaluate two suites of high-resolution (4-7 km, convection-resolving) simulations of the Advanced Research Weather Research and Forecasting (WRF) model with a focus on the performance of different cloud microphysics (MP) schemes. The major difference between these two suites of simulations is with and without the reinitializing process. Whenreinitialized every three days, the four cloud MP schemes evaluated can capture the general profiles of cloud fraction, temperature, water vapor, winds, and cloud liquid and ice water content (LWC and IWC, respectively). However, compared with surface measurements of radiative and moisture fluxes and satellite retrieval of top-of-the-atmosphere (TOA) fluxes, disagreements do exist. Large discrepancies with observed LWC and IWC and derived radiative heating profiles can be attributed to both the limitations of the cloud property retrievals and model performance. The simulated precipitation also shows a wide range of uncertainty as compared with observations, which could be caused by the cloud MP schemes, complexity of land-sea configuration, and the high temporal and spatial variability. In general, our result indicates the importance of large-scale initial and lateral boundary conditions in re-producing basic features of cloudiness and its vertical structures. Based on our case study, we find overall the six-hydrometer single-moment MP scheme(WSM6) [Hong and Lim, 2006] in the WRF model si25 mulates the best agree- ment with the TWPICE observational analysis.

  2. Time-dependent, non-monotonic response of warm convective cloud fields to changes in aerosol loading

    Directory of Open Access Journals (Sweden)

    G. Dagan

    2017-06-01

    Full Text Available Large eddy simulations (LESs with bin microphysics are used here to study cloud fields' sensitivity to changes in aerosol loading and the time evolution of this response. Similarly to the known response of a single cloud, we show that the mean field properties change in a non-monotonic trend, with an optimum aerosol concentration for which the field reaches its maximal water mass or rain yield. This trend is a result of competition between processes that encourage cloud development versus those that suppress it. However, another layer of complexity is added when considering clouds' impact on the field's thermodynamic properties and how this is dependent on aerosol loading. Under polluted conditions, rain is suppressed and the non-precipitating clouds act to increase atmospheric instability. This results in warming of the lower part of the cloudy layer (in which there is net condensation and cooling of the upper part (net evaporation. Evaporation at the upper part of the cloudy layer in the polluted simulations raises humidity at these levels and thus amplifies the development of the next generation of clouds (preconditioning effect. On the other hand, under clean conditions, the precipitating clouds drive net warming of the cloudy layer and net cooling of the sub-cloud layer due to rain evaporation. These two effects act to stabilize the atmospheric boundary layer with time (consumption of the instability. The evolution of the field's thermodynamic properties affects the cloud properties in return, as shown by the migration of the optimal aerosol concentration toward higher values.

  3. Improving Climate Projections by Understanding How Cloud Phase affects Radiation

    Science.gov (United States)

    Cesana, Gregory; Storelvmo, Trude

    2017-01-01

    Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth's sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections.

  4. What's in a name? Commonalities and differences in public understanding of "climate change" and "global warming"

    OpenAIRE

    Whitmarsh, Lorraine E.

    2009-01-01

    This paper reports on findings from a survey of public understanding of climate change and global warming amongst residents in the south of England. Whereas much previous research has relied on survey checklists to measure public understanding of climate change, this study employed a more qualitative approach to reveal participants' unprompted conceptions of climate change and global warming. Overall, the findings show a tendency for the public to dissociate themselves from the causes, impact...

  5. Solar Radiation and Cloud Radiative Forcing in the Pacific Warm Pool Estimated Using TOGA COARE Measurements

    Science.gov (United States)

    Chou, Ming-Dah; Chou, Shu-Hsien; Zhao, Wenzhong

    1999-01-01

    The energy budget of the tropical western Pacific (TWP) is particularly important because this is one of the most energetic convection regions on the Earth. Nearly half of the solar radiation incident at the top of atmosphere is absorbed at the surface and only about 22% absorbed in the atmosphere. A large portion of the excess heat absorbed at the surface is transferred to the atmosphere through evaporation, which provides energy and water for convection and precipitation. The western equatorial Pacific is characterized by the highest sea surface temperature (SST) and heaviest rainfall in the world ocean. A small variation of SST associated with the eastward shift of the warm pool during El-Nino/Souther Oscillation changes the atmospheric circulation pattern and affects the global climate. In a study of the TWP surface heat and momentum fluxes during the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) Intensive observing period (IOP) from November 1992 to February have found that the solar radiation is the most important component of the surface energy budget, which undergoes significant temporal and spatial variation. The variations are influenced by the two 40-50 days Madden Julian Oscillations (MJOs) which propagated eastward from the Indian Ocean to the Central Pacific during the IOP. The TWP surface solar radiation during the COARE IOP was investigated by a number of studies. In addition, the effects of clouds on the solar heating of the atmosphere in the TWP was studied using energy budget analysis. In this study, we present some results of the TWP surface solar shortwave or SW radiation budget and the effect of clouds on the atmospheric solar heating using the surface radiation measurements and Japan's Geostationary Meteorological Satellite 4 radiance measurements during COARE IOP.

  6. Interactions between summer warm-air advection, melting sea ice and low clouds

    Science.gov (United States)

    Tjernstrom, M. K. H.; Achtert, P.; Shupe, M.; Prytherch, J.; Sedlar, J.; Brooks, B. J.; Brooks, I. M.; Persson, O. P. G.; Salisbury, D.; Sotiropoulou, G.

    2017-12-01

    Over the last decade or more, the influence of advection of heat and moisture into the Arctic from the south has been discussed. Very few studies were based on observations and the focus has mainly been on winter and spring conditions. In summer the situation is slightly different; the ice and any snow on top of it is melting, constraining the surface temperature to the melting point of fresh water. As warm and moist air is advected from south in over the ice, this leads to formation of very strong surface inversions with high relative humidity, often leading to fog formation. In a zone from the ice edge and downstream a competition between several factors becomes important: Radiative cooling at the fog top, potentially leading to turbulent overturning; Strong static stability leading to reduced turbulence; Increased wind shear promoting more shear-generated turbulence, and; Maintenance of the fog, by moisture advection, and the stability, by temperature advection. The vertical structure of the PBL and hence the forcing on the ice from turbulence and radiation is determined by the balance of these factors. We will present an analysis of these processes using observations from the Arctic Clouds in Summer Experiment (ACSE), conducted on board the Swedish icebreaker Oden in summer/autumn 2014, traversing across the Arctic from Tromsö, Norway, to Barrow, Alaska, and back. Using an extensive suite of in-situ and ship-borne remote sensing, we explore all the times that the Oden spent in the sea ice, and show how the different atmospheric parameters, and ultimately the surface energy budget, vary with the existence of a surface inversions and show that these almost exclusively occurred in cases with flow from the south and advection of warm and sometimes moist air onto the ice.

  7. Aerosols' influence on the interplay between condensation, evaporation and rain in warm cumulus cloud

    Directory of Open Access Journals (Sweden)

    O. Altaratz

    2008-01-01

    Full Text Available A numerical cloud model is used to study the influence of aerosol on the microphysics and dynamics of moderate-sized, coastal, convective clouds that develop under the same meteorological conditions. The results show that polluted convective clouds start their precipitation later and precipitate less than clean clouds but produce larger rain drops. The evaporation process is more significant at the margins of the polluted clouds (compared to the clean cloud due to a higher drop surface area to volume ratio and it is mostly from small drops. It was found that the formation of larger raindrops in the polluted cloud is due to a more efficient collection process.

  8. Understanding Seasonal Variability in thin Cirrus Clouds from Continuous MPLNET Observations at GSFC in 2012

    Directory of Open Access Journals (Sweden)

    Lolli Simone

    2016-01-01

    Full Text Available Optically thin cirrus cloud (optical depth < 0.3 net radiative forcing represents one of the primary uncertainties in climate feedback, as sub-visible clouds play a fundamental role in atmospheric radiation balance and climate change. A lidar is a very sensitive optical device to detect clouds with an optical depth as low as 10−4. In this paper we assess the daytime net radiative forcing of subvisible cirrus clouds detected at Goddard Space Flight Center, a permanent observational site of the NASA Micro Pulse Lidar Network in 2012. Depending on their height, season and hour of the day, the solar albedo effect can outweigh the infrared greenhouse effect, cooling the earthatmosphere system rather than warming it exclusively. As result, based on latitude, the net forcing of sub-visible cirrus clouds can be more accurately parameterized in climate models.

  9. The Dominant Snow-forming Process in Warm and Cold Mixed-phase Orographic Clouds: Effects of Cloud Condensation Nuclei and Ice Nuclei

    Science.gov (United States)

    Fan, J.; Rosenfeld, D.; Leung, L. R.; DeMott, P. J.

    2014-12-01

    Mineral dust aerosols often observed over California in winter and spring from long-range transport can be efficient ice nuclei (IN) and enhance snow precipitation in mixed-phase orographic clouds. On the other hand, local pollution particles can serve as good CCN and suppress warm rain, but their impacts on cold rain processes are uncertain. The main snow-forming mechanism in warm and cold mixed-phase orographic clouds (refer to as WMOC and CMOC, respectively) could be very different, leading to different precipitation response to CCN and IN. We have conducted 1-km resolution model simulations using the Weather Research and Forecasting (WRF) model coupled with a spectral-bin cloud microphysical model for WMOC and CMOC cases from CalWater2011. We investigated the response of cloud microphysical processes and precipitation to CCN and IN with extremely low to extremely high concentrations using ice nucleation parameterizations that connect with dust and implemented based on observational evidences. We find that riming is the dominant process for producing snow in WMOC while deposition plays a more important role than riming in CMOC. Increasing IN leads to much more snow precipitation mainly due to an increase of deposition in CMOC and increased rimming in WMOC. Increasing CCN decreases precipitation in WMOC by efficiently suppressing warm rain, although snow is increased. In CMOC where cold rain dominates, increasing CCN significantly increases snow, leading to a net increase in precipitation. The sensitivity of supercooled liquid to CCN and IN has also been analyzed. The mechanism for the increased snow by CCN and caveats due to uncertainties in ice nucleation parameterizations will be discussed.

  10. Chinese Grade Eight Students' Understanding about the Concept of Global Warming

    Science.gov (United States)

    Lin, Jing

    2017-01-01

    China is one of the world's biggest greenhouse gas emitters. Chinese students' awareness and understanding about global warming have a significant impact on the future of mankind. This study, as an initial research of this kind in Mainland China, uses clinical interviews to survey 37 grade eight students on their understanding about global…

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Accelerated Global Warming by Black Carbon due to its Burnoff of Clouds

    Science.gov (United States)

    Jacobson, M. Z.

    2012-12-01

    This study examines the impact of black carbon (BC) on global and Arctic climate primarily through its impacts on clouds. BC influences clouds in three major ways: (1) through cloud absorption effects (CAEs) I and II, which are the effects on cloud heating of absorbing inclusions in cloud particles and of absorbing aerosol particles interstitially between cloud particles at the cloud's actual relative humidity (RH), respectively; (2) through the semi-direct effect, which is the change in cloudiness due to the decrease in near-cloud RH and increase in atmospheric stability caused by absorbing aerosol particles below, within, or above a cloud; and (3) through indirect effects, which are the increase in cloud reflectivity (first indirect effect) and decrease in precipitation thus increase in cloud liquid water content and lifetime (second indirect effects) due to the addition of anthropogenic aerosol particles to an evolving cloud. Simulations with the 3-D model GATOR-GCMOM were first run to calculate the hydrometeor mass absorption coefficient (HMAC) due to BC inclusions within cloud particles. The globally-averaged HMAC was ~17.7 (10.6-19) m2/g, ~9.3% higher than the globally-averaged mass-absorption coefficient of aged, externally- plus internally-mixed aerosol BC, which itself was ~2.4 (2-2.9) times higher than that of externally-mixed BC. Aerosol absorption optical depths were compared globally with OMI and AERONET data. Further simulations were run that found that BC inclusions in cloud drops (CAE I) can triple a cloud's heating rate. Interstitial BC at the RH of the cloud (CAE II) can increase the heating rate by ~30% compared with aged BC in the clear sky. These results suggested a greater potential for BC inclusions to burn off clouds than previously recognized since previous global studies had not considered the absorption of BC interstitially between drops at the RH of the cloud or solved radiative transfer through a cloud while the cloud was shrinking

  13. Metagenomics-Enabled Understanding of Soil Microbial Feedbacks to Climate Warming

    Science.gov (United States)

    Zhou, J.; Wu, L.; Zhili, H.; Kostas, K.; Luo, Y.; Schuur, E. A. G.; Cole, J. R.; Tiedje, J. M.

    2014-12-01

    Understanding the response of biological communities to climate warming is a central issue in ecology and global change biology, but it is poorly understood microbial communities. To advance system-level predictive understanding of the feedbacks of belowground microbial communities to multiple climate change factors and their impacts on soil carbon (C) and nitrogen (N) cycling processes, we have used integrated metagenomic technologies (e.g., target gene and shotgun metagenome sequencing, GeoChip, and isotope) to analyze soil microbial communities from experimental warming sites in Alaska (AK) and Oklahoma (OK), and long-term laboratory incubation. Rapid feedbacks of microbial communities to warming were observed in the AK site. Consistent with the changes in soil temperature, moisture and ecosystem respiration, microbial functional community structure was shifted after only 1.5-year warming, indicating rapid responses and high sensitivity of this permafrost ecosystem to climate warming. Also, warming stimulated not only functional genes involved in aerobic respiration of both labile and recalcitrant C, contributing to an observed 24% increase in 2010 growing season and 56% increase of decomposition of a standard substrate, but also functional genes for anaerobic processes (e.g., denitrification, sulfate reduction, methanogenesis). Further comparisons by shotgun sequencing showed significant differences of microbial community structure between AK and OK sites. The OK site was enriched in genes annotated for cellulose degradation, CO2 production, denitrification, sporulation, heat shock response, and cellular surface structures (e.g., trans-membrane transporters for glucosides), while the AK warmed plots were enriched in metabolic pathways related to labile C decomposition. Together, our results demonstrate the vulnerability of permafrost ecosystem C to climate warming and the importance of microbial feedbacks in mediating such vulnerability.

  14. The cloud understanding the security, privacy and trust challenges

    CERN Document Server

    Robinson, Neil; Cave, Jonathan; Starkey, Tony; Graux, Hans

    2011-01-01

    This report discusses how policy-makers might address the challenges and risks in respect of the security, privacy and trust aspects of cloud computing that could undermine the attainment of broader economic and societal objectives across Europe.

  15. Cloud Computing Value Chains: Understanding Businesses and Value Creation in the Cloud

    Science.gov (United States)

    Mohammed, Ashraf Bany; Altmann, Jörn; Hwang, Junseok

    Based on the promising developments in Cloud Computing technologies in recent years, commercial computing resource services (e.g. Amazon EC2) or software-as-a-service offerings (e.g. Salesforce. com) came into existence. However, the relatively weak business exploitation, participation, and adoption of other Cloud Computing services remain the main challenges. The vague value structures seem to be hindering business adoption and the creation of sustainable business models around its technology. Using an extensive analyze of existing Cloud business models, Cloud services, stakeholder relations, market configurations and value structures, this Chapter develops a reference model for value chains in the Cloud. Although this model is theoretically based on porter's value chain theory, the proposed Cloud value chain model is upgraded to fit the diversity of business service scenarios in the Cloud computing markets. Using this model, different service scenarios are explained. Our findings suggest new services, business opportunities, and policy practices for realizing more adoption and value creation paths in the Cloud.

  16. Understanding the cloud : The social implications of cloud computing and the need for accountability

    NARCIS (Netherlands)

    Niezen, M.G.H.; Steijn, W.M.P.

    2015-01-01

    Five years ago, cloud computing was one of the top emerging new technologies, nowadays it is almost common place. This rapid introduction of cloud business models in our society coincides with critical questions on the cloud’s risks, such as security and privacy. Moreover, there seems to be an

  17. Understanding and Predicting Students' Intention to Pay for Private Cloud Storage Services

    OpenAIRE

    Meier, Philip

    2017-01-01

    Date: 05 June 2017 Level: Bachelor Thesis in Business Administration, 15 ECTS Institution: School of Business, Society and Engineering, Mälardalen University Authors: Meier, Philip Soltani, Nazila Khodabandeloo (88/03/11) (93/07/05) Title: Understanding and Predicting Students’ Intention to Pay for Private Cloud Storage Services Tutour: Konstantin Lampou Keywords: cloud storage service, iCloud, technology acceptance model, information systems, user acceptance, intention to pay Research Questi...

  18. Turkish Primary Science Teacher Candidates' Understandings of Global Warming and Ozone Layer Depletion

    Science.gov (United States)

    Yalcin, Fatma Aggul; Yalcin, Mehmet

    2017-01-01

    The purpose of the study was to explore Turkish primary science teacher candidates' understanding of global warming and ozone layer depletion. In the study, as the research approach the survey method was used. The sample consisted of one hundred eighty nine third grade science teacher candidates. Data was collected using the tool developed by the…

  19. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    Energy Technology Data Exchange (ETDEWEB)

    Cecchini, Micael A.; Machado, Luiz A. T.; Comstock, Jennifer M.; Mei, Fan; Wang, Jian; Fan, Jiwen; Tomlinson, Jason M.; Schmid, Beat; Albrecht, Rachel; Martin, Scot T.; Artaxo, Paulo

    2016-01-01

    The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analysing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analysed period corresponds to the wet season (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1) of GoAmazon2014/5). The droplet size distributions reported are in the range 1 µm ≤ D≤50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40% for the effective diameter and are as high as 1000% for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km₋1), as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (>20 µm) near the cloud base, which would contribute significantly to the growth rates through the collision

  20. Impacts of the Manaus pollution plume on the microphysical properties of Amazonian warm-phase clouds in the wet season

    Directory of Open Access Journals (Sweden)

    M. A. Cecchini

    2016-06-01

    Full Text Available The remote atmosphere over the Amazon can be similar to oceanic regions in terms of aerosol conditions and cloud type formations. This is especially true during the wet season. The main aerosol-related disturbances over the Amazon have both natural sources, such as dust transport from Africa, and anthropogenic sources, such as biomass burning or urban pollution. The present work considers the impacts of the latter on the microphysical properties of warm-phase clouds by analysing observations of the interactions between the Manaus pollution plume and its surroundings, as part of the GoAmazon2014/5 Experiment. The analysed period corresponds to the wet season (specifically from February to March 2014 and corresponding to the first Intensive Operating Period (IOP1 of GoAmazon2014/5. The droplet size distributions reported are in the range 1 µm ≤ D ≤ 50 µm in order to capture the processes leading up to the precipitation formation. The wet season largely presents a clean background atmosphere characterized by frequent rain showers. As such, the contrast between background clouds and those affected by the Manaus pollution can be observed and detailed. The focus is on the characteristics of the initial microphysical properties in cumulus clouds predominantly at their early stages. The pollution-affected clouds are found to have smaller effective diameters and higher droplet number concentrations. The differences range from 10 to 40 % for the effective diameter and are as high as 1000 % for droplet concentration for the same vertical levels. The growth rates of droplets with altitude are slower for pollution-affected clouds (2.90 compared to 5.59 µm km−1, as explained by the absence of bigger droplets at the onset of cloud development. Clouds under background conditions have higher concentrations of larger droplets (> 20 µm near the cloud base, which would contribute significantly to the growth rates through the

  1. Value Creation in the Cloud: Understanding Business Model Factors Affecting Value of Cloud Computing

    OpenAIRE

    Morgan, Lorraine; Conboy, Kieran

    2013-01-01

    peer-reviewed Despite the rapid emergence of cloud technology, its prevalence and accessibility to all types of organizations and its potential to predominantly shift competitive landscapes by providing a new platform for creating and delivering business value, empirical research on the business value of cloud computing, and in particular how service providers create value for their customers, is quite limited. Of what little research exists to date, most focuses on technical issu...

  2. The impact of horizontal heterogeneities, cloud fraction, and liquid water path on warm cloud effective radii from CERES-like Aqua MODIS retrievals

    Directory of Open Access Journals (Sweden)

    D. Painemal

    2013-10-01

    Full Text Available The impact of horizontal heterogeneities, liquid water path (LWP from AMSR-E, and cloud fraction (CF on MODIS cloud effective radius (re, retrieved from the 2.1 μm (re2.1 and 3.8 μm (re3.8 channels, is investigated for warm clouds over the southeast Pacific. Values of re retrieved using the CERES algorithms are averaged at the CERES footprint resolution (∼20 km, while heterogeneities (Hσ are calculated as the ratio between the standard deviation and mean 0.64 μm reflectance. The value of re2.1 strongly depends on CF, with magnitudes up to 5 μm larger than those for overcast scenes, whereas re3.8 remains insensitive to CF. For cloudy scenes, both re2.1 and re3.8 increase with Hσ for any given AMSR-E LWP, but re2.1 changes more than for re3.8. Additionally, re3.8–re2.1 differences are positive (Hσ 45 gm−2, and negative (up to −4 μm for larger Hσ. While re3.8–re2.1 differences in homogeneous scenes are qualitatively consistent with in situ microphysical observations over the region of study, negative differences – particularly evinced in mean regional maps – are more likely to reflect the dominant bias associated with cloud heterogeneities rather than information about the cloud vertical structure. The consequences for MODIS LWP are also discussed.

  3. UNDERSTANDING TRENDS ASSOCIATED WITH CLOUDS IN IRRADIATED EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Demory, Brice-Olivier, E-mail: kevin.heng@csh.unibe.ch, E-mail: demory@mit.edu [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2013-11-10

    Unlike previously explored relationships between the properties of hot Jovian atmospheres, the geometric albedo and the incident stellar flux do not exhibit a clear correlation, as revealed by our re-analysis of Q0-Q14 Kepler data. If the albedo is primarily associated with the presence of clouds in these irradiated atmospheres, a holistic modeling approach needs to relate the following properties: the strength of stellar irradiation (and hence the strength and depth of atmospheric circulation), the geometric albedo (which controls both the fraction of starlight absorbed and the pressure level at which it is predominantly absorbed), and the properties of the embedded cloud particles (which determine the albedo). The anticipated diversity in cloud properties renders any correlation between the geometric albedo and the stellar flux weak and characterized by considerable scatter. In the limit of vertically uniform populations of scatterers and absorbers, we use an analytical model and scaling relations to relate the temperature-pressure profile of an irradiated atmosphere and the photon deposition layer and to estimate whether a cloud particle will be lofted by atmospheric circulation. We derive an analytical formula for computing the albedo spectrum in terms of the cloud properties, which we compare to the measured albedo spectrum of HD 189733b by Evans et al. Furthermore, we show that whether an optical phase curve is flat or sinusoidal depends on whether the particles are small or large as defined by the Knudsen number. This may be an explanation for why Kepler-7b exhibits evidence for the longitudinal variation in abundance of condensates, while Kepler-12b shows no evidence for the presence of condensates despite the incident stellar flux being similar for both exoplanets. We include an 'observer's cookbook' for deciphering various scenarios associated with the optical phase curve, the peak offset of the infrared phase curve, and the geometric

  4. Understanding primary school science teachers' pedagogical content knowledge: The case of teaching global warming

    Science.gov (United States)

    Chordnork, Boonliang; Yuenyong, Chokchai

    2018-01-01

    This aim of this research was to investigate primary school science teachers understanding and teaching practice as well as the influence on teaching and learning a topic like global warming. The participants were four primary science teachers, who were not graduated in science education. Methodology was the case study method, which was under the qualitative research regarded from interpretive paradigm. Data were collected by openended questionnaire, semi-structure interview, and document colleting. The questionnaire examined teachers' background, teachers' understanding of problems and threats of science teaching, desiring of development their PCK, sharing the teaching approaches, and their ideas of strength and weakness. a semi-structured interview was conducted based on the approach for capturing PCK of Loughran [23] content representation (CoRe). And, the document was collected to clarify what evidence which was invented to effect on students' learning. These document included lesson plan, students' task, and painting about global warming, science projects, the picture of activities of science learning, the exercise and test. Data analysis employed multiple approach of evidence looking an issue from each primary science teachers and used triangulation method to analyze the data with aiming to make meaning of teachers' representation of teaching practice. These included descriptive statistics, CoRe interpretation, and document analysis. The results show that teachers had misunderstanding of science teaching practice and they has articulated the pedagogical content knowledge in terms of assessment, goal of teaching and linking to the context of socio cultural. In contrast, knowledge and belief of curriculum, students' understanding of content global warming, and strategies of teaching were articulated indistinct by non-graduate science teacher. Constructing opportunities for personal development, the curiosity of the student learning center, and linking context

  5. Determination of optical and microphysical properties of thin warm clouds using ground based hyper-spectral analysis

    Directory of Open Access Journals (Sweden)

    E. Hirsch

    2012-04-01

    Full Text Available Clouds play a critical role in the Earth's radiative budget as they modulate the atmosphere by reflecting shortwave solar radiation and absorbing long wave IR radiation emitted by the Earth's surface. Although extensively studied for decades, cloud modelling in global circulation models is far from adequate, mostly due to insufficient spatial resolution of the circulation models. In addition, measurements of cloud properties still need improvement, since the vast majority of remote sensing techniques are focused in relatively large, thick clouds. In this study, we utilize ground based hyperspectral measurements and analysis to explore very thin water clouds. These clouds are characterized by liquid water path (LWP that spans from as high as ~50g m−2 and down to 65 mg m−2 with a minimum of about 0.01 visible optical depth. The retrieval methodology relies on three elements: a detailed radiative transfer calculations in the longwave IR regime, signal enhancement by subtraction of a clear sky reference, and spectral matching method which exploits fine spectral differences between water droplets of different radii. A detailed description of the theoretical basis for the retrieval technique is provided along with a comprehensive discussion regarding its limitations. The proposed methodology was validated in a controlled experiment where artificial clouds were sprayed and their effective radii were both measured and retrieved simultaneously. This methodology can be used in several ways: (1 the frequency and optical properties of very thin water clouds can be studied more precisely in order to evaluate their total radiative forcing on the Earth's radiation budget. (2 The unique optical properties of the inter-region between clouds (clouds' "twilight zone" can be studied in order to more rigorously understanding of the governing physical processes which dominate this region. (3 Since the optical thickness of a developed cloud

  6. Understanding decreases in land relative humidity with global warming: conceptual model and GCM simulations

    OpenAIRE

    Byrne, Michael P.; O'Gorman, Paul A.

    2016-01-01

    Climate models simulate a strong land-ocean contrast in the response of near-surface relative humidity to global warming: relative humidity tends to increase slightly over oceans but decrease substantially over land. Surface energy balance arguments have been used to understand the response over ocean but are difficult to apply over more complex land surfaces. Here, a conceptual box model is introduced, involving moisture transport between the land and ocean boundary layers and evapotranspira...

  7. Global Warming: A Myth?

    Indian Academy of Sciences (India)

    On replacing rela-tive humidity cloud scheme with water clouds in the models, global annual average surface temperature comes down from 5.2 OK to 2.7 OK. If cloud radiative properties are allowed to depend on the cloud water content, warming is further reduced to 1.9 OK [7]. (iii) Cloud Radiative Forcing: Clouds reflect a ...

  8. Do Americans Understand That Global Warming Is Harmful to Human Health? Evidence From a National Survey.

    Science.gov (United States)

    Maibach, Edward W; Kreslake, Jennifer M; Roser-Renouf, Connie; Rosenthal, Seth; Feinberg, Geoff; Leiserowitz, Anthony A

    2015-01-01

    Organization, and their local public health department. Most Americans report a general sense that global warming can be harmful to health, but relatively few understand the types of harm it causes or who is most likely to be affected. Perhaps as a result, there is only moderate support for an expanded public health response. Primary care physicians and public health officials appear well positioned to educate the public about the health relevance of climate change. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  9. 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

  10. Interaction of clouds, radiation, and the tropical warm pool sea surface temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, N.; Zhang, G.J.; Barnett, T.P.; Ramanathan, V. [Scripps Institution of Oceanography, La Jolla, CA (United States)] [and others

    1996-04-01

    The primary focus of this study is the Tropical Western Pacific (TWP). In this study, we combine in-situ observations Tropical Ocean Global Atmosphere [TOGA]-Coupled Ocean Atmosphere Response Experiment [COARE] and Central Equatorial Pacific Experiment [CEPEX] with satellite cloud data.

  11. Understanding and Improving CRM and GCM Simulations of Cloud Systems with ARM Observations

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaoqing [Iowa State Univ., Ames, IA (United States). Dept. of Geological and Atmospheric Sciences

    2014-02-25

    The works supported by this ASR project lay the solid foundation for improving the parameterization of convection and clouds in the NCAR CCSM and the climate simulations. We have made a significant use of CRM simulations and ARM observations to produce thermodynamically and dynamically consistent multi-year cloud and radiative properties; improve the GCM simulations of convection, clouds and radiative heating rate and fluxes using the ARM observations and CRM simulations; and understand the seasonal and annual variation of cloud systems and their impacts on climate mean state and variability. We conducted multi-year simulations over the ARM SGP site using the CRM with multi-year ARM forcing data. The statistics of cloud and radiative properties from the long-term CRM simulations were compared and validated with the ARM measurements and value added products (VAP). We evaluated the multi-year climate simulations produced by the GCM with the modified convection scheme. We used multi-year ARM observations and CRM simulations to validate and further improve the trigger condition and revised closure assumption in NCAR GCM simulations that demonstrate the improvement of climate mean state and variability. We combined the improved convection scheme with the mosaic treatment of subgrid cloud distributions in the radiation scheme of the GCM. The mosaic treatment of cloud distributions has been implemented in the GCM with the original convection scheme and enables the use of more realistic cloud amounts as well as cloud water contents in producing net radiative fluxes closer to observations. A physics-based latent heat (LH) retrieval algorithm was developed by parameterizing the physical linkages of observed hydrometeor profiles of cloud and precipitation to the major processes related to the phase change of atmospheric water.

  12. Higher Education Cloud Computing in South Africa: Towards Understanding Trust and Adoption issues

    Directory of Open Access Journals (Sweden)

    Karl Van Der Schyff

    2014-12-01

    Full Text Available This paper sets out to study the views of key stakeholders on the issue of cloud information security within institutions of Higher Education. A specific focus is on understanding trust and the adoption of cloud computing in context of the unique operational requirements of South African universities. Contributions are made on both a methodological and theoretical level. Methodologically the study contributes by employing an Interpretivist approach and using Thematic Analysis in a topic area often studied quantitatively, thus affording researchers the opportunity to gain the necessary in-depth insight into how key stakeholders view cloud security and trust. A theoretical contribution is made in the form of a trust-centric conceptual framework that illustrates how the qualitative data relates to concepts innate to cloud computing trust and adoption. Both these contributions lend credence to the fact that there is a need to address cloud information security with a specific focus on the contextual elements that surround South African universities. The paper concludes with some considerations for implementing and investigating cloud computing services in Higher Education contexts in South Africa.

  13. The dynamic warm pool: A new paradigm for understanding the role of the tropics in the global heat balance

    Science.gov (United States)

    Webster, P. J.; Hoyos, C. D.

    2008-12-01

    The region of atmospheric heating in the tropics, here termed the dynamic warm pool, represents the "boiler box" of the planetary heat engine and plays a determining role in global climate and tropical weather variability, modulating the genesis and intensification of tropical cyclones, the ascending branches of the Walker and Hadley circulations, monsoons and ENSO variability, and the nature of global teleconnections emanating from the tropics. Hence, it is important to understand how the tropical warm pool has changed in the past and how it may change in the future, and how these changes may alter climate both regionally and globally. The concept of the dynamic warm pool, which encloses the region of net atmospheric convective heating in the tropics, is fundamentally different to the traditionally defined oceanic warm pool corresponding to the area occupied by sea surface temperatures above a pre-defined threshold, typically 28C. While the traditionally defined warm pool has expanded as a result of global warming, the dynamical warm pool has remained constant as a result of an increasing column integrated heating-sea surface temperature threshold. In other words, in a warming climate the convective area does not expand with the area of SST>28C. However, despite the near constancy of the dynamic warm pool area, the magnitude of the column integrated heating in the tropics increases substantially. In light of these results, the traditional warm pool definition and the thresholds for convection and cyclogenesis are not climatically meaningful and lack a physical basis. Rather than a static definition set by a constant temperature, the climatically active warm pool should be defined dynamically by the large-scale coupled ocean-atmosphere system rather than just by the temperature of the ocean surface. In this work we use the concept of the dynamical warm pool as a physical basis to explore and understand long-term variability of tropical cyclogenesis and

  14. TWO-FLUID MAGNETOHYDRODYNAMICS SIMULATIONS OF CONVERGING H I FLOWS IN THE INTERSTELLAR MEDIUM. II. ARE MOLECULAR CLOUDS GENERATED DIRECTLY FROM A WARM NEUTRAL MEDIUM?

    International Nuclear Information System (INIS)

    Inoue, Tsuyoshi; Inutsuka, Shu-ichiro

    2009-01-01

    Formation of interstellar clouds as a consequence of thermal instability is studied using two-dimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the interstellar medium that generate a shocked slab of thermally unstable gas in which clouds form. We find, as speculated in Paper I, that in the shocked slab magnetic pressure dominates thermal pressure and the thermal instability grows in the isochorically cooling, thermally unstable slab that leads to the formation of H I clouds whose number density is typically n ∼ -3 , even if the angle between magnetic field and converging flows is small. We also find that even if there is a large dispersion of magnetic field, evolution of the shocked slab is essentially determined by the angle between the mean magnetic field and converging flows. Thus, the direct formation of molecular clouds by piling up warm neutral medium does not seem to be a typical molecular cloud formation process, unless the direction of supersonic converging flows is biased to the orientation of mean magnetic field by some mechanism. However, when the angle is small, the H I shell generated as a result of converging flows is massive and possibly evolves into molecular clouds, provided gas in the massive H I shell is piled up again along the magnetic field line. We expect that another subsequent shock wave can again pile up the gas of the massive shell and produce a larger cloud. We thus emphasize the importance of multiple episodes of converging flows, as a typical formation process of molecular clouds.

  15. Global Warming: Understanding and Teaching the Forecast. Part A The Greenhouse Effect.

    Science.gov (United States)

    Andrews, Bill

    1993-01-01

    Provides information necessary for an interdisciplinary analysis of the greenhouse effect, enhanced greenhouse effect, global warming, global climate change, greenhouse gases, carbon dioxide, and scientific study of global warming for students grades 4-12. Several activity ideas accompany the information. (LZ)

  16. Implementation of a micro-physical scheme for warm clouds in the meteorological model 'MERCURE': Application to cooling tower plumes and to orographic precipitation

    International Nuclear Information System (INIS)

    Bouzereau, Emmanuel

    2004-01-01

    A two-moment semi-spectral warm micro-physical scheme has been implemented inside the meteorological model 'MERCURE'. A new formulation of the buoyancy flux () is proposed, which is coherent with the corrigendum of Mellor (1977) but differs from Bougeault (1981). The non-precipitating cloud microphysics is validated by comparing the numerical simulations of fifteen cases of cooling tower plumes with data from a measurement campaign in Bugey in 1980. Satisfactory results are obtained on the plumes shape, on the temperature and vertical velocity fields and on the droplets spectrums, although the liquid water contents tend to be overestimated. The precipitating cloud microphysics is tested by reproducing the academical cases of orographic precipitation of Chaumerliac et al. (1987) and Richard and Chaumerliac (1989). The simulations allow a check of the action of different micro-physical terms. (author) [fr

  17. Six years of surface remote sensing of stratiform warm clouds in marine and continental air over Mace Head, Ireland

    Science.gov (United States)

    Preißler, Jana; Martucci, Giovanni; Saponaro, Giulia; Ovadnevaite, Jurgita; Vaishya, Aditya; Kolmonen, Pekka; Ceburnis, Darius; Sogacheva, Larisa; de Leeuw, Gerrit; O'Dowd, Colin

    2016-12-01

    A total of 118 stratiform water clouds were observed by ground-based remote sensing instruments at the Mace Head Atmospheric Research Station on the west coast of Ireland from 2009 to 2015. Microphysical and optical characteristics of these clouds were studied as well as the impact of aerosols on these properties. Microphysical and optical cloud properties were derived using the algorithm SYRSOC (SYnergistic Remote Sensing Of Clouds). Ground-based in situ measurements of aerosol concentrations and the transport path of air masses at cloud level were investigated as well. The cloud properties were studied in dependence of the prevailing air mass at cloud level and season. We found higher cloud droplet number concentrations (CDNC) and smaller effective radii (reff) with greater pollution. Median CDNC ranged from 60 cm-3 in marine air masses to 160 cm-3 in continental air. Median reff ranged from 8 μm in polluted conditions to 10 μm in marine air. Effective droplet size distributions were broader in marine than in continental cases. Cloud optical thickness (COT) and albedo were lower in cleaner air masses and higher in more polluted conditions, with medians ranging from 2.1 to 4.9 and 0.22 to 0.39, respectively. However, calculation of COT and albedo was strongly affected by liquid water path (LWP) and departure from adiabatic conditions. A comparison of SYRSOC results with MODIS (Moderate-Resolution Imaging Spectroradiometer) observations showed large differences for LWP and COT but good agreement for reff with a linear fit with slope near 1 and offset of -1 μm.

  18. Public understanding of the politics of global warming in the news media: the hostile media approach.

    Science.gov (United States)

    Kim, Kyun Soo

    2011-09-01

    This study uses the politics of global warming in the US to investigate an affective mechanism of hostile media perception and the democratic consequences of such perception, in an effort to delineate audience and journalistic barriers to stimulating urgent concern about climate change. The study confirms that partisanship played a significant role in perceptual differences with regard to media bias in an important area of science journalism--climate change. News consumers' anger perception was tested as a mediator in seeking an affective mechanism of hostile media perception. Hostile media perception has important democratic consequences in that it is positively associated with individuals' trust in news coverage of global warming and with selective media use.

  19. Clouds and Climate Change. Understanding Global Change: Earth Science and Human Impacts. Global Change Instruction Program.

    Science.gov (United States)

    Shaw, Glenn E.

    The Global Change Instruction Program was designed by college professors to fill a need for interdisciplinary materials on the emerging science of global change. This instructional module introduces the basic features and classifications of clouds and cloud cover, and explains how clouds form, what they are made of, what roles they play in…

  20. Understanding the Impact of Model Surfactants on Cloud Condensation Nuclei Activity of Sea Spray Aerosols

    Science.gov (United States)

    Forestieri, S.; Cappa, C. D.; Ruehl, C. R.; Bertram, T. H.; Staudt, S.; Kuborn, T.

    2017-12-01

    Aerosol impacts on cloud properties, also known as indirect effects, remain a major source of uncertainty in modeling global radiative forcing. Reducing this uncertainty necessitates better understanding of how aerosol chemical composition impacts the cloud-forming ability of aerosols. The presence of surfactants in aerosols can decrease the surface tension of activating droplets relative to water and lead to more efficient activation. The importance of this effect has been debated, but recent surface tension measurements of microscopic droplets indicate that surface tension is substantially depressed relative to water for lab-generated particles consisting of salt and a single organic species and for complex mixtures of organic matter. However, little work has been done on understanding how chemical complexity (i.e. interaction between different surfactant species) impacts surface tension for particles containing mixtures of surfactants. In this work, we quantified the surface tension of lab-generated aerosols containing surfactants that are commonly found in nascent sea spray aerosol (SSA) at humidities close to activation using a continuous flow stream-wise thermal gradient chamber (CFSTGC). Surface tension was quantified for particles containing single surfactant species and mixtures of these surfactants to investigate the role of chemical complexity on surface tension and molecular packing at the air-water interface. For all surfactants tested in this study, substantial surface tension depression (20-40 mN/m) relative to water was observed for particles containing large fractions of organic matter at humidities just below activation. However, the presence of these surfactants only weakly depressed surface tension at activation. Kinetic limitations were observed for particles coated with just palmitic acid, since palmitic acid molecules inhibit water uptake through their ability to pack tightly at the surface. However, these kinetic limitations disappeared when

  1. Mechanisms behind low-cloud optical depth response to temperature in ARM site observations

    Science.gov (United States)

    Terai, Christopher; Zhang, Yunyan; Klein, Stephen; Zelinka, Mark

    2017-04-01

    Most state-of-the-art climate models predict the cloud optical depth increases with warming in the mid- and high-latitudes. Proposed mechanisms exist in the literature to support this increase in cloud optical depth, and the cloud processes driving the negative cloud feedback have been identified in several climate models. However, recent studies find that this negative cloud feedback in the mid- and high-latitudes is likely overestimated in climate models. For example, an analysis of satellite retrievals suggests that the optical depth of low-level clouds decreases with warming. Less attention has been placed on understanding the cloud processes that drive cloud optical depth changes in observations. In this study, we use ground-based observations from three mid- and high-latitude sites, managed by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Program, to determine the mechanisms that drive cloud changes at those sites. We test whether there is evidence in the observations that support three mechanisms that have been proposed to drive a cloud optical depth response to warming. We test a) whether cloud liquid water content increases with warming following changes in the adiabatic lapse rate of the saturated water vapor, as determined by the Clausius-Clapeyron relationship, b) whether the change in phase-partitioning of clouds due to warming increase the optical depth by changing the cloud optical and microphysical properties and processes, and c) whether warming leads to a thinning of clouds by enhancing the drying efficiency of cloud top mixing. We find that although increases in cloud liquid content with warming is consistent with the Clausius-Clapeyron relationship at the one oceanic site, they do not hold over the two continental sites. We also find that the liquid-ice partitioning of total cloud water differs between sites and find evidence that increasing ice fraction leads to clouds with lower LWP. We also test whether the

  2. Understanding factors influencing vulnerable older people keeping warm and well in winter: a qualitative study using social marketing techniques.

    Science.gov (United States)

    Tod, Angela Mary; Lusambili, Adelaide; Homer, Catherine; Abbott, Joanne; Cooke, Joanne Mary; Stocks, Amanda Jayne; McDaid, Kathleen Anne

    2012-01-01

    To understand the influences and decisions of vulnerable older people in relation to keeping warm in winter. A qualitative study incorporating in-depth, semi-structured individual and group interviews, framework analysis and social marketing segmentation techniques. Rotherham, South Yorkshire, UK. 50 older people (>55) and 25 health and social care staff underwent individual interview. The older people also had household temperature measurements. 24 older people and 19 health and social care staff participated in one of the six group interviews. Multiple complex factors emerged to explain whether vulnerable older people were able to keep warm. These influences combined in various ways that meant older people were not able to or preferred not to access help or change home heating behaviour. Factors influencing behaviours and decisions relating to use of heating, spending money, accessing cheaper tariffs, accessing benefits or asking for help fell into three main categories. These were situational and contextual factors, attitudes and values, and barriers. Barriers included poor knowledge and awareness, technology, disjointed systems and the invisibility of fuel and fuel payment. Findings formed the basis of a social marketing segmentation model used to develop six pen portraits that illustrated how factors that conspire against older people being able to keep warm. The findings illustrate how and why vulnerable older people may be at risk of a cold home. The pen portraits provide an accessible vehicle and reflective tool to raise the capacity of the NHS in responding to their needs in line with the Cold Weather Plan.

  3. Understanding the Warm Water Volume Precursor of ENSO Events and its Interdecadal Variation

    Science.gov (United States)

    Neske, S.; McGregor, S.

    2018-02-01

    A wind forced ocean model is used to decompose the equatorial Pacific warm water volume (WWV) between 1980 and 2016 into two components: the (i) adjusted wind response, which is found by letting the model evolve unforced for three months, and (ii) instantaneous wind response, which are the instantaneous WWV changes due to Ekman transports. Our results suggest that roughly half of WWV variability is only as predictable as the winds that drive the instantaneous change. Separate examinations of pre-2000 and post-2000 periods reveal (i) nearly equal importance of instantaneous and adjusted responses for the pre-2000 period and (ii) dominance of the instantaneous response during the post-2000 period, which is most apparent during the recharged phase. This increasing instantaneous contribution prominence explains the post-2000 reduction in WWV/El Niño-Southern Oscillation sea surface temperature lead times (from six to nine months pre-2000 down to three months post-2000) and is consistent with the reduction in post-2000 El Niño-Southern Oscillation prediction skill.

  4. Global and regional estimates of warm cloud droplet number concentration based on 13 years of AQUA-MODIS observations

    Science.gov (United States)

    Bennartz, Ralf; Rausch, John

    2017-08-01

    We present and evaluate a climatology of cloud droplet number concentration (CDNC) based on 13 years of Aqua-MODIS observations. The climatology provides monthly mean 1 × 1° CDNC values plus associated uncertainties over the global ice-free oceans. All values are in-cloud values, i.e. the reported CDNC value will be valid for the cloudy part of the grid box. Here, we provide an overview of how the climatology was generated and assess and quantify potential systematic error sources including effects of broken clouds, and remaining artefacts caused by the retrieval process or related to observation geometry. Retrievals and evaluations were performed at the scale of initial MODIS observations (in contrast to some earlier climatologies, which were created based on already gridded data). This allowed us to implement additional screening criteria, so that observations inconsistent with key assumptions made in the CDNC retrieval could be rejected. Application of these additional screening criteria led to significant changes in the annual cycle of CDNC in terms of both its phase and magnitude. After an optimal screening was established a final CDNC climatology was generated. Resulting CDNC uncertainties are reported as monthly-mean standard deviations of CDNC over each 1 × 1° grid box. These uncertainties are of the order of 30 % in the stratocumulus regions and 60 to 80 % elsewhere.

  5. Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C7H in Molecular Clouds

    Science.gov (United States)

    Araki, Mitsunori; Takano, Shuro; Sakai, Nami; Yamamoto, Satoshi; Oyama, Takahiro; Kuze, Nobuhiko; Tsukiyama, Koichi

    2017-09-01

    Long carbon-chain molecules were searched for toward the low-mass star-forming region L1527, which is a prototypical source of warm carbon-chain chemistry (WCCC), using the 100 m Green Bank Telescope. Long carbon-chain molecules, C7H (2Π1/2), C6H (2Π3/2 and 2Π1/2), CH3C4H, and C6H2 (cumulene carbene, CCCCCCH2), and cyclic species of C3H and C3H2O were detected. In particular, C7H was detected for the first time in molecular clouds. The column density of C7H is determined to be 6 × 1010 cm-2. The column densities of the carbon-chain molecules including CH3C4H and C6H in L1527 relative to those in the starless dark cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP) tend to be systematically lower for long carbon-chain lengths. However, the column densities of C7H and C6H2 do not follow this trend and are found to be relatively abundant in L1527. This result implies that these long carbon-chain molecules are remnants of the cold starless phase. The results—that both the remnants and WCCC products are observed toward L1527—are consistent with the suggestion that the protostar can also be born in the parent core at a relatively early stage in the chemical evolution.

  6. Improving our fundamental understanding of the role of aerosol-cloud interactions in the climate system.

    Science.gov (United States)

    Seinfeld, John H; Bretherton, Christopher; Carslaw, Kenneth S; Coe, Hugh; DeMott, Paul J; Dunlea, Edward J; Feingold, Graham; Ghan, Steven; Guenther, Alex B; Kahn, Ralph; Kraucunas, Ian; Kreidenweis, Sonia M; Molina, Mario J; Nenes, Athanasios; Penner, Joyce E; Prather, Kimberly A; Ramanathan, V; Ramaswamy, Venkatachalam; Rasch, Philip J; Ravishankara, A R; Rosenfeld, Daniel; Stephens, Graeme; Wood, Robert

    2016-05-24

    The effect of an increase in atmospheric aerosol concentrations on the distribution and radiative properties of Earth's clouds is the most uncertain component of the overall global radiative forcing from preindustrial time. General circulation models (GCMs) are the tool for predicting future climate, but the treatment of aerosols, clouds, and aerosol-cloud radiative effects carries large uncertainties that directly affect GCM predictions, such as climate sensitivity. Predictions are hampered by the large range of scales of interaction between various components that need to be captured. Observation systems (remote sensing, in situ) are increasingly being used to constrain predictions, but significant challenges exist, to some extent because of the large range of scales and the fact that the various measuring systems tend to address different scales. Fine-scale models represent clouds, aerosols, and aerosol-cloud interactions with high fidelity but do not include interactions with the larger scale and are therefore limited from a climatic point of view. We suggest strategies for improving estimates of aerosol-cloud relationships in climate models, for new remote sensing and in situ measurements, and for quantifying and reducing model uncertainty.

  7. Improving Our Fundamental Understanding of the Role of Aerosol Cloud Interactions in the Climate System

    Science.gov (United States)

    Seinfeld, John H.; Bretherton, Christopher; Carslaw, Kenneth S.; Coe, Hugh; DeMott, Paul J.; Dunlea, Edward J.; Feingold, Graham; Ghan, Steven; Guenther, Alex B.; Kahn, Ralph; hide

    2016-01-01

    The effect of an increase in atmospheric aerosol concentrations on the distribution and radiative properties of Earth's clouds is the most uncertain component of the overall global radiative forcing from preindustrial time. General circulation models (GCMs) are the tool for predicting future climate, but the treatment of aerosols, clouds, and aerosol-cloud radiative effects carries large uncertainties that directly affect GCM predictions, such as climate sensitivity. Predictions are hampered by the large range of scales of interaction between various components that need to be captured. Observation systems (remote sensing, in situ) are increasingly being used to constrain predictions, but significant challenges exist, to some extent because of the large range of scales and the fact that the various measuring systems tend to address different scales. Fine-scale models represent clouds, aerosols, and aerosol-cloud interactions with high fidelity but do not include interactions with the larger scale and are therefore limited from a climatic point of view. We suggest strategies for improving estimates of aerosol-cloud relationships in climate models, for new remote sensing and in situ measurements, and for quantifying and reducing model uncertainty.

  8. Improving our fundamental understanding of the role of aerosol−cloud interactions in the climate system

    Science.gov (United States)

    Seinfeld, John H.; Bretherton, Christopher; Carslaw, Kenneth S.; Coe, Hugh; DeMott, Paul J.; Dunlea, Edward J.; Feingold, Graham; Ghan, Steven; Guenther, Alex B.; Kraucunas, Ian; Molina, Mario J.; Nenes, Athanasios; Penner, Joyce E.; Prather, Kimberly A.; Ramanathan, V.; Ramaswamy, Venkatachalam; Rasch, Philip J.; Ravishankara, A. R.; Rosenfeld, Daniel; Stephens, Graeme; Wood, Robert

    2016-01-01

    The effect of an increase in atmospheric aerosol concentrations on the distribution and radiative properties of Earth’s clouds is the most uncertain component of the overall global radiative forcing from preindustrial time. General circulation models (GCMs) are the tool for predicting future climate, but the treatment of aerosols, clouds, and aerosol−cloud radiative effects carries large uncertainties that directly affect GCM predictions, such as climate sensitivity. Predictions are hampered by the large range of scales of interaction between various components that need to be captured. Observation systems (remote sensing, in situ) are increasingly being used to constrain predictions, but significant challenges exist, to some extent because of the large range of scales and the fact that the various measuring systems tend to address different scales. Fine-scale models represent clouds, aerosols, and aerosol−cloud interactions with high fidelity but do not include interactions with the larger scale and are therefore limited from a climatic point of view. We suggest strategies for improving estimates of aerosol−cloud relationships in climate models, for new remote sensing and in situ measurements, and for quantifying and reducing model uncertainty. PMID:27222566

  9. 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

  10. The Polar Ocean in a Warming Planet: Understanding for managing a unique resource of the Humankind

    Science.gov (United States)

    Azzolini, R.; Campus, P.; Weber, J.

    2012-04-01

    waters. Besides this, the marine living resources and the reservoirs of energy and bio-chemical resources (e.g. gas hydrates, bio-prospecting) have a growing strategic importance in the global economy. The Antarctic Ocean, due to its isolation and extreme climatic conditions, has always been an area of international cooperation and technological challenges in support of scientific progress. In this scenario, the rapid environmental changes and the need of humankind for new and alternative reservoirs of food and energy to be exploited play a crucial role in understanding and managing the Polar oceans. The newly emerging opportunities and associated emerging threats for Arctic people increase the number of policy areas in which EU involvement is relevant and necessary. In order to gain insight into the this complex scenario and into the needs in terms of research programmes and infrastructures, policy and education to manage it, the European Polar Board launched an initiative in Polar marine science. The ESF/EPB marine initiative is intended to focus on various aspect of the Polar marine environment and to indicate a strategy focused on innovative scientific and technological topics, capable of combining together different research capacities as well as political, economic and strategic objectives, toward goals of economic and social interest. Therefore, it is based on a wide and multidisciplinary participation.

  11. A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b.

    Science.gov (United States)

    Ehrenreich, David; Bourrier, Vincent; Wheatley, Peter J; des Etangs, Alain Lecavelier; Hébrard, Guillaume; Udry, Stéphane; Bonfils, Xavier; Delfosse, Xavier; Désert, Jean-Michel; Sing, David K; Vidal-Madjar, Alfred

    2015-06-25

    Exoplanets orbiting close to their parent stars may lose some fraction of their atmospheres because of the extreme irradiation. Atmospheric mass loss primarily affects low-mass exoplanets, leading to the suggestion that hot rocky planets might have begun as Neptune-like, but subsequently lost all of their atmospheres; however, no confident measurements have hitherto been available. The signature of this loss could be observed in the ultraviolet spectrum, when the planet and its escaping atmosphere transit the star, giving rise to deeper and longer transit signatures than in the optical spectrum. Here we report that in the ultraviolet the Neptune-mass exoplanet GJ 436b (also known as Gliese 436b) has transit depths of 56.3 ± 3.5% (1σ), far beyond the 0.69% optical transit depth. The ultraviolet transits repeatedly start about two hours before, and end more than three hours after the approximately one hour optical transit, which is substantially different from one previous claim (based on an inaccurate ephemeris). We infer from this that the planet is surrounded and trailed by a large exospheric cloud composed mainly of hydrogen atoms. We estimate a mass-loss rate in the range of about 10(8)-10(9) grams per second, which is far too small to deplete the atmosphere of a Neptune-like planet in the lifetime of the parent star, but would have been much greater in the past.

  12. Applying Chemical Imaging Analysis to Improve Our Understanding of Cold Cloud Formation

    Science.gov (United States)

    Laskin, A.; Knopf, D. A.; Wang, B.; Alpert, P. A.; Roedel, T.; Gilles, M. K.; Moffet, R.; Tivanski, A.

    2012-12-01

    The impact that atmospheric ice nucleation has on the global radiation budget is one of the least understood problems in atmospheric sciences. This is in part due to the incomplete understanding of various ice nucleation pathways that lead to ice crystal formation from pre-existing aerosol particles. Studies investigating the ice nucleation propensity of laboratory generated particles indicate that individual particle types are highly selective in their ice nucleating efficiency. This description of heterogeneous ice nucleation would present a challenge when applying to the atmosphere which contains a complex mixture of particles. Here, we employ a combination of micro-spectroscopic and optical single particle analytical methods to relate particle physical and chemical properties with observed water uptake and ice nucleation. Field-collected particles from urban environments impacted by anthropogenic and marine emissions and aging processes are investigated. Single particle characterization is provided by computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). A particle-on-substrate approach coupled to a vapor controlled cooling-stage and a microscope system is applied to determine the onsets of water uptake and ice nucleation including immersion freezing and deposition ice nucleation as a function of temperature (T) as low as 200 K and relative humidity (RH) up to water saturation. We observe for urban aerosol particles that for T > 230 K the oxidation level affects initial water uptake and that subsequent immersion freezing depends on particle mixing state, e.g. by the presence of insoluble particles. For T cloud formation. Initial results applying single particle IN analysis using CCSEM/EDX and STXM/NEXAFS reveal that a significant amount of IN are coated by organics and, thus, are similar to the

  13. Understanding the Performance of Low Power Raspberry Pi Cloud for Big Data

    Directory of Open Access Journals (Sweden)

    Wajdi Hajji

    2016-06-01

    Full Text Available Nowadays, Internet-of-Things (IoT devices generate data at high speed and large volume. Often the data require real-time processing to support high system responsiveness which can be supported by localised Cloud and/or Fog computing paradigms. However, there are considerably large deployments of IoT such as sensor networks in remote areas where Internet connectivity is sparse, challenging the localised Cloud and/or Fog computing paradigms. With the advent of the Raspberry Pi, a credit card-sized single board computer, there is a great opportunity to construct low-cost, low-power portable cloud to support real-time data processing next to IoT deployments. In this paper, we extend our previous work on constructing Raspberry Pi Cloud to study its feasibility for real-time big data analytics under realistic application-level workload in both native and virtualised environments. We have extensively tested the performance of a single node Raspberry Pi 2 Model B with httperf and a cluster of 12 nodes with Apache Spark and HDFS (Hadoop Distributed File System. Our results have demonstrated that our portable cloud is useful for supporting real-time big data analytics. On the other hand, our results have also unveiled that overhead for CPU-bound workload in virtualised environment is surprisingly high, at 67.2%. We have found that, for big data applications, the virtualisation overhead is fractional for small jobs but becomes more significant for large jobs, up to 28.6%.

  14. Implementation of warm-cloud processes in a source-oriented WRF/Chem model to study the effect of aerosol mixing state on fog formation in the Central Valley of California

    Directory of Open Access Journals (Sweden)

    H.-H. Lee

    2016-07-01

    Full Text Available The source-oriented Weather Research and Forecasting chemistry model (SOWC was modified to include warm cloud processes and was applied to investigate how aerosol mixing states influence fog formation and optical properties in the atmosphere. SOWC tracks a 6-D chemical variable (X, Z, Y, size bins, source types, species through an explicit simulation of atmospheric chemistry and physics. A source-oriented cloud condensation nuclei module was implemented into the SOWC model to simulate warm clouds using the modified two-moment Purdue Lin microphysics scheme. The Goddard shortwave and long-wave radiation schemes were modified to interact with source-oriented aerosols and cloud droplets so that aerosol direct and indirect effects could be studied. The enhanced SOWC model was applied to study a fog event that occurred on 17 January 2011, in the Central Valley of California. Tule fog occurred because an atmospheric river effectively advected high moisture into the Central Valley and nighttime drainage flow brought cold air from mountains into the valley. The SOWC model produced reasonable liquid water path, spatial distribution and duration of fog events. The inclusion of aerosol–radiation interaction only slightly modified simulation results since cloud optical thickness dominated the radiation budget in fog events. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into cloud condensation nuclei (CCN at a supersaturation of 0.5 % in the Central Valley decreased from 94 % in the internal mixture model to 80 % in the source-oriented model. This increased surface energy flux by 3–5 W m−2 and surface temperature by as much as 0.25 K in the daytime.

  15. 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.

  16. Northern-hemispheric differential warming is the key to understanding the discrepancies in the projected Sahel rainfall.

    Science.gov (United States)

    Park, Jong-Yeon; Bader, Jürgen; Matei, Daniela

    2015-01-21

    Future projections of the Sahel rainfall are highly uncertain, with different climate models showing widely differing rainfall trends. Moreover, the twentieth-century cross-model consensus linking Sahel rainfall to tropical sea-surface temperatures (SSTs) is no longer applicable in the twenty-first century. Here we show that the diverse future Northern Hemisphere differential warming between extratropical and tropical SSTs can explain the discrepancy in the projected Sahel rainfall. The relationship between SST and Sahel rainfall that holds for the twentieth-century persists into the twenty-first century when the differential SST warming is taken into account. A suite of SST-sensitivity experiments confirms that strong Northern Hemisphere extratropical warming induces a significant increase in Sahel rainfall, which can predominate over the drying impact of tropical SST warming. These results indicate that a trustworthy projection of Sahel rainfall requires the estimation of the most likely future Northern-hemispheric differential warming.

  17. Understanding the causes of recent warming of mediterranean waters. How much could be attributed to climate change?

    Science.gov (United States)

    Macias, Diego; Garcia-Gorriz, Elisa; Stips, Adolf

    2013-01-01

    During the past two decades, Mediterranean waters have been warming at a rather high rate resulting in scientific and social concern. This warming trend is observed in satellite data, field data and model simulations, and affects both surface and deep waters throughout the Mediterranean basin. However, the warming rate is regionally different and seems to change with time, which has led to the question of what causes underlie the observed trends. Here, we analyze available satellite information on sea surface temperature (SST) from the last 25 years using spectral techniques and find that more than half of the warming tendency during this period is due to a non-linear, wave-like tendency. Using a state of the art hydrodynamic model, we perform a hindcast simulation and obtain the simulated SST evolution of the Mediterranean basin for the last 52 years. These SST results show a clear sinusoidal tendency that follows the Atlantic Multidecadal Oscillation (AMO) during the simulation period. Our results reveal that 58% of recent warming in Mediterranean waters could be attributed to this AMO-like oscillation, being anthropogenic-induced climate change only responsible for 42% of total trend. The observed acceleration of water warming during the 1990s therefore appears to be caused by a superimposition of anthropogenic-induced warming with the positive phase of the AMO, while the recent slowdown of this tendency is likely due to a shift in the AMO phase. It has been proposed that this change in the AMO phase will mask the effect of global warming in the forthcoming decades, and our results indicate that the same could also be applicable to the Mediterranean Sea. Henceforth, natural multidecadal temperature oscillations should be taken into account to avoid underestimation of the anthropogenic-induced warming of the Mediterranean basin in the future.

  18. Understanding the causes of recent warming of mediterranean waters. How much could be attributed to climate change?

    Directory of Open Access Journals (Sweden)

    Diego Macias

    Full Text Available During the past two decades, Mediterranean waters have been warming at a rather high rate resulting in scientific and social concern. This warming trend is observed in satellite data, field data and model simulations, and affects both surface and deep waters throughout the Mediterranean basin. However, the warming rate is regionally different and seems to change with time, which has led to the question of what causes underlie the observed trends. Here, we analyze available satellite information on sea surface temperature (SST from the last 25 years using spectral techniques and find that more than half of the warming tendency during this period is due to a non-linear, wave-like tendency. Using a state of the art hydrodynamic model, we perform a hindcast simulation and obtain the simulated SST evolution of the Mediterranean basin for the last 52 years. These SST results show a clear sinusoidal tendency that follows the Atlantic Multidecadal Oscillation (AMO during the simulation period. Our results reveal that 58% of recent warming in Mediterranean waters could be attributed to this AMO-like oscillation, being anthropogenic-induced climate change only responsible for 42% of total trend. The observed acceleration of water warming during the 1990s therefore appears to be caused by a superimposition of anthropogenic-induced warming with the positive phase of the AMO, while the recent slowdown of this tendency is likely due to a shift in the AMO phase. It has been proposed that this change in the AMO phase will mask the effect of global warming in the forthcoming decades, and our results indicate that the same could also be applicable to the Mediterranean Sea. Henceforth, natural multidecadal temperature oscillations should be taken into account to avoid underestimation of the anthropogenic-induced warming of the Mediterranean basin in the future.

  19. The Coupled Mars Dust and Water Cycles: Understanding How Clouds Affect the Vertical Distribution and Meridional Transport of Dust and Water.

    Science.gov (United States)

    Kahre, M. A.

    2015-01-01

    The dust and water cycles are crucial to the current Martian climate, and they are coupled through cloud formation. Dust strongly impacts the thermal structure of the atmosphere and thus greatly affects atmospheric circulation, while clouds provide radiative forcing and control the hemispheric exchange of water through the modification of the vertical distributions of water and dust. Recent improvements in the quality and sophistication of both observations and climate models allow for a more comprehensive understanding of how the interaction between the dust and water cycles (through cloud formation) affects the dust and water cycles individually. We focus here on the effects of clouds on the vertical distribution of dust and water, and how those vertical distributions control the net meridional transport of water. For this study, we utilize observations of temperature, dust and water ice from the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter (MRO) combined with the NASA ARC Mars Global Climate Model (MGCM). We demonstrate that the magnitude and nature of the net meridional transport of water between the northern and southern hemispheres during NH summer is sensitive to the vertical structure of the simulated aphelion cloud belt. We further examine how clouds influence the atmospheric thermal structure and thus the vertical structure of the cloud belt. Our goal is to identify and understand the importance of radiative/dynamic feedbacks due to the physical processes involved with cloud formation and evolution on the current climate of Mars.

  20. Understanding the El Niño-like Oceanic Response in the Tropical Pacific to Global Warming

    Science.gov (United States)

    Luo, Y.; Lu, J.; Liu, F.

    2015-12-01

    The enhanced central and eastern Pacific SST warming and the associated ocean processes under global warming are investigated using the ocean component of the Community Earth System Model (CESM), Parallel Ocean Program version 2 (POP2). The tropical SST warming pattern in the coupled CESM can be faithfully reproduced by the POP2 forced with surface fluxes computed using the aerodynamic bulk formula. By prescribing the wind stress and/or wind speed through the bulk formula, the effects of wind stress change and/or the wind-evaporation-SST (WES) feedback are isolated and their linearity is evaluated in this ocean-alone setting. Result shows that, although the weakening of the equatorial easterlies contributes positively to the El Niño-like SST warming, 80% of which can be simulated by the POP2 without considering the effects of wind change in both mechanical and thermodynamic fluxes. This result points to the importance of the air-sea thermal interaction and the relative feebleness of the ocean dynamical process in the El Niño-like equatorial Pacific SST response to global warming. On the other hand, the wind stress change is found to play a dominant role in the oceanic response in the tropical Pacific, accounting for most of the changes in the equatorial ocean current system and thermal structures, including the weakening of the surface westward currents, the enhancement of the near-surface stratification and the shoaling of the equatorial thermocline. Interestingly, greenhouse gas warming in the absence of wind stress change and WES feedback also contributes substantially to the changes at the subsurface equatorial Pacific. Further, this warming impact can be largely replicated by an idealized ocean experiment forced by a uniform surface heat flux, whereby, arguably, a purest form of oceanic dynamical thermostat is revealed.

  1. Understanding the El Niño-like Oceanic Response in the Tropical Pacific to Global Warming

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yiyong; Lu, Jian; Liu, Fukai; Liu, Wei

    2015-10-10

    The enhanced central and eastern Pacific SST warming and the associated ocean processes under global warming are investigated using the ocean component of the Community Earth System Model (CESM), Parallel Ocean Program version 2 (POP2). The tropical SST warming pattern in the coupled CESM can be faithfully reproduced by the POP2 forced with surface fluxes computed using the aerodynamic bulk formula. By prescribing the wind stress and/or wind speed through the bulk formula, the effects of wind stress change and/or the wind-evaporation-SST (WES) feedback are isolated and their linearity is evaluated in this ocean-alone setting. Result shows that, although the weakening of the equatorial easterlies contributes positively to the El Niño-like SST warming, 80% of which can be simulated by the POP2 without considering the effects of wind change in both mechanical and thermodynamic fluxes. This result points to the importance of the air-sea thermal interaction and the relative feebleness of the ocean dynamical process in the El Niño-like equatorial Pacific SST response to global warming. On the other hand, the wind stress change is found to play a dominant role in the oceanic response in the tropical Pacific, accounting for most of the changes in the equatorial ocean current system and thermal structures, including the weakening of the surface westward currents, the enhancement of the near-surface stratification and the shoaling of the equatorial thermocline. Interestingly, greenhouse gas warming in the absence of wind stress change and WES feedback also contributes substantially to the changes at the subsurface equatorial Pacific. Further, this warming impact can be largely replicated by an idealized ocean experiment forced by a uniform surface heat flux, whereby, arguably, a purest form of oceanic dynamical thermostat is revealed.

  2. 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

  3. The JCMT Gould Belt Survey: Understanding the influence of outflows on Gould Belt clouds

    Science.gov (United States)

    Drabek-Maunder, E.; Hatchell, J.; Buckle, J. V.; Di Francesco, J.; Richer, J.

    2016-03-01

    Using James Clerk Maxwell Telescope (JCMT) Gould Belt Survey data from CO J = 3 → 2 isotopologues, we present a meta-analysis of the outflows and energetics of star-forming regions in several Gould Belt clouds. The majority of the regions are strongly gravitationally bound. There is evidence that molecular outflows transport large quantities of momentum and energy. Outflow energies are at least 20 per cent of the total turbulent kinetic energies in all of the regions studied and greater than the turbulent energy in half of the regions. However, we find no evidence that outflows increase levels of turbulence, and there is no correlation between the outflow and turbulent energies. Even though outflows in some regions contribute significantly to maintaining turbulence levels against dissipation, this relies on outflows efficiently coupling to bulk motions. Other mechanisms (e.g. supernovae) must be the main drivers of turbulence in most if not all of these regions.

  4. Understanding the Atmosphere of 51 Eri b: Do Photochemical Hazes Cloud the Planets Spectrum?

    Science.gov (United States)

    Marley, Mark Scott; Zahnle, Kevin; Moses, J.; Morley, C.

    2015-01-01

    The first young giant planet to be discovered by the Gemini Planet Imager was the (is) approximately 2MJ planet 51 Eri b. This approximately 20 Myr old young Jupiter is the first directly imaged planet to show unmistakable methane in H band. To constrain the planet's mass, atmospheric temperature, and composition, the GPI J and H band spectra as well as some limited photometric points were compared to the predictions of substellar atmosphere models. The best fitting models reported in the discovery paper (Macintosh et al. 2015) relied upon a combination of clear and cloudy atmospheric columns to reproduce the data. However for an object as cool as 700 K, the origin of the cloud coverage is somewhat puzzling, as the global silicate and iron clouds would be expected to have sunk well below the photosphere by this effective temperature. While strong vertical mixing in these low gravity atmospheres remains a plausible explanation, we have explored whether atmospheric photochemistry, driven by the UV flux from the primary star, may yield hazes that also influence the observed spectrum of the planet. To explore this possibility we have modeled the atmospheric photochemistry of 51 Eri b using two state-of-the-art photochemical models, both capable of predicting yields of complex hydrocarbons under various atmospheric conditions. In our presentation we will summarize the modeling approach employed to characterize 51 Eri b, explaining constraints on the planet's effective temperature, gravity, and atmospheric composition and also present results of our studies of atmospheric photochemistry. We will discuss whether photochemical hazes could indeed be responsible for the particulate opacity that apparently sculpts the spectrum of the planet.

  5. A further study of the method for estimation of SAGE II opaque cloud occurrence

    Science.gov (United States)

    Wang, Pi-Huan; Veiga, Robert E.; Vann, Lelia B.; Minnis, Patrick; Kent, Geoffrey S.

    2001-01-01

    Information on vertical cloud distribution is important to atmospheric radiative calculation, general circulation modeling, and climate study. The method used for estimating the vertical structure of opaque cloud occurrence from the solar occultation observations obtained by the Stratospheric Aerosol and Gas Experiment (SAGE) II has been reviewed for further understanding of the nature of the derived cloud statistics. Most importantly, based on the SAGE II tropical observations (1985-1998), the present study illustrates that the derived opaque cloud occurrence at a given altitude is generally independent of the cloud occurrence at other altitudes, except for some anticorrelation between high-level (12.5 km) and low-level (1-3 km) clouds. This feature of the layer cloud frequency independence is also evident when regional data over the Pacific warm pool and the eastern Pacific are examined. The independent information of the layer cloud frequency is significant and makes it possible to use the derived vertical distribution of cloud occurrence to estimate the probability of multilayer clouds. The limitation is that it is difficult to determine how frequently the multilayer clouds are actually overlapping or how frequently thick cloud (>1 km) really occurs based on the SAGE II observations alone. A discussion of the SAGE II tropical opaque cloud occurrence in relation to the cloud climatology based on visual observations from surface stations and ships, the International Satellite Cloud Climatology Project data, and the cloud statistics using rawinsonde records is also provided.

  6. 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...

  7. Feedback attribution of the land-sea warming contrast in a global warming simulation of the NCAR CCSM4

    International Nuclear Information System (INIS)

    Sejas, Sergio A; Albert, Oriene S; Cai, Ming; Deng, Yi

    2014-01-01

    One of the salient features in both observations and climate simulations is a stronger land warming than sea. This paper provides a quantitative understanding of the main processes that contribute to the land-sea warming asymmetry in a global warming simulation of the NCAR CCSM4. The CO 2 forcing alone warms the surface nearly the same for both land and sea, suggesting that feedbacks are responsible for the warming contrast. Our analysis on one hand confirms that the principal contributor to the above-unity land-to-sea warming ratio is the evaporation feedback; on the other hand the results indicate that the sensible heat flux feedback has the largest land-sea warming difference that favors a greater ocean than land warming. Therefore, the results uniquely highlight the importance of other feedbacks in establishing the above-unity land-to-sea warming ratio. Particularly, the SW cloud feedback and the ocean heat storage in the transient response are key contributors to the greater warming over land than sea. (letter)

  8. Microphysical and radiative effects of aerosols on warm clouds during the Amazon biomass burning season as observed by MODIS: impacts of water vapor and land cover

    Directory of Open Access Journals (Sweden)

    J. E. Ten Hoeve

    2011-04-01

    Full Text Available Aerosol, cloud, water vapor, and temperature profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS are utilized to examine the impact of aerosols on clouds during the Amazonian biomass burning season in Rondônia, Brazil. It is found that increasing background column water vapor (CWV throughout this transition season between the Amazon dry and wet seasons likely exerts a strong effect on cloud properties. As a result, proper analysis of aerosol-cloud relationships requires that data be stratified by CWV to account better for the influence of background meteorological variation. Many previous studies of aerosol-cloud interactions over Amazonia have ignored the systematic changes to meteorological factors during the transition season, leading to possible misinterpretation of their results. Cloud fraction (CF is shown to increase or remain constant with aerosol optical depth (AOD, depending on the value of CWV, whereas the relationship between cloud optical depth (COD and AOD is quite different. COD increases with AOD until AOD ~ 0.3, which is assumed to be due to the first indirect (microphysical effect. At higher values of AOD, COD is found to decrease with increasing AOD, which may be due to: (1 the inhibition of cloud development by absorbing aerosols (radiative effect/semi-direct effect and/or (2 a possible retrieval artifact in which the measured reflectance in the visible is less than expected from a cloud top either from the darkening of clouds through the addition of carbonaceous biomass burning aerosols within or above clouds or subpixel dark surface contamination in the measured cloud reflectance. If (1 is a contributing mechanism, as we suspect, then an empirically-derived increasing function between cloud drop number and aerosol concentration, assumed in a majority of global climate models, is inaccurate since these models do not include treatment of aerosol absorption in and around clouds. The relationship between

  9. Global Measurements of Optically Thin Ice Clouds Using CALIOP

    Science.gov (United States)

    Ryan, R.; Avery, M.; Tackett, J.

    2017-01-01

    Optically thin ice clouds have been shown to have a net warming effect on the globe but, because passive instruments are not sensitive to optically thin clouds, the occurrence frequency of this class of clouds is greatly underestimated in historical passive sensor cloud climatology. One major strength of CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization), onboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) spacecraft, is its ability to detect these thin clouds, thus filling an important missing piece in the historical data record. This poster examines the full mission of CALIPSO Level 2 data, focusing on those CALIOP retrievals identified as thin ice clouds according to the definition shown to the right. Using this definition, thin ice clouds are identified and counted globally and vertically for each season. By examining the spatial and seasonal distributions of these thin clouds we hope to gain a better understanding these thin ice clouds and how their global distribution has changed over the mission. This poster showcases when and where CALIOP detects thin ice clouds and examines a case study of the eastern pacific and the effects seen from the El Nino-Southern Oscillation (ENSO).

  10. ORACLES and LASIC: New observational campaigns to improve understanding of the effects of Southern African Biomass Burning Aerosol on Radiation, Clouds and Climate.

    Science.gov (United States)

    Wood, R.; Redemann, J.; Zuidema, P.

    2016-12-01

    Southern Africa produces almost a third of the Earth's biomass burning (BB) aerosol particles. Particles lofted into the mid-troposphere are transported westward over the South-East Atlantic, home to one of the three permanent subtropical Stratocumulus (Sc) cloud decks in the world. The stratocumulus "climate radiators" are critical to the regional and global climate system. They interact with dense layers of BB aerosols that initially overlay the cloud deck, but later subside and are mixed into the clouds. These interactions include adjustments to aerosol-induced solar heating and microphysical effects, and their global representation in climate models remains one of the largest uncertainties in estimates of future climate. Hence, new observations over the SE Atlantic have significant implications for global climate change scenarios. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) is a five-year investigation between 2015 and 2019 with three Intensive Observation Periods (IOP), recently funded by the NASA Earth-Venture Suborbital Program. ORACLES is designed to improve understanding of aerosol-radiation-cloud-climate interactions in the SE Atlantic. These interactions will be studied using aircraft observations from the NASA P-3 and ER-2 aircraft, which will provide key aerosol and cloud property information to improve process and large-scale models. LASIC (Layered Atlantic Smoke Interactions with Clouds) is a DOE deployment of the ARM Mobile Facility to Ascension Island (June 2016 - October 2017) that will provide ground-based in situ and remote sensing observations of aerosols and clouds from Ascension Island (8S, 14W). BB aerosols from Africa frequently advect to Ascension Island where they mix down into the trade wind boundary layer and interact with clouds. This presentation will describe "first-light" observations from the 2016 ORACLES and LASIC deployments, focusing upon the absorptive and cloud nucleating properties of aerosols

  11. Understanding why the volume of suboxic waters does not increase over centuries of global warming in an Earth System Model

    Directory of Open Access Journals (Sweden)

    A. Gnanadesikan

    2012-03-01

    Full Text Available Global warming is expected to reduce oxygen solubility and vertical exchange in the ocean, changes which would be expected to result in an increase in the volume of hypoxic waters. A simulation made with a full Earth System model with dynamical atmosphere, ocean, sea ice and biogeochemical cycling (the Geophysical Fluid Dynamics Laboratory's Earth System Model 2.1 shows that this holds true if the condition for hypoxia is set relatively high. However, the volume of the most hypoxic (i.e., suboxic waters does not increase under global warming, as these waters actually become more oxygenated. We show that the rise in dissolved oxygen in the tropical Pacific is associated with a drop in ventilation time. A term-by-term analysis within the least oxygenated waters shows an increased supply of dissolved oxygen due to lateral diffusion compensating an increase in remineralization within these highly hypoxic waters. This lateral diffusive flux is the result of an increase of ventilation along the Chilean coast, as a drying of the region under global warming opens up a region of wintertime convection in our model. The results highlight the potential sensitivity of suboxic waters to changes in subtropical ventilation as well as the importance of constraining lateral eddy transport of dissolved oxygen in such waters.

  12. When Injury Clouds Understanding of Others: Theory of Mind after Mild TBI in Preschool Children.

    Science.gov (United States)

    Bellerose, Jenny; Bernier, Annie; Beaudoin, Cindy; Gravel, Jocelyn; Beauchamp, Miriam H

    2015-08-01

    There is evidence to suggest that social skills, such as the ability to understand the perspective of others (theory of mind), may be affected by childhood traumatic brain injuries; however, studies to date have only considered moderate and severe traumatic brain injury (TBI). This study aimed to assess theory of mind after early, mild TBI (mTBI). Fifty-one children who sustained mTBI between 18 and 60 months were evaluated 6 months post-injury on emotion and desires reasoning and false-belief understanding tasks. Their results were compared to that of 50 typically developing children. The two groups did not differ on baseline characteristics, except for pre- and post-injury externalizing behavior. The mTBI group obtained poorer scores relative to controls on both the emotion and desires task and the false-belief understanding task, even after controlling for pre-injury externalizing behavior. No correlations were found between TBI injury characteristics and theory of mind. This is the first evidence that mTBI in preschool children is associated with theory of mind difficulties. Reduced perspective taking abilities could be linked with the social impairments that have been shown to arise following TBI.

  13. Further evidence for CCN aerosol concentrations determining the height of warm rain and ice initiation in convective clouds over the Amazon basin

    Science.gov (United States)

    Campos Braga, Ramon; Rosenfeld, Daniel; Weigel, Ralf; Jurkat, Tina; Andreae, Meinrat O.; Wendisch, Manfred; Pöschl, Ulrich; Voigt, Christiane; Mahnke, Christoph; Borrmann, Stephan; Albrecht, Rachel I.; Molleker, Sergej; Vila, Daniel A.; Machado, Luiz A. T.; Grulich, Lucas

    2017-12-01

    We have investigated how aerosols affect the height above cloud base of rain and ice hydrometeor initiation and the subsequent vertical evolution of cloud droplet size and number concentrations in growing convective cumulus. For this purpose we used in situ data of hydrometeor size distributions measured with instruments mounted on HALO aircraft during the ACRIDICON-CHUVA campaign over the Amazon during September 2014. The results show that the height of rain initiation by collision and coalescence processes (Dr, in units of meters above cloud base) is linearly correlated with the number concentration of droplets (Nd in cm-3) nucleated at cloud base (Dr ≈ 5 ṡ Nd). Additional cloud processes associated with Dr, such as GCCN, cloud, and mixing with ambient air and other processes, produce deviations of ˜ 21 % in the linear relationship, but it does not mask the clear relationship between Dr and Nd, which was also found at different regions around the globe (e.g., Israel and India). When Nd exceeded values of about 1000 cm-3, Dr became greater than 5000 m, and the first observed precipitation particles were ice hydrometeors. Therefore, no liquid water raindrops were observed within growing convective cumulus during polluted conditions. Furthermore, the formation of ice particles also took place at higher altitudes in the clouds in polluted conditions because the resulting smaller cloud droplets froze at colder temperatures compared to the larger drops in the unpolluted cases. The measured vertical profiles of droplet effective radius (re) were close to those estimated by assuming adiabatic conditions (rea), supporting the hypothesis that the entrainment and mixing of air into convective clouds is nearly inhomogeneous. Additional CCN activation on aerosol particles from biomass burning and air pollution reduced re below rea, which further inhibited the formation of raindrops and ice particles and resulted in even higher altitudes for rain and ice initiation.

  14. Understanding why the volume of suboxic waters does not increase over centuries of global warming in an Earth System Model

    OpenAIRE

    A. Gnanadesikan; J. P. Dunne; J. John

    2012-01-01

    Global warming is expected to reduce oxygen solubility and vertical exchange in the ocean, changes which would be expected to result in an increase in the volume of hypoxic waters. A simulation made with a full Earth System model with dynamical atmosphere, ocean, sea ice and biogeochemical cycling (the Geophysical Fluid Dynamics Laboratory's Earth System Model 2.1) shows that this holds true if the condition for hypoxia is set relatively high. However, the volume of the most hypoxic (i.e., su...

  15. Understanding the drivers of marine liquid-water cloud occurrence and properties with global observations using neural networks

    Directory of Open Access Journals (Sweden)

    H. Andersen

    2017-08-01

    Full Text Available The role of aerosols, clouds and their interactions with radiation remain among the largest unknowns in the climate system. Even though the processes involved are complex, aerosol–cloud interactions are often analyzed by means of bivariate relationships. In this study, 15 years (2001–2015 of monthly satellite-retrieved near-global aerosol products are combined with reanalysis data of various meteorological parameters to predict satellite-derived marine liquid-water cloud occurrence and properties by means of region-specific artificial neural networks. The statistical models used are shown to be capable of predicting clouds, especially in regions of high cloud variability. On this monthly scale, lower-tropospheric stability is shown to be the main determinant of cloud fraction and droplet size, especially in stratocumulus regions, while boundary layer height controls the liquid-water amount and thus the optical thickness of clouds. While aerosols show the expected impact on clouds, at this scale they are less relevant than some meteorological factors. Global patterns of the derived sensitivities point to regional characteristics of aerosol and cloud processes.

  16. Advances in Understanding the Role of Aerosols on Ice Clouds from the Fifth International Ice Nucleation (FIN) Workshops

    Science.gov (United States)

    Cziczo, D. J.; Moehler, O.; DeMott, P. J.

    2015-12-01

    The relationship of ambient aerosol particles to the formation of ice-containing clouds is one of the largest uncertainties in understanding climate. This is due to several poorly understood processes including the microphysics of how particles nucleate ice, the number of effective heterogeneous ice nuclei and their atmospheric distribution, the role of anthropogenic activities in producing or changing the behavior of ice forming particles and the interplay between effective heterogeneous ice nuclei and homogeneous ice formation. Our team recently completed a three-part international workshop to improve our understanding of atmospheric ice formation. Termed the Fifth International Ice Nucleation (FIN) Workshops, our motivation was the limited number of measurements and a lack of understanding of how to compare data acquired by different groups. The first activity, termed FIN1, addressed the characterization of ice nucleating particle size, number and chemical composition. FIN2 addressed the determination of ice nucleating particle number density. Groups modeling ice nucleation joined FIN2 to provide insight on measurements critically needed to model atmospheric ice nucleation and to understand the performance of ice chambers. FIN1 and FIN2 took place at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber at the Karlsruhe Institute of Technology. A particular emphasis of FIN1 and FIN2 was the use of 'blind' intercomparisons using a highly characterized, but unknown to the instrument operators, aerosol sample. The third activity, FIN3, took place at the Desert Research Institute's Storm Peak Laboratory (SPL). A high elevation site not subject to local emissions, SPL allowed for a comparison of ice chambers and subsequent analysis of the ice residuals under the challenging conditions of low particle loading, temperature and pressure found in the atmosphere. The presentation focuses on the improvement in understanding how mass spectra from different

  17. Role of Atmospheric Cloud Radiative Effects in the Intermodal Spread in the Shift of Southern Hemispheric Eddy-driven Jet in Responses to Global Warming

    Science.gov (United States)

    Li, Y.; Thompson, D. W. J.; Bony, S.

    2017-12-01

    Observations and most climate models suggest storm track and extratropical eddy driven jet shifts poleward in a warmer climate, particularly in the Southern Hemisphere. However, the magnitude of such shifts remains uncertain. Even for a prescribed uniform SST changes, models produce large inter-model spread in the magnitude of jet shift, suggesting that a substantial part of these uncertainties are caused by the impact of cloud radiative effects on the atmospheric heating rate per se. In this study we will investigate 1) how much do clouds contribute to the spread of the circulation response in the absence of SST coupling? 2) how much do clouds contribute to the spread of the direct CO2 and SST-only response?

  18. Processes limiting the emergence of detectable aerosol indirect effects on tropical warm clouds in global aerosol-climate model and satellite data

    Directory of Open Access Journals (Sweden)

    Karsten Peters

    2014-05-01

    Full Text Available We use data from simulations performed with the global aerosol-climate model ECHAM5-HAM to test the proposition that shipping emissions do not have a statistically significant effect on water clouds over tropical oceans on climate scales put forward in earlier satellite based work. We analyse a total of four sensitivity experiments, three of which employ global shipping emissions and one simulation which only employs shipping emissions in the mid-Atlantic Ocean. To ensure comparability to earlier results from observations, we sample the model data using a method previously applied to satellite data aimed at separating ‘clean’ from ‘polluted’ oceanic regions based on i the location of main shipping routes and ii wind direction at 10 m above sea level. The model simulations run with realistic present-day shipping emissions show changes in the lower tropospheric aerosol population attributable to shipping emissions across major shipping corridors over tropical oceans. However, we find the resulting effect on cloud properties to be non-distinguishable from natural gradients and variability, that is, gradients of cloud properties sampled across major shipping corridors over tropical oceans are very similar among those simulations. Our results therefore compare well to the earlier findings from satellite observations. Substantial changes of the aerosol population and cloud properties only occur when shipping emissions are increased 10-fold. We find that aerosol advection and rapid aerosol removal from the atmosphere play an important role in determining the non-significant response in i column integrated aerosol properties and ii cloud microphysical properties in the realistic simulations. Additionally, high variability and infrequent occurrence of simulated low-level clouds over tropical oceans in ECHAM5-HAM limit the development of aerosol indirect effects because i in-cloud production of sulphate from ship-emitted sulphuric species via

  19. A study of the link between cosmic rays and clouds with a cloud chamber at the CERN PS

    CERN Document Server

    Fastrup, B; Lillestøl, Egil; Thorn, E; Bosteels, Michel; Gonidec, A; Harigel, G G; Kirkby, Jasper; Mele, S; Minginette, P; Nicquevert, Bertrand; Schinzel, D; Seidl, W; Grundsøe, P; Marsh, N D; Polny, J; Svensmark, H; Viisanen, Y; Kurvinen, K L; Orava, Risto; Hämeri, K; Kulmala, M; Laakso, I; Mäkelä, J M; O'Dowd, C D; Afrosimov, V; Basalaev, A; Panov, M; Laaksonen, B D; Joutsensaari, J; Ermakov, V; Makhmutov, V S; Maksumov, O; Pokrevsky, P; Stozhkov, Yu I; Svirzhevsky, N S; Carslaw, K; Yin, Y; Trautmann, T; Arnold, F; Wohlfrom, K H; Hagen, D; Schmitt, J; Whitefield, P; Aplin, K; Harrison, R G; Bingham, R; Close, Francis Edwin; Gibbins, C; Irving, A; Kellett, B; Lockwood, M; Petersen, D; Szymanski, W W; Wagner, P E; Vrtala, A; CERN. Geneva. SPS-PS Experiments Committee

    2000-01-01

    Recent satellite data have revealed a surprising correlation between galactic cosmic ray (GCR) intensity and the fraction of the Earth covered by clouds. If this correlation were to be established by a causal mechanism, it could provide a crucial step in understanding the long-sought mechanism connecting solar and climate variability. The Earth's climate seems to be remarkably sensitive to solar activity, but variations of the Sun's electromagnetic radiation appear to be too small to account for the observed climate variability. However, since the GCR intensity is strongly modulated by the solar wind, a GCR-cloud link may provide a sufficient amplifying mechanism. Moreover if this connection were to be confirmed, it could have profound consequences for our understanding of the solar contributions to the current global warming. The CLOUD (Cosmics Leaving OUtdoor Droplets) project proposes to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical me...

  20. Leveraging Cababilities of the National Laboratories and Academia to Understand the Properties of Warm Dense MgSiO3

    Science.gov (United States)

    Mattsson, Thomas R.; Townsend, Joshua P.; Shulenburger, Luke; Seagle, Christopher T.; Furnish, Michael D.; Fei, Yingwei

    2017-06-01

    For the past seven years, the Z Fundamental Science program has fostered collaboration between scientists at the national laboratories and academic research groups to utilize the Z-machine to explore properties of matter in extreme conditions. A recent example of this involves a collaboration between the Carnegie institution of Washington and Sandia to determine the properties of warm dense MgSiO3 by performing shock experiments using the Z-machine. To reach the higher densities desired, bridgmanite samples are being fabricated at Carnegie using multi-anvil presses. We will describe the preparations under way for these experiments, including pre-shot ab-initio calculations of the Hugoniot and the deployment of dual-layer flyer plates that allow for the measurement of sound velocities along the Hugoniot. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  1. Understanding the Greenhouse Effect: Is Global Warming Real? An Integrated Lab-Lecture Case Study for Non-science Majors

    Science.gov (United States)

    Dunnivant, Frank M.; Moore, A.; Alfano, M. J.; Brzenk, R.; Buckley, P. T.; Newman, M. E.

    2000-12-01

    Numerous colleges and universities offer chemistry, geology, biology, and mathematics courses for students not majoring in science. However, these courses are often taught in a segmented format, spread over a four-year period, with separate lectures and laboratories, and in different departments. We are experimenting with a series of courses that combine a variety of disciplines into three courses that are taught in an integrated lab-lecture format using case studies and guided-inquiry teaching methods. We have developed a variety of modules for these courses. This article describes one case-study module that allows the student to evaluate data sets to study greenhouse gases and determine if global warming is real and due to anthropogenic activities. The exercise stresses hands-on activities and includes performing two laboratory exercises, the use of two computer programs, a mathematical exercise, an Internet and spreadsheet exercise, and interpretation of scientific data sets and figures. The entire module requires at least 18 contact hours.

  2. Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors

    Science.gov (United States)

    Winker, David; Chepfer, Helene; Noel, Vincent; Cai, Xia

    2017-11-01

    Cloud profiling from active lidar and radar in the A-train satellite constellation has significantly advanced our understanding of clouds and their role in the climate system. Nevertheless, the response of clouds to a warming climate remains one of the largest uncertainties in predicting climate change and for the development of adaptions to change. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. We review recent progress in our understanding of the cloud feedback problem. Capabilities and advantages of active sensors for observing clouds are discussed, along with the importance of active sensors for deriving constraints on cloud feedbacks as an essential component of a global climate observing system.

  3. An A-Train Climatology of Extratropical Cyclone Clouds

    Science.gov (United States)

    Posselt, Derek J.; van den Heever, Susan C.; Booth, James F.; Del Genio, Anthony D.; Kahn, Brian; Bauer, Mike

    2016-01-01

    Extratropical cyclones (ETCs) are the main purveyors of precipitation in the mid-latitudes, especially in winter, and have a significant radiative impact through the clouds they generate. However, general circulation models (GCMs) have trouble representing precipitation and clouds in ETCs, and this might partly explain why current GCMs disagree on to the evolution of these systems in a warming climate. Collectively, the A-train observations of MODIS, CloudSat, CALIPSO, AIRS and AMSR-E have given us a unique perspective on ETCs: over the past 10 years these observations have allowed us to construct a climatology of clouds and precipitation associated with these storms. This has proved very useful for model evaluation as well in studies aimed at improving understanding of moist processes in these dynamically active conditions. Using the A-train observational suite and an objective cyclone and front identification algorithm we have constructed cyclone centric datasets that consist of an observation-based characterization of clouds and precipitation in ETCs and their sensitivity to large scale environments. In this presentation, we will summarize the advances in our knowledge of the climatological properties of cloud and precipitation in ETCs acquired with this unique dataset. In particular, we will present what we have learned about southern ocean ETCs, for which the A-train observations have filled a gap in this data sparse region. In addition, CloudSat and CALIPSO have for the first time provided information on the vertical distribution of clouds in ETCs and across warm and cold fronts. We will also discuss how these observations have helped identify key areas for improvement in moist processes in recent GCMs. Recently, we have begun to explore the interaction between aerosol and cloud cover in ETCs using MODIS, CloudSat and CALIPSO. We will show how aerosols are climatologically distributed within northern hemisphere ETCs, and how this relates to cloud cover.

  4. 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

  5. Clouds and their Impacts on the Greenland Ice Sheet

    Science.gov (United States)

    Shupe, M.; Miller, N.; Solomon, A.; Stone, M.; Cox, C. J.

    2016-12-01

    Clouds play a central role in the climate of the Greenland Ice Sheet, influencing the surface energy and mass budgets. Using observations from the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) campaign and coordinated measurements, we provide a synthesis of cloud information in central Greenland over the past six years. The observations combine a suite of ground-based active and passive remote sensors along with in situ measurements to characterize basic cloud properties, their annual variability, and the manner in which they interact with the surface energy budget. The frequent occurrence and critical role of liquid water clouds is specifically highlighted. It is shown that over the central ice sheet domain due to the high surface albedo, clouds warm the surface year round. Regional synoptic analyses are used to provide insight into the larger-scale drivers of cloudiness over central Greenland, including drivers of moisture advection. A regional coupled system model is used to examine cloud processes in more detail and to up-scale our understanding of cloud-surface interactions to cover the full ice sheet. Simulations reveal a spatially variable role of clouds that may have key implications for both enhancing and modulating melt processes over Greenland.

  6. The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue - metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

    Science.gov (United States)

    Tsushima, Yoko; Brient, Florent; Klein, Stephen A.; Konsta, Dimitra; Nam, Christine C.; Qu, Xin; Williams, Keith D.; Sherwood, Steven C.; Suzuki, Kentaroh; Zelinka, Mark D.

    2017-11-01

    The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. This paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments will also be facilitated by the sharing of diagnostic codes via this catalogue.Any code which implements diagnostics relevant to analysing clouds - including cloud-circulation interactions and the contribution of clouds to estimates of climate sensitivity in models - and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.

  7. Analyses of GOES infrared convective cloud-top temperatures for extended periods - An overview of the 1990 warm season for a subtropical region

    Science.gov (United States)

    Maddox, Robert A.; Howard, Kenneth W.; Negri, Andrew J.

    1992-01-01

    Full-resolution GOES data archived over North America at hourly time intervals are used to examine the seasonal climatology of deep convective cloudiness for two warm seasons. The analyses discussed here concern convective activity across subtropical latitudes from east of Florida to westward of Baja California. It is demonstrated that high-resolution GOES data can be processed on long-time scales to elucidate aspects of regional convective activity and its monthly, seasonal, and interannual variability. The results can be directly compared with corresponding analyses of mean tropospheric features to identify key forcing mechanisms for regional convection.

  8. Achieve a Better Understanding of Cloud and Precipitation Processes for the Promotion of Water Security in Arid and Semi-Arid Regions

    Science.gov (United States)

    Farrah, S.; Al Yazidi, O.

    2016-12-01

    The UAE Research Program for Rain Enhancement Science (UAEREP) is an international research initiative designed to advance the science and technology of rain enhancement. It comes from an understanding of the needs of countries suffering from scarcity of fresh water, and its will to support innovation globally. The Program focuses on the following topics: Climate change, Climate modelling, Climatology, Atmospheric physics, Atmospheric dynamics, Weather modification, Cloud physics, Cloud dynamics, Cloud seeding, Weather radars, Dust modelling, Aerosol physics , Aerosol chemistry, Aerosol/cloud interactions, Water resources, Physics, Numerical modelling, Material science, Nanotechnology, Meteorology, Hydrology, Hydrogeology, Rocket technology, Laser technology, Water sustainability, Remote sensing, Environmental sciences... In 2015, three research teams from Japan, Germany and the UAE led by Prof. Masataka Murakami, Volker Wulfmeyer and Linda Zou have been respectively awarded. Together, they are addressing the issue of water security through innovative ideas: algorithms and sensors, land cover modification, and nanotechnologies to accelerate condensation. These three projects are undergoing now with extensive research and progresses. This session will be an opportunity to present their latest results as well as to detail the evolution of research in rain enhancement. In 2016 indeed, the Program saw a remarkable increase in participation, with 91 pre-proposals from 398 scientists, researchers and technologists affiliated to 180 institutes from 45 countries. The projects submitted are now focusing on modelling to predict weather, autonomous vehicles, rocket technology, lasers or new seeding materials… The science of rain enhancement offers considerable potential in terms of research, development and innovation. Though cloud seeding has been pursued since the late 1940s, it has been viewed as a relatively marginal field of interest for scientists. This benign neglect

  9. Understanding the role of fog in forest hydrology: Stable isotopes as tools for determining input and partitioning of cloud water in montane forests

    Science.gov (United States)

    Scholl, M.; Eugster, W.; Burkard, R.

    2011-01-01

    Understanding the hydrology of tropical montane cloud forests (TMCF) has become essential as deforestation of mountain areas proceeds at an increased rate worldwide. Passive and active cloud-water collectors, throughfall and stemflow collectors, visibility or droplet size measurements, and micrometeorological sensors are typically used to measure the fog water inputs to ecosystems. In addition, stable isotopes may be used as a natural tracer for fog and rain. Previous studies have shown that the isotopic signature of fog tends to be more enriched in the heavier isotopes 2H and 18O than that of rain, due to differences in condensation temperature and history. Differences between fog and rain isotopes are largest when rain is from synoptic-scale storms, and fog or orographic cloud water is generated locally. Smaller isotopic differences have been observed between rain and fog on mountains with orographic clouds, but only a few studies have been conducted. Quantifying fog deposition using isotope methods is more difficult in forests receiving mixed precipitation, because of limitations in the ability of sampling equipment to separate fog from rain, and because fog and rain may, under some conditions, have similar isotopic composition. This article describes the various types of fog most relevant to montane cloud forests and the importance of fog water deposition in the hydrologic budget. A brief overview of isotope hydrology provides the background needed to understand isotope applications in cloud forests. A summary of previous work explains isotopic differences between rain and fog in different environments, and how monitoring the isotopic signature of surface water, soil water and tree xylem water can yield estimates of the contribution of fog water to streamflow, groundwater recharge and transpiration. Next, instrumentation to measure fog and rain, and methods to determine isotopic concentrations in plant and soil water are discussed. The article concludes with

  10. 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

  11. 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…

  12. Reducing the uncertainty in subtropical cloud feedback

    Science.gov (United States)

    Myers, Timothy A.; Norris, Joel R.

    2016-03-01

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

  13. The Cloud Feedback Model Intercomparison Project (CFMIP Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models

    Directory of Open Access Journals (Sweden)

    Y. Tsushima

    2017-11-01

    Full Text Available The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. This paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments will also be facilitated by the sharing of diagnostic codes via this catalogue.Any code which implements diagnostics relevant to analysing clouds – including cloud–circulation interactions and the contribution of clouds to estimates of climate sensitivity in models – and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs.

  14. On the influence of cloud fraction diurnal cycle and sub-grid cloud optical thickness variability on all-sky direct aerosol radiative forcing

    International Nuclear Information System (INIS)

    Min, Min; Zhang, Zhibo

    2014-01-01

    The objective of this study is to understand how cloud fraction diurnal cycle and sub-grid cloud optical thickness variability influence the all-sky direct aerosol radiative forcing (DARF). We focus on the southeast Atlantic region where transported smoke is often observed above low-level water clouds during burning seasons. We use the CALIOP observations to derive the optical properties of aerosols. We developed two diurnal cloud fraction variation models. One is based on sinusoidal fitting of MODIS observations from Terra and Aqua satellites. The other is based on high-temporal frequency diurnal cloud fraction observations from SEVIRI on board of geostationary satellite. Both models indicate a strong cloud fraction diurnal cycle over the southeast Atlantic region. Sensitivity studies indicate that using a constant cloud fraction corresponding to Aqua local equatorial crossing time (1:30 PM) generally leads to an underestimated (less positive) diurnal mean DARF even if solar diurnal variation is considered. Using cloud fraction corresponding to Terra local equatorial crossing time (10:30 AM) generally leads overestimation. The biases are a typically around 10–20%, but up to more than 50%. The influence of sub-grid cloud optical thickness variability on DARF is studied utilizing the cloud optical thickness histogram available in MODIS Level-3 daily data. Similar to previous studies, we found the above-cloud smoke in the southeast Atlantic region has a strong warming effect at the top of the atmosphere. However, because of the plane-parallel albedo bias the warming effect of above-cloud smoke could be significantly overestimated if the grid-mean, instead of the full histogram, of cloud optical thickness is used in the computation. This bias generally increases with increasing above-cloud aerosol optical thickness and sub-grid cloud optical thickness inhomogeneity. Our results suggest that the cloud diurnal cycle and sub-grid cloud variability are important factors

  15. Understanding the Spatiotemporal Structures in Atmosphere-Land Surface Exchange at the Jülich Observatory for Cloud Evolution

    Science.gov (United States)

    Marke, T.; Crewell, S.; Loehnert, U.; Rascher, U.; Schween, J. H.

    2015-12-01

    This study aims at identifying spatial and temporal patterns of surface-atmosphere exchange parameters from highly-resolved and long-term observations. For this purpose, a combination of continuous ground-based measurements and dedicated aircraft campaigns using state-of-the-art remote sensing instrumentation at the Jülich Observatory for Cloud Evolution (JOYCE) is available. JOYCE provides a constantly growing multi-year data set for detailed insight into boundary layer processes and patterns related to surface conditions since 2011. The JOYCE site is embedded in a rural environment with different crop types. The availability of a scanning microwave radiometer and cloud radar is a unique component of JOYCE. The hemispheric scans of the ground-based radiometer allow the identification and quantification of horizontal gradients in water vapor and liquid water path measurements. How these gradients are connected to near-surface fluxes and the topography depending on the mean wind flow and surface fluxes is investigated by exploring the long-term data set. Additionally, situations with strong coupling to the surface can be identified by observing the atmospheric turbulence and stability within the boundary layer, using different lidar systems. Furthermore, the influence of thin liquid water clouds, which are typical for the boundary layer development, on the radiation field and the interaction with the vegetation is examined. Applying a synergistic statistical retrieval approach, using passive microwave and infrared observations, shows an improvement in retrieving thin liquid cloud microphysical properties. The role of vegetation is assessed by exploiting the time series of the sun-induced chlorophyll fluorescence (SIF) signal measured at the ground level using automated measurements. For selected case studies, a comparison to maps of hyperspectral reflectance and SIF obtained from an airborne high-resolution imaging spectrometer is realized.

  16. 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.

  17. Evaluation of the Cloud Fields in the UK Met Office HadGEM3-UKCA Model Using the CCCM Satellite Data Product to Advance Our Understanding of the Influence of Clouds on Tropospheric Composition and Chemistry

    Science.gov (United States)

    Varma, Sunil; Voulgarakis, Apostolos; Liu, Hongyu; Crawford, James H.; White, James

    2016-01-01

    To determine the role of clouds in driving inter-annual and inter-seasonal variability of trace gases in the troposphere and lower stratosphere with a particular focus on the importance of cloud modification of photolysis. To evaluate the cloud fields and their vertical distribution in the HadGEM3 model utilizing CCCM, a unique 3-D cloud data product merged from multiple A-Train satellites (CERES, CloudSat, CALIPSO, and MODIS) developed at the NASA Langley Research Center.

  18. Water isotope tracers of tropical hydroclimate in a warming world

    Science.gov (United States)

    Konecky, B. L.; Noone, D.; Nusbaumer, J. M.; Cobb, K. M.; Di Nezio, P. N.; Otto-Bliesner, B. L.

    2016-12-01

    The tropical water cycle is projected to undergo substantial changes under a warming climate, but direct meteorological observations to contextualize these changes are rare prior to the 20th century. Stable oxygen and hydrogen isotope ratios (δ18O, δD) of environmental waters preserved in geologic archives are increasingly being used to reconstruct terrestrial rainfall over many decades to millions of years. However, a rising number of new, modern-day observations and model simulations have challenged previous interpretations of these isotopic signatures. This presentation systematically evaluates the three main influences on the δ18O and δD of modern precipitation - rainfall amount, cloud type, and moisture transport - from terrestrial stations throughout the tropics, and uses this interpretive framework to understand past changes in terrestrial tropical rainfall. Results indicate that cloud type and moisture transport have a larger influence on modern δ18O and δD of tropical precipitation than previously believed, indicating that isotope records track changes in cloud characteristics and circulation that accompany warmer and cooler climate states. We use our framework to investigate isotopic records of the land-based tropical rain belt during the Last Glacial Maximum, the period of warming following the Little Ice Age, and the 21st century. Proxy and observational data are compared with water isotope-enabled simulations with the Community Earth System Model in order to discuss how global warming and cooling may influence tropical terrestrial hydroclimate.

  19. Evidence for climate change in the satellite cloud record.

    Science.gov (United States)

    Norris, Joel R; Allen, Robert J; Evan, Amato T; Zelinka, Mark D; O'Dell, Christopher W; Klein, Stephen A

    2016-08-04

    Clouds substantially affect Earth's energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts. Here we show that several independent, empirically corrected satellite records exhibit large-scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. These results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature.

  20. The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6.

    Science.gov (United States)

    Webb, Mark J.; Andrews, Timothy; Bodas-Salcedo, Alejandro; Bony, Sandrine; Bretherton, Christopher S.; Chadwick, Robin; Chepfer, Helene; Douville, Herve; Good, Peter; Kay, Jennifer E.; hide

    2017-01-01

    The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud-climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions 'How does the Earth system respond to forcing?' and 'What are the origins and consequences of systematic model biases?' and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity. A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation

  1. 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.

  2. CERN plans global-warming experiment

    CERN Multimedia

    De Laine, M

    1998-01-01

    A controversial theory that proposes that cosmic rays are responsible for global warming, is going to be tested at CERN. Experimentalists will use a cloud chamber to mimic the Earth's atmosphere in order to try and find out if cloud formation is influenced by solar activity (1 page).

  3. Cosmic rays and global warming

    Energy Technology Data Exchange (ETDEWEB)

    Erlykin, A.D. [P.N. Lebedev Physical Institute, Moscow (Russian Federation); Sloan, T. [Lancaster University (United Kingdom); Wolfendale, A.W. [Durham University (United Kingdom)

    2010-07-01

    The possible effects of cosmic rays on clouds could contribute to global warming. The argument is that the observed increased solar activity during the last century caused a decrease in the ionization due to cosmic rays since the lower energy cosmic particles are deflected by the magnetic field created by the increasing solar wind. This would lead to a decrease in cloud cover allowing more heating of the earth by the sun. Meteorological data combined to solar activity observations and simulations show that any effect of solar activity on clouds and the climate is likely to be through irradiance rather than cosmic rays. Since solar irradiance transfers 8 orders of magnitude more energy to the atmosphere than cosmic rays it is more plausible that this can produce a real effect. The total contribution of variable solar activity to global warming is shown to be less than 14% of the total temperature rise. (A.C.)

  4. Microphysical imprint of entrainment in warm cumulus

    Directory of Open Access Journals (Sweden)

    Jennifer D. Small

    2013-07-01

    Full Text Available We analyse the cloud microphysical response to entrainment mixing in warm cumulus clouds observed from the CIRPAS Twin Otter during the GoMACCS field campaign near Houston, Texas, in summer 2006. Cloud drop size distributions and cloud liquid water contents from the Artium Flight phase-Doppler interferometer in conjunction with meteorological observations are used to investigate the degree to which inhomogeneous versus homogeneous mixing is preferred as a function of height above cloud base, distance from cloud edge and aerosol concentration. Using four complete days of data with 101 cloud penetrations (minimum 300 m in length, we find that inhomogeneous mixing primarily explains liquid water variability in these clouds. Furthermore, we show that there is a tendency for mixing to be more homogeneous towards the cloud top, which we attribute to the combination of increased turbulent kinetic energy and cloud drop size with altitude which together cause the Damköhler number to increase by a factor of between 10 and 30 from cloud base to cloud top. We also find that cloud edges appear to be air from cloud centres that have been diluted solely through inhomogeneous mixing. Theory predicts the potential for aerosol to affect mixing type via changes in drop size over the range of aerosol concentrations experienced (moderately polluted rural sites to highly polluted urban sites. However, the observations, while consistent with this hypothesis, do not show a statistically significant effect of aerosol on mixing type.

  5. International Satellite Cloud Climatology Project (ISCCP)

    Data.gov (United States)

    National Aeronautics and Space Administration — International Satellite Cloud Climatology Project (ISCCP) focuses on the distribution and variation of cloud radiative properties to improve the understanding of the...

  6. 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

  7. “Using Statistical Comparisons between SPartICus Cirrus Microphysical Measurements, Detailed Cloud Models, and GCM Cloud Parameterizations to Understand Physical Processes Controlling Cirrus Properties and to Improve the Cloud Parameterizations”

    Energy Technology Data Exchange (ETDEWEB)

    Woods, Sarah [SPEC Inc., Boulder, CO (United States)

    2015-12-01

    The dual objectives of this project were improving our basic understanding of processes that control cirrus microphysical properties and improvement of the representation of these processes in the parameterizations. A major effort in the proposed research was to integrate, calibrate, and better understand the uncertainties in all of these measurements.

  8. Aerosols and clouds in chemical transport models and climate models.

    Energy Technology Data Exchange (ETDEWEB)

    Lohmann,U.; Schwartz, S. E.

    2008-03-02

    Clouds exert major influences on both shortwave and longwave radiation as well as on the hydrological cycle. Accurate representation of clouds in climate models is a major unsolved problem because of high sensitivity of radiation and hydrology to cloud properties and processes, incomplete understanding of these processes, and the wide range of length scales over which these processes occur. Small changes in the amount, altitude, physical thickness, and/or microphysical properties of clouds due to human influences can exert changes in Earth's radiation budget that are comparable to the radiative forcing by anthropogenic greenhouse gases, thus either partly offsetting or enhancing the warming due to these gases. Because clouds form on aerosol particles, changes in the amount and/or composition of aerosols affect clouds in a variety of ways. The forcing of the radiation balance due to aerosol-cloud interactions (indirect aerosol effect) has large uncertainties because a variety of important processes are not well understood precluding their accurate representation in models.

  9. Cosmic rays, clouds, and climate

    DEFF Research Database (Denmark)

    Marsh, N.; Svensmark, Henrik

    2000-01-01

    between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (> 273 K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (similar to1%) a liquid cloud...... that a mechanism to explain the cosmic ray-cloud link might be found through the role of atmospheric ionisation in aerosol production and/or growth. Observations of local aerosol increases in low cloud due to ship exhaust indicate that a small perturbation in atmospheric aerosol can have a major impact on low...... cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth's radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability...

  10. Understanding the Relationships Between Lightning, Cloud Microphysics, and Airborne Radar-derived Storm Structure During Hurricane Karl (2010)

    Science.gov (United States)

    Reinhart, Brad; Fuelberg, Henry; Blakeslee, Richard; Mach, Douglas; Heymsfield, Andrew; Bansemer, Aaron; Durden, Stephen L.; Tanelli, Simone; Heymsfield, Gerald; Lambrigtsen, Bjorn

    2013-01-01

    This study explores relationships between lightning, cloud microphysics, and tropical cyclone (TC) storm structure in Hurricane Karl (16 September 2010) using data collected by the NASA DC-8 and Global Hawk (GH) aircraft during NASA's Genesis and Rapid Intensification Processes (GRIP) experiment. The research capitalizes on the unique opportunity provided by GRIP to synthesize multiple datasets from two aircraft and analyze the microphysical and kinematic properties of an electrified TC. Five coordinated flight legs through Karl by the DC-8 and GH are investigated, focusing on the inner-core region (within 50km of the storm center) where the lightning was concentrated and the aircraft were well coordinated. GRIP datasets are used to compare properties of electrified and nonelectrified inner-core regions that are related to the noninductive charging mechanism, which is widely accepted to explain the observed electric fields within thunderstorms. Three common characteristics of Karl's electrified regions are identified: 1) strong updrafts of 10-20ms21, 2) deep mixed-phase layers indicated by reflectivities.30 dBZ extending several kilometers above the freezing level, and 3) microphysical environments consisting of graupel, very small ice particles, and the inferred presence of supercooled water. These characteristics describe an environment favorable for in situ noninductive charging and, hence, TC electrification. The electrified regions in Karl's inner core are attributable to a microphysical environment that was conducive to electrification because of occasional, strong convective updrafts in the eyewall.

  11. Satellite-Based Analysis of a Warm Conveyor Belt in a Marine Extratropical Cyclone

    Science.gov (United States)

    Crespo, J.; Posselt, D. J.

    2015-12-01

    Extratropical cyclones play a paramount role in Earth's climate through meridional energy transport from the equator to the poles, as well as through cloud and precipitation formation by providing a majority of observed precipitation in the midlatitudes. The warm conveyor belt is a poleward airstream of ascending moisture that rises from the boundary layer to the upper troposphere. It is responsible for transporting a preponderant amount of water vapor present in an extratropical cyclone, with nearly 100% efficiency at precipitating all transported moisture. The community's understanding of marine extratropical cyclones and their synoptic dynamics originates from the Shapiro and Keyser Model, but there is less understanding of the mesoscale evolution of the cloud and precipitation structures within an extratropical cyclone and its warm conveyor belt. This research aims to better understand extratropical cyclone and warm conveyor belt evolution on the mesoscale using a specific case study. In late November 2006, a marine extratropical cyclone formed east of Florida in the Atlantic Ocean, travelling parallel to the eastern seaboard for nearly a week. Model analysis showed the presence of a strong warm conveyor belt associated with the cyclone. Given that the system remained in nearly the same longitudinal position, it was observed multiple times by NASA's Afternoon-Train (A-Train) satellite constellation. CloudSat radar reflectivity profiles and ECMWF-AUX thermodynamic fields show a transition from stratiform to convective precipitation along the northern edge of the conveyer belt, with larger vertical instability and isolated higher rain rates. Examination of the storm scale context indicates this convection may develop in place rather than via interaction with the cold front. These results give us a better understanding of structural evolution of clouds and precipitation as it interacts with the cyclone-scale dynamics and surrounding thermodynamic environment.

  12. Advanced Understanding of Convection Initiation and Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification over the United Arab Emirates

    Science.gov (United States)

    Wulfmeyer, V.; Behrendt, A.; Branch, O.; Schwitalla, T.

    2016-12-01

    A prerequisite for significant precipitation amounts is the presence of convergence zones. These are due to land surface heterogeneity, orography as well as mesoscale and synoptic scale circulations. Only, if these convergence zones are strong enough and interact with an upper level instability, deep convection can be initiated. For the understanding of convection initiation (CI) and optimal cloud seeding deployment, it is essential that these convergence zones are detected before clouds are developing in order to preempt the decisive microphysical processes for liquid water and ice formation. In this presentation, a new project on Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL) is introduced, which is funded by the United Arab Emirates Rain Enhancement Program (UAEREP). This project has two research components. The first component focuses on an improved detection and forecasting of convergence zones and CI by a) operation of scanning Doppler lidar and cloud radar systems during two seasonal field campaigns in orographic terrain and over the desert in the UAE, and b) advanced forecasting of convergence zones and CI with the WRF-NOAHMP model system. Nowcasting to short-range forecasting of convection will be improved by the assimilation of Doppler lidar and the UAE radar network data. For the latter, we will apply a new model forward operator developed at our institute. Forecast uncertainties will be assessed by ensemble simulations driven by ECMWF boundaries. The second research component of OCAL will study whether artificial modifications of land surface heterogeneity are possible through plantations or changes of terrain, leading to an amplification of convergence zones. This is based on our pioneering work on high-resolution modeling of the impact of plantations on weather and climate in arid regions. A specific design of the shape and location of plantations can lead to the formation of convergence zones, which can

  13. Instantaneous Linkages between Clouds and Large-Scale Meteorology over the Southern Ocean in Observations and a Climate Model

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Casey J. [Department of Atmospheric Sciences, University of Washington, Seattle, Washington; Hartmann, Dennis L. [Department of Atmospheric Sciences, University of Washington, Seattle, Washington; Ma, Po-Lun [Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington

    2017-12-01

    Instantaneous, coincident, footprint-level satellite observations of cloud properties and radiation taken during austral summer over the Southern Ocean are used to study relationships between clouds and large-scale meteorology. Cloud properties are very sensitive to the strength of vertical motion in the middle-troposphere, and low-cloud properties are sensitive to estimated inversion strength, low-level temperature advection, and sea surface temperature. These relationships are quantified. An index for the meteorological anomalies associated with midlatitude cyclones is presented, and it is used to reveal the sensitivity of clouds to the meteorology within the warm- and cold-sector of cyclones. The observed relationships between clouds and meteorology are compared to those in the Community Atmosphere Model version 5 (CAM5) using satellite simulators. Low-clouds simulated by CAM5 are too few, too bright, and contain too much ice, and low-clouds located in the cold-sector of cyclones are too sensitive to variations in the meteorology. The latter two biases are dramatically reduced when CAM5 is coupled with an updated boundary layer parameterization know as Cloud Layers Unified by Binormals (CLUBB). More generally, this study demonstrates that examining the instantaneous timescale is a powerful approach to understanding the physical processes that control clouds and how they are represented in climate models. Such an evaluation goes beyond the cloud climatology and exposes model bias under various meteorological conditions.

  14. Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review

    Science.gov (United States)

    Klein, Stephen A.; Hall, Alex; Norris, Joel R.; Pincus, Robert

    2017-11-01

    The response to warming of tropical low-level clouds including both marine stratocumulus and trade cumulus is a major source of uncertainty in projections of future climate. Climate model simulations of the response vary widely, reflecting the difficulty the models have in simulating these clouds. These inadequacies have led to alternative approaches to predict low-cloud feedbacks. Here, we review an observational approach that relies on the assumption that observed relationships between low clouds and the "cloud-controlling factors" of the large-scale environment are invariant across time-scales. With this assumption, and given predictions of how the cloud-controlling factors change with climate warming, one can predict low-cloud feedbacks without using any model simulation of low clouds. We discuss both fundamental and implementation issues with this approach and suggest steps that could reduce uncertainty in the predicted low-cloud feedback. Recent studies using this approach predict that the tropical low-cloud feedback is positive mainly due to the observation that reflection of solar radiation by low clouds decreases as temperature increases, holding all other cloud-controlling factors fixed. The positive feedback from temperature is partially offset by a negative feedback from the tendency for the inversion strength to increase in a warming world, with other cloud-controlling factors playing a smaller role. A consensus estimate from these studies for the contribution of tropical low clouds to the global mean cloud feedback is 0.25 ± 0.18 W m-2 K-1 (90% confidence interval), suggesting it is very unlikely that tropical low clouds reduce total global cloud feedback. Because the prediction of positive tropical low-cloud feedback with this approach is consistent with independent evidence from low-cloud feedback studies using high-resolution cloud models, progress is being made in reducing this key climate uncertainty.

  15. Evaluation of Arctic Clouds And Their Response to External Forcing in Climate Models

    Science.gov (United States)

    Wang, Y.; Jiang, J. H.; Ming, Y.; Su, H.; Yung, Y. L.

    2017-12-01

    A warming Arctic is undergoing significant environmental changes, mostly evidenced by the reduction in Arctic sea-ice extent (SIE). However, the role of Arctic clouds in determining the sea ice melting remains elusive, as different phases of clouds can induce either positive or negative radiative forcing in different seasons. The possible cloud feedbacks following the opened ocean surface are also debatable due to variations of polar boundary structure. Therefore, Arctic cloud simulation has long been considered as the largest source of uncertainty in the climate sensitivity assessment. Other local or remote atmospheric factors, such as poleward moisture and heat transport as well as atmospheric aerosols seeding liquid and ice clouds, further complicate our understanding of the Arctic cloud change. Our recent efforts focus on the post-CMIP5 and CMIP6 models, which improve atmospheric compositions, cloud macro- and microphysics, convection parameterizations, etc. In this study, we utilize long-term satellite measurements with high-resolution coverage and broad wavelength spectrum to evaluate the mean states and variations of mixed-phase clouds in the Arctic, along with the concurrent moisture and SIE measurements. The model sensitivity experiments to understand external perturbations on the atmosphere-cryosphere coupling in the Arctic will be presented.

  16. Dynamical and thermodynamical coupling between the North Atlantic subtropical high and the marine boundary layer clouds in boreal summer

    Science.gov (United States)

    Wei, Wei; Li, Wenhong; Deng, Yi; Yang, Song; Jiang, Jonathan H.; Huang, Lei; Liu, W. Timothy

    2018-04-01

    This study investigates dynamical and thermodynamical coupling between the North Atlantic subtropical high (NASH), marine boundary layer (MBL) clouds, and the local sea surface temperatures (SSTs) over the North Atlantic in boreal summer for 1984-2009 using NCEP/DOE Reanalysis 2 dataset, various cloud data, and the Hadley Centre sea surface temperature. On interannual timescales, the summer mean subtropical MBL clouds to the southeast of the NASH is actively coupled with the NASH and local SSTs: a stronger (weaker) NASH is often accompanied with an increase (a decrease) of MBL clouds and abnormally cooler (warmer) SSTs along the southeast flank of the NASH. To understand the physical processes between the NASH and the MBL clouds, the authors conduct a data diagnostic analysis and implement a numerical modeling investigation using an idealized anomalous atmospheric general circulation model (AGCM). Results suggest that significant northeasterly anomalies in the southeast flank of the NASH associated with an intensified NASH tend to induce stronger cold advection and coastal upwelling in the MBL cloud region, reducing the boundary surface temperature. Meanwhile, warm advection associated with the easterly anomalies from the African continent leads to warming over the MBL cloud region at 700 hPa. Such warming and the surface cooling increase the atmospheric static stability, favoring growth of the MBL clouds. The anomalous diabatic cooling associated with the growth of the MBL clouds dynamically excites an anomalous anticyclone to its north and contributes to strengthening of the NASH circulation in its southeast flank. The dynamical and thermodynamical couplings and their associated variations in the NASH, MBL clouds, and SSTs constitute an important aspect of the summer climate variability over the North Atlantic.

  17. Cloud-based Virtual Reality Integrated Automatic Presentation Script for Understanding Urban Design Concepts in the Consensus Process

    OpenAIRE

    Yuanyi, Zhang; Zhenjiang, Shen; Kai, Wang; Fumihiko, Kobayashi; Xinyi, Lin

    2017-01-01

    In recent years, designers have used various types of tools, such as public Participation GIS (PP GIS) and Virtual Reality Modelling Language (VRML), to improve urban design concept understanding in the consensus process. However, these tools were frequently criticized as being too complex for the majority of potential users. Moreover, due to the limitations of data compression, hardware performance, network bandwidth and costs of current virtual reality platforms, the users need to gather in...

  18. 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

  19. Global Warming Blame the Sun

    CERN Document Server

    Calder, N

    1997-01-01

    Concern about climate change reaches a political peak at a UN conference in Kyoto, 1-10 December, but behind the scenes the science is in turmoil. A challenge to the hypothesis that greenhouse gases are responsible for global warming comes from the discovery that cosmic rays from the Galaxy are involved in making clouds (Svensmark and Friis-Christensen, 1997). During the 20th Century the wind from the Sun has grown stronger and the count of cosmic rays has diminished. With fewer clouds, the EarthÕs surface has warmed up. This surprising mechanism explains the link between the Sun and climate change that astronomers and geophysicists have suspected for 200 years.

  20. Understanding the Asian summer monsoon response to greenhouse warming: the relative roles of direct radiative forcing and sea surface temperature change

    Science.gov (United States)

    Li, Xiaoqiong; Ting, Mingfang

    2017-10-01

    Future hydroclimate projections from state-of-the-art climate models show large uncertainty and model spread, particularly in the tropics and over the monsoon regions. The precipitation and circulation responses to rising greenhouse gases involve a fast component associated with direct radiative forcing and a slow component associated with sea surface temperature (SST) warming; the relative importance of the two may contribute to model discrepancies. In this study, regional hydroclimate responses to greenhouse warming are assessed using output from coupled general circulation models in the Coupled Model Intercomparison Project-Phase 5 (CMIP5) and idealized atmospheric general circulation model experiments from the Atmosphere Model Intercomparison Project. The thermodynamic and dynamic mechanisms causing the rainfall changes are examined using moisture budget analysis. Results show that direct radiative forcing and SST change exert significantly different responses both over land and ocean. For most part of the Asian monsoon region, the summertime rainfall changes are dominated by the direct CO2 radiative effect through enhanced monsoon circulation. The response to SST warming shows a larger model spread compared to direct radiative forcing, possibly due to the cancellation between the thermodynamical and dynamical components. While the thermodynamical response of the Asian monsoon is robust across the models, there is a lack of consensus for the dynamical response among the models and weak multi-model mean responses in the CMIP5 ensemble, which may be related to the multiple physical processes evolving on different time scales.

  1. Regional air pollution brightening reverses the greenhouse gases induced warming-elevation relationship

    Science.gov (United States)

    Zeng, Zhenzhong; Chen, Anping; Ciais, Philippe; Li, Yue; Li, Laurent Z. X.; Vautard, Robert; Zhou, Liming; Yang, Hui; Huang, Mengtian; Piao, Shilong

    2015-06-01

    Mountain waters, glaciers, hazards, and biodiversity are vulnerable to the impacts of global warming. Warming is projected to amplify over mountains by global climate models, yet meteorological records do not show a uniform acceleration of warming with elevation. Here we explore warming-elevation relationships using records from 2660 meteorological stations and determine that the vertical gradient of warming rate varies with location. The warming is faster at higher altitudes in Asia and western North America, but the opposite is observed over Central Europe and eastern North America which have received more short-wave radiation (brightening) associated with a decrease of aerosols and clouds since the 1980s. We found that altitudinal differences in air pollution (brightening), with observations showing more short-wave radiation received at low altitudes than at mountains, modulate the warming-elevation relationships. The advance in understanding of the drivers of regional climate change will contribute to the formulation of strategies for climate change mitigation at high elevations.

  2. Atlantic Multidecadal Oscillation footprint on global high cloud cover

    Science.gov (United States)

    Vaideanu, Petru; Dima, Mihai; Voiculescu, Mirela

    2017-12-01

    Due to the complexity of the physical processes responsible for cloud formation and to the relatively short satellite database of continuous data records, cloud behavior in a warming climate remains uncertain. Identifying physical links between climate modes and clouds would contribute not only to a better understanding of the physical processes governing their formation and dynamics, but also to an improved representation of the clouds in climate models. Here, we identify the global footprint of the Atlantic Multidecadal Oscillation (AMO) on high cloud cover, with focus on the tropical and North Atlantic, tropical Pacific and on the circum-Antarctic sector. In the tropical band, the sea surface temperature (SST) and high cloud cover (HCC) anomalies are positively correlated, indicating a dominant role played by convection in mediating the influence of the AMO-related SST anomalies on the HCC field. The negative SST-HCC correlation observed in North Atlantic could be explained by the reduced meridional temperature gradient induced by the AMO positive phase, which would be reflected in less storms and negative HCC anomalies. A similar negative SST-HCC correlation is observed around Antarctica. The corresponding negative correlation around Antarctica could be generated dynamically, as a response to the intensified upward motion in the Ferrel cell. Despite the inherent imperfection of the observed and reanalysis data sets, the AMO footprint on HCC is found to be robust to the choice of dataset, statistical method, and specific time period considered.

  3. 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

  4. Marine cloud brightening - as effective without clouds

    Science.gov (United States)

    Ahlm, Lars; Jones, Andy; Stjern, Camilla W.; Muri, Helene; Kravitz, Ben; Egill Kristjánsson, Jón

    2017-11-01

    Marine cloud brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine cloud brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of cloud droplets. Here we present results from coordinated simulations with three Earth system models (ESMs) participating in the Geoengineering Model Intercomparison Project (GeoMIP) G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30° N and 30° S are set in each model to generate a global-mean effective radiative forcing (ERF) of -2.0 W m-2 at the top of the atmosphere. We find that the injection increases the cloud droplet number concentration in lower layers, reduces the cloud-top effective droplet radius, and increases the cloud optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of clouds occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. These findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought.

  5. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    Science.gov (United States)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter N.; Austin, Phillip H.; Bacmeister, Julio T.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; DelGenio, Anthony; hide

    2013-01-01

    1] CGILS-the CFMIP-GASS Intercomparison of Large Eddy Models (LESs) and single column models (SCMs)-investigates the mechanisms of cloud feedback in SCMs and LESs under idealized climate change perturbation. This paper describes the CGILS results from 15 SCMs and 8 LES models. Three cloud regimes over the subtropical oceans are studied: shallow cumulus, cumulus under stratocumulus, and well-mixed coastal stratus/stratocumulus. In the stratocumulus and coastal stratus regimes, SCMs without activated shallow convection generally simulated negative cloud feedbacks, while models with active shallow convection generally simulated positive cloud feedbacks. In the shallow cumulus alone regime, this relationship is less clear, likely due to the changes in cloud depth, lateral mixing, and precipitation or a combination of them. The majority of LES models simulated negative cloud feedback in the well-mixed coastal stratus/stratocumulus regime, and positive feedback in the shallow cumulus and stratocumulus regime. A general framework is provided to interpret SCM results: in a warmer climate, the moistening rate of the cloudy layer associated with the surface-based turbulence parameterization is enhanced; together with weaker large-scale subsidence, it causes negative cloud feedback. In contrast, in the warmer climate, the drying rate associated with the shallow convection scheme is enhanced. This causes positive cloud feedback. These mechanisms are summarized as the "NESTS" negative cloud feedback and the "SCOPE" positive cloud feedback (Negative feedback from Surface Turbulence under weaker Subsidence-Shallow Convection PositivE feedback) with the net cloud feedback depending on how the two opposing effects counteract each other. The LES results are consistent with these interpretations

  6. Quantifying Amount and Variability of Cloud Water Inputs Using Active-Strand Collector, Ceilometer, Dewpoint, and Photographic Measurements

    Science.gov (United States)

    Scholl, M. A.; Bassiouni, M.; Murphy, S. F.; Gonzalez, G.; Van Beusekom, A. E.; Torres-Sanchez, A.; Estrada-Ruiz, C.

    2015-12-01

    Cloud water associated with orographic processes contributes to soil moisture and streamflow, suppresses transpiration, and moderates drought in tropical mountain forests. It is difficult to quantify, yet may be vulnerable to changes in amount and frequency due to warming climate. Cloud immersion is characterized and monitored as part of the ecohydrology research of the USGS Water, Energy and Biogeochemical Budgets (WEBB) program and the Luquillo Critical Zone Observatory (CZO). Stable-isotope studies indicated cloud water may contribute significantly to headwater streamflow, and measurements with an active-strand collector yielded estimates of overnight cloud water deposition rates on Pico del Este (1050 m); but cloud liquid water content and spatial and temporal variability are not well understood. At five sites spanning the lifting condensation level to ridge-top (600-1000 m) in the Luquillo Mountains, cloud immersion conditions are monitored using time-lapse photography and temperature/ relative humidity (T/RH) sensors. A ceilometer, installed at 99 m on the windward slope on 4/29/2013, provides longer-term data to understand variation in cloud base altitude and to detect changes that may occur with warming climate. The cloud-zone sites range from tropical wet forest (mixed species) to rain forest (sierra palm) to elfin cloud forest. T/RH sensors indicated foggy conditions when temperature measurements to the images. These complementary data sets provide quantification of spatial and temporal patterns of cloud immersion, and areal estimates of cloud water deposition will be made to determine importance in the water budget.

  7. Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review

    Science.gov (United States)

    Vial, Jessica; Bony, Sandrine; Stevens, Bjorn; Vogel, Raphaela

    2017-11-01

    Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important topic of investigation. We review physical understanding of these key controlling factors and discuss the value of the different approaches that have been developed so far, based on global and high-resolution model experimentations and process-oriented analyses across a range of models and for observations. The trade-wind cloud feedbacks appear to depend on two important aspects: (1) how cloudiness near cloud-base is controlled by the local interplay between turbulent, convective and radiative processes; (2) how these processes interact with their surrounding environment and are influenced by mesoscale organization. Our synthesis of studies that have explored these aspects suggests that the large diversity of model responses is related to fundamental differences in how the processes controlling trade cumulus operate in models, notably, whether they are parameterized or resolved. In models with parameterized convection, cloudiness near cloud-base is very sensitive to the vigor of convective mixing in response to changes in environmental conditions. This is in contrast with results from high-resolution models, which suggest that cloudiness near cloud-base is nearly invariant with warming and independent of large-scale environmental changes. Uncertainties are difficult to narrow using current observations, as the trade cumulus variability and its relation to large-scale environmental factors strongly depend on the time and/or spatial scales at which the mechanisms are evaluated. New opportunities for testing physical understanding of the factors controlling shallow cumulus cloud responses using

  8. Understanding the Mechanisms Underlying Heterotrophic CO2 and CH4 Fluxes in a Peatland with Deep Soil Warming and Atmospheric CO2 Enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Bridgham, Scott D. [Univ. of Oregon, Eugene, OR (United States). Inst. of Ecology and Evolution; Keller, Jason K. [Chapman Univ., Orange, CA (United States). Schmid College of Science and Technology; Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States). Dept. of Earth and Atmospheric Sciences and Agronomy

    2016-09-12

    This project was funded from June 15, 2012 through June 15, 2015, with a no-cost extension until Sept. 15, 2016. Our project focused on a whole-ecosystem warming and enhanced atmospheric CO2 experiment in the S1 Bog in Marcell Experimental Forest in northern Minnesota, USA called “Spruce and Peatland Responses Under Climatic and Environmental Change” (SPRUCE; http://mnspruce.ornl.gov). Construction of substantial infrastructure required for these treatments was beyond our control and led to a staggered initiation of experimental treatments at this site. Deep peat heating (DPH) was instituted in June 2014, whole-ecosystem warming began in August 2015, and the CO2 enhancement began in June 2016. Prior to the initiation of the experimental treatments, we completed a large amount of research to better understand factors controlling anaerobic carbon (C) cycling, and particularly methane (CH4) dynamics, in northern peatlands in an effort to put the SPRUCE project in a broader context. We additionally focused extensively on the DPH treatment, which provided a unique opportunity to isolate warming effects on the vast reservoir of permanently anaerobic C stored in peatlands below the water table.

  9. The Influence of Sea Ice on Arctic Low Cloud Properties and Radiative Effects

    Science.gov (United States)

    Taylor, Patrick C.

    2015-01-01

    The Arctic is one of the most climatically sensitive regions of the Earth. Climate models robustly project the Arctic to warm 2-3 times faster than the global mean surface temperature, termed polar warming amplification (PWA), but also display the widest range of surface temperature projections in this region. The response of the Arctic to increased CO2 modulates the response in tropical and extra-tropical regions through teleconnections in the atmospheric circulation. An increased frequency of extreme precipitation events in the northern mid-latitudes, for example, has been linked to the change in the background equator-to-pole temperature gradient implied by PWA. Understanding the Arctic climate system is therefore important for predicting global climate change. The ice albedo feedback is the primary mechanism driving PWA, however cloud and dynamical feedbacks significantly contribute. These feedback mechanisms, however, do not operate independently. How do clouds respond to variations in sea ice? This critical question is addressed by combining sea ice, cloud, and radiation observations from satellites, including CERES, CloudSAT, CALIPSO, MODIS, and microwave radiometers, to investigate sea ice-cloud interactions at the interannual timescale in the Arctic. Cloud characteristics are strongly tied to the atmospheric dynamic and thermodynamic state. Therefore, the sensitivity of Arctic cloud characteristics, vertical distribution and optical properties, to sea ice anomalies is computed within atmospheric dynamic and thermodynamic regimes. Results indicate that the cloud response to changes in sea ice concentration differs significantly between atmospheric state regimes. This suggests that (1) the atmospheric dynamic and thermodynamic characteristics and (2) the characteristics of the marginal ice zone are important for determining the seasonal forcing by cloud on sea ice variability.

  10. Characterization of the cloud conditions at Ny-Ålesund using sensor synergy and representativeness of the observed clouds across Arctic sites

    Science.gov (United States)

    Nomokonova, Tatiana; Ebell, Kerstin; Löhnert, Ulrich; Maturilli, Marion

    2017-04-01

    Clouds are one of the crucial components of the hydrological and energy cycles and thus affecting the global climate. Their special importance in Arctic regions is defined by cloud's influence on the radiation budget. Arctic clouds usually occur at low altitudes and often contain highly concentrated tiny liquid drops. During winter, spring, and autumn periods such clouds tend to conserve the long-wave radiation in the atmosphere and, thus, produce warming of the Arctic climate. In summer though clouds efficiently scatter the solar radiation back to space and, therefore, induce a cooling effect. An accurate characterization of the net effect of clouds on the Arctic climate requires long-term and precise observations. However, only a few measurement sites exist which perform continuous, vertically resolved observations of clouds in the Arctic, e.g. in Alaska, Canada, and Greenland. These sites typically make use of a combination of different ground-based remote sensing instruments, e.g. cloud radar, ceilometer and microwave radiometer in order to characterize clouds. Within the Transregional Collaborative Research Center (TR 172) "Arctic Amplification: Climate Relevant Atmospheric and Surface Processes, and Feedback Mechanisms (AC)3" comprehensive observations of the atmospheric column are performed at the German-French Research Station AWIPEV at Ny-Ålesund, Svalbard. Ny-Ålesund is located in the warmest part of the Arctic where climate is significantly influenced by adiabatic heating from the warm ocean. Thus, measurements at Ny-Ålesund will complement our understanding of cloud formation and development in the Arctic. This particular study is devoted to the characterization of the cloud macro- and microphysical properties at Ny-Ålesund and of the atmospheric conditions, under which these clouds form and develop. To this end, the information of the various instrumentation at the AWIPEV observatory is synergistically analysed: information about the thermodynamic

  11. Fractal Quasar Clouds

    Science.gov (United States)

    Bottorff, Mark; Ferland, Gary

    2001-03-01

    This paper examines whether a fractal cloud geometry can reproduce the emission-line spectra of active galactic nuclei (AGNs). The nature of the emitting clouds is unknown, but many current models invoke various types of magnetohydrodynamic confinement. Recent studies have argued that a fractal distribution of clouds, in which subsets of clouds occur in self-similar hierarchies, is a consequence of such confinement. Whatever the confinement mechanism, fractal cloud geometries are found in nature and may be present in AGNs too. We first outline how a fractal geometry can apply at the center of a luminous quasar. Scaling laws are derived that establish the number of hierarchies, typical sizes, column densities, and densities. Photoionization simulations are used to predict the integrated spectrum from the ensemble. Direct comparison with observations establishes all model parameters so that the final predictions are fully constrained. Theory suggests that denser clouds might form in regions of higher turbulence and that larger turbulence results in a wider dispersion of physical gas densities. An increase in turbulence is expected deeper within the gravitational potential of the black hole, resulting in a density gradient. We mimic this density gradient by employing two sets of clouds with identical fractal structuring but different densities. The low-density clouds have a lower column density and large covering factor similar to the warm absorber. The high-density clouds have high column density and smaller covering factor similar to the broad-line region (BLR). A fractal geometry can simultaneously reproduce the covering factor, density, column density, BLR emission-line strengths, and BLR line ratios as inferred from observation. Absorption properties of the model are consistent with the integrated line-of-sight column density as determined from observations of X-ray absorption, and when scaled to a Seyfert galaxy, the model is consistent with the number of

  12. The Oceans 2015 Initiative, Part II - An updated understanding of the observed and projected impacts of ocean warming and acidification on marine and coastal socioeconomic activities/sectors

    International Nuclear Information System (INIS)

    Weatherdon, Lauren; Sumaila, Rashid; Cheung, William W.L.; Rogers, Alex; Magnan, Alexandre

    2015-01-01

    Between 1971 and 2010, the oceans have absorbed approximately 93% of the excess heat caused by global warming, leading to several major changes such as the increase in stratification, limitation in the circulation of nutrients from deep waters to the surface, and sea level rise. In addition, the oceans absorbed 26% of anthropogenic CO 2 emitted since the start of the Industrial Revolution, which resulted in ocean acidification. Together, these processes strongly affect marine and coastal species' geographic distribution, abundance, migration patterns and phenology. As a consequence of these complex environmental changes, marine and coastal human sectors (i.e., fisheries, aquaculture, coastal tourism and health) are in turn at risk. This report provides an updated synthesis of what the science tells us about such a risk, based upon IPCC AR5 (2013- 2014) and published scientific articles and grey literature that have been published between July 2013 and April 2015. Although uncertainty remains strong, there is growing scientific evidence that ocean warming and acidification will affect key resources for societies through ecosystems services. For example, while AR5 indicated that coral reefs had little scope for adaptation, recent research has suggested that there may be some capacity for some coral species to recover from climatic hocks and bleaching events, and to acquire heat resistance through acclimatization. This will have huge implications on many coastal economies in the developing and developed countries. More generally, key sectors will be affected. For example, while the fish catch potential is expected to decrease at the global scale, it will show diversified trends at the regional scale as fish stocks have started shifting in latitudes or by depth. This will impact regional to local fisheries systems. Also, climate and acidification-related impacts to existing aquaculture are expected to be generally negative, with impacts varying by location

  13. Global warming

    CERN Document Server

    Hulme, M

    1998-01-01

    Global warming-like deforestation, the ozone hole and the loss of species- has become one of the late 20the century icons of global environmental damage. The threat, is not the reality, of such a global climate change has motivated governments. businesses and environmental organisations, to take serious action ot try and achieve serious control of the future climate. This culminated last December in Kyoto in the agreement for legally-binding climate protocol. In this series of three lectures I will provide a perspective on the phenomenon of global warming that accepts the scientific basis for our concern, but one that also recognises the dynamic interaction between climate and society that has always exited The future will be no different. The challenge of global warning is not to pretend it is not happening (as with some pressure groups), nor to pretend it threatens global civilisation (as with other pressure groups), and it is not even a challenge to try and stop it from happening-we are too far down the ro...

  14. 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.

  15. Understanding climatic change

    International Nuclear Information System (INIS)

    Fellous, J.L.; Gautier, C.; Andre, J.C.; Balstad, R.; Boucher, O.; Brasseur, G.; Chahine, M.T.; Chanin, M.L.; Ciais, P.; Corell, W.; Duplessy, J.C.; Hourcade, J.C.; Jouzel, J.; Kaufman, Y.J.; Laval, K.; Le Treut, H.; Minster, J.F.; Moore, B. III; Morel, P.; Rasool, S.I.; Remy, F.; Smith, R.C.; Somerville, R.C.J.; Wood, E.F.; Wood, H.; Wunsch, C.

    2007-01-01

    Climatic change is gaining ground and with no doubt is stimulated by human activities. It is therefore urgent to better understand its nature, importance and potential impacts. The chapters of this book have been written by US and French experts of the global warming question. After a description of the Intergovernmental Panel on Climate Change (IPCC, GIEC in French) consensus, they present the past and present researches on each of the main component of the climate system, on the question of climatic change impacts and on the possible answers. The conclusion summarizes the results of each chapter. Content: presentation of the IPCC; greenhouse effect, radiation balance and clouds; atmospheric aerosols and climatic change; global water cycle and climate; influence of climatic change on the continental hydrologic cycle; ocean and climate; ice and climate; global carbon cycle; about some impacts of climatic change on Europe and the Atlantic Ocean; interaction between atmospheric chemistry and climate; climate and society, the human dimension. (J.S.)

  16. Committed warming inferred from observations

    Science.gov (United States)

    Mauritsen, Thorsten; Pincus, Robert

    2017-09-01

    Due to the lifetime of CO2, the thermal inertia of the oceans, and the temporary impacts of short-lived aerosols and reactive greenhouse gases, the Earth’s climate is not equilibrated with anthropogenic forcing. As a result, even if fossil-fuel emissions were to suddenly cease, some level of committed warming is expected due to past emissions as studied previously using climate models. Here, we provide an observational-based quantification of this committed warming using the instrument record of global-mean warming, recently improved estimates of Earth’s energy imbalance, and estimates of radiative forcing from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Compared with pre-industrial levels, we find a committed warming of 1.5 K (0.9-3.6, 5th-95th percentile) at equilibrium, and of 1.3 K (0.9-2.3) within this century. However, when assuming that ocean carbon uptake cancels remnant greenhouse gas-induced warming on centennial timescales, committed warming is reduced to 1.1 K (0.7-1.8). In the latter case there is a 13% risk that committed warming already exceeds the 1.5 K target set in Paris. Regular updates of these observationally constrained committed warming estimates, although simplistic, can provide transparent guidance as uncertainty regarding transient climate sensitivity inevitably narrows and the understanding of the limitations of the framework is advanced.

  17. Exploring the differences in cloud properties observed by the Terra and Aqua MODIS Sensors

    Directory of Open Access Journals (Sweden)

    N. Meskhidze

    2009-05-01

    Full Text Available The aerosol-cloud interaction in different parts of the globe is examined here using multi-year statistics of remotely sensed data from two MODIS sensors aboard NASA's Terra (morning and Aqua (afternoon satellites. Simultaneous retrievals of aerosol loadings and cloud properties by the MODIS sensor allowed us to explore morning-to-afternoon variation of liquid cloud fraction (CF and optical thickness (COT for clean, moderately polluted and heavily polluted clouds in different seasons. Data analysis for seven-years of MODIS retrievals revealed strong temporal and spatial patterns in morning-to-afternoon variation of cloud fraction and optical thickness over different parts of the global oceans and the land. For the vast areas of stratocumulus cloud regions, the data shows that the days with elevated aerosol abundance were also associated with enhanced afternoon reduction of CF and COT pointing to the possible reduction of the indirect climate forcing. A positive correlation between aerosol optical depth and morning-to-afternoon variation of trade wind cumulus cloud cover was also found over the northern Indian Ocean, though no clear relationship between the concentration of Indo-Asian haze and morning-to-afternoon variation of COT was established. Over the Amazon region during wet conditions, aerosols are associated with an enhanced convective process in which morning shallow warm clouds are organized into afternoon deep convection with greater ice cloud coverage. Analysis presented here demonstrates that the new technique for exploring morning-to-afternoon variability in cloud properties by using the differences in data products from the two daily MODIS overpasses is capable of capturing some of the major features of diurnal variations in cloud properties and can be used for better understanding of aerosol radiative effects.

  18. Understanding Environmental Change and Biodiversity in a Dryland Ecosystem through Quantification of Climate Variability and Land Modification: The Case of the Dhofar Cloud Forest, Oman

    Science.gov (United States)

    Galletti, Christopher S.

    The Dhofar Cloud Forest is one of the most diverse ecosystems on the Arabian Peninsula. As part of the South Arabian Cloud Forest that extends from southern Oman to Yemen, the cloud forest is an important center of endemism and provides valuable ecosystem services to those living in the region. There have been various claims made about the health of the cloud forest and its surrounding region, the most prominent of which are: 1) variability of the Indian Summer Monsoon threatens long-term vegetation health, and 2) human encroachment is causing deforestation and land degradation. This dissertation uses three independent studies to test these claims and bring new insight about the biodiversity of the cloud forest. Evidence is presented that shows that the vegetation dynamics of the cloud forest are resilient to most of the variability in the monsoon. Much of the biodiversity in the cloud forest is dominated by a few species with high abundance and a moderate number of species at low abundance. The characteristic tree species include Anogeissus dhofarica and Commiphora spp. These species tend to dominate the forested regions of the study area. Grasslands are dominated by species associated with overgrazing (Calotropis procera and Solanum incanum). Analysis from a land cover study conducted between 1988 and 2013 shows that deforestation has occurred to approximately 8% of the study area and decreased vegetation fractions are found throughout the region. Areas around the city of Salalah, located close to the cloud forest, show widespread degradation in the 21st century based on an NDVI time series analysis. It is concluded that humans are the primary driver of environmental change. Much of this change is tied to national policies and development priorities implemented after the Dhofar War in the 1970's.

  19. EDITORIAL: Aerosol cloud interactions—a challenge for measurements and modeling at the cutting edge of cloud climate interactions

    Science.gov (United States)

    Spichtinger, Peter; Cziczo, Daniel J.

    2008-04-01

    Research in aerosol properties and cloud characteristics have historically been considered two separate disciplines within the field of atmospheric science. As such, it has been uncommon for a single researcher, or even research group, to have considerable expertise in both subject areas. The recent attention paid to global climate change has shown that clouds can have a considerable effect on the Earth's climate and that one of the most uncertain aspects in their formation, persistence, and ultimate dissipation is the role played by aerosols. This highlights the need for researchers in both disciplines to interact more closely than they have in the past. This is the vision behind this focus issue of Environmental Research Letters. Certain interactions between aerosols and clouds are relatively well studied and understood. For example, it is known that an increase in the aerosol concentration will increase the number of droplets in warm clouds, decrease their average size, reduce the rate of precipitation, and extend the lifetime. Other effects are not as well known. For example, persistent ice super-saturated conditions are observed in the upper troposphere that appear to exceed our understanding of the conditions required for cirrus cloud formation. Further, the interplay of dynamics versus effects purely attributed to aerosols remains highly uncertain. The purpose of this focus issue is to consider the current state of knowledge of aerosol/cloud interactions, to define the contemporary uncertainties, and to outline research foci as we strive to better understand the Earth's climate system. This focus issue brings together laboratory experiments, field data, and model studies. The authors address issues associated with warm liquid water, cold ice, and intermediate temperature mixed-phase clouds. The topics include the uncertainty associated with the effect of black carbon and organics, aerosol types of anthropogenic interest, on droplet and ice formation. Phases

  20. Initiation of secondary ice production in clouds

    Science.gov (United States)

    Sullivan, Sylvia C.; Hoose, Corinna; Kiselev, Alexei; Leisner, Thomas; Nenes, Athanasios

    2018-02-01

    Disparities between the measured concentrations of ice-nucleating particles (INPs) and in-cloud ice crystal number concentrations (ICNCs) have led to the hypothesis that mechanisms other than primary nucleation form ice in the atmosphere. Here, we model three of these secondary production mechanisms - rime splintering, frozen droplet shattering, and ice-ice collisional breakup - with a six-hydrometeor-class parcel model. We perform three sets of simulations to understand temporal evolution of ice hydrometeor number (Nice), thermodynamic limitations, and the impact of parametric uncertainty when secondary production is active. Output is assessed in terms of the number of primarily nucleated ice crystals that must exist before secondary production initiates (NINP(lim)) as well as the ICNC enhancement from secondary production and the timing of a 100-fold enhancement. Nice evolution can be understood in terms of collision-based nonlinearity and the phasedness of the process, i.e., whether it involves ice hydrometeors, liquid ones, or both. Ice-ice collisional breakup is the only process for which a meaningful NINP(lim) exists (0.002 up to 0.15 L-1). For droplet shattering and rime splintering, a warm enough cloud base temperature and modest updraft are the more important criteria for initiation. The low values of NINP(lim) here suggest that, under appropriate thermodynamic conditions for secondary ice production, perturbations in cloud concentration nuclei concentrations are more influential in mixed-phase partitioning than those in INP concentrations.

  1. 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....

  2. Cloud Computing

    Indian Academy of Sciences (India)

    IAS Admin

    2014-03-01

    Mar 1, 2014 ... decade in computing. In this article we define cloud computing, various services available on the cloud infrastructure, and the different types of cloud. We then discuss the technological trends which have led to its emergence, its advantages and disadvan- tages, and the applications which are appropriate ...

  3. VMware vCloud director cookbook

    CERN Document Server

    Langenhan, Daniel

    2013-01-01

    VMware vCloud Director Cookbook will adopt a Cookbook-based approach. Packed with illustrations and programming examples, this book explains the simple as well as the complex recipes in an easy-to-understand language.""VMware vCloud Director Cookbook"" is aimed at system administrators and technical architects moving from a virtualized environment to cloud environments. Familiarity with cloud computing platforms and some knowledge of virtualization and managing cloud environments is expected.

  4. Statistical Comparison of Cloud and Aerosol Vertical Properties between Two Eastern China Regions Based on CloudSat/CALIPSO Data

    Directory of Open Access Journals (Sweden)

    Yujun Qiu

    2017-01-01

    Full Text Available The relationship between cloud and aerosol properties was investigated over two 4° × 4° adjacent regions in the south (R1 and in the north (R2 in eastern China. The CloudSat/CALIPSO data were used to extract the cloud and aerosol profiles properties. The mean value of cloud occurrence probability (COP was the highest in the mixed cloud layer (−40°C~0°C and the lowest in the warm cloud layer (>0°C. The atmospheric humidity was more statistically relevant to COP in the warm cloud layer than aerosol condition. The differences in COP between the two regions in the mixed cloud layer and ice cloud layer (<−40°C had good correlations with those in the aerosol extinction coefficient. A radar reflectivity factor greater than −10 dBZ occurred mainly in warm cloud layers and mixed cloud layers. A high-COP zone appeared in the above-0°C layer with cloud thicknesses of 2-3 km in both regions and in all the four seasons, but the distribution of the zonal layer in R2 was more continuous than that in R1, which was consistent with the higher aerosol optical thickness in R2 than in R1 in the above-0°C layer, indicating a positive correlation between aerosol and cloud probability.

  5. 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.

  6. EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

    Science.gov (United States)

    Bony, Sandrine; Stevens, Bjorn; Ament, Felix; Bigorre, Sebastien; Chazette, Patrick; Crewell, Susanne; Delanoë, Julien; Emanuel, Kerry; Farrell, David; Flamant, Cyrille; Gross, Silke; Hirsch, Lutz; Karstensen, Johannes; Mayer, Bernhard; Nuijens, Louise; Ruppert, James H.; Sandu, Irina; Siebesma, Pier; Speich, Sabrina; Szczap, Frédéric; Totems, Julien; Vogel, Raphaela; Wendisch, Manfred; Wirth, Martin

    2017-11-01

    Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

  7. Cosmic Rays and Global Warming

    OpenAIRE

    Sloan, T.; Wolfendale, A W

    2007-01-01

    It has been claimed by others that observed temporal correlations of terrestrial cloud cover with `the cosmic ray intensity' are causal. The possibility arises, therefore, of a connection between cosmic rays and Global Warming. If true, the implications would be very great. We have examined this claim to look for evidence to corroborate it. So far we have not found any and so our tentative conclusions are to doubt it. Such correlations as appear are more likely to be due to the small variatio...

  8. Attribution of the United States “warming hole”: Aerosol indirect effect and precipitable water vapor

    OpenAIRE

    Shaocai Yu; Kiran Alapaty; Rohit Mathur; Jonathan Pleim; Yuanhang Zhang; Chris Nolte; Brian Eder; Kristen Foley; Tatsuya Nagashima

    2014-01-01

    Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20th century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. “warming hole”). Here we used observations of temperature, shortwave cloud forcing (S...

  9. Cirrus Cloud Seeding has Potential to Cool Climate

    Science.gov (United States)

    Storelvmo, T.; Kristjansson, J. E.; Muri, H.; Pfeffer, M.; Barahona, D.; Nenes, A.

    2013-01-01

    Cirrus clouds, thin ice clouds in the upper troposphere, have a net warming effect on Earth s climate. Consequently, a reduction in cirrus cloud amount or optical thickness would cool the climate. Recent research indicates that by seeding cirrus clouds with particles that promote ice nucleation, their lifetimes and coverage could be reduced. We have tested this hypothesis in a global climate model with a state-of-the-art representation of cirrus clouds and find that cirrus cloud seeding has the potential to cancel the entire warming caused by human activity from pre-industrial times to present day. However, the desired effect is only obtained for seeding particle concentrations that lie within an optimal range. With lower than optimal particle concentrations, a seeding exercise would have no effect. Moreover, a higher than optimal concentration results in an over-seeding that could have the deleterious effect of prolonging cirrus lifetime and contributing to global warming.

  10. Does the climate warming hiatus exist over the Tibetan Plateau?

    Science.gov (United States)

    Duan, Anmin; Xiao, Zhixiang

    2015-09-02

    The surface air temperature change over the Tibetan Plateau is determined based on historical observations from 1980 to 2013. In contrast to the cooling trend in the rest of China, and the global warming hiatus post-1990s, an accelerated warming trend has appeared over the Tibetan Plateau during 1998-2013 (0.25 °C decade(-1)), compared with that during 1980-1997 (0.21 °C decade(-1)). Further results indicate that, to some degree, such an accelerated warming trend might be attributable to cloud-radiation feedback. The increased nocturnal cloud over the northern Tibetan Plateau would warm the nighttime temperature via enhanced atmospheric back-radiation, while the decreased daytime cloud over the southern Tibetan Plateau would induce the daytime sunshine duration to increase, resulting in surface air temperature warming. Meanwhile, the in situ surface wind speed has recovered gradually since 1998, and thus the energy concentration cannot explain the accelerated warming trend over the Tibetan Plateau after the 1990s. It is suggested that cloud-radiation feedback may play an important role in modulating the recent accelerated warming trend over the Tibetan Plateau.

  11. The physics and history of global warming

    International Nuclear Information System (INIS)

    Hu Yongyun

    2012-01-01

    Global warming is not only a hot research area in atmospheric sciences and even all Earth sciences but is also a controversial topic in the international community. The purpose of this paper is not to clarify these controversies, but instead, to address the physical basis on which our understanding of global warming is founded, and to briefly review the nearly 200-year history of global warming sciences. We hope the paper will help readers, who have no background in the atmospheric and climate sciences, understand scientific issues of global warming. (author)

  12. CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter; Austin, Phillip A.; Bacmeister, J.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; Del Genio, Anthony D.; De Roode, Stephan R.; Endo , Satoshi; Franklin, Charmaine N.; Golaz, Jean-Christophe; Hannay, Cecile; Heus, Thijs; Isotta, Francesco A.; Jean-Louis, Dufresne; Kang, In-Sik; Kawai, Hideaki; Koehler, M.; Larson, Vincent E.; Liu, Yangang; Lock, Adrian; Lohmann, U.; Khairoutdinov, Marat; Molod, Andrea M.; Neggers, Roel; Rasch, Philip J.; Sandu, Irina; Senkbeil, Ryan; Siebesma, A. P.; Siegenthaler-Le Drian, Colombe; Stevens, Bjorn; Suarez, Max; Xu, Kuan-Man; Von Salzen, Knut; Webb, Mark; Wolf, Audrey; Zhao, M.

    2013-12-26

    Large Eddy Models (LES) and Single Column Models (SCM) are used in a surrogate climate change 101 to investigate the physical mechanism of low cloud feedbacks in climate models. Enhanced surface-102 driven boundary layer turbulence and shallow convection in a warmer climate are found to be 103 dominant mechanisms in SCMs.

  13. Value Co-creation in the Cloud : Understanding Software-as-a-Service-Driven Convergence of the Enterprise Systems and Financial Services Industries

    NARCIS (Netherlands)

    Teracino, Elizabeth Anne

    2017-01-01

    Enterprise systemen worden meer en meer gehost in de cloud en aangeboden als een dienst, volgens het zogenaamde software-als-een-dienst (Software-as-a-Service, of afgekort, SaaS) business model. Ook financiële dienstverleners zijn SaaS aan het invoeren en passen hierdoor de wijze waarop zij hun

  14. Understanding Discrepancies between Simulated and Measured Upwelling Microwave Brightness Temperatures: A Sensitivity Study on the Impact of Cloud Ice Microphysical and Scattering Parameterizations

    Science.gov (United States)

    Casella, D.; Hashino, T.; Mugnai, A.; Sanò, P.; Smith, E. A.; Tripoli, G. J.

    2009-09-01

    Most physically-based Bayesian algorithms for precipitation retrieval from satellite-borne microwave (MW) radiometers use cloud-radiation databases (CRD’s) that are composed of numerous detailed microphysical cloud profiles obtained from cloud resolving model (CRM) simulations, coupled with the simulated upwelling brightness temperatures (TB’s) at several MW frequencies. These TB’s are computed by applying radiative transfer (RT) schemes to the CRM profiles for the same frequencies and polarizations of the satellite MW radiometer measurements in use. Then, the ensemble of simulations is compared with the measurements to estimate the precipitation rate. A good agreement between simulations and measurements is obviously needed. Nevertheless, depending on frequency, there are several sources of discrepancy between simulated and measured TB’s. Here, we show the results of a sensitivity study on the impact of several different parameterizations that are used to compute the radiative properties of ice particles, as well as on the CRM skill in providing realistic descriptions of the microphysical structures of precipitating clouds. To this end, we use 2D-simulations of a case study of the KWAJEX campaign (that took place from 23 July to 14 September 1999), that were performed by the University of Wisconsin - Nonhydrostatic Modeling System (UW-NMS) using both a bulk microphysics scheme, as well as a new microphysical scheme called Advanced Microphysical Prediction System (AMPS) that explicitly predicts ice particle properties (such as size, particle density, and crystal habits).

  15. Marine Aerosols and Clouds.

    Science.gov (United States)

    Brooks, Sarah D; Thornton, Daniel C O

    2018-01-03

    The role of marine bioaerosols in cloud formation and climate is currently so uncertain that even the sign of the climate forcing is unclear. Marine aerosols form through direct emissions and through the conversion of gas-phase emissions to aerosols in the atmosphere. The composition and size of aerosols determine how effective they are in catalyzing the formation of water droplets and ice crystals in clouds by acting as cloud condensation nuclei and ice nucleating particles, respectively. Marine organic aerosols may be sourced both from recent regional phytoplankton blooms that add labile organic matter to the surface ocean and from long-term global processes, such as the upwelling of old refractory dissolved organic matter from the deep ocean. Understanding the formation of marine aerosols and their propensity to catalyze cloud formation processes are challenges that must be addressed given the major uncertainties associated with aerosols in climate models.

  16. Marine Aerosols and Clouds

    Science.gov (United States)

    Brooks, Sarah D.; Thornton, Daniel C. O.

    2018-01-01

    The role of marine bioaerosols in cloud formation and climate is currently so uncertain that even the sign of the climate forcing is unclear. Marine aerosols form through direct emissions and through the conversion of gas-phase emissions to aerosols in the atmosphere. The composition and size of aerosols determine how effective they are in catalyzing the formation of water droplets and ice crystals in clouds by acting as cloud condensation nuclei and ice nucleating particles, respectively. Marine organic aerosols may be sourced both from recent regional phytoplankton blooms that add labile organic matter to the surface ocean and from long-term global processes, such as the upwelling of old refractory dissolved organic matter from the deep ocean. Understanding the formation of marine aerosols and their propensity to catalyze cloud formation processes are challenges that must be addressed given the major uncertainties associated with aerosols in climate models.

  17. 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

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

    Science.gov (United States)

    Kidder, Stanley Q.; Hafner, Jan

    2001-01-01

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

  19. 85Kr induced global warming

    International Nuclear Information System (INIS)

    Zakharov, V.I.

    1996-01-01

    It's well known that the trace atmospheric constituent as 85 Kr is at present about 10 6 cm -3 and increasing considerably (twice every 8--10 years) as a result of nuclear fuel utilization. This paper presents the model of influence of 85 Kr accumulation in the earth atmosphere on climate perturbation and global warming. The process of increasing the concentrations in the troposphere due to the anthropogenic emission of 85 Kr and its radioactive decay is analyzed, based on master kinetic equations. Results indicate that anthropogenic emissions contributing to the total equilibrium concentration of tropospheric ions due to 85 Kr is about equal to the natural level of tropospheric ions. The influence of atmospheric electricity on the transformation between water vapor and clouds which result in an increase in the concentration of ions in troposphere is investigated. The paper shows that the process of anthropogenic accumulation of 85 Kr in the troposphere at present rate up to 2005--2010 increases the mean of the dew-point temperature several degrees on the global scale. Relevant change of height for the lower level of clouds has been obtained. Positive feedback between the process of warming of the lower atmosphere and the concentration of tropospheric ions has been considered

  20. Subtropical Low Cloud Response to a Warmer Climate in an Superparameterized Climate Model: Part I. Regime Sorting and Physical Mechanisms

    Directory of Open Access Journals (Sweden)

    Peter N Blossey

    2009-07-01

    Full Text Available The subtropical low cloud response to a climate with SST uniformly warmed by 2 K is analyzed in the SP- CAM superparameterized climate model, in which each grid column is replaced by a two-dimensional cloud-resolving model (CRM. Intriguingly, SP-CAM shows substantial low cloud increases over the subtropical oceans in the warmer climate. The paper aims to understand the mechanism for these increases. The subtropical low cloud increase is analyzed by sorting grid-column months of the climate model into composite cloud regimes using percentile ranges of lower tropospheric stability (LTS. LTS is observed to be well correlated to subtropical low cloud amount and boundary layer vertical structure. The low cloud increase in SP-CAM is attributed to boundary-layer destabilization due to increased clear-sky radiative cooling in the warmer climate. This drives more shallow cumulus convection and a moister boundary layer, inducing cloud increases and further increasing the radiative cooling. The boundary layer depth does not change substantially, due to compensation between increased radiative cooling (which promotes more turbulent mixing and boundary-layer deepening and slight strengthening of the boundary-layer top inversion (which inhibits turbulent entrainment and promotes a shallower boundary layer. The widespread changes in low clouds do not appear to be driven by changes in mean subsidence.
    In a companion paper we use column-mode CRM simulations based on LTS-composite profiles to further study the low cloud response mechanisms and to explore the sensitivity of low cloud response to grid resolution in SP-CAM.

  1. 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...

  2. 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…

  3. 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…

  4. Indian Ocean warming during peak El Niño cools surrounding land masses

    Science.gov (United States)

    Herold, N.; Santoso, A.

    2017-11-01

    Understanding the interactions between the Pacific and other ocean basins during extreme phases of the El Niño-Southern Oscillation (ENSO) is necessary for explaining its global climate impacts. Here climate model experiments are used to highlight a mechanism by which the characteristic warming of the Indian Ocean during peak El Niño months can cool North Africa and South Asia, an area encompassing over three billion people. It is found that warming of the Indian Ocean during extreme El Niño events leads to broader upper tropospheric geopotential height anomalies than would otherwise occur. This weakens the extratropical Rossby wave response initiated in the tropics and leads to higher pressure and reduced cloud forcing over North Africa and South Asia. Reanalysis data provides empirical support for this mechanism, although it is likely only to be prominent during strong El Niño events when Indian Ocean warming tends to be larger. This dampening effect needs to be taken into account in understanding the climatic impact of extreme El Niño events, which are projected to increase under global warming.

  5. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  7. Cirrus clouds and climate feedback: Is the sky falling and should we go tell the king

    Science.gov (United States)

    Stephens, Graeme L.

    1990-01-01

    It is widely believed that thin cirrus clouds act to enhance the greenhouse effect owing to a particular combination of their optical properties. It is demonstrated how this effect is perhaps based on inadequate resolution of the physics of cirrus clouds and that the more likely impact of cirrus clouds to climate change remains somewhat elusive. These conclusions are developed within the context of a specific feedback mechanism incorporated into a simple mechanistic climate model. A specific scientific question addressed is whether or not the observed relationship between the ice water content and temperature of cirrus provides any significant feedback to the CO2 greenhouse warming. A related question also examined concerns the specific role of cloud microphysics and radiation in this feedback. This raises several pertinent issues about the understanding of cirrus clouds and their likely role in climate change as there presently exists a considerable uncertainty about the microphysics of these clouds (size and shape of ice crystals) and their radiative influences.

  8. Cloud and circulation feedbacks in a near-global aquaplanet cloud-resolving model

    Science.gov (United States)

    Narenpitak, Pornampai; Bretherton, Christopher S.; Khairoutdinov, Marat F.

    2017-06-01

    A near-global aquaplanet cloud-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate cloud feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S-N. It produces plausible mean distributions of clouds, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO2. The Intertropical Convergence Zone width and tropical cloud cover are not strongly affected by SST warming or CO2 increase, except for the expected upward shift in high clouds with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low cloud fraction and in-cloud liquid water content but decreases midlatitude cloud, yielding slightly positive domain-mean shortwave cloud feedbacks. CO2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low cloud fraction. Warming-induced low cloud changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary layer radiative cooling in the warmer climate accompanies the robust subtropical low cloud increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate.

  9. Screaming Clouds

    Science.gov (United States)

    Fikke, Svein; Egill Kristjánsson, Jón; Nordli, Øyvind

    2017-04-01

    "Mother-of-pearl clouds" appear irregularly in the winter stratosphere at high northern latitudes, about 20-30 km above the surface of the Earth. The size range of the cloud particles is near that of visible light, which explains their extraordinary beautiful colours. We argue that the Norwegian painter Edvard Munch could well have been terrified when the sky all of a sudden turned "bloodish red" after sunset, when darkness was expected. Hence, there is a high probability that it was an event of mother-of-pearl clouds which was the background for Munch's experience in nature, and for his iconic Scream. Currently, the leading hypothesis for explaining the dramatic colours of the sky in Munch's famous painting is that the artist was captivated by colourful sunsets following the enormous Krakatoa eruption in 1883. After carefully considering the historical accounts of some of Munch's contemporaries, especially the physicist Carl Störmer, we suggest an alternative hypothesis, namely that Munch was inspired by spectacular occurrences of mother-of-pearl clouds. Such clouds, which have a wave-like structure akin to that seen in the Scream were first observed and described only a few years before the first version of this motive was released in 1892. Unlike clouds related to conventional weather systems in the troposphere, mother-of-pearl clouds appear in the stratosphere, where significantly different physical conditions prevail. This result in droplet sizes within the range of visible light, creating the spectacular colour patterns these clouds are famous for. Carl Störmer observed such clouds, and described them in minute details at the age of 16, but already with a profound interest in science. He later noted that "..these mother-of-pearl clouds was a vision of indescribable beauty!" The authors find it logical that the same vision could appear scaring in the sensible mind of a young artist unknown to such phenomena.

  10. 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.

  11. Global warming-setting the stages

    International Nuclear Information System (INIS)

    1994-01-01

    Most of us have heard or read about global warming. However, the messages we receive are often in conflict, raising more questions than answer. Is global warming a good or a bad thing? has it already started or is it part of our future? Are we, or are we not doing anything about it? Should we be concerned? This primer on Global Warming is designed to clear up some of this confusion by providing basic scientific information on global warming issue. It is clear that there is still much to learn about global warming. However, it is also clear that there is a lot that we already know - and that dose provide cause for concern. We must understand the global warming issue if we are to make wise decisions and take responsible actions in response to the challenges and opportunities posed by global warming. Chapter 1 of 'the primer on global Warming' set the stage with a brief overview of science of global warming within the context of climate change. In addition, it introduces the specific issues that surround the global warming problem. As far as the science of global warming is concerned the following questions are discussed. What is global climate? Is climate change natural? What causes climate to vary on a global scale? How does the composition of the atmosphere relate to climate change. but there are also certain issues discussed here which surround the global warming such as: If climate varies naturally, why is there a concern about 'global warming'? What are the potential consequences of 'global warning'. What human activities contribute to 'global warming'. (Author)

  12. Synoptic weather conditions, clouds, and sea ice in the Beaufort and Chukchi Seasonal Ice Zone

    Science.gov (United States)

    Liu, Z.; Schweiger, A. J. B.

    2017-12-01

    The connections between synoptic conditions and clouds and sea ice over the Beaufort and Chukchi Seasonal Ice Zone are examined. Four synoptic states with distinct thermodynamic and dynamic spatial and vertical signatures are identified using a k-means classification algorithm and the ERA-Interim reanalysis data from 1979 to 2014. The combined CloudSat and Calipso cloud observations suggest control of clouds by synoptic states. Warm continental air advection is associated with the fewest low-level clouds, cold air advection under low pressure generates the most low-level clouds. Low-level cloud fractions are related to lower-tropospheric stability and both are regulated by synoptic conditions. Observed cloud vertical and spatial variability is reproduced well in ERA-Interim, but winter low-level cloud fraction is overestimated. Sea ice melt onset is related to synoptic conditions. Melt onsets occur more frequently and earlier with warm air advection states. The warm continental air advection state with the highest temperature is the most favorable for melt onsets even though fewer low-level clouds are associated with this state. The other warm advection state is cloudier but colder. In the Beaufort and Chukchi Seasonal Ice Zone, the much higher temperature and total column water of the warm continental air advection state compensate the smaller cloud longwave radiative fluxes due to the smaller low-level cloud fraction. In addition, the higher shortwave radiative fluxes and turbulent fluxes to the surface are also favorable for sea ice melt onset.

  13. How warm days increase belief in global warming

    Science.gov (United States)

    Zaval, Lisa; Keenan, Elizabeth A.; Johnson, Eric J.; Weber, Elke U.

    2014-02-01

    Climate change judgements can depend on whether today seems warmer or colder than usual, termed the local warming effect. Although previous research has demonstrated that this effect occurs, studies have yet to explain why or how temperature abnormalities influence global warming attitudes. A better understanding of the underlying psychology of this effect can help explain the public's reaction to climate change and inform approaches used to communicate the phenomenon. Across five studies, we find evidence of attribute substitution, whereby individuals use less relevant but available information (for example, today's temperature) in place of more diagnostic but less accessible information (for example, global climate change patterns) when making judgements. Moreover, we rule out alternative hypotheses involving climate change labelling and lay mental models. Ultimately, we show that present temperature abnormalities are given undue weight and lead to an overestimation of the frequency of similar past events, thereby increasing belief in and concern for global warming.

  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. Experimental Studies of the Microphysics of Cloud Condensation Nuclei as a Function of Organic Solute

    Science.gov (United States)

    Dure, E.; Morris, V. R.; Greene, N.

    2003-12-01

    Biomass burning has played, and continues to play a significant part in the lives of indigenous people across the world. Biomass burning results from brushfires, land clearing, and cloud-to-ground lightning strikes, this is particularly true in the tropics. A unique feature about the biomass burning aerosols is that its sources are overwhelmingly confined to the tropics despite evidence that their effects may be global in extent. Recently, Rosenfeld has argued that the inclusion of biomass aerosols into warm clouds can also inhibit precipitation. However, several reported case studies in the literature report precipitation enhancements due to aerosol entrainment as well. Quantitative relationships between the indirect forcing from clouds and anthropogenic aerosol inclusions have not been developed to a point where the resultant prediction of cloud optical properties is reliable. The problem is the lack of understanding of the basic microphysical processes governing cloud droplet nucleation and evolution. This level of understanding requires that the physical chemistry of the systems be well understood. Because such a large fraction of anthropogenic aerosol and specifically biomass aerosol are organic in nature, we have performed laboratory simulations of the nucleation of aerosols with organic inclusions. In our study, homogeneous and heterogeneous nucleation effects were studied for several organic solutions; n-Hexane, benzene, chlorobenzene, nitrobenzene, with and without crushed graphite. We will report results of the analyses of the size distribution characteristics, electrical mobility, and number density characteristics.

  16. Microphysics and Southern Ocean Cloud Feedback

    Science.gov (United States)

    McCoy, Daniel T.

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

  17. 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

  18. Thermodynamic control of anvil cloud amount

    Science.gov (United States)

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

    2016-01-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation. PMID:27412863

  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. Sudden Stratospheric Warming Compendium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sudden Stratospheric Warming Compendium (SSWC) data set documents the stratospheric, tropospheric, and surface climate impacts of sudden stratospheric warmings. This...

  1. Urbanization Causes Increased Cloud Base Height and Decreased Fog in Coastal Southern California

    Science.gov (United States)

    Williams, A. Park; Schwartz, Rachel E.; Iacobellis, Sam; Seager, Richard; Cook, Benjamin I.; Still, Christopher J.; Husak, Gregory; Michaelsen, Joel

    2015-01-01

    Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability above the marine boundary layer (MBL) and MBL height. Trends, however, have been spatially variable since records began in the mid-1900s due to differences in nighttime warming. Among CSCA airfields, differences in nighttime warming, but not daytime warming, are strongly and positively related to fraction of nearby urban cover, consistent with an urban heat island effect. Nighttime warming raises the near-surface dew point depression, which lifts the altitude of condensation and cloud base height, thereby reducing fog frequency. Continued urban warming, rising cloud base heights, and associated effects on energy and water balance would profoundly impact ecological and human systems in highly populated and ecologically diverse CSCA.

  2. Cloud Effects on Meridional Atmospheric Energy Budget Estimated from Clouds and the Earth's Radiant Energy System (CERES) Data

    Science.gov (United States)

    Kato, Seiji; Rose, Fred G.; Rutan, David A.; Charlock, Thomas P.

    2008-01-01

    The zonal mean atmospheric cloud radiative effect, defined as the difference of the top-of-atmosphere (TOA) and surface cloud radiative effects, is estimated from three years of Clouds and the Earth's Radiant Energy System (CERES) data. The zonal mean shortwave effect is small, though it tends to be positive (warming). This indicates that clouds increase shortwave absorption in the atmosphere, especially in midlatitudes. The zonal mean atmospheric cloud radiative effect is, however, dominated by the longwave effect. The zonal mean longwave effect is positive in the tropics and decreases with latitude to negative values (cooling) in polar regions. The meridional gradient of cloud effect between midlatitude and polar regions exists even when uncertainties in the cloud effect on the surface enthalpy flux and in the modeled irradiances are taken into account. This indicates that clouds increase the rate of generation of mean zonal available potential energy. Because the atmospheric cooling effect in polar regions is predominately caused by low level clouds, which tend to be stationary, we postulate that the meridional and vertical gradients of cloud effect increase the rate of meridional energy transport by dynamics in the atmosphere from midlatitude to polar region, especially in fall and winter. Clouds then warm the surface in polar regions except in the Arctic in summer. Clouds, therefore, contribute in increasing the rate of meridional energy transport from midlatitude to polar regions through the atmosphere.

  3. Global Warming: A Myth?

    Indian Academy of Sciences (India)

    warming trend. Efforts are on to explain this temperature anomaly and it may take time to say conclusively whether. 'global warming' exists or not. Introduction. Global warming is one ... puted, as atmospheric temperature trends measured by radio- sondes and .... heat and keeping the surroundings warmer. Burning of large.

  4. On the distribution of relative humidity in cirrus clouds

    Directory of Open Access Journals (Sweden)

    P. Spichtinger

    2004-01-01

    Full Text Available We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC. The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than −40°C to considerably positively skew (i.e. towards high humidities in colder clouds. These results are in agreement to findings obtained recently from the INterhemispheric differences in Cirrus properties from Anthropogenic emissions (INCA campaign (Ovarlez et al., 2002. We interprete the temperature dependence of the shapes of the humidity distributions as an effect of the length of time a cirrus cloud needs from formation to a mature equilibrium stage, where the humidity is close to saturation. The duration of this transitional period increases with decreasing temperature. Hence cold cirrus clouds are more often met in the transitional stage than warm clouds.

  5. Climate goals and computing the future of clouds

    OpenAIRE

    Schneider Tapio; Teixeira João; Bretherton Christopher S.; Brient Florent; Pressel Kyle G.; Schär Christoph; Siebesma A. Pier

    2017-01-01

    How clouds respond to warming remains the greatest source of uncertainty in climate projections. Improved computational and observational tools can reduce this uncertainty. Here we discuss the need for research focusing on high-resolution atmosphere models and the representation of clouds and turbulence within them.

  6. Initiation of secondary ice production in clouds

    Directory of Open Access Journals (Sweden)

    S. C. Sullivan

    2018-02-01

    Full Text Available Disparities between the measured concentrations of ice-nucleating particles (INPs and in-cloud ice crystal number concentrations (ICNCs have led to the hypothesis that mechanisms other than primary nucleation form ice in the atmosphere. Here, we model three of these secondary production mechanisms – rime splintering, frozen droplet shattering, and ice–ice collisional breakup – with a six-hydrometeor-class parcel model. We perform three sets of simulations to understand temporal evolution of ice hydrometeor number (Nice, thermodynamic limitations, and the impact of parametric uncertainty when secondary production is active. Output is assessed in terms of the number of primarily nucleated ice crystals that must exist before secondary production initiates (NINP(lim as well as the ICNC enhancement from secondary production and the timing of a 100-fold enhancement. Nice evolution can be understood in terms of collision-based nonlinearity and the phasedness of the process, i.e., whether it involves ice hydrometeors, liquid ones, or both. Ice–ice collisional breakup is the only process for which a meaningful NINP(lim exists (0.002 up to 0.15 L−1. For droplet shattering and rime splintering, a warm enough cloud base temperature and modest updraft are the more important criteria for initiation. The low values of NINP(lim here suggest that, under appropriate thermodynamic conditions for secondary ice production, perturbations in cloud concentration nuclei concentrations are more influential in mixed-phase partitioning than those in INP concentrations.

  7. ARM Cloud Aerosol Precipitation Experiment (ACAPEX) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Leung, L. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prather, K. [Scripps Institution of Oceanography, La Jolla, CA (United States); Ralph, R. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Rosenfeld, D. [The Hebrew University of Jerusalem (Israel); Spackman, R. [Science and Technology Corporation (STC), Hampton, VA (United States); DeMott, P. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Fan, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hagos, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hughes, M. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Long, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rutledge, S. [Colorado State Univ., Fort Collins, CO (United States); Waliser, D. [National Aeronautics and Space Administration (NASA), Washington, DC (United States); Wang, H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-09-01

    The western U.S. receives precipitation predominantly during the cold season when storms approach from the Pacific Ocean. The snowpack that accumulates during winter storms provides about 70-90% of water supply for the region. Understanding and modeling the fundamental processes that govern the large precipitation variability and extremes in the western U.S. is a critical test for the ability of climate models to predict the regional water cycle, including floods and droughts. Two elements of significant importance in predicting precipitation variability in the western U.S. are atmospheric rivers and aerosols. Atmospheric rivers (ARs) are narrow bands of enhanced water vapor associated with the warm sector of extratropical cyclones over the Pacific and Atlantic oceans. Because of the large lower-tropospheric water vapor content, strong atmospheric winds and neutral moist static stability, some ARs can produce heavy precipitation by orographic enhancement during landfall on the U.S. West Coast. While ARs are responsible for a large fraction of heavy precipitation in that region during winter, much of the rest of the orographic precipitation occurs in post-frontal clouds, which are typically quite shallow, with tops just high enough to pass the mountain barrier. Such clouds are inherently quite susceptible to aerosol effects on both warm rain and ice precipitation-forming processes.

  8. Climate stability and cloud optical thickness feedbacks

    Science.gov (United States)

    Somerville, Richard C. J.; Iacobellis, Sam

    1989-01-01

    An improved radiative-convective model (RCM) has been developed and used to examine the role of cirrus clouds in the optical thickness feedback mechanism. Low and middle clouds are approximately black bodies for infrared radiative transfer, and so any increase in their optical thickness primarily increases the cloud albedo. Thus, if a climate warming is accompanied by an increase in average atmospheric absolute humidity and hence in average cloud liquid water content, low and middle cloud optical thickness and albedo may increase. The result is a negative feedback on the climate change, tending to reduce the surface temperature increase. Recent research suggests that the optical thickness feedback can depend sensitively on aspects of cirrus which are not well observed or adequately incorporated in typical present-day climate models.

  9. Electron cloud effects in hadron beams

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [TU-Darmstadt, Institut fuer Theorie Elektromagnetischer Felder,Schlossgartenstr. 8 64289 Darmstadt (Germany)

    2013-07-01

    Accelerators operating with intense positively charged beams can suffer from the electron cloud phenomenon. For example, it is the intensity limiting factor in CERN LHC and SPS. In past decades a lot of progress in understanding the electron cloud effects was made worldwide. Methods to suppress or weaken the electron cloud phenomenon were proposed. Theories governing the bunch stability in presence of the electron cloud were developed. Recently the theory was introduced to describe the bunch energy loss due to the electron cloud. However, most of the publications concern the single bunch electron cloud effects. In reality bunches are packed into trains. A disturbance of the cloud caused by the bunch in the beginning of the train affects the subsequent bunches. We present a further investigation of single-bunch electron cloud effects and planned activities to study the phenomenon in case of multiple bunches.

  10. Factors influencing the organizational adoption of cloud computing: a survey among cloud workers

    Directory of Open Access Journals (Sweden)

    Mark Stieninger

    2018-01-01

    Full Text Available Cloud computing presents an opportunity for organizations to leverage affordable, scalable, and agile technologies. However, even with the demonstrated value of cloud computing, organizations have been hesitant to adopt such technologies. Based on a multi-theoretical research model, this paper provides an empirical study targeted to better understand the adoption of cloud services. An online survey addressing the factors derived from literature for three specific popular cloud application types (cloud storage, cloud mail and cloud office was undertaken. The research model was analyzed by using variance-based structural equation modelling. Results show that the factors of compatibility, relative advantage, security and trust, as well as, a lower level of complexity lead to a more positive attitude towards cloud adoption. Complexity, compatibility, image and security and trust have direct and indirect effects on relative advantage. These factors further explain a large part of the attitude towards cloud adoption but not of its usage.

  11. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    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...... examples of mobile clouds applications, based on both existing commercial initiatives as well as proof-of-concept test-beds. Visions and prospects are also discussed, paving the way for further development. As mobile networks and social networks become more and more reliant on each other, the concept...... of resource sharing takes a wider and deeper meaning, creating the foundations for a global real-time multidimensional resource pool, the underlying infrastructure for shareconomy. Above all, this is an inspiring book for anyone who is concerned about the future of wireless and mobile communications networks...

  12. 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...

  13. Marine cloud brightening – as effective without clouds

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2017-11-01

    Full Text Available Marine cloud brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine cloud brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of cloud droplets. Here we present results from coordinated simulations with three Earth system models (ESMs participating in the Geoengineering Model Intercomparison Project (GeoMIP G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30° N and 30° S are set in each model to generate a global-mean effective radiative forcing (ERF of −2.0 W m−2 at the top of the atmosphere. We find that the injection increases the cloud droplet number concentration in lower layers, reduces the cloud-top effective droplet radius, and increases the cloud optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of clouds occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. These findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought.

  14. Gathering clouds.

    Science.gov (United States)

    Conde, Crystal

    2012-01-01

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

  15. Interweaving climate research and public understanding

    Science.gov (United States)

    Betts, A. K.

    2016-12-01

    For the past 10 years I have been using research into land-atmosphere-cloud coupling to address Vermont's need to understand climate change, and develop plans for greater resilience in the face of increasing severe weather. The research side has shown that the fraction of days with snow cover determines the cold season climate, because snow acts as a fast climate switch between non-overlapping climates with and without snow cover. Clouds play opposite roles in warm and cold seasons: surface cooling in summer and warming in winter. The later fall freeze-up and earlier spring ice-out on lakes, coupled to the earlier spring phenology, are clear markers both of a warming climate, as well as the large interannual variability. Severe flooding events have come with large-scale quasi-stationary weather patterns. This past decade I have given 230 talks to schools, business and professional groups, as well as legislative committees and state government. I have written 80 environmental columns for two Vermont newspapers, as part of a weekly series I helped start in 2008. Commentaries and interviews on radio and TV enable me to explain directly the issues we face, as the burning of fossil fuels destabilizes the climate system. The public in Vermont is eager to learn and understand these issues since many have roots in the land; while professional groups need all the information and guidance possible to prepare for the future. My task as a scientist is to map out what we know in ways that can readily be grasped in terms of past experience, even though the climate system is already moving outside this range - and at the same time outline general principles and hopeful strategies for dealing with global and local climate change.

  16. Using MODIS Cloud Regimes to Sort Diagnostic Signals of Aerosol-Cloud-Precipitation Interactions.

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin

    2017-05-27

    Coincident multi-year measurements of aerosol, cloud, precipitation and radiation at near-global scales are analyzed to diagnose their apparent relationships as suggestive of interactions previously proposed based on theoretical, observational, and model constructs. Specifically, we examine whether differences in aerosol loading in separate observations go along with consistently different precipitation, cloud properties, and cloud radiative effects. Our analysis uses a cloud regime (CR) framework to dissect and sort the results. The CRs come from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and are defined as distinct groups of cloud systems with similar co-variations of cloud top pressure and cloud optical thickness. Aerosol optical depth used as proxy for aerosol loading comes from two sources, MODIS observations, and the MERRA-2 re-analysis, and its variability is defined with respect to local seasonal climatologies. The choice of aerosol dataset impacts our results substantially. We also find that the responses of the marine and continental component of a CR are frequently quite disparate. Overall, CRs dominated by warm clouds tend to exhibit less ambiguous signals, but also have more uncertainty with regard to precipitation changes. Finally, we find weak, but occasionally systematic co-variations of select meteorological indicators and aerosol, which serves as a sober reminder that ascribing changes in cloud and cloud-affected variables solely to aerosol variations is precarious.

  17. Cloud's Center of Gravity – a compact approach to analyze convective cloud development

    Directory of Open Access Journals (Sweden)

    I. Koren

    2009-01-01

    Full Text Available As cloud resolving models become more detailed, with higher resolution outputs, it is often complicated to isolate the physical processes that control the cloud attributes. Moreover, due to the high dimensionality and complexity of the model output, the analysis and interpretation of the results can be very complicated. Here we suggest a novel approach to convective cloud analysis that yields more insight into the physical and temporal evolution of clouds, and is compact and efficient. The different (3-D cloud attributes are weighted and projected onto a single point in space and in time, that has properties of, or similar to, the Center Of Gravity (COG. The location, magnitude and spread of this variable are followed in time. The implications of the COG approach are demonstrated for a study of aerosol effects on a warm convective cloud. We show that in addition to reducing dramatically the dimensionality of the output, such an approach often enhances the signal, adds more information, and makes the physical description of cloud evolution clearer, allowing unambiguous comparison of clouds evolving in different environmental conditions. This approach may also be useful for analysis of cloud data retrieved from surface or space-based cloud radars.

  18. Preliminarily Assessment of Long-term Cloud Top Heights in Central Taiwan

    Science.gov (United States)

    Lai, Y. J.; Po-Hsiung, L.

    2015-12-01

    The Xitou region, as the epitome of mid-elevation forest ecosystem and known as a famous forest recreation area in Taiwan. Although two disasters, "921 earthquake" in 1999 and typhoon Toraji in 2001, heavily hit this area and cause a significant reduction in visitors from 1 to about 0.4 million per year, the tourists have returned after the reconstruction in 2003 and approached 1.5 million high since 2010. The high quantity of tourists obviously drives the development of tourism industry which, unfortunately, increases the local sources of heating. A preliminarily analysis showed the warming rate was 0.29 oC/decade for June 2005 to May 2013 while from the 1940s to the 1980s, it was only 0.1 oC/decade. The warming pattern in Xitou region is similar to the global warming situation that a more dramatic trend happened during the past 10 years. The change of land use, which derived from the pressure of tourism industry, might accelerate regional climate warming. For the purpose of understanding cloud response to anthropogenic forcing, the long-term 1-km spatial resolution cloud top heights (cth) data sets (collection 6) from the Moderate Resolution Imaging Spectroradiometer (MODIS) were assessed. The results showed the annual cloud event amounts of the Terra and Aqua changed insignificantly since 2003 disregard of the cth. However, the cloud fraction of the cth less than 2000m was 18% in 2003 and dropped dramatically to 7% since 2011. Correspondingly, the cth between 2000m to 4000m was increased from 35% in 2003 to 45% in 2014. Further analysis the nighttime events indicated similar pattern but only 6% different between 2003 and 2014. The Aqua daytime events showed a more dramatic fraction anomaly which was decreased 18% at the cth less than 2000m and increased 18% at the cth between 2000m to 4000m. This preliminary assessment represents the cloud is pushing higher which might be caused by the anthropogenic forcing during the last decade. However, this study also found

  19. A Multi-model Study on Warm Precipitation Biases in Global Models Compared to Satellite Observations

    Science.gov (United States)

    Jing, X.; Suzuki, K.; Guo, H.; Goto, D.; Ogura, T.; Koshiro, T.; Mulmenstadt, J.

    2017-12-01

    The cloud-to-precipitation transition process in warm clouds simulated by state-of-the-art global climate models (GCMs), including both traditional climate models and a global cloud-resolving model, is evaluated against A-Train satellites observations. The models and satellite observations are compared in the form of the statistics obtained from combined analysis of multiple satellite observables that probe signatures of the cloud-to-precipitation transition process. One common problem identified among these models is the too frequent occurrence of warm precipitation. The precipitation is found to form when the cloud particle size and the liquid water path (LWP) are both much smaller than those in observations. The too efficient formation of precipitation is found to be compensated for by errors of cloud microphysical properties, such as underestimated cloud particle size and LWP, to an extent that varies among the models. However, this does not completely cancel the precipitation formation bias. Robust errors are also found in the evolution of cloud microphysical properties in precipitation process in some GCMs, implying unrealistic interaction between precipitation and cloud water. Nevertheless, auspicious information is found for future improvement of warm precipitation representations: the adoption of more realistic autoconversion scheme or subgrid variability scheme is shown to improve the triggering of precipitation and evolution of cloud microphysical properties.

  20. New insights about cloud vertical structure from CloudSat and CALIPSO observations

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin

    2017-09-01

    Active cloud observations from A-Train's CloudSat and CALIPSO satellites offer new opportunities to examine the vertical structure of hydrometeor layers. We use the 2B-CLDCLASS-LIDAR merged CloudSat-CALIPSO product to examine global aspects of hydrometeor vertical stratification. We group the data into major cloud vertical structure (CVS) classes based on our interpretation of how clouds in three standard atmospheric layers overlap and provide their global frequency of occurrence. The two most frequent CVS classes are single-layer (per our definition) low and high clouds that represent 53% of cloudy skies, followed by high clouds overlying low clouds, and vertically extensive clouds that occupy near-contiguously a large portion of the troposphere. The prevalence of these configurations changes seasonally and geographically, between daytime and nighttime, and between continents and oceans. The radiative effects of the CVS classes reveal the major radiative warmers and coolers from the perspective of the planet as a whole, the surface, and the atmosphere. Single-layer low clouds dominate planetary and atmospheric cooling and thermal infrared surface warming. We also investigate the consistency between passive and active views of clouds by providing the CVS breakdowns of Moderate Resolution Imaging Spectroradiometer cloud regimes for spatiotemporally coincident MODIS-Aqua (also on the A-Train) and CloudSat-CALIPSO daytime observations. When the analysis is expanded for a more in-depth look at the most heterogeneous of the MODIS cloud regimes, it ultimately confirms previous interpretations of their makeup that did not have the benefit of collocated active observations.

  1. 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 a...

  2. 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.

  3. Theory on the uncertainty in cloud microphysical processes and climate

    Science.gov (United States)

    Liou, Kuo-Nan; Ou, Szu-Cheng S.

    1988-01-01

    The interactive role of clouds and precipitation processes in a climate model is investigated. The basic model structure and parameterizations for condensation, evaporation, and precipitation are outlined. Results simulated from the cloud-climate model are discussed. The potential link between microphysical cloud processes and climate is theorized. The need to develop a climatology of the mean particle radius for clouds at the global scale, in order to understand the role of clouds in climate is stressed.

  4. On the impact of clouds on the energy balance of the Antarctic Peninsula Ice Sheet

    Science.gov (United States)

    Caballero, Marta; Braun, Matthias; Mölg, Thomas

    2017-04-01

    Radiative effects of clouds play a key role in the energy balance of the atmosphere and have a critical influence on the ice sheet's radiation budget, causing a warming effect (by absorption and emission of longwave radiation) or cooling effect (by reducing the downwelling shortwave radiation) at the surface. On the Antarctic Peninsula, changes in the glacier system have been observed, such as the disintegration of ice shelves, acceleration and thinning of glaciers, variations in the limits between glacier faces and retreat of glacier fronts. However, rising surface air and ocean temperatures, as well as substantially increased snow fall in some regions, are also known. These tendencies were linked to changes in atmospheric circulation. Hence, a better understanding of the processes and mechanisms leading to such changes is required. The role of clouds has not been well studied yet in this context. Here, preliminary retrievals of satellite-derived cloud macrophysical and microphysical properties in the Antarctic Peninsula will be presented. The data will be analyzed in the special light of improving parameterizations in the Polar Weather Research and Forecasting model. This has the goal to ultimately enhance our understanding of how variations in the cloud cover and properties impact the energy balance on the Antarctic Peninsula at regional scales.

  5. Banner clouds observed at Mount Zugspitze

    Directory of Open Access Journals (Sweden)

    V. Wirth

    2012-04-01

    Full Text Available Systematic observations of banner clouds at Mount Zugspitze in the Bavarian Alps are presented and discussed. One set of observations draws on daily time lapse movies, which were taken over several years at this mountain. Identifying banner clouds with the help of these movies and using simultaneous observations of standard variables at the summit of the mountain provides climatological information regarding the banner clouds. In addition, a week-long measurement campaign with an entire suite of instruments was carried through yielding a comprehensive set of data for two specific banner cloud events.

    The duration of banner cloud events has a long-tailed distribution with a mean of about 40 min. The probability of occurrence has both a distinct diurnal and a distinct seasonal cycle, with a maximum in the afternoon and in the warm season, respectively. These cycles appear to correspond closely to analogous cycles of relative humidity, which maximize in the late afternoon and during the warm season. In addition, the dependence of banner cloud occurrence on wind speed is weak. Both results suggest that moisture conditions are a key factor for banner cloud occurrence. The distribution of wind direction during banner cloud events slightly deviates from climatology, suggesting an influence from the specific Zugspitz orography.

    The two banner cloud events during the campaign have a number of common features: the windward and the leeward side are characterized by different wind regimes, however, with mean upward flow on both sides; the leeward air is both moister and warmer than the windward air; the background atmosphere has an inversion just above the summit of Mt. Zugspitze; the lifting condensation level increases with altitude. The results are discussed, and it is argued that they are consistent with previous Large Eddy Simulations using idealized orography.

  6. 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”.

  7. Medical aspects of global warming.

    Science.gov (United States)

    Yoganathan, D; Rom, W N

    2001-08-01

    Global warming is caused by increased carbon dioxide (CO2)resulting in a greenhouse effect with enhanced warming of the earth. Measurements of CO2 show a steady increase over the past 30 years caused by the burning of fossil fuels and from the loss of natural CO2 sinks. A 100-year increase in global temperature by 0.3 to 0.6 degrees C is reflected in atmospheric warming, glacier shrinkage, and rising sea levels. Planetary ecosystem dynamics are being altered, challenging public health. It is predicted that morbidity and mortality will increase as a result of heat stress, as seen in recent heat waves in the U.S. Weather disaster effects will increase in number and magnitude, and both noninfectious and infectious diseases may flourish. A significant challenge will be the changes in life cycles of microbial species due to the warmer environs. Specific increases in incidence have been noted for vector-borne diseases, in addition to pulmonary findings, cardiovascular morbidity, neurological diseases, and occupational diseases. Warming can be demonstrated by the observed changes that have already occurred in the environment, particularly the thinning of polar ice caps. The United States Global Research Program has been established to coordinate research activities, which responds to issues deemed important by the United Nations Framework Convention on Climate Change. Research issues pertain to the scientific uncertainties in the greenhouse effect, temperature measurements at various atmospheric levels and latitudes, and impact on biota redistribution. The Kyoto Protocol has mandated specific solutions, e.g., a 7% reduction in CO2 levels within 10 years. Future recommendations involve supporting new technologies that are available to decrease emissions as well as understanding the role that occupational and environmental specialists have in global warming recognition. Copyright 2001 Wiley-Liss, Inc.

  8. An improved algorithm for calculating cloud radiation

    International Nuclear Information System (INIS)

    Yuan Guibin; Sun Xiaogang; Dai Jingmin

    2005-01-01

    Clouds radiation characteristic is very important in cloud scene simulation, weather forecasting, pattern recognition, and other fields. In order to detect missiles against cloud backgrounds, to enhance the fidelity of simulation, it is critical to understand a cloud's thermal radiation model. Firstly, the definition of cloud layer infrared emittance is given. Secondly, the discrimination conditions of judging a pixel of focal plane on a satellite in daytime or night time are shown and equations are given. Radiance such as reflected solar radiance, solar scattering, diffuse solar radiance, solar and thermal sky shine, solar and thermal path radiance, cloud blackbody and background radiance are taken into account. Thirdly, the computing methods of background radiance for daytime and night time are given. Through simulations and comparison, this algorithm is proved to be an effective calculating algorithm for cloud radiation

  9. Low-Power, Lightweight Cloud Water Content Sensor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The measurement of cloud water content is of great importance in understanding the formation of clouds, their structure, and their radiative properties which in turn...

  10. 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.

  11. Cloud Computing

    Science.gov (United States)

    2010-04-29

    attacks SQL injection attacks  ,        exposing multiple customers’ data stored in  the same table and side channel attacks)    ,        .  17Bingue...or er to  sync ronize  multiple distributed machine images, images  distributed across multiple physical machines        ,  between cloud

  12. Clouded research

    CERN Multimedia

    Solomon, Lawrence

    2007-01-01

    In 1998, Jasper Kirkby, anticipating he'd be leading a path-breaking experiment into the sun's role in global warming, he made the mistake of stating that the sun and cosmis rays "will probably be able to account for somewhere between a half and the whole of the increase in the Earth's temperature that we have seen in the last century. ( 1 page)

  13. The role of cloud microphysical processes in climate - An assessment from a one-dimensional perspective

    Science.gov (United States)

    Liou, Kuo-Nan; Ou, Szu-Cheng

    1989-01-01

    A one-dimensional climate model with an interactive cloud formation and precipitation program is used to study the relationship between cloud microphysical processes and climate. It is shown that the rate of precipitation is directly proportional to the fourth power of the mean cloud particle radius. The effects of CO2 doubling on the climate are examined. It is suggested that smaller cloud droplets may be produced by condensation nuclei over the oceans, as a result of greenhouse warming and pollution over land. Larger cloud droplets could be caused by the removal of cloud-forming nuclei, resulting from enhance precipitation due to greenhouse perturbations.

  14. 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.

  15. Robust relations between CCN and the vertical evolution of cloud drop size distribution in deep convective clouds

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2008-03-01

    Full Text Available In-situ measurements in convective clouds (up to the freezing level over the Amazon basin show that smoke from deforestation fires prevents clouds from precipitating until they acquire a vertical development of at least 4 km, compared to only 1–2 km in clean clouds. The average cloud depth required for the onset of warm rain increased by ~350 m for each additional 100 cloud condensation nuclei per cm3 at a super-saturation of 0.5% (CCN0.5%. In polluted clouds, the diameter of modal liquid water content grows much slower with cloud depth (at least by a factor of ~2, due to the large number of droplets that compete for available water and to the suppressed coalescence processes. Contrary to what other studies have suggested, we did not observe this effect to reach saturation at 3000 or more accumulation mode particles per cm3. The CCN0.5% concentration was found to be a very good predictor for the cloud depth required for the onset of warm precipitation and other microphysical factors, leaving only a secondary role for the updraft velocities in determining the cloud drop size distributions.

    The effective radius of the cloud droplets (re was found to be a quite robust parameter for a given environment and cloud depth, showing only a small effect of partial droplet evaporation from the cloud's mixing with its drier environment. This supports one of the basic assumptions of satellite analysis of cloud microphysical processes: the ability to look at different cloud top heights in the same region and regard their re as if they had been measured inside one well developed cloud. The dependence of re on the adiabatic fraction decreased higher in the clouds, especially for cleaner conditions, and disappeared at re≥~10 μm. We propose that droplet coalescence, which is at its peak when warm rain is formed in the cloud at

  16. Mastering cloud computing foundations and applications programming

    CERN Document Server

    Buyya, Rajkumar; Selvi, SThamarai

    2013-01-01

    Mastering Cloud Computing is designed for undergraduate students learning to develop cloud computing applications. Tomorrow's applications won't live on a single computer but will be deployed from and reside on a virtual server, accessible anywhere, any time. Tomorrow's application developers need to understand the requirements of building apps for these virtual systems, including concurrent programming, high-performance computing, and data-intensive systems. The book introduces the principles of distributed and parallel computing underlying cloud architectures and specifical

  17. Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment

    Science.gov (United States)

    Pierce, J. R.

    2017-08-01

    The Cosmics Leaving OUtdoor Droplets (CLOUD) experiment was created to systematically test the link between galactic cosmic rays (GCR) and climate, specifically, the connection of ions from GCR to aerosol nucleation and cloud condensation nuclei (CCN), the particles on which cloud droplets form. The CLOUD experiment subsequently unlocked many of the mysteries of nucleation and growth in our atmosphere, and it has improved our understanding of human influences on climate. Their most recent publication (Gordon et al., 2017) provides their first estimate of the GCR-CCN connection, and they show that CCN respond too weakly to changes in GCR to yield a significant influence on clouds and climate.

  18. Speeding Clouds May Reveal Invisible Black Holes

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    Several small, speeding clouds have been discovered at the center of our galaxy. A new study suggests that these unusual objects may reveal the lurking presence of inactive black holes.Peculiar Cloudsa) Velocity-integrated intensity map showing the location of the two high-velocity compact clouds, HCN0.0090.044 and HCN0.0850.094, in the context of larger molecular clouds. b) and c) Latitude-velocity and longitude-velocity maps for HCN0.0090.044 and HCN0.0850.094, respectively. d) and e) spectra for the two compacts clouds, respectively. Click for a closer look. [Takekawa et al. 2017]Sgr A*, the supermassive black hole marking the center of our galaxy, is surrounded by a region roughly 650 light-years across known as the Central Molecular Zone. This area at the heart of our galaxy is filled with large amounts of warm, dense molecular gas that has a complex distribution and turbulent kinematics.Several peculiar gas clouds have been discovered within the Central Molecular Zone within the past two decades. These clouds, dubbed high-velocity compact clouds, are characterized by their compact sizes and extremely broad velocity widths.What created this mysterious population of energetic clouds? The recent discovery of two new high-velocity compact clouds, reported on in a paper led by Shunya Takekawa (Keio University, Japan), may help us to answer this question.Two More to the CountUsing the James Clerk Maxwell Telescope in Hawaii, Takekawa and collaborators detected the small clouds near the circumnuclear disk at the centermost part of our galaxy. These two clouds have velocity spreads of -80 to -20 km/s and -80 to 0 km/s and compact sizes of just over 1 light-year. The clouds similar appearances and physical properties suggest that they may both have been formed by the same process.Takekawa and collaborators explore and discard several possible origins for these clouds, such as outflows from massive protostars (no massive, luminous stars have been detected affiliated

  19. Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Preliminary Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Varble, Adam [Univ. of Utah, Salt Lake City, UT (United States); Nesbitt, Steve [Univ. of Illinois, Urbana-Champaign, IL (United States); Salio, Paola [Univ. of Buenos Aires (Argentina); Zipser, Edward [Univ. of Utah, Salt Lake City, UT (United States); van den Heever, Susan [Colorado State Univ., Fort Collins, CO (United States); McFarquhar, Greg [Univ. of Illinois, Urbana-Champaign, IL (United States); Kollias, Pavlos [Stony Brook Univ., NY (United States); Kreidenweis, Sonia [Colorado State Univ., Fort Collins, CO (United States); DeMott, Paul [Colorado State Univ., Fort Collins, CO (United States); Jensen, Michael [Brookhaven National Lab. (BNL), Upton, NY (United States); Houze, Jr., Robert [Univ. of Washington, Seattle, WA (United States); Rasmussen, Kristen [Colorado State Univ., Fort Collins, CO (United States); Leung, Ruby [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Romps, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gochis, David [National Center for Atmospheric Research, Boulder, CO (United States); Avila, Eldo [National Univ. of Cordoba (Argentina); Williams, Christopher [Univ. of Colorado, Boulder, CO (United States); National Center for Atmospheric Research, Boulder, CO (United States)

    2017-02-01

    General circulation models and downscaled regional models exhibit persistent biases in deep convective initiation location and timing, cloud top height, stratiform area and precipitation fraction, and anvil coverage. Despite important impacts on the distribution of atmospheric heating, moistening, and momentum, nearly all climate models fail to represent convective organization, while system evolution is not represented at all. Improving representation of convective systems in models requires characterization of their predictability as a function of environmental conditions, and this characterization depends on observing many cases of convective initiation, non-initiation, organization, and non-organization. The Cloud, Aerosol, and Complex Terrain Interactions (CACTI) experiment in the Sierras de Córdoba mountain range of north-central Argentina is designed to improve understanding of cloud life cycle and organization in relation to environmental conditions so that cumulus, microphysics, and aerosol parameterizations in multi-scale models can be improved. The Sierras de Córdoba range has a high frequency of orographic boundary-layer clouds, many reaching congestus depths, many initiating into deep convection, and some organizing into mesoscale systems uniquely observable from a single fixed site. Some systems even grow upscale to become among the deepest, largest, and longest-lived in the world. These systems likely contribute to an observed regional trend of increasing extreme rainfall, and poor prediction of them likely contributes to a warm, dry bias in climate models downstream of the Sierras de Córdoba range in a key agricultural region. Many environmental factors influence the convective lifecycle in this region including orographic, low-level jet, and frontal circulations, surface fluxes, synoptic vertical motions influenced by the Andes, cloud detrainment, and aerosol properties. Local and long-range transport of smoke resulting from biomass burning as

  20. Aerosol-cloud interactions in mixed-phase convective clouds - Part 1: Aerosol perturbations

    Science.gov (United States)

    Miltenberger, Annette K.; Field, Paul R.; Hill, Adrian A.; Rosenberg, Phil; Shipway, Ben J.; Wilkinson, Jonathan M.; Scovell, Robert; Blyth, Alan M.

    2018-03-01

    Changes induced by perturbed aerosol conditions in moderately deep mixed-phase convective clouds (cloud top height ˜ 5 km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud-AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and aerosol fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of aerosol fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. Accumulated precipitation is suppressed for higher-aerosol conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with aerosol processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with aerosol concentrations. Condensate production increases with the aerosol concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-aerosol scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further

  1. Black carbon semi-direct effects on cloud cover: review and synthesis

    Directory of Open Access Journals (Sweden)

    D. Koch

    2010-08-01

    Full Text Available Absorbing aerosols (AAs such as black carbon (BC or dust absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover. Previous studies have described conditions under which AAs either increase or decrease cloud cover. The effect depends on several factors, including the altitude of the AA relative to the cloud and the cloud type. We attempt to categorize the effects into several likely regimes. Cloud cover is decreased if the AAs are embedded in the cloud layer. AAs below cloud may enhance convection and cloud cover. AAs above cloud top stabilize the underlying layer and tend to enhance stratocumulus clouds but may reduce cumulus clouds. AAs can also promote cloud cover in convergent regions as they enhance deep convection and low level convergence as it draws in moisture from ocean to land regions. Most global model studies indicate a regional variation in the cloud response but generally increased cloud cover over oceans and some land regions, with net increased low-level and/or reduced upper level cloud cover. The result is a net negative semi-direct effect feedback from the cloud response to AAs. In some of these climate model studies, the cooling effect of BC due to cloud changes is strong enough to essentially cancel the warming direct effects.

  2. Warm autoimmune hemolytic anemia.

    Science.gov (United States)

    Naik, Rakhi

    2015-06-01

    Warm autoimmune hemolytic anemia (AIHA) is defined as the destruction of circulating red blood cells (RBCs) in the setting of anti-RBC autoantibodies that optimally react at 37°C. The pathophysiology of disease involves phagocytosis of autoantibody-coated RBCs in the spleen and complement-mediated hemolysis. Thus far, treatment is aimed at decreasing autoantibody production with immunosuppression or reducing phagocytosis of affected cells in the spleen. The role of complement inhibitors in warm AIHA has not been explored. This article addresses the diagnosis, etiology, and treatment of warm AIHA and highlights the role of complement in disease pathology. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Evaluating the Dominant Components of Warming in Pliocene Climate Simulations

    Science.gov (United States)

    Hill, D. J.; Haywood, A. M.; Lunt, D. J.; Hunter, S. J.; Bragg, F. J.; Contoux, C.; Stepanek, C.; Sohl, L.; Rosenbloom, N. A.; Chan, W.-L.; hide

    2014-01-01

    The Pliocene Model Intercomparison Project (PlioMIP) is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean-atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with the cloud component of planetary albedo enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere midlatitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo, only partially offset by the increases in the cooling impact of cloud albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with clouds in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that albedo feedbacks, particularly those of sea ice and ice sheets, provide the most significant enhancements to high latitude warming in the Pliocene.

  4. Fast Cloud Adjustment to Increasing CO2 in a Superparameterized Climate Model

    Directory of Open Access Journals (Sweden)

    Marat Khairoutdinov

    2012-05-01

    Full Text Available Two-year simulation experiments with a superparameterized climate model, SP-CAM, are performed to understand the fast tropical (30S-30N cloud response to an instantaneous quadrupling of CO2 concentration with SST held fixed at present-day values.The greenhouse effect of the CO2 perturbation quickly warms the tropical land surfaces by an average of 0.5 K. This shifts rising motion, surface precipitation, and cloud cover at all levels from the ocean to the land, with only small net tropical-mean cloud changes. There is a widespread average reduction of about 80 m in the depth of the trade inversion capping the marine boundary layer (MBL over the cooler subtropical oceans.One apparent contributing factor is CO2-enhanced downwelling longwave radiation, which reduces boundary-layer radiative cooling, a primary driver of turbulent entrainment through the trade inversion. A second contributor is a slight CO2-induced heating of the free troposphere above the MBL, which strengthens the trade inversion and also inhibits entrainment. There is a corresponding downward displacement of MBL clouds with a very slight decrease in mean cloud cover and albedo.Two-dimensional cloud-resolving model (CRM simulations of this MBL response are run to steady state using composite SP-CAM simulated thermodynamic and wind profiles from a representative cool subtropical ocean regime, for the control and 4xCO2 cases. Simulations with a CRM grid resolution equal to that of SP-CAM are compared with much finer resolution simulations. The coarse-resolution simulations maintain a cloud fraction and albedo comparable to SP-CAM, but the fine-resolution simulations have a much smaller cloud fraction. Nevertheless, both CRM configurations simulate a reduction in inversion height comparable to SP-CAM. The changes in low cloud cover and albedo in the CRM simulations are small, but both simulations predict a slight reduction in low cloud albedo as in SP-CAM.

  5. The role of cloud phase in Earth's radiation budget

    Science.gov (United States)

    Matus, Alexander V.; L'Ecuyer, Tristan S.

    2017-03-01

    The radiative impact of clouds strongly depends on their partitioning between liquid and ice phases. Until recently, however, it has been challenging to unambiguously discriminate cloud phase in a number of important global regimes. CloudSat and CALIPSO supply vertically resolved measurements necessary to identify clouds composed of both liquid and ice that are not easily detected using conventional passive sensors. The capability of these active sensors to discriminate cloud phase has been incorporated into the fifth generation of CloudSat's 2B-FLXHR-LIDAR algorithm. Comparisons with Clouds and the Earth's Radiant Energy System fluxes at the top of atmosphere reveal that an improved representation of cloud phase leads to better agreement compared to earlier versions of the algorithm. The RMS differences in annual mean outgoing longwave (LW) radiation gridded at 2.5° resolution are 4.9 W m-2, while RMS differences in outgoing shortwave (SW) are slightly larger at 8.9 W m-2 due to the larger diurnal range of solar insolation. This study documents the relative contributions of clouds composed of only liquid, only ice, and a combination of both phases to global and regional radiation budgets. It is found that mixed-phase clouds exert a global net cloud radiative effect of -3.4 W m-2, with contributions of -8.1 W m-2 and 4.7 W m-2 from SW and LW radiation, respectively. When compared with the effects of warm liquid clouds (-11.8 W m-2), ice clouds (3.5 W m-2), and multilayered clouds consisting of distinct liquid and ice layers (-4.6 W m-2), these results reinforce the notion that accurate representation of mixed-phase clouds is essential for quantifying cloud feedbacks in future climate scenarios.

  6. Lidar Penetration Depth Observations for Constraining Cloud Longwave Feedbacks

    Science.gov (United States)

    Vaillant de Guelis, T.; Chepfer, H.; Noel, V.; Guzman, R.; Winker, D. M.; Kay, J. E.; Bonazzola, M.

    2017-12-01

    Satellite-borne active remote sensing Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations [CALIPSO; Winker et al., 2010] and CloudSat [Stephens et al., 2002] provide direct measurements of the cloud vertical distribution, with a very high vertical resolution. The penetration depth of the laser of the lidar Z_Opaque is directly linked to the LongWave (LW) Cloud Radiative Effect (CRE) at Top Of Atmosphere (TOA) [Vaillant de Guélis et al., in review]. In addition, this measurement is extremely stable in time making it an excellent observational candidate to verify and constrain the cloud LW feedback mechanism [Chepfer et al., 2014]. In this work, we present a method to decompose the variations of the LW CRE at TOA using cloud properties observed by lidar [GOCCP v3.0; Guzman et al., 2017]. We decompose these variations into contributions due to changes in five cloud properties: opaque cloud cover, opaque cloud altitude, thin cloud cover, thin cloud altitude, and thin cloud emissivity [Vaillant de Guélis et al., in review]. We apply this method, in the real world, to the CRE variations of CALIPSO 2008-2015 record, and, in climate model, to LMDZ6 and CESM simulations of the CRE variations of 2008-2015 period and of the CRE difference between a warm climate and the current climate. In climate model simulations, the same cloud properties as those observed by CALIOP are extracted from the CFMIP Observation Simulator Package (COSP) [Bodas-Salcedo et al., 2011] lidar simulator [Chepfer et al., 2008], which mimics the observations that would be performed by the lidar on board CALIPSO satellite. This method, when applied on multi-model simulations of current and future climate, could reveal the altitude of cloud opacity level observed by lidar as a strong constrain for cloud LW feedback, since the altitude feedback mechanism is physically explainable and the altitude of cloud opacity accurately observed by lidar.

  7. Aerosols, clouds and their climatic impacts

    Energy Technology Data Exchange (ETDEWEB)

    Kulmala, M.; Laaksonen, A.; Korhonen, P. [Helsinki Univ. (Finland). Dept. of Physics

    1995-12-31

    The increasing atmospheric concentrations of greenhouse gases such as carbon dioxide and methane may drive a significant warming of the earth`s climate. However, a topic of more recent attention is the possibility that increased atmospheric concentrations of aerosol particles might drive a cooling of the planet. There are two distinct cooling mechanisms related to the enhanced concentrations of aerosol particles: the increase in the direct reflection of solar radiation (the direct effect), and the increase in cloud reflectivity caused by greater numbers of cloud condensation nuclei available (the indirect effect). Aerosols and clouds play a major role in the scattering and absorption of radiation in the Earth`s atmosphere. Locally the net effect can vary because of different kinds of surfaces. But according to measurements, the global net effect of clouds (and aerosols) on the atmosphere is net cooling and thus in opposition to the effect of greenhouse gases. The prediction of the future evolution of the climate involves substantial uncertainties. Clouds have a major effect on the radiation balance of the Earth and the prediction of amount and radiative properties of clouds is very difficult. Also the formation mechanisms and residence times of aerosol particles in the atmosphere involve large uncertainties. Thus the most serious difficulties arise in the area of the physics of clouds and aerosols

  8. Global Warming: A Myth?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 7. Global Warming: A Myth? - Credibility of Climate Scenarios Predicted by Systems Simulations. Deepanjan Majumdar. General Article Volume 6 Issue 7 July 2001 pp 13-21 ...

  9. Warm and Cool Dinosaurs.

    Science.gov (United States)

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  10. Global Warming: A Myth?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 6. Global Warming: A Myth? - Anomalous Temperature Trends Recorded from Satellites and Radiosondes. Deepanjan Majumdar. General Article Volume 6 Issue 6 June 2001 pp 43-52 ...

  11. 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.

  12. Media Pembelajaran Global Warming

    OpenAIRE

    Tham, Fikri Jufri; Liliana, Liliana; Purba, Kristo Radion

    2016-01-01

    Computer based learning media is one of the media has an important role in learning. Learning media will be attractive when packaged through interactive media , such as interactive media created in paper manufacture " instructional media global warming" . The advantage gained is that it can increase knowledge, generally educate people to be more concerned about the environment , and also can be a means of entertainment. This application is focused to learn about global warming and packaged in...

  13. A framework for cloud - Aerosol interaction study

    NARCIS (Netherlands)

    Sarna, K.; Russchenberg, H.W.J.

    2012-01-01

    Aerosols can indirectly influence climate either by cloud albedo or lifetime effect. In order to have better understanding of these processes it is crucial to measure detailed vertical profiles of the radiative transfer and the microphysical evolution of clouds. Best results can be achieved by using

  14. Refrigeration and global warming

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    Some aspects of global warming in general, and the implications for refrigerants and refrigerator efficiency in particular, are briefly considered in a question and answer format. The concepts of Global Warming Potential (GWP) and Total Equivalent Warming Impact (TEWI) are explained. GWP is an index which allows a simple comparison to be make between the warming effects of different gases on a kg to kg basis relative to carbon. The GWP depends both on the lifetime of a substance in the atmosphere and its infra-red absorption capacity. The overall warming effect of operating a refrigeration system for its entire life is measured by its TEWI. Chloroflourocarbons (CFCs) which have been widely used as refrigerants are powerful greenhouse gases with high GWPs. Because of the bank of CFCs in refrigerating systems, their levels in the atmosphere are still increasing and it will be some time before refrigerant changes will be effective in reducing the warming effects of refrigerant releases. Hydrocarbons, hydroflourocarbons and ammonia all have a part to play as substitute refrigerants. Refrigerator efficiency is very important in terms of reducing CO 2 emissions. (UK)

  15. 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...

  16. Securing Cloud Storage Service

    OpenAIRE

    Zapolskas, Vytautas

    2012-01-01

    Cloud computing brought flexibility, scalability, and capital cost savings to the IT industry. As more companies turn to cloud solutions, securing cloud based services becomes increasingly important, because for many organizations, the final barrier to adopting cloud computing is whether it is sufficiently secure. More users rely on cloud storage as it is mainly because cloud storage is available to be used by multiple devices (e.g. smart phones, tablets, notebooks, etc.) at the same time. Th...

  17. 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.

  18. Occurrence of lower cloud albedo in ship tracks

    Directory of Open Access Journals (Sweden)

    Y.-C. Chen

    2012-09-01

    Full Text Available The concept of geoengineering by marine cloud brightening is based on seeding marine stratocumulus clouds with sub-micrometer sea-salt particles to enhance the cloud droplet number concentration and cloud albedo, thereby producing a climate cooling effect. The efficacy of this as a strategy for global cooling rests on the extent to which aerosol-perturbed marine clouds will respond with increased albedo. Ship tracks, quasi-linear cloud features prevalent in oceanic regions impacted by ship exhaust, are a well-known manifestation of the effect of aerosol injection on marine clouds. We present here an analysis of the albedo responses in ship tracks, based on in situ aircraft measurements and three years of satellite observations of 589 individual ship tracks. It is found that the sign (increase or decrease and magnitude of the albedo response in ship tracks depends on the mesoscale cloud structure, the free tropospheric humidity, and cloud top height. In a closed cell structure (cloud cells ringed by a perimeter of clear air, nearly 30% of ship tracks exhibited a decreased albedo. Detailed cloud responses must be accounted for in global studies of the potential efficacy of sea-spray geoengineering as a means to counteract global warming.

  19. A Multimodel Study on Warm Precipitation Biases in Global Models Compared to Satellite Observations

    Science.gov (United States)

    Jing, Xianwen; Suzuki, Kentaroh; Guo, Huan; Goto, Daisuke; Ogura, Tomoo; Koshiro, Tsuyoshi; Mülmenstädt, Johannes

    2017-11-01

    The cloud-to-precipitation transition process in warm clouds simulated by state-of-the-art global climate models (GCMs), including both traditional climate models and a high-resolution model, is evaluated against A-Train satellite observations. The models and satellite observations are compared in the form of the statistics obtained from combined analysis of multiple-satellite observables that probe signatures of the cloud-to-precipitation transition process. One common problem identified among these models is the too-frequent occurrence of warm precipitation. The precipitation is found to form when the cloud particle size and the liquid water path (LWP) are both much smaller than those in observations. The too-efficient formation of precipitation is found to be compensated for by errors of cloud microphysical properties, such as underestimated cloud particle size and LWP, to an extent that varies among the models. However, this does not completely cancel the precipitation formation bias. Robust errors are also found in the evolution of cloud microphysical properties from nonprecipitating to drizzling and then to raining clouds in some GCMs, implying unrealistic interaction between precipitation and cloud water. Nevertheless, auspicious information is found for future improvement of warm precipitation representations: the adoption of more realistic autoconversion scheme in the high-resolution model improves the triggering of precipitation, and the introduction of a sophisticated subgrid variability scheme in a traditional model improves the simulated precipitation frequency over subtropical eastern ocean. However, deterioration in other warm precipitation characteristics is also found accompanying these improvements, implying the multisource nature of warm precipitation biases in GCMs.

  20. Cloudonomics the business value of cloud computing

    CERN Document Server

    Weinman, Joe

    2012-01-01

    The ultimate guide to assessing and exploiting the customer value and revenue potential of the Cloud A new business model is sweeping the world—the Cloud. And, as with any new technology, there is a great deal of fear, uncertainty, and doubt surrounding cloud computing. Cloudonomics radically upends the conventional wisdom, clearly explains the underlying principles and illustrates through understandable examples how Cloud computing can create compelling value—whether you are a customer, a provider, a strategist, or an investor. Cloudonomics covers everything you need to consider f

  1. Cloud optical thickness feedbacks in the CO2 climate problem

    Science.gov (United States)

    Somerville, R. C. J.

    1985-01-01

    A radiative-convective equilibrium model is developed and applied to study cloud optical thickness feedbacks in the CO2 climate problem. The basic hypothesis is that in the warmer and moister CO2-rich atmosphere, cloud liquid water content will generally be larger than at present, so that cloud optical thickness will be larger too. For clouds other than thin cirrus, the result is to increase the albedo more than to increase the greenhouse effect. Thus the sign of the feedback is negative: cloud optical properties alter in such a way as to reduce the surface and tropospheric warming caused by the addition of CO2. This negative feedback can be substantial. When observational estimates of the temperature dependence of cloud liquid water content are employed in the model, the surface temperature change due to doubling CO2 is reduced by about one half.

  2. Smoke Invigoration Versus Inhibition of Clouds over the Amazon

    Science.gov (United States)

    Koren, Ilan; Martins, J. Vanderlei; Lorraine, A. Remer; Afargan, Hila

    2008-01-01

    The effect of anthropogenic aerosols on clouds is one of the most important and least understood aspects of human-induced climate change. Small changes in the amount of cloud coverage can produce a climate forcing equivalent in magnitude and opposite in sign to that caused by anthropogenic greenhouse gases, and changes in cloud height can shift the effect of clouds from cooling to warming. Focusing on the Amazon, we show a smooth transition between two opposing effects of aerosols on clouds: the microphysical and the radiative. We show how a feedback between the optical properties of aerosols and the cloud fraction can modify the aerosol forcing, changing the total radiative energy and redistributing it over the atmospheric column.

  3. 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.

  4. Heterotrophic respiration does not acclimate to continuous warming in a subtropical forest

    OpenAIRE

    Wu, Chuansheng; Liang, Naishen; Sha, Liqing; Xu, Xingliang; Zhang, Yiping; Lu, Huazheng; Song, Liang; Song, Qinghai; Xie, Youneng

    2016-01-01

    As heterotrophic respiration (R H) has great potential to increase atmospheric CO2 concentrations, it is important to understand warming effects on R H for a better prediction of carbon?climate feedbacks. However, it remains unclear how R H responds to warming in subtropical forests. Here, we carried out trenching alone and trenching with warming treatments to test the climate warming effect on R H in a subtropical forest in southwestern China. During the measurement period, warming increased...

  5. 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....

  6. Data intensive ATLAS workflows in the Cloud

    CERN Document Server

    Rzehorz, Gerhard Ferdinand; The ATLAS collaboration

    2018-01-01

    From 2025 onwards, the ATLAS collaboration at the Large Hadron Collider (LHC) at CERN will experience a massive increase in data quantity as well as complexity. Including mitigating factors, the prevalent computing power by that time will only fulfil one tenth of the requirement. This contribution will focus on Cloud computing as an approach to help overcome this challenge by providing flexible hardware that can be configured to the specific needs of a workflow. Experience with Cloud computing exists, but there is a large uncertainty if and to which degree it can be able to reduce the burden by 2025. In order to understand and quantify the benefits of Cloud computing, the "Workflow and Infrastructure Model" was created. It estimates the viability of Cloud computing by combining different inputs from the workflow side with infrastructure specifications. The model delivers metrics that enable the comparison of different Cloud configurations as well as different Cloud offerings with each other. A wide range of r...

  7. Wyoming Cloud Lidar: instrument description and applications.

    Science.gov (United States)

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

    2009-08-03

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

  8. Cloud a particle beam facility to investigate the influence of cosmic rays on clouds

    CERN Document Server

    Kirkby, Jasper

    2001-01-01

    Palaeoclimatic data provide extensive evidence for solar forcing of the climate during the Holocene and the last ice age, but the underlying mechanism remains a mystery. However recent observations suggest that cosmic rays may play a key role. Satellite data have revealed a surprising correlation between cosmic ray intensity and the fraction of the Earth covered by low clouds \\cite{svensmark97,marsh}. Since the cosmic ray intensity is modulated by the solar wind, this may be an important clue to the long-sought mechanism for solar-climate variability. In order to test whether cosmic rays and clouds are causally linked and, if so, to understand the microphysical mechanisms, a novel experiment known as CLOUD\\footnotemark\\ has been proposed \\cite{cloud_proposal}--\\cite{cloud_addendum_2}. CLOUD proposes to investigate ion-aerosol-cloud microphysics under controlled laboratory conditions using a beam from a particle accelerator, which provides a precisely adjustable and measurable artificial source of cosmic rays....

  9. 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.

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

    International Nuclear Information System (INIS)

    Line, Michael R.; Parmentier, Vivien

    2016-01-01

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

  11. Clouds and aerosols in Puerto Rico ─ a new evaluation

    Directory of Open Access Journals (Sweden)

    U. Dusek

    2008-03-01

    Full Text Available The influence of aerosols, both natural and anthropogenic, remains a major area of uncertainty when predicting the properties and behaviour of clouds and their influence on climate. In an attempt to better understand warm cloud formation in a tropical marine environment, a period of intensive measurements took place in December 2004 in Puerto Rico, using some of the latest developments in online instrumentation such as aerosol mass spectrometers, cloud condensation nuclei counters and a hygroscopicity tandem differential mobility analyser. Simultaneous online measurements of aerosol size distributions, composition, hygroscopicity and optical properties were made near the lighthouse of Cape San Juan in the north-eastern corner of the island and at the top of East Peak mountain (1040 m a.s.l., the two sites separated by 17 km. Additional measurements of the cloud droplet residual and interstitial aerosol properties were made at the mountain site, accompanied by measurements of cloud droplet size distributions, liquid water content and the chemical composition of cloud and rain water samples. Both aerosol composition and cloud properties were found to be sensitive to wind sector. Air from the east-northeast (ENE was mostly free of anthropogenic influences, the submicron fraction being mainly composed of non-sea salt sulphate, while that from the east-southeast (ESE was found to be moderately influenced by populated islands upwind, adding smaller (<100 nm, externally mixed, carbonaceous particles to the aerosol that increased the number concentrations by over a factor of 3. This change in composition was also accompanied with a reduction in the measured hygroscopicity and fractional cloud activation potential of the aerosol. At the mountain site, the average cloud droplet concentrations increased from 193 to 519 cm−3, median volume diameter decreased from 20 to 14 μm and the liquid water content increased from 0.24 to 0.31 g m−3 when the winds

  12. Automatic Cloud Bursting under FermiCloud

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  13. Global warming on trial

    International Nuclear Information System (INIS)

    Broeker, W.S.

    1992-01-01

    Jim Hansen, a climatologist at NASA's Goddard Space Institute, is convinced that the earth's temperature is rising and places the blame on the buildup of greenhouse gases in the atmosphere. Unconvinced, John Sununu, former White House chief of staff, doubts that the warming will be great enough to produce serious threat and fears that measures to reduce the emissions would throw a wrench into the gears that drive the Unites States' troubled economy. During his three years at the White House, Sununu's view prevailed, and although his role in the debate has diminished, others continue to cast doubt on the reality of global warming. A new lobbying group called the Climate Council has been created to do just this. Burning fossil fuels is not the only problem; a fifth of emissions of carbon dioxide now come from clearing and burning forests. Scientists are also tracking a host of other greenhouse gases that emanate from a variety of human activities; the warming effect of methane, chlorofluorocarbons and nitrous oxide combined equals that of carbon dioxide. Although the current warming from these gases may be difficult to detect against the background noise of natural climate variation, most climatologists are certain that as the gases continue to accumulate, increases in the earth's temperature will become evident even to skeptics. If the reality of global warming were put on trial, each side would have trouble making its case. Jim Hansen's side could not prove beyond a reasonable doubt that carbon dioxide and other greenhouse gases have warmed the planet. But neither could John Sununu's side prove beyond a reasonable doubt that the warming expected from greenhouse gases has not occurred. To see why each side would have difficulty proving its case, this article reviews the arguments that might be presented in such a hearing

  14. Long range global warming

    International Nuclear Information System (INIS)

    Rolle, K.C.; Pulkrabek, W.W.; Fiedler, R.A.

    1995-01-01

    This paper explores one of the causes of global warming that is often overlooked, the direct heating of the environment by engineering systems. Most research and studies of global warming concentrate on the modification that is occurring to atmospheric air as a result of pollution gases being added by various systems; i.e., refrigerants, nitrogen oxides, ozone, hydrocarbons, halon, and others. This modification affects the thermal radiation balance between earth, sun and space, resulting in a decrease of radiation outflow and a slow rise in the earth's steady state temperature. For this reason the solution to the problem is perceived as one of cleaning up the processes and effluents that are discharged into the environment. In this paper arguments are presented that suggest, that there is a far more serious cause for global warming that will manifest itself in the next two or three centuries; direct heating from the exponential growth of energy usage by humankind. Because this is a minor contributor to the global warming problem at present, it is overlooked or ignored. Energy use from the combustion of fuels and from the output of nuclear reactions eventually is manifest as warming of the surroundings. Thus, as energy is used at an ever increasing rate the consequent global warming also increases at an ever increasing rate. Eventually this rate will become equal to a few percent of solar radiation. When this happens the earth's temperature will have risen by several degrees with catastrophic results. The trends in world energy use are reviewed and some mathematical models are presented to suggest future scenarios. These models can be used to predict when the global warming problem will become undeniably apparent, when it will become critical, and when it will become catastrophic

  15. The evolution of cloud computing how to plan for change

    CERN Document Server

    Longbottom, Clive

    2017-01-01

    Cloud computing has been positioned as today's ideal IT platform. This book looks at what cloud promises and how it's likely to evolve in the future. Readers will be able to ensure that decisions made now will hold them in good stead in the future and will gain an understanding of how cloud can deliver the best outcome for their organisations.

  16. ENSO and greenhouse warming

    Science.gov (United States)

    Cai, Wenju; Santoso, Agus; Wang, Guojian; Yeh, Sang-Wook; An, Soon-Il; Cobb, Kim M.; Collins, Mat; Guilyardi, Eric; Jin, Fei-Fei; Kug, Jong-Seong; Lengaigne, Matthieu; McPhaden, Michael J.; Takahashi, Ken; Timmermann, Axel; Vecchi, Gabriel; Watanabe, Masahiro; Wu, Lixin

    2015-09-01

    The El Niño/Southern Oscillation (ENSO) is the dominant climate phenomenon affecting extreme weather conditions worldwide. Its response to greenhouse warming has challenged scientists for decades, despite model agreement on projected changes in mean state. Recent studies have provided new insights into the elusive links between changes in ENSO and in the mean state of the Pacific climate. The projected slow-down in Walker circulation is expected to weaken equatorial Pacific Ocean currents, boosting the occurrences of eastward-propagating warm surface anomalies that characterize observed extreme El Niño events. Accelerated equatorial Pacific warming, particularly in the east, is expected to induce extreme rainfall in the eastern equatorial Pacific and extreme equatorward swings of the Pacific convergence zones, both of which are features of extreme El Niño. The frequency of extreme La Niña is also expected to increase in response to more extreme El Niños, an accelerated maritime continent warming and surface-intensified ocean warming. ENSO-related catastrophic weather events are thus likely to occur more frequently with unabated greenhouse-gas emissions. But model biases and recent observed strengthening of the Walker circulation highlight the need for further testing as new models, observations and insights become available.

  17. Forecasting phenology under global warming.

    Science.gov (United States)

    Ibáñez, Inés; Primack, Richard B; Miller-Rushing, Abraham J; Ellwood, Elizabeth; Higuchi, Hiroyoshi; Lee, Sang Don; Kobori, Hiromi; Silander, John A

    2010-10-12

    As a consequence of warming temperatures around the world, spring and autumn phenologies have been shifting, with corresponding changes in the length of the growing season. Our understanding of the spatial and interspecific variation of these changes, however, is limited. Not all species are responding similarly, and there is significant spatial variation in responses even within species. This spatial and interspecific variation complicates efforts to predict phenological responses to ongoing climate change, but must be incorporated in order to build reliable forecasts. Here, we use a long-term dataset (1953-2005) of plant phenological events in spring (flowering and leaf out) and autumn (leaf colouring and leaf fall) throughout Japan and South Korea to build forecasts that account for these sources of variability. Specifically, we used hierarchical models to incorporate the spatial variability in phenological responses to temperature to then forecast species' overall and site-specific responses to global warming. We found that for most species, spring phenology is advancing and autumn phenology is getting later, with the timing of events changing more quickly in autumn compared with the spring. Temporal trends and phenological responses to temperature in East Asia contrasted with results from comparable studies in Europe, where spring events are changing more rapidly than are autumn events. Our results emphasize the need to study multiple species at many sites to understand and forecast regional changes in phenology.

  18. Forecasting phenology under global warming

    Science.gov (United States)

    Ibáñez, Inés; Primack, Richard B.; Miller-Rushing, Abraham J.; Ellwood, Elizabeth; Higuchi, Hiroyoshi; Lee, Sang Don; Kobori, Hiromi; Silander, John A.

    2010-01-01

    As a consequence of warming temperatures around the world, spring and autumn phenologies have been shifting, with corresponding changes in the length of the growing season. Our understanding of the spatial and interspecific variation of these changes, however, is limited. Not all species are responding similarly, and there is significant spatial variation in responses even within species. This spatial and interspecific variation complicates efforts to predict phenological responses to ongoing climate change, but must be incorporated in order to build reliable forecasts. Here, we use a long-term dataset (1953–2005) of plant phenological events in spring (flowering and leaf out) and autumn (leaf colouring and leaf fall) throughout Japan and South Korea to build forecasts that account for these sources of variability. Specifically, we used hierarchical models to incorporate the spatial variability in phenological responses to temperature to then forecast species' overall and site-specific responses to global warming. We found that for most species, spring phenology is advancing and autumn phenology is getting later, with the timing of events changing more quickly in autumn compared with the spring. Temporal trends and phenological responses to temperature in East Asia contrasted with results from comparable studies in Europe, where spring events are changing more rapidly than are autumn events. Our results emphasize the need to study multiple species at many sites to understand and forecast regional changes in phenology. PMID:20819816

  19. Can marine cloud brightening reduce coral bleaching?

    OpenAIRE

    Latham, J; Kleypas, J; Hauser, R; Parkes, B; Gadian, A

    2013-01-01

    Increases in coral bleaching events over the last few decades have been largely caused by rising sea surface temperatures (SST), and continued warming is expected to cause even greater increases through this century. We use a Global Climate Model to examine the potential of marine cloud brightening (MCB) to cool oceanic surface waters in three coral reef provinces. Our simulations indicate that under doubled CO conditions, the substantial increases in coral bleaching conditions from current v...

  20. Developing and evaluating a cloud service relationship theory

    CERN Document Server

    Huntgeburth, Jan

    2014-01-01

    This book develops, evaluates and refines a cloud service relationship theory that explains how cloud users' uncertainties arise in these relationships and how they can be mitigated. To that end, the book employs principal-agent theory and the concepts of bounded rationality and social embeddedness. Beyond advancing IS research, the findings presented can greatly benefit governments, IT departments and IT providers, helping them to better understand cloud service relationships and to adjust their cloud service strategies accordingly.

  1. The global warming problem

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    In this chapter, a discussion is presented of the global warming problem and activities contributing to the formation of acid rain, urban smog and to the depletion of the ozone layer. Globally, about two-thirds of anthropogenic carbon dioxide emissions arise from fossil-fuel burning; the rest arise primarily from deforestation. Chlorofluorocarbons are the second largest contributor to global warming, accounting for about 20% of the total. The third largest contributor is methane, followed by ozone and nitrous oxide. A study of current activities in the US that contribute to global warming shows the following: electric power plants account for about 33% of carbon dioxide emissions; motor vehicles, planes and ships (31%); industrial plants (24%); commercial and residential buildings (11%)

  2. 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.

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

    Science.gov (United States)

    Guy, N.; Rowe, A.

    2014-12-01

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

  4. Role of orbital dynamics and cloud-cloud collisions in the formation of giant molecular clouds in global spiral structures

    International Nuclear Information System (INIS)

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

    1987-01-01

    The role of orbit crowding and cloud-cloud collisions in the formation of GMCs and their organization in global spiral structure is investigated. Both N-body simulations of the cloud system and a detailed analysis of individual particle orbits are used to develop a conceptual understanding of how individual clouds participate in the collective density response. Detailed comparisons are made between a representative cloud-particle simulation in which the cloud particles collide inelastically with one another and give birth to and subsequently interact with young star associations and stripped down simulations in which the cloud particles are allowed to follow ballistic orbits in the absence of cloud-cloud collisions or any star formation processes. Orbit crowding is then related to the behavior of individual particle trajectories in the galactic potential field. The conceptual picture of how GMCs are formed in the clumpy ISMs of spiral galaxies is formulated, and the results are compared in detail with those published by other authors. 68 references

  5. Robots and sensor clouds

    CERN Document Server

    Shakshuki, Elhadi

    2016-01-01

    This book comprises four chapters that address some of the latest research in clouds robotics and sensor clouds. The first part of the book includes two chapters on cloud robotics. The first chapter introduces a novel resource allocation framework for cloud robotics and proposes a Stackelberg game model and the corresponding task oriented pricing mechanism for resource allocation. In the second chapter, the authors apply Cloud Computing for building a Cloud-Based 3D Point Cloud extractor for stereo images. Their objective is to have a dynamically scalable and applicable to near real-time scenarios.  .

  6. An Examination of the Nature of Global MODIS Cloud Regimes

    Science.gov (United States)

    Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji; Huffman, George J.

    2014-01-01

    We introduce global cloud regimes (previously also referred to as "weather states") derived from cloud retrievals that use measurements by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua and Terra satellites. The regimes are obtained by applying clustering analysis on joint histograms of retrieved cloud top pressure and cloud optical thickness. By employing a compositing approach on data sets from satellites and other sources, we examine regime structural and thermodynamical characteristics. We establish that the MODIS cloud regimes tend to form in distinct dynamical and thermodynamical environments and have diverse profiles of cloud fraction and water content. When compositing radiative fluxes from the Clouds and the Earth's Radiant Energy System instrument and surface precipitation from the Global Precipitation Climatology Project, we find that regimes with a radiative warming effect on the atmosphere also produce the largest implied latent heat. Taken as a whole, the results of the study corroborate the usefulness of the cloud regime concept, reaffirm the fundamental nature of the regimes as appropriate building blocks for cloud system classification, clarify their association with standard cloud types, and underscore their distinct radiative and hydrological signatures.

  7. Instant CloudFlare starter

    CERN Document Server

    Dickey, Jeff

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. Written as a practical guide, CloudFlare Starter will show you all you need to know in order to effectively improve your online presence in a multitude of different ways. ""Instant CloudFlare Starter"" is a practical yet accessible guide for website owners looking to optimize their site for optimum security and maximum performance.

  8. PEDAGOGICAL ASPECTS OF CLOUD COMPUTING

    Directory of Open Access Journals (Sweden)

    N. Morze

    2011-05-01

    Full Text Available Recent progress in computer science in the field of redundancy and protection has led to the sharing of data in many different repositories. Modern infrastructure has made cloud computing safe and reliable, and advancement of such computations radically changes the understanding of the use of resources and services. The materials in this article are connected with the definition of pedagogical possibilities of using cloud computing to provide education on the basis of competence-based approach and monitoring of learners (students.

  9. Progress in Understanding Land-Surface-Atmosphere Coupling from LBA Research

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2010-06-01

    Full Text Available LBA research has deepened our understanding of the role of soil water storage, clouds and aerosols in land-atmosphere coupling. We show how the reformulation of cloud forcing in terms of an effective cloud albedo per unit area of surface gives a useful measure of the role of clouds in the surface energy budget over the Amazon. We show that the diurnal temperature range has a quasi-linear relation to the daily mean longwave cooling; and to effective cloud albedo because of the tight coupling between the near-surface climate, the boundary layer and the cloud field. The coupling of surface and atmospheric processes is critical to the seasonal cycle: deep forest rooting systems make water available throughout the year, whereas in the dry season the shortwave cloud forcing is reduced by regional scale subsidence, so that more light is available for photosynthesis. At sites with an annual precipitation above 1900 mm and a dry season length less than 4 months, evaporation rates increased in the dry season, coincident with increased radiation. In contrast, ecosystems with precipitation less than 1700 mm and a longer dry season showed clear evidence of reduced evaporation in the dry season coming from water stress. In all these sites, the seasonal variation of the effective cloud albedo is a major factor in determining the surface available energy. Dry season fires add substantial aerosol to the atmosphere. Aerosol scattering and absorption both reduce the total downward surface radiative flux, but increase the diffuse/direct flux ratio, which increases photosynthetic efficiency. Convective plumes produced by fires enhance the vertical transport of aerosols over the Amazon, and effectively inject smoke aerosol and gases directly into the middle troposphere with substantial impacts on mid- tropospheric dispersion. In the rainy season in Rondônia, convection in low-level westerly flows with low aerosol content resembles oceanic convection with

  10. Is global warming mostly at night?

    International Nuclear Information System (INIS)

    Kukla, G.; Quayle, R.G.; Karl, T.

    1994-01-01

    The release of greenhouse gases is expected to lead to substantial future warming. The global mean temperature has indeed risen in recent decades. The causes of the observed warming, and its relation to the greenhouse gas buildup are, however, still debated. One important aspect of the observed temperature change relates to its asymmetry during the day and night. The day-night temperature difference over land in North America, most of Eurasia, Oceania, and portions of Africa and Australia shows a decrease since about 1950. The changes of the daily mean temperature in these areas are principally due to the rising night or early morning temperature, and are accompanied by increasing cloudiness. Their results support the notion that the increase of cloud cover, possibly due to industrial sulfur emissions, mitigates the greenhouse warming. The causes of the changing diurnal temperature range and of the increasing cloudiness will have to be clarified and the future SO 2 emissions reliably projected before any trustworthy prediction of future climates can be made. 37 refs., 7 figs., 2 tabs

  11. 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.

  12. Diurnal cloud cycle biases in climate models.

    Science.gov (United States)

    Yin, Jun; Porporato, Amilcare

    2017-12-22

    Clouds' efficiency at reflecting solar radiation and trapping the terrestrial radiation is strongly modulated by the diurnal cycle of clouds (DCC). Much attention has been paid to mean cloud properties due to their critical role in climate projections; however, less research has been devoted to the DCC. Here we quantify the mean, amplitude, and phase of the DCC in climate models and compare them with satellite observations and reanalysis data. While the mean appears to be reliable, the amplitude and phase of the DCC show marked inconsistencies, inducing overestimation of radiation in most climate models. In some models, DCC appears slightly shifted over the ocean, likely as a result of tuning and fortuitously compensating the large DCC errors over the land. While this model tuning does not seem to invalidate climate projections because of the limited DCC response to global warming, it may potentially increase the uncertainty of climate predictions.

  13. Electron Cloud observation in the LHC

    CERN Document Server

    Rumolo, G; Baglin, V; Bartosik, H; Biancacci, N; Baudrenghien, P; Bregliozzi, G; Chiggiato, P; Claudet, S; De Maria, R; Esteban-Muller, J; Favier, M; Hansen, C; Höfle, W; Jimenez, J M; Kain, V; Lanza, G; Li, K S B; Maury Cuna, G H I; Métral, E; Papotti, G; Pieloni, T; Roncarolo, F; Salvant, B; Shaposhnikova, E N; Steinhagen, R J; Tavian, L J; Valuch, D; Venturini Delsolaro, W; Zimmermann, F; Iriso, U; Dominguez, O; Koukovini-Platia, E; Mounet, N; Zannini, C; Bhat, C M

    2011-01-01

    Operation of LHC with bunch trains at different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with models will be presented. The efficiency of scrubbing to improve the machine running performance will be briefly discussed.

  14. 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

  15. Focusing on the Interfaces, Estuaries and Redox Transition Zones, for Understanding the Microbial Processes and Biogeochemical Cycling of Carbon under the Looming Influence of Global Warming and Anthropogenic Perturbations

    Science.gov (United States)

    Dang, H.; Jiao, N.

    2013-12-01

    Estuaries are the natural interface between terrestrial and marine ecosystems. These are also the zones where human activities exert the strongest impact on the earth and ocean environments. Due to high pressure from the effects of global warming and anthropogenic activities, many estuaries are deteriorating and experiencing significant change of the ecological processes and environmental functions. Certain fundamental microbial processes, including carbon fixation and respiration, have been changing as responses to and consequences of the altered estuarine environment and geochemistry. Increased inputs of terrigenous and anthropogenic organic materials and nutrients and elevated temperature make estuaries easy to be subjected to harmful algal blooms and hypoxic and even anoxic events. The change of the redox status of the estuarine and coastal waters and the increased nutrient loads such as that from terrestrial nitrate stimulate anaerobic respiration processes, such as nitrate reduction and denitrification. This may have strong negative impact on the marine environment, ecosystem and even climate, such as those caused by greenhouse gas production (N2O, CH4) by anaerobic microbial processes. In addition, some nutrients may be consumed by anaerobically respiring heterotrophic microorganisms, instead of being utilized by phytoplankton for carbon fixation. In this regard, the ecological function of the estuarine ecosystem may be altered and the ecological efficiency may be lowered, as less energy is produced by the microbial respiration process and less carbon is fixed by phytoplankton. However, on the other side, in hypoxic and anoxic waters, inorganic carbon fixation by anaerobic microorganisms may happen, such as those via the chemolithoautotrophic denitrifying sulfur oxidizing process and the anaerobic ammonium oxidation (anammox) process. Global warming and anthropogenic perturbations may have lowered the diversity, complexity, stability and sustainability of

  16. RACORO Extended-Term Aircraft Observations of Boundary-Layer Clouds

    Science.gov (United States)

    Vogelmann, Andrew M.; McFarquhar, Greg M.; Ogren, John A.; Turner, David D.; Comstock, Jennifer M.; Feingold, Graham; Long, Charles N.; Jonsson, Haflidi H.; Bucholtz, Anthony; Collins, Don R.; hide

    2012-01-01

    Small boundary-layer clouds are ubiquitous over many parts of the globe and strongly influence the Earths radiative energy balance. However, our understanding of these clouds is insufficient to solve pressing scientific problems. For example, cloud feedback represents the largest uncertainty amongst all climate feedbacks in general circulation models (GCM). Several issues complicate understanding boundary-layer clouds and simulating them in GCMs. The high spatial variability of boundary-layer clouds poses an enormous computational challenge, since their horizontal dimensions and internal variability occur at spatial scales much finer than the computational grids used in GCMs. Aerosol-cloud interactions further complicate boundary-layer cloud measurement and simulation. Additionally, aerosols influence processes such as precipitation and cloud lifetime. An added complication is that at small scales (order meters to 10s of meters) distinguishing cloud from aerosol is increasingly difficult, due to the effects of aerosol humidification, cloud fragments and photon scattering between clouds.

  17. On the Effect of Dust Particles on Global Cloud Condensation Nuclei and Cloud Droplet Number

    Science.gov (United States)

    Karydis, V. A.; Kumar, P.; Barahona, D.; Sokolik, I. N.; Nenes, A.

    2011-01-01

    Aerosol-cloud interaction studies to date consider aerosol with a substantial fraction of soluble material as the sole source of cloud condensation nuclei (CCN). Emerging evidence suggests that mineral dust can act as good CCN through water adsorption onto the surface of particles. This study provides a first assessment of the contribution of insoluble dust to global CCN and cloud droplet number concentration (CDNC). Simulations are carried out with the NASA Global Modeling Initiative chemical transport model with an online aerosol simulation, considering emissions from fossil fuel, biomass burning, marine, and dust sources. CDNC is calculated online and explicitly considers the competition of soluble and insoluble CCN for water vapor. The predicted annual average contribution of insoluble mineral dust to CCN and CDNC in cloud-forming areas is up to 40 and 23.8%, respectively. Sensitivity tests suggest that uncertainties in dust size distribution and water adsorption parameters modulate the contribution of mineral dust to CDNC by 23 and 56%, respectively. Coating of dust by hygroscopic salts during the atmospheric aging causes a twofold enhancement of the dust contribution to CCN; the aged dust, however, can substantially deplete in-cloud supersaturation during the initial stages of cloud formation and can eventually reduce CDNC. Considering the hydrophilicity from adsorption and hygroscopicity from solute is required to comprehensively capture the dust-warm cloud interactions. The framework presented here addresses this need and can be easily integrated in atmospheric models.

  18. Paralyzed warming world

    Czech Academy of Sciences Publication Activity Database

    Ač, Alexander

    2010-01-01

    Roč. 2, č. 2 (2010), s. 81-86 ISSN 1876-8156 Institutional research plan: CEZ:AV0Z60870520 Keywords : global warming * climate Subject RIV: EH - Ecology, Behaviour http://ojs.ubvu.vu.nl/alf/article/view/134/250

  19. The global warming scare

    International Nuclear Information System (INIS)

    Sunavala, P.D.

    1992-01-01

    It is argued that the present propaganda about the global warming with its disastrous consequences is a scare spread by some First World countries, especially the United States, to prevent the rapid industrialization of developing third world countries. (author). 6 refs., 1 tab

  20. Bigdata Driven Cloud Security: A Survey

    Science.gov (United States)

    Raja, K.; Hanifa, Sabibullah Mohamed

    2017-08-01

    Cloud Computing (CC) is a fast-growing technology to perform massive-scale and complex computing. It eliminates the need to maintain expensive computing hardware, dedicated space, and software. Recently, it has been observed that massive growth in the scale of data or big data generated through cloud computing. CC consists of a front-end, includes the users’ computers and software required to access the cloud network, and back-end consists of various computers, servers and database systems that create the cloud. In SaaS (Software as-a-Service - end users to utilize outsourced software), PaaS (Platform as-a-Service-platform is provided) and IaaS (Infrastructure as-a-Service-physical environment is outsourced), and DaaS (Database as-a-Service-data can be housed within a cloud), where leading / traditional cloud ecosystem delivers the cloud services become a powerful and popular architecture. Many challenges and issues are in security or threats, most vital barrier for cloud computing environment. The main barrier to the adoption of CC in health care relates to Data security. When placing and transmitting data using public networks, cyber attacks in any form are anticipated in CC. Hence, cloud service users need to understand the risk of data breaches and adoption of service delivery model during deployment. This survey deeply covers the CC security issues (covering Data Security in Health care) so as to researchers can develop the robust security application models using Big Data (BD) on CC (can be created / deployed easily). Since, BD evaluation is driven by fast-growing cloud-based applications developed using virtualized technologies. In this purview, MapReduce [12] is a good example of big data processing in a cloud environment, and a model for Cloud providers.

  1. Global impact of 3D cloud-radiation interactions

    Science.gov (United States)

    Schäfer, Sophia; Hogan, Robin; Fielding, Mark; Chiu, Christine

    2017-04-01

    Clouds have a decisive impact on the Earth's radiation budget and on the temperature of the atmosphere and surface. However, in global weather and climate models, cloud-radiation interaction is treated in only the vertical dimension using several non-realistic assumptions, which contributes to the large uncertainty on the climatic role of clouds. We provide a first systematic investigation into the impact of horizontal radiative transport for both shortwave and longwave radiation on a global, long-term scale. For this purpose, we have developed and validated the SPARTACUS radiation scheme, a method for including three-dimensional radiative transfer effects approximately in a one-dimensional radiation calculation that is numerically efficient enough for global calculations, allowing us to conduct 1D and quasi-3D radiation calculations for a year of global of ERA-Interim re-analysis atmospheric data and compare the results of various radiation treatments. SPARTACUS includes the effects of cloud internal inhomogeneity, horizontal in-region transport and the spatial distribution of in-cloud radiative fluxes.The impact of varying three-dimensional cloud geometry can be described by one parameter, the effective cloud scale, which has a characteristic value for each cloud type. We find that both the 3D effects of cloud-side transport and of horizontal in-cloud radiative transport in the shortwave are significant. Overall, 3D cloud effects warm the Earth by about 4 W m -2 , with warming effects in both the shortwave and the longwave. The dominant 3D cloud effect is the previously rarely investigated in-region horizontal transfer effect in the shortwave, which significantly decreases cloud reflectance and warms the Earth system by 5 W m -2 , partly counteracted by the cooling effect of shortwave 3D cloud-side transport. Longwave heating and cooling at various heights is strengthened by up to 0.2 K d ^{-1} and -0.3 K d ^{-1} respectively. These 3D effects, neglected by

  2. A Contribution by Ice Nuclei to Global Warming

    Science.gov (United States)

    Zeng, Xiping; Tao, Wei-Kuo; Zhang, Minghua; Hou, Arthur Y.; Xie, Shaocheng; Lang, Stephen; Li, Xiaowen; Starr, David O.; Li, Xiaofan

    2009-01-01

    Ice nuclei (IN) significantly affect clouds via supercooled droplets, that in turn modulate atmospheric radiation and thus climate change. Since the IN effect is relatively strong in stratiform clouds but weak in convective ones, the overall effect depends on the ratio of stratiform to convective cloud amount. In this paper, 10 years of TRMM (Tropical Rainfall Measuring Mission) satellite data are analyzed to confirm that stratiform precipitation fraction increases with increasing latitude, which implies that the IN effect is stronger at higher latitudes. To quantitatively evaluate the IN effect versus latitude, large-scale forcing data from ten field campaigns are used to drive a CRM (cloud-resolving model) to generate longterm cloud simulations. As revealed in the simulations, the increase in the net downward radiative flux at the TOA (top of the atmosphere) from doubling the current IN concentrations is larger at higher latitude, which is attributed to the meridional tendency in the stratiform precipitation fraction. Surface warming from doubling the IN concentrations, based on the radiative balance of the globe, is compared with that from anthropogenic COZ . It is found that the former effect is stronger than the latter in middle and high latitudes but not in the Tropics. With regard to the impact of IN on global warming, there are two factors to consider: the radiative effect from increasing the IN concentration and the increase in IN concentration itself. The former relies on cloud ensembles and thus varies mainly with latitude. In contrast, the latter relies on IN sources (e.g., the land surface distribution) and thus varies not only with latitude but also longitude. Global desertification and industrialization provide clues on the geographic variation of the increase in IN concentration since pre-industrial times. Thus, their effect on global warming can be inferred and then be compared with observations. A general match in geographic and seasonal

  3. 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...

  4. 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) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction...

  5. Towards Successful Cloud Ordering Service

    Directory of Open Access Journals (Sweden)

    Chen Yan-Kwang

    2015-03-01

    Full Text Available Background: The rise of cloud services has led to a drastic growth of e-commerce and a greater investment in development of new cloud services systems by related industries. For SaaS developers, it is important to understand customer needs and make use of available resources at as early as the system design and development stage. Objectives: This study integrates E-commerce Systems (ECS Success model and Importance-Performance Analysis (IPA into empirical research of the critical factors for cloud ordering system success. Methods/Approach: A survey research is conducted to collect data on customer perceptions of the importance and performance of each attribute of the particular cloud ordering service. The sample is further divided according to the degree of use of online shopping into high-usage users and low-usage users in order to explore their views regarding the system and generate adequate coping strategies. Results: Developers of online ordering systems can refer to the important factors obtained in this study when planning strategies of product/service improvement. Conclusions: The approach proposed in this study can also be applied to evaluation of other kinds of cloud services systems.

  6. Global warming in the public sphere.

    Science.gov (United States)

    Corfee-Morlot, Jan; Maslin, Mark; Burgess, Jacquelin

    2007-11-15

    Although the science of global warming has been in place for several decades if not more, only in the last decade and a half has the issue moved clearly into the public sphere as a public policy issue and a political priority. To understand how and why this has occurred, it is essential to consider the history of the scientific theory of the greenhouse effect, the evidence that supports it and the mechanisms through which science interacts with lay publics and other elite actors, such as politicians, policymakers and business decision makers. This article reviews why and how climate change has moved from the bottom to the top of the international political agenda. It traces the scientific discovery of global warming, political and institutional developments to manage it as well as other socially mediated pathways for understanding and promoting global warming as an issue in the public sphere. The article also places this historical overview of global warming as a public issue into a conceptual framework for understanding relationships between society and nature with emphasis on the co-construction of knowledge.

  7. 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.

  8. Warm Absorber Diagnostics of AGN Dynamics

    Science.gov (United States)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  9. SOFIA Observations of S106: Dynamics of the Warm Gas

    Science.gov (United States)

    Simon, R.; Schneider, N.; Stutzki, J.; Gusten, R.; Graf, U. U.; Hartogh, P.; Guan, X.; Staguhn, J. G.; Benford, D. J.

    2012-01-01

    Context The H II region/PDR/molecular cloud complex S106 is excited by a single O-star. The full extent of the warm and dense gas close to the star has not been mapped in spectrally resolved high-J CO or [C II] lines, so the kinematics of the warm. partially ionized gas, are unknown. Whether the prominent dark lane bisecting the hourglass-shaped nebula is due solely to the shadow cast by a small disk around the exciting star or also to extinction in high column foreground gas was an open question until now. Aims. To disentangle the morphology and kinematics of warm neutral and ionized gas close to the star, study their relation to the bulk of the molecular gas. and to investigate the nature of the dark lane. Methods. We use the heterodyne receiver GREAT on board SOFIA to observe velocity resolved spectral lines of [C II] and CO 11 yields 10 in comparison with so far unpublished submm continuum data at 350 micron (8HARC-Il) and complementary molecular line data. Results. The high angular and spectral resolution observations show a very complex morphology and kinematics of the inner S106 region, with many different components at different excitation conditions contributing to the observed emission. The [C II] lines are found to be bright and very broad. tracing high velocity gas close to the interface of molecular cloud and H II region. CO 11 yields 10 emission is more confined.. both spatially and in velocity, to the immediate surroundings of S 106 IR showing the presence of warm, high density (clumpy) gas. Our high angular resolution submm continuum observations rule out the scenario where the dark lane separating the two lobes is due solely to the shadow cast by a small disk close to the star. The lane is clearly seen also as warm, high column density gas at the boundary of the molecular cloud and H II region.

  10. [Treatment of cloud radiative effects in general circulation models

    International Nuclear Information System (INIS)

    Wang, W.C.

    1993-01-01

    This is a renewal proposal for an on-going project of the Department of Energy (DOE)/Atmospheric Radiation Measurement (ARM) Program. The objective of the ARM Program is to improve the treatment of radiation-cloud in GCMs so that reliable predictions of the timing and magnitude of greenhouse gas-induced global warming and regional responses can be made. The ARM Program supports two research areas: (I) The modeling and analysis of data related to the parameterization of clouds and radiation in general circulation models (GCMs); and (II) the development of advanced instrumentation for both mapping the three-dimensional structure of the atmosphere and high accuracy/precision radiometric observations. The present project conducts research in area (I) and focuses on GCM treatment of cloud life cycle, optical properties, and vertical overlapping. The project has two tasks: (1) Development and Refinement of GCM Radiation-Cloud Treatment Using ARM Data; and (2) Validation of GCM Radiation-Cloud Treatment

  11. Exploring the factors influencing the cloud computing adoption: a systematic study on cloud migration.

    Science.gov (United States)

    Rai, Rashmi; Sahoo, Gadadhar; Mehfuz, Shabana

    2015-01-01

    Today, most of the organizations trust on their age old legacy applications, to support their business-critical systems. However, there are several critical concerns, as maintainability and scalability issues, associated with the legacy system. In this background, cloud services offer a more agile and cost effective platform, to support business applications and IT infrastructure. As the adoption of cloud services has been increasing recently and so has been the academic research in cloud migration. However, there is a genuine need of secondary study to further strengthen this research. The primary objective of this paper is to scientifically and systematically identify, categorize and compare the existing research work in the area of legacy to cloud migration. The paper has also endeavored to consolidate the research on Security issues, which is prime factor hindering the adoption of cloud through classifying the studies on secure cloud migration. SLR (Systematic Literature Review) of thirty selected papers, published from 2009 to 2014 was conducted to properly understand the nuances of the security framework. To categorize the selected studies, authors have proposed a conceptual model for cloud migration which has resulted in a resource base of existing solutions for cloud migration. This study concludes that cloud migration research is in seminal stage but simultaneously it is also evolving and maturing, with increasing participation from academics and industry alike. The paper also identifies the need for a secure migration model, which can fortify organization's trust into cloud migration and facilitate necessary tool support to automate the migration process.

  12. Limits to Cloud Susceptibility

    Science.gov (United States)

    Coakley, James A., Jr.

    2002-01-01

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

  13. Analysis on Cloud Computing Database in Cloud Environment – Concept and Adoption Paradigm

    Directory of Open Access Journals (Sweden)

    Elena-Geanina ULARU

    2012-08-01

    Full Text Available With the development of the Internet’s new technical functionalities, new concepts have started to take shape. These concepts have an important role especially in the development of corporate IT. Such a concept is „the Cloud”. Various marketing campaigns have started to focus on the Cloud and began to promote it in different but confusing ways. This campaigns do little, to explain what cloud computing is and why it is becoming increasingly necessary. The lack of understanding in this new technology generates a lack of knowledge in business cloud adoption regarding database and also application. Only by focusing on the business processes and objectives an enterprise can achieve the full benefits of the cloud and mitigate the potential risks. In this article we create our own complete definition of the cloud and we analyze the essential aspects of cloud adoption for a banking financial reporting application.

  14. 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

  15. Aura MLS Cloud Measurements: First-Year Results

    Science.gov (United States)

    Jiang, Jonathan H.; Wu, Dong L.

    2005-01-01

    Aura MLS provides the first vertical upper tropospheric cloud profiling from space, enabling global survey of the vertical structure of cloud systems, with seasonal and geographical variations, needed to evaluate the way clouds are parameterized in global models, thereby contributing to the understanding of cloud-climate feedbacks, and improved weather and climate predictions. The vertical structure of cloud systems is fundamentally important for understanding how clouds affect both their regional and large-scale atmospheric and radiative environments. The regional cloud profiles provide a critical tests of important parameterizations that enable the calculation of radiative flux profiles and heating rates throughout the atmospheric column, which in turn also regulates the water and energy cycles in the upper troposphere

  16. Global warming due to increasing absorbed solar radiation

    Science.gov (United States)

    Trenberth, Kevin E.; Fasullo, John T.

    2009-04-01

    Global climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) are examined for the top-of-atmosphere radiation changes as carbon dioxide and other greenhouse gases build up from 1950 to 2100. There is an increase in net radiation absorbed, but not in ways commonly assumed. While there is a large increase in the greenhouse effect from increasing greenhouse gases and water vapor (as a feedback), this is offset to a large degree by a decreasing greenhouse effect from reducing cloud cover and increasing radiative emissions from higher temperatures. Instead the main warming from an energy budget standpoint comes from increases in absorbed solar radiation that stem directly from the decreasing cloud amounts. These findings underscore the need to ascertain the credibility of the model changes, especially insofar as changes in clouds are concerned.

  17. Airborne remote sensing of cloud optical thickness, effective radius, thermodynamic phase and cloud droplet number concentration with SMART-HALO.

    Science.gov (United States)

    Wolf, Kevin; Ehrlich, André; Wendisch, Manfred; Crewell, Susanne; Jacob, Marek

    2017-04-01

    Solar spectral measurements of upward and downward irradiance and upward radiance in the wavelength range from 0.3 µm to 2.2 µm by the Spectral Modular Airborne Radiation measurement system (SMART) on board the High Altitude and Long Range Research Aircraft (HALO) were performed during two campaigns dedicated to investigate cloud properties in different cloud regimes. During NARVAL-II shallow convection in the trade-wind region and deep convection along the ITCZ were investigated over the Atlantic Ocean in August 2016. The NAWDEX campaign focused on clouds along warm-conveyor belts in the North Atlantic and the Norwegian Sea in September and October 2016. Applying an iterative retrieval the Liquid Water Path was derived from measurements of the reflected radiation from cloud top at a wavelength of 0.8 µm sensitive to the optical thickness and 1.2 µm, 1.6 µm, and 2.1 µm sensitive to the effective radius with different vertical weighting functions. Using ratios of upward radiance instead of absolute values reduces retrieval uncertainties noticeably. The thermodynamic phase at cloud top was determined by measuring the spectral slopes in the wavelength range between 1.0 µm and 2.2 µm. The statistical cloud situation / frequency of occurrence along the flight track was determined by a cloud discrimination scheme using the different spectral behavior of liquid water clouds and sea surface at wavelengths of 0.8 µm, 1.1 µm and 1.3 µm. All derived cloud properties were used to investigate the spectral cloud top albedo measured simultaneously by SMART-HALO. A statistical analysis of how strong the different cloud properties affect the cloud albedo will be presented. In conjunction with measurements of the Liquid Water Path by the HALO Microwave Package (HAMP) a first estimate of the cloud droplet number concentration for selected flight sections over non-precipitating liquid trade-wind cumulus was achieved.

  18. Slowing global warming

    International Nuclear Information System (INIS)

    Flavin, C.

    1990-01-01

    According to the authors, global warming promises to be one of the central environmental issues of the nineties. After a decade of scientific concern but popular neglect, the eighties ended with a growing political as well as scientific consensus that the world can no longer afford to procrastinate about this issue. This paper reports on coping with global warming which, according to the author, will force societies to move rapidly into uncharted terrain, reversing powerful trends that have dominated the industrial age. This challenge cannot be met without a strong commitment on the part of both individual consumers and governments. In terms of the earth's carbon balance, the unprecedented policy changes that have now become urgent include a new commitment to greater energy efficiency and renewable energy sources, a carbon tax on fossil fuels, a reversal of deforestation in tropical countries, and the rapid elimination of CFCs

  19. Thinking About Global Warming

    International Nuclear Information System (INIS)

    Baron, J.

    2006-01-01

    Attitudes toward global warming are influenced by various heuristics, which may distort policy away from what is optimal for the well-being of people. These possible distortions, or biases, include: a focus on harms that we cause, as opposed to those that we can remedy more easily; a feeling that those who cause a problem should fix it; a desire to undo a problem rather than compensate for its presence; parochial concern with one's own group (nation); and neglect of risks that are not available. Although most of these biases tend to make us attend relatively too much to global warming, other biases, such as wishful thinking, cause us to attend too little. I discuss these possible effects and illustrate some of them with an experiment conducted on the World Wide Web

  20. Climate change - global warming

    International Nuclear Information System (INIS)

    Ciconkov, Risto

    2001-01-01

    An explanation about climate, weather, climate changes. What is a greenhouse effect, i.e. global warming and reasons which contribute to this effect. Greenhouse gases (GHG) and GWP (Global Warming Potential) as a factor for estimating their influence on the greenhouse effect. Indicators of the climate changes in the previous period by known international institutions, higher concentrations of global average temperature. Projecting of likely scenarios for the future climate changes and consequences of them on the environment and human activities: industry, energy, agriculture, water resources. The main points of the Kyoto Protocol and problems in its realization. The need of preparing a country strategy concerning the acts of the Kyoto Protocol, suggestions which could contribute in the preparation of the strategy. A special attention is pointed to the energy, its resources, the structure of energy consumption and the energy efficiency. (Author)

  1. Reconstructing warm inflation

    Science.gov (United States)

    Herrera, Ramón

    2018-03-01

    The reconstruction of a warm inflationary universe model from the scalar spectral index n_S(N) and the tensor to scalar ratio r( N) as a function of the number of e-folds N is studied. Under a general formalism we find the effective potential and the dissipative coefficient in terms of the cosmological parameters n_S and r considering the weak and strong dissipative stages under the slow roll approximation. As a specific example, we study the attractors for the index n_S given by nS-1∝ N^{-1} and for the ratio r∝ N^{-2}, in order to reconstruct the model of warm inflation. Here, expressions for the effective potential V(φ ) and the dissipation coefficient Γ (φ ) are obtained.

  2. Global Warming: A Myth?

    Indian Academy of Sciences (India)

    IPCC 2nd Assessment, the range of projected global mean warm- ing by 2100 is set at 1-3.5 °C [2]. Another estimate says that, if the present trend of greenhouse gases continue, atmosphere may, on an average, get warmer by 0.7-2°C by the year 2030 and more thereafter [3]. Predictions on global mean surface tem-.

  3. EFFECTS OF GLOBAL WARMING

    OpenAIRE

    Dr. Basanti Jain

    2017-01-01

    The abnormal increase in the concentration of the greenhouse gases is resulting in higher temperatures. We call this effect is global warming. The average temperature around the world has increased about 1'c over 140 years, 75% of this has risen just over the past 30 years. The solar radiation, as it reaches the earth, produces "greenhouse effect" in the atmosphere. The thick atmospheric layers over the earth behaves as a glass surface, as it permits short wave radiations from coming in, but ...

  4. Attribution of the United States “warming hole”: Aerosol indirect effect and precipitable water vapor

    Science.gov (United States)

    Yu, Shaocai; Alapaty, Kiran; Mathur, Rohit; Pleim, Jonathan; Zhang, Yuanhang; Nolte, Chris; Eder, Brian; Foley, Kristen; Nagashima, Tatsuya

    2014-01-01

    Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20th century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. “warming hole”). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the “warming hole”. We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed “warming hole” can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin. PMID:25373416

  5. Attribution of the United States "warming hole": aerosol indirect effect and precipitable water vapor.

    Science.gov (United States)

    Yu, Shaocai; Alapaty, Kiran; Mathur, Rohit; Pleim, Jonathan; Zhang, Yuanhang; Nolte, Chris; Eder, Brian; Foley, Kristen; Nagashima, Tatsuya

    2014-11-06

    Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20(th) century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. "warming hole"). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the "warming hole". We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed "warming hole" can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin.

  6. The influence of aerosol particle number and hygroscopicity on the evolution of convective cloud systems and their precipitation: A numerical study based on the COPS observations on 12 August 2007

    Science.gov (United States)

    Planche, Céline; Wobrock, Wolfram; Flossmann, Andrea I.; Tridon, Frédéric; Van Baelen, Joël; Pointin, Yves; Hagen, Martin

    2010-10-01

    The 3D cloud model DESCAM-3D with bin resolved microphysics for ice, water and aerosol particles is used to study the role of particles on the evolution of summertime mid-level convective clouds and the subsequent precipitation during the COPS field campaign which occurred at mid-latitude near the French/German border in summer 2007. Using a 3D grid resolution of 250 m, DESCAM-3D, is able to simulate well the dynamical, cloud and precipitation features of the convective cloud system observed during the afternoon of the 12th August. This mid-level convective system was dominated by warm-phase microphysics. The simulated convective system led to a 1.5 h long lasting precipitation event in agreement with the radar observations. The results of the fine numerical scale compare well with the high resolved radar reflectivities of the LaMP X-band radar and the DLR-Poldirad radar. The prediction of the liquid hydrometeor spectra allows a detailed calculation of the cloud radar reflectivity. In order to better understand the role of aerosol particles on cloud evolution and precipitation formation, several sensitivity studies were performed by modifying aerosol number concentration as well as their physico-chemical properties. Drastic changes in the aerosol solubility lead to a variation in precipitation on the order of 10% for the same convective case. In contrast, changes in the aerosol number concentrations can lead to a variation in total precipitation of up to 30%. Hence, the role of changes in aerosol number concentrations is more important than changes in particle solubility for this case of continental mid-level convection at mid-latitude. A subsequent analysis of the in-cloud microphysics revealed that in-cloud properties are modified significantly in all scenarios. Key parameter is the supersaturation whose magnitude influences both cloud microphysics (cloud droplet and rain drop formation) as well as cloud thermodynamics and cloud dynamics. Furthermore

  7. The global warming hiatus: Slowdown or redistribution?

    Science.gov (United States)

    Yan, Xiao-Hai; Boyer, Tim; Trenberth, Kevin; Karl, Thomas R.; Xie, Shang-Ping; Nieves, Veronica; Tung, Ka-Kit; Roemmich, Dean

    2016-11-01

    Global mean surface temperatures (GMST) exhibited a smaller rate of warming during 1998-2013, compared to the warming in the latter half of the 20th Century. Although, not a "true" hiatus in the strict definition of the word, this has been termed the "global warming hiatus" by IPCC (2013). There have been other periods that have also been defined as the "hiatus" depending on the analysis. There are a number of uncertainties and knowledge gaps regarding the "hiatus." This report reviews these issues and also posits insights from a collective set of diverse information that helps us understand what we do and do not know. One salient insight is that the GMST phenomenon is a surface characteristic that does not represent a slowdown in warming of the climate system but rather is an energy redistribution within the oceans. Improved understanding of the ocean distribution and redistribution of heat will help better monitor Earth's energy budget and its consequences. A review of recent scientific publications on the "hiatus" shows the difficulty and complexities in pinpointing the oceanic sink of the "missing heat" from the atmosphere and the upper layer of the oceans, which defines the "hiatus." Advances in "hiatus" research and outlooks (recommendations) are given in this report.

  8. Irrigation enhances local warming with greater nocturnal warming effects than daytime cooling effects

    Science.gov (United States)

    Chen, Xing; Jeong, Su-Jong

    2018-02-01

    To meet the growing demand for food, land is being managed to be more productive using agricultural intensification practices, such as the use of irrigation. Understanding the specific environmental impacts of irrigation is a critical part of using it as a sustainable way to provide food security. However, our knowledge of irrigation effects on climate is still limited to daytime effects. This is a critical issue to define the effects of irrigation on warming related to greenhouse gases (GHGs). This study shows that irrigation led to an increasing temperature (0.002 °C year-1) by enhancing nighttime warming (0.009 °C year-1) more than daytime cooling (-0.007 °C year-1) during the dry season from 1961-2004 over the North China Plain (NCP), which is one of largest irrigated areas in the world. By implementing irrigation processes in regional climate model simulations, the consistent warming effect of irrigation on nighttime temperatures over the NCP was shown to match observations. The intensive nocturnal warming is attributed to energy storage in the wetter soil during the daytime, which contributed to the nighttime surface warming. Our results suggest that irrigation could locally amplify the warming related to GHGs, and this effect should be taken into account in future climate change projections.

  9. 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.

  10. In the clouds

    NARCIS (Netherlands)

    Russchenberg, H.; Wassink, J.

    2012-01-01

    Clouds always used to be the least understood element of the weather system, but that is rapidly changing . Computer clouds increasingly correspond with those in the sky, which promises weather forecasts at street level and more accurate climate scenarios.

  11. 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

  12. 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.

  13. 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 ...

  14. 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...

  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 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...

  17. 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...

  18. Trustworthy Cloud Storage

    OpenAIRE

    Augier, Maxime

    2016-01-01

    The Cloud trend is an attempt to leverage economics of scale in the domain of computing resources. Unfortunately, this often means losing control of the lower levels of a computer system, and exposing users to new threat vectors. These threats may be significant enough to forbid the use of clouds, and force giving up on their economical advantages. Chapter 1 introduces some issues with current cloud storage systems, that should be fixed before a cloud storage system can be considered as safe ...

  19. 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...

  20. Increasing potential for intense tropical and subtropical thunderstorms under global warming

    Science.gov (United States)

    Singh, Martin S.; Kuang, Zhiming; Maloney, Eric D.; Hannah, Walter M.; Wolding, Brandon O.

    2017-10-01

    Intense thunderstorms produce rapid cloud updrafts and may be associated with a range of destructive weather events. An important ingredient in measures of the potential for intense thunderstorms is the convective available potential energy (CAPE). Climate models project increases in summertime mean CAPE in the tropics and subtropics in response to global warming, but the physical mechanisms responsible for such increases and the implications for future thunderstorm activity remain uncertain. Here, we show that high percentiles of the CAPE distribution (CAPE extremes) also increase robustly with warming across the tropics and subtropics in an ensemble of state-of-the-art climate models, implying strong increases in the frequency of occurrence of environments conducive to intense thunderstorms in future climate projections. The increase in CAPE extremes is consistent with a recently proposed theoretical model in which CAPE depends on the influence of convective entrainment on the tropospheric lapse rate, and we demonstrate the importance of this influence for simulated CAPE extremes using a climate model in which the convective entrainment rate is varied. We further show that the theoretical model is able to account for the climatological relationship between CAPE and a measure of lower-tropospheric humidity in simulations and in observations. Our results provide a physical basis on which to understand projected future increases in intense thunderstorm potential, and they suggest that an important mechanism that contributes to such increases may be present in Earth's atmosphere.

  1. Increasing potential for intense tropical and subtropical thunderstorms under global warming.

    Science.gov (United States)

    Singh, Martin S; Kuang, Zhiming; Maloney, Eric D; Hannah, Walter M; Wolding, Brandon O

    2017-10-31

    Intense thunderstorms produce rapid cloud updrafts and may be associated with a range of destructive weather events. An important ingredient in measures of the potential for intense thunderstorms is the convective available potential energy (CAPE). Climate models project increases in summertime mean CAPE in the tropics and subtropics in response to global warming, but the physical mechanisms responsible for such increases and the implications for future thunderstorm activity remain uncertain. Here, we show that high percentiles of the CAPE distribution (CAPE extremes) also increase robustly with warming across the tropics and subtropics in an ensemble of state-of-the-art climate models, implying strong increases in the frequency of occurrence of environments conducive to intense thunderstorms in future climate projections. The increase in CAPE extremes is consistent with a recently proposed theoretical model in which CAPE depends on the influence of convective entrainment on the tropospheric lapse rate, and we demonstrate the importance of this influence for simulated CAPE extremes using a climate model in which the convective entrainment rate is varied. We further show that the theoretical model is able to account for the climatological relationship between CAPE and a measure of lower-tropospheric humidity in simulations and in observations. Our results provide a physical basis on which to understand projected future increases in intense thunderstorm potential, and they suggest that an important mechanism that contributes to such increases may be present in Earth's atmosphere. Published under the PNAS license.

  2. Governmental Cloud - Part of Cloud Computing

    Directory of Open Access Journals (Sweden)

    Cristian IVANUS

    2014-01-01

    Full Text Available Large IT (Information Technology companies propose cloud government's (G-Cloud development model through investment from the private sector, which will facilitate the access of users from public sector to the new generation IT services. Through the G-Cloud private operators that operate governmental cloud infrastructure by adding specific SaaS (Software as a Service functionalities, proposed model by big companies, supports public institutions in optimizing costs and increased operational efficiency, bringing tangible benefits in relation with citizens and thus with the whole society. These optimizations are achieved by moving the initial investment to the private sector, through type subscription model cost by eliminating dependency on human factors (technical and by providing a low cost [1]. This paper aims to bring to the attention of specialists, some aspects of Governmental Cloud from the European Union (EU countries to be understood and implemented in Romania.

  3. Inconsistent Subsurface and Deeper Ocean Warming Signals During Recent Global Warming and Hiatus

    Science.gov (United States)

    Su, Hua; Wu, Xiangbai; Lu, Wenfang; Zhang, Weiwei; Yan, Xiao-Hai

    2017-10-01

    Ocean heat content (OHC) evolutions calculated from the data sets (WOA, MyOcean, ORAS4, and SODA) were examined at different depth ranges in this study. According to the OHC changes, the subsurface and deeper ocean (SDO, 300-2000 m) heat content rapidly increased over the world's ocean basins during 1998-2013, indicating significant warming in the SDO during the recent global surface warming hiatus. Almost all the ocean basins warmed up, but with various contributions to the global SDO warming tied to the recent hiatus. The role of the Indian Ocean is particularly important as it has accounted for about 30% of global SDO heat uptake during the hiatus. The combined use of multiple data sets can reveal inconsistencies in SDO warming analysis results, and improve our understanding of the role of the SDO in the recent hiatus. The heat uptake in global SDO during the hiatus was about 2.37, 5.44, 3.75, and 2.44 × 1022 joules with trends of 0.40, 0.70, 0.77, and 0.48 W m-2 according to WOA, MyOcean, ORAS4, and SODA respectively, presenting obviously inconsistent SDO warming signals. MyOcean shows OHC overestimates in different ocean basins, while ORAS4 presents more reliable SDO OHC analysis. In general, the global SDO has sequestered a significant amount of heat—about 3.50 × 1022 joules with trends of 0.59 W m-2 on average among the four data sets—during the recent hiatus, demonstrating widespread and significant warming signals in the global SDO. There remain substantial uncertainties and discrepancies, however (especially in the PO and SO), in the available SDO warming information due to insufficient subsurface observation coverage and variations in the data set generation techniques used among different researchers.

  4. 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.

  5. 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

  6. 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.

  7. Some cloud population statistics

    Science.gov (United States)

    Snow, J. William

    1985-01-01

    Photographs of cloud scenes taken from the orbiting space shuttle are being used to assess the overestimation in the amount of cloud cover sensed by satellites at angles other than nadir. Also these photographs and Landsat images indicate that the frequency distributions of clear and of cloudy intervals, at least in simple tropical cloud scenes, may be approximated by common distribution functions.

  8. 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.

  9. A Report of Clouds on Titan

    Science.gov (United States)

    Corlies, Paul; Hayes, Alexander; Adamkovics, Mate; Rodriguez, Sebastien; Kelland, John; Turtle, Elizabeth P.; Mitchell, Jonathan; Lora, Juan M.; Rojo, Patricio; Lunine, Jonathan I.

    2017-10-01

    We present in this work a detailed analysis of many of the clouds in the Cassini Visual and Infrared Mapping Spectrometer (VIMS) dataset in order to understand their global and seasonal properties. Clouds are one of the few direct observables in Titan’s atmosphere (Griffith et al 2009, Rodriguez et al 2009, Adamkovics et al 2010), and so determining their characteristics allows for a better understanding of surface atmosphere interactions, winds, transport of volatile material, and general circulation. We find the clouds on Titan generally reside in at 5-15km altitude, which agrees with previous modelling efforts (Rafkin et al. 2015), as well as a power law distribution for cloud optical depth. We assume an average cloud droplet size of 100um. No seasonal dependence is observed with either cloud altitude or optical depth, suggesting there is no preferred seasonal formation mechanisms. Combining these characteristics with cloud size (Kelland et al 2017) can trace the transport of volatiles in Titan’s atmosphere, which can be compared against general circulation models (GCMs) (Lora et al 2015). We also present some specific analysis of interesting cloud systems including hypothesized surface fogs (Brown et al 2009) and orographic cloud formation (Barth et al 2010, Corlies et al 2017). In this analysis we use a correlation between Cassini VIMS and RADAR observations as well as an updated topographic map of Titan’s southern hemisphere to better understand the role that topography plays in influencing and driving atmospheric phenomena.Finally, with the end of the Cassini mission, ground based observing now acts as the only means with which to observe clouds on Titan. We present an update of an ongoing cloud campaign to search for clouds on Titan and to understand their seasonal evolution.References:Adamkovics et al. 2010, Icarus 208:868Barth et al. 2010, Planet. Space Sci. 58:1740Corlies et al. 2017, 48th LPSC, 2870CGriffith et al. 2009, ApJ 702:L105Kelland et al

  10. Studying an effect of salt powder seeding used for precipitation enhancement from convective clouds

    Science.gov (United States)

    Drofa, A. S.; Ivanov, V. N.; Rosenfeld, D.; Shilin, A. G.

    2010-08-01

    Experimental and theoretical studies of cloud microstructure modification with hygroscopic particles for obtaining additional precipitation amounts from convective clouds are performed. The experiment used salt powder with the particle sizes that gave the greatest effectiveness according to the simulations of Segal et al. (2004). The experiments were carried out in a cloud chamber at the conditions corresponding to the formation of convective clouds. The results have shown that the introduction of the salt powder before a cloud medium is formed in the chamber results in the formation on a "tail" of additional large drops. In this case seeding with the salt powder leads also to enlargement of the whole population of cloud drops and to a decrease of their total concentration as compared to a cloud medium that is formed on background aerosols. These results are the positive factors for stimulating coagulation processes in clouds and for subsequent formation of precipitation in them. An overseeding effect, which is characterized by increased droplet concentration and decreased droplet size, was not observed even at high salt powder concentrations. The results of numerical simulations have shown that the transformation of cloud drop spectra induced by the introduction of the salt powder results in more intense coagulation processes in clouds as compared to the case of cloud modification with hygroscopic particles with relatively narrow particle size distributions, and for the distribution of the South African hygroscopic flares. The calculation results obtained with a one-dimensional model of a warm convective cloud demonstrated that the effect of salt powder on clouds (total amounts of additional precipitation) is significantly higher than the effect caused by the use of hygroscopic particles with narrow particle size distributions at comparable consumptions of seeding agents, or with respect to the hygroscopic flares. Here we show that seeding at rather low

  11. Interesting Scientific Questions Regarding Interactions in the Gas-aerosol-cloud System

    Science.gov (United States)

    Tabazadeh, Azadeh

    2002-01-01

    The growth of human population and their use of land, food and energy resources affect the Earth's atmosphere, biosphere and oceans in a complex manner. Many important questions in earth sciences today deal with issues regarding the impact of human activities on our immediate and future environment, ranging in scope from local (i.e. air pollution) to global (i.e. global warming) scale problems. Because the mass of the Earth's atmosphere is negligible compare to that found in the oceans and the biosphere, the atmosphere can respond quickly to natural and/or manmade perturbations. For example, seasonal 'ozone hole' formation in the Antarctic is a result of manmade CFC emissions in just the last 40 years. Also, the observed rise in global temperatures (known as global warming) is linked to a rapid increase in carbon dioxide and other greenhouse gas concentrations (emitted primarily by combustion processes) over the last century. The Earth's atmosphere is composed of a mixture of gases, aerosol and cloud particles. Natural and anthropogenic emissions of gases and aerosols affect the composition of the Earth's atmosphere. Changes in the chemical and physical makeup of the atmosphere can influence how the Earth will interact with the incoming solar radiation and the outgoing infrared radiation and vise versa. While, some perturbations are short-lived, others are long-lived and can affect the Earth's global climate and chemistry in many decades to come, In order to be able to separate the natural effects from anthropogenic ones, it is essential that we understand the basic physics and chemistry of interactions in the gas-aerosol-cloud system in the Earth's atmosphere. The important physics and chemistry that takes place in the coupled gas-aerosol-cloud system as it relates to aircraft observations are discussed.

  12. Process-model simulations of cloud albedo enhancement by aerosols in the Arctic

    Science.gov (United States)

    Kravitz, Ben; Wang, Hailong; Rasch, Philip J.; Morrison, Hugh; Solomon, Amy B.

    2014-01-01

    A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through geoengineering or other increased sources of Arctic aerosols. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol–cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic geoengineering is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects. PMID:25404677

  13. Cloud computing security requirements: a systematic review

    OpenAIRE

    Iankoulova, Iliana; Daneva, Maia; Rolland, C; Castro, J.; Pastor, O

    2012-01-01

    Many publications have dealt with various types of security requirements in cloud computing but not all types have been explored in sufficient depth. It is also hard to understand which types of requirements have been under-researched and which are most investigated. This paper's goal is to provide a comprehensive and structured overview of cloud computing security requirements and solutions. We carried out a systematic review and identified security requirements from previous publications th...

  14. Instant VMware vCloud starter

    CERN Document Server

    Langenhan, Daniel

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. This book is written in an easytoread style, with a strong emphasis on realworld, practical examples. Stepbystep explanations are provided for performing important tasks.If you are a Cloud engineer or administrator looking forward to working with vCloud, then this is the best guide to get you started with it.

  15. Warming impact on herbivore population composition affects top-down control by predators

    OpenAIRE

    Ying-Jie Wang; Takefumi Nakazawa; Chuan-Kai Ho

    2017-01-01

    Understanding warming impact on herbivores facilitates predicting plant/crop dynamics in natural/agricultural systems. However, it remains unclear how warming will affect herbivore population size and population composition, consequently altering herbivore colonization in a tri-trophic system (plant-herbivore-predator or crop-pest-biocontrol agent). We studied a soybean-aphid-lady beetle system, by conducting (1) a laboratory warming experiment to examine warming impact (+2??C or +4??C) on th...

  16. Revisiting social and deep ecology in the light of global warming

    OpenAIRE

    Krøvel, Roy

    2013-01-01

    The purpose of this article is largely theoretical. It asks what type of perspective is needed in order for left libertarians and anarchists to develop a deeper understanding of global warming. This way of framing the question builds on a set of premises which I will spell out. First, global warming is real. Second, the reality of global warming exists independently of our discourse about it. Third, global warming will have real and dangerous consequences for humans and human s...

  17. Laboratory study of orographic cloud-like flow

    Science.gov (United States)

    Singh, Kanwar Nain; Sreenivas, K. R.

    2013-11-01

    Clouds are one of the major sources of uncertainty in climate prediction, listed in ``the most urgent scientific problems requiring attention'' IPCC. Also, convective clouds are of utmost importance to study the dynamics of tropical meteorology and therefore, play a key role in understanding monsoons. The present work is to study the dynamics of orographic clouds. Parameterization of these clouds will help in forecasting the precipitation accurately. Also, one could validate laboratory results from our study by actually measuring cloud development along a sloping terrain. In this context a planar buoyant turbulent wall jet is considered as an appropriate low order fluid-dynamical model for studying the turbulence and entrainment in orographic-clouds. Flow is volumetrically heated to mimic the latent heat release due to condensation in an actual cloud. This is the first step in studying the entrainment dynamics of the evolving orographic cloud. We are going to present some results on the cloud development using techniques that allows us to construct a 3-dimensional flow field at each instance and its development over the time. By combining velocity field from PIV and flow volume from PLIF at successive instances, we estimate the entrainment coefficient. Since the life-cycle of a cloud is determined by the entrainment of ambient air, these results could be extremely helpful in understanding the dynamics of the clouds. Detailed results will be presented at the conference.

  18. Global warning, global warming

    International Nuclear Information System (INIS)

    Benarde, M.A.

    1992-01-01

    This book provides insights into the formidable array of issues which, in a warmer world, could impinge upon every facet of readers lives. It examines climatic change and long-term implications of global warming for the ecosystem. Topics include the ozone layer and how it works; the greenhouse effect; the dangers of imbalance and its effects on human and animal life; disruptions to the basic ecology of the planet; and the real scientific evidence for and against aberrant climatic shifts. The author also examines workable social and political programs and changes that must be instituted to avoid ecological disaster

  19. Sensitivity of liquid clouds to homogenous freezing parameterizations.

    Science.gov (United States)

    Herbert, Ross J; Murray, Benjamin J; Dobbie, Steven J; Koop, Thomas

    2015-03-16

    Water droplets in some clouds can supercool to temperatures where homogeneous ice nucleation becomes the dominant freezing mechanism. In many cloud resolving and mesoscale models, it is assumed that homogeneous ice nucleation in water droplets only occurs below some threshold temperature typically set at -40°C. However, laboratory measurements show that there is a finite rate of nucleation at warmer temperatures. In this study we use a parcel model with detailed microphysics to show that cloud properties can be sensitive to homogeneous ice nucleation as warm as -30°C. Thus, homogeneous ice nucleation may be more important for cloud development, precipitation rates, and key cloud radiative parameters than is often assumed. Furthermore, we show that cloud development is particularly sensitive to the temperature dependence of the nucleation rate. In order to better constrain the parameterization of homogeneous ice nucleation laboratory measurements are needed at both high (>-35°C) and low (<-38°C) temperatures. Homogeneous freezing may be significant as warm as -30°CHomogeneous freezing should not be represented by a threshold approximationThere is a need for an improved parameterization of homogeneous ice nucleation.

  20. 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

  1. 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...

  2. 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

  3. 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...

  4. 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.

  5. 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.

  6. A Study of the Response of Deep Tropical Clouds to Mesoscale Processes. Part 1; Modeling Strategies and Simulations of TOGA-COARE Convective Systems

    Science.gov (United States)

    Johnson, Daniel E.; Tao, W.-K.; Simpson, J.; Sui, C.-H.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Interactions between deep tropical clouds over the western Pacific warm pool and the larger-scale environment are key to understanding climate change. Cloud models are an extremely useful tool in simulating and providing statistical information on heat and moisture transfer processes between cloud systems and the environment, and can therefore be utilized to substantially improve cloud parameterizations in climate models. In this paper, the Goddard Cumulus Ensemble (GCE) cloud-resolving model is used in multi-day simulations of deep tropical convective activity over the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Large-scale temperature and moisture advective tendencies, and horizontal momentum from the TOGA-COARE Intensive Flux Array (IFA) region, are applied to the GCE version which incorporates cyclical boundary conditions. Sensitivity experiments show that grid domain size produces the largest response to domain-mean temperature and moisture deviations, as well as cloudiness, when compared to grid horizontal or vertical resolution, and advection scheme. It is found that a minimum grid-domain size of 500 km is needed to adequately resolve the convective cloud features. The control experiment shows that the atmospheric heating and moistening is primarily a response to cloud latent processes of condensation/evaporation, and deposition/sublimation, and to a lesser extent, melting of ice particles. Air-sea exchange of heat and moisture is found to be significant, but of secondary importance, while the radiational response is small. The simulated rainfall and atmospheric heating and moistening, agrees well with observations, and performs favorably to other models simulating this case.

  7. Introduction to MODIS Cloud Products. Chapter 5

    Science.gov (United States)

    Baum, Bryan A.; Platnick, Steven

    2006-01-01

    The Earth's radiative energy balance and hydrological cycle are fundamentally coupled with the distribution and properties of clouds. Therefore, the ability to remotely infer cloud properties and their variation in space and time is crucial for establishing climatologies as a reference for validation of present-day climate models and in assessing future climate change. Remote cloud observations also provide data sets useful for testing and improving cloud model physics, and for assimilation into numerical weather prediction models. The MODerate Resolution Imaging Spectroradiometer (MODIS) imagers on the Terra and Aqua Earth Observing System (EOS) platforms provide the capability for globally retrieving these properties using passive solar reflectance and infrared techniques. In addition to providing measurements similar to those offered on a suite of historical operational weather platforms such as the Advanced Very High Resolution Radiometer (AVHRR), the High-resolution Infrared Radiation Sounder (HIRS), and the Geostationary Operational Environmental Satellite (GOES), MODIS provides additional spectral and/or spatial resolution in key atmospheric bands, along with on-board calibration, to expand the capability for global cloud property retrievals. The core MODIS operational cloud products include cloud top pressure, thermodynamic phase, optical thickness, particle size, and water path, and are derived globally at spatial resolutions of either 1- or 5-km (referred to as Level-2 or pixel-level products). In addition, the MODIS atmosphere team (collectively providing cloud, aerosol, and clear sky products) produces a combined gridded product (referred to as Level-3) aggregated to a 1 equal-angle grid, available for daily, eight-day, and monthly time periods. The wealth of information available from these products provides critical information for climate studies as well as the continuation and improved understanding of existing satellite-based cloud climatologies

  8. The Impact Of Cloud Computing Technology On The Audit Process And The Audit Profession

    OpenAIRE

    Yati Nurhajati

    2015-01-01

    In the future cloud computing audits will become increasingly The use of that technology has influenced of the audit process and be a new challenge for both external and the Internal Auditors to understand IT and learn how to use cloud computing and cloud services that hire in cloud service provider CSP and considering the risks of cloud computing and how to audit cloud computing by risk based audit approach. The wide range of unique risks and depend on the type and model of the cloud soluti...

  9. 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].

  10. Global assessment of experimental climate warming on tundra vegetation

    DEFF Research Database (Denmark)

    Elmendorf, S.C.; Henry, G.H.R.; Bjorkman, A.D.

    2012-01-01

    Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations...... of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups...... to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed...

  11. 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.

  12. Impact of Aerosols and Atmospheric Thermodynamics on Cloud Properties within the Climate System

    Science.gov (United States)

    Matsui, Toshihisa; Masunaga, Hirohiko; Pielke, Roger, Sr.; Tao, Wei-Kuo

    2003-01-01

    A combination of cloud-top and columnar droplet sizes derived from the multi Tropical Rainfall Measurement Mission (TRMM) sensors reveals the sensitivity of the aerosols effect on cloud-precipitation process due to environmental vertical thermodynamic structure. First, the magnitude of aerosol indirect effect could be larger with the analysis of columnar droplet sizes than that derived from the cloud-top droplet sizes, since column-droplet size can account for the broader droplet spectra in the cloud layers. Second, a combination of cloud- top and columnar droplet sizes reveals that the warm rain process is prevented regardless of the aerosols concentration under a high static stability such as when a strong temperature inversion exists, while a high aerosol concentration suppresses the warm rain formulation under a low static stability.

  13. Is Global Warming Accelerating?

    Science.gov (United States)

    Shukla, J.; Delsole, T. M.; Tippett, M. K.

    2009-12-01

    A global pattern that fluctuates naturally on decadal time scales is identified in climate simulations and observations. This newly discovered component, called the Global Multidecadal Oscillation (GMO), is related to the Atlantic Meridional Oscillation and shown to account for a substantial fraction of decadal fluctuations in the observed global average sea surface temperature. IPCC-class climate models generally underestimate the variance of the GMO, and hence underestimate the decadal fluctuations due to this component of natural variability. Decomposing observed sea surface temperature into a component due to anthropogenic and natural radiative forcing plus the GMO, reveals that most multidecadal fluctuations in the observed global average sea surface temperature can be accounted for by these two components alone. The fact that the GMO varies naturally on multidecadal time scales implies that it can be predicted with some skill on decadal time scales, which provides a scientific rationale for decadal predictions. Furthermore, the GMO is shown to account for about half of the warming in the last 25 years and hence a substantial fraction of the recent acceleration in the rate of increase in global average sea surface temperature. Nevertheless, in terms of the global average “well-observed” sea surface temperature, the GMO can account for only about 0.1° C in transient, decadal-scale fluctuations, not the century-long 1° C warming that has been observed during the twentieth century.

  14. Study of Mechanisms of Aerosol Indirect Effects on Glaciated Clouds: Progress during the Project Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2013-10-18

    This 3-year project has studied how aerosol pollution influences glaciated clouds. The tool applied has been an 'aerosol-cloud model'. It is a type of Cloud-System Resolving Model (CSRM) modified to include 2-moment bulk microphysics and 7 aerosol species, as described by Phillips et al. (2009, 2013). The study has been done by, first, improving the model and then performing sensitivity studies with validated simulations of a couple of observed cases from ARM. These are namely the Tropical Warm Pool International Cloud Experiment (TWP-ICE) over the tropical west Pacific and the Cloud and Land Surface Interaction Campaign (CLASIC) over Oklahoma. During the project, sensitivity tests with the model showed that in continental clouds, extra liquid aerosols (soluble aerosol material) from pollution inhibited warm rain processes for precipitation production. This promoted homogeneous freezing of cloud droplets and aerosols. Mass and number concentrations of cloud-ice particles were boosted. The mean sizes of cloud-ice particles were reduced by the pollution. Hence, the lifetime of glaciated clouds, especially ice-only clouds, was augmented due to inhibition of sedimentation and ice-ice aggregation. Latent heat released from extra homogeneous freezing invigorated convective updrafts, and raised their maximum cloud-tops, when aerosol pollution was included. In the particular cases simulated in the project, the aerosol indirect effect of glaciated clouds was twice than of (warm) water clouds. This was because glaciated clouds are higher in the troposphere than water clouds and have the first interaction with incoming solar radiation. Ice-only clouds caused solar cooling by becoming more extensive as a result of aerosol pollution. This 'lifetime indirect effect' of ice-only clouds was due to higher numbers of homogeneously nucleated ice crystals causing a reduction in their mean size, slowing the ice-crystal process of snow production and slowing

  15. 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.

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

    Science.gov (United States)

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

    1993-01-01

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

  17. Greenhouse effect. DOE's programs and activities relevant to the global warming phenomenon

    International Nuclear Information System (INIS)

    Allen, Robert E. Jr.; Iager, Richard E.; Che, Deborah

    1990-03-01

    While considerable understanding of global climate systems has been gained in the past few years, major sources of uncertainty remain, including the role played by factors such as cloud cover, oceans, and vegetation growth. To help fill these information gaps, DOE undertakes direct research and collects data needed for carbon and climate system models used to predict potential climate changes. These direct research and development efforts represent a requested $28 million in fiscal year 1990 funds, an increase of about $5 million over fiscal year 1989 funding. DOE also conducts a wide range of other research development and demonstration programs it considers indirectly related to the global warming issue, including efforts to increase energy efficiencies, promote conservation, and develop non-fossil energy technologies. For fiscal year 1990, DOE requested about $1.3 billion for these program areas, about $330 million more than the fiscal year 1989 funding level. In these program areas DOE has not established any written criteria or guidance to give special priority to projects on the basis of their relevance or potential impact on global climate change. Senior DOE officials stated that management considers the issue when making funding decisions. In July 1989, the Secretary of Energy established six principles that will form DOE's approach to the global climate change issue, and stated that the issue will be a central part of DOE's efforts to develop a new National Energy Strategy. In addition, several management initiatives have been taken that were related to the issue. These efforts have included compiling an inventory of DOE programs relevant to the issue, organizing a global warming conference, and establishing a DOE Climate Issue Response Group. Public and private organizations, including the Environmental Protection Agency and the World Resources Institute, have made many proposals to address global warming. Generally, the proposals suggested increasing

  18. Abrupt warming of the Red Sea

    KAUST Repository

    Raitsos, D. E.

    2011-07-19

    Coral reef ecosystems, often referred to as “marine rainforests,” concentrate the most diverse life in the oceans. Red Sea reef dwellers are adapted in a very warm environment, fact that makes them vulnerable to further and rapid warming. The detection and understanding of abrupt temperature changes is an important task, as ecosystems have more chances to adapt in a slowly rather than in a rapid changing environment. Using satellite derived sea surface and ground based air temperatures, it is shown that the Red Sea is going through an intense warming initiated in the mid-90s, with evidence for an abrupt increase after 1994 (0.7°C difference pre and post the shift). The air temperature is found to be a key parameter that influences the Red Sea marine temperature. The comparisons with Northern Hemisphere temperatures revealed that the observed warming is part of global climate change trends. The hitherto results also raise additional questions regarding other broader climatic impacts over the area.

  19. Retrieval of Boundary Layer 3D Cloud Properties Using Scanning Cloud Radar and 3D Radiative Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, Roger [Univ. of Washington, Seattle, WA (United States)

    2017-01-24

    Retrievals of cloud optical and microphysical properties for boundary layer clouds, including those widely used by ASR investigators, frequently assume that clouds are sufficiently horizontally homogeneous that scattering and absorption (at all wavelengths) can be treated using one dimensional (1D) radiative transfer, and that differences in the field-of-view of different sensors are unimportant. Unfortunately, most boundary layer clouds are far from horizontally homogeneous, and numerous theoretical and observational studies show that the assumption of horizontal homogeneity leads to significant errors. The introduction of scanning cloud and precipitation radars at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program sites presents opportunities to move beyond the horizontally homogeneous assumption. The primary objective of this project was to develop a 3D retrieval for warm-phase (liquid only) boundary layer cloud microphysical properties, and to assess errors in current 1D (non-scanning) approaches. Specific research activities also involved examination of the diurnal cycle of hydrometeors as viewed by ARM cloud radar, and continued assessment of precipitation impacts on retrievals of cloud liquid water path using passive microwaves.

  20. International Satellite Cloud Climatology Project (ISCCP) Climate Data Record, H-Series

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The International Satellite Cloud Climatology Project (ISCCP) focuses on the distribution and variation of cloud radiative properties to improve the understanding of...

  1. Spontaneous baryogenesis in warm inflation

    OpenAIRE

    Brandenberger, Robert H.; Yamaguchi, Masahide

    2003-01-01

    We discuss spontaneous baryogenesis in the warm inflation scenario. In contrast with standard inflation models, radiation always exists in the warm inflation scenario, and the inflaton must be directly coupled to it. Also, the transition to the post-inflationary radiation dominated phase is smooth and the entropy is not significantly increased at the end of the period of inflation. In addition, after the period of warm inflation ends, the inflaton does not oscillate coherently but slowly roll...

  2. ISM-induced erosion and gas-dynamical drag in the Oort Cloud

    International Nuclear Information System (INIS)

    Stern, S.A.

    1990-01-01

    The model presently used to examine the physical interactions between the ISM and the Oort Cloud can account for sputtering, sticking, and grain-impact erosion, as well as gas drag, by envisioning the ISM as a multiphase medium with distinct atomic and molecular cloud-phase regimes and coronal and warm/ambient gas-phase regimes. Erosion, which reduces the effectiveness of the thermal and radiation-damage processes acting on cometary surfaces in the Oort cloud, is found to be the dominant ISM interaction; ISM drag effects were found to efficiently remove submicron particles from the Cloud. 67 refs

  3. ISM-induced erosion and gas-dynamical drag in the Oort Cloud

    Science.gov (United States)

    Stern, S. Alan

    1990-01-01

    The model presently used to examine the physical interactions between the ISM and the Oort Cloud can account for sputtering, sticking, and grain-impact erosion, as well as gas drag, by envisioning the ISM as a multiphase medium with distinct atomic and molecular cloud-phase regimes and coronal and warm/ambient gas-phase regimes. Erosion, which reduces the effectiveness of the thermal and radiation-damage processes acting on cometary surfaces in the Oort cloud, is found to be the dominant ISM interaction; ISM drag effects were found to efficiently remove submicron particles from the Cloud.

  4. Air-sea interactions and cirrus cloud-radiation feedbacks on climate

    Science.gov (United States)

    Somerville, Richard C. J.; Iacobellis, Sam

    1988-01-01

    A single cloud-radiation feedback mechanism, which may play a role in the climate changes expected from increased atmospheric concentrations of carbon dioxide and other trace greenhouse gases, is described. An improved radiative-convective model was developed and used to study the role of cirrus clouds in the optical thickness feedback mechanism. The model includes prescribed relative humidity and ozone profiles and a surface energy balance. The results suggest that the cloud optical thickness feedback mechanism can cause a substantial reduction in the surface warming due to doubling CO2, even in the presence of cirrus clouds.

  5. 3D modeling of GJ1214b's atmosphere: formation of inhomogeneous high clouds and observational implications

    OpenAIRE

    Charnay, Benjamin; Meadows, Victoria; Misra, Amit; Leconte, Jérémy; Arney, Giada

    2015-01-01

    The warm sub-Neptune GJ1214b has a featureless transit spectrum which may be due to the presence of high and thick clouds or haze. Here, we simulate the atmosphere of GJ1214b with a 3D General Circulation Model for cloudy hydrogen-dominated atmospheres, including cloud radiative effects. We show that the atmospheric circulation is strong enough to transport micrometric cloud particles to the upper atmosphere and generally leads to a minimum of cloud at the equator. By scattering stellar light...

  6. Committed warming inferred from observations and an energy balance model

    Science.gov (United States)

    Pincus, R.; Mauritsen, T.

    2017-12-01

    Due to the lifetime of CO2 and thermal inertia of the ocean, the Earth's climate is not equilibrated with anthropogenic forcing. As a result, even if fossil fuel emissions were to suddenly cease, some level of committed warming is expected due to past emissions. Here, we provide an observational-based quantification of this committed warming using the instrument record of global-mean warming, recently-improved estimates of Earth's energy imbalance, and estimates of radiative forcing from the fifth IPCC assessment report. Compared to pre-industrial levels, we find a committed warming of 1.5K [0.9-3.6, 5-95 percentile] at equilibrium, and of 1.3K [0.9-2.3] within this century. However, when assuming that ocean carbon uptake cancels remnant greenhouse gas-induced warming on centennial timescales, committed warming is reduced to 1.1K [0.7-1.8]. Conservatively, there is a 32% risk that committed warming already exceeds the 1.5K target set in Paris, and that this will likely be crossed prior to 2053. Regular updates of these observationally-constrained committed warming estimates, though simplistic, can provide transparent guidance as uncertainty regarding transient climate sensitivity inevitably narrows and understanding the limitations of the framework is advanced.

  7. Research on Key Technologies of Cloud Computing

    Science.gov (United States)

    Zhang, Shufen; Yan, Hongcan; Chen, Xuebin

    With the development of multi-core processors, virtualization, distributed storage, broadband Internet and automatic management, a new type of computing mode named cloud computing is produced. It distributes computation task on the resource pool which consists of massive computers, so the application systems can obtain the computing power, the storage space and software service according to its demand. It can concentrate all the computing resources and manage them automatically by the software without intervene. This makes application offers not to annoy for tedious details and more absorbed in his business. It will be advantageous to innovation and reduce cost. It's the ultimate goal of cloud computing to provide calculation, services and applications as a public facility for the public, So that people can use the computer resources just like using water, electricity, gas and telephone. Currently, the understanding of cloud computing is developing and changing constantly, cloud computing still has no unanimous definition. This paper describes three main service forms of cloud computing: SAAS, PAAS, IAAS, compared the definition of cloud computing which is given by Google, Amazon, IBM and other companies, summarized the basic characteristics of cloud computing, and emphasized on the key technologies such as data storage, data management, virtualization and programming model.

  8. MOLECULAR CLOUD EVOLUTION. III. ACCRETION VERSUS STELLAR FEEDBACK

    International Nuclear Information System (INIS)

    Vazquez-Semadeni, Enrique; ColIn, Pedro; Gomez, Gilberto C.; Ballesteros-Paredes, Javier; Watson, Alan W.

    2010-01-01

    characteristic of thermally bistable flows, and extend down to densities corresponding to the warm atomic medium, because the warm gas interpenetrates the clouds. The general picture arising from our simulations is that the gas involved in the gravitational contraction leading to star formation extends to large scales and is not confined to the local environment of the final collapse, where the effect of the feedback is active, in agreement with recent proposals of a gravitationally driven mass cascade from large to small scales.

  9. Chemical cloud tracking systems

    Science.gov (United States)

    Grim, Larry B.; Gruber, Thomas C., Jr.; Marshall, Martin; Rowland, Brad

    2002-02-01

    This paper describes the Chemical Cloud Tracking System (CCTS) which has been installed at Dugway Proving Ground. The CCTS allows mapping of chemical clouds in real time from a safe standoff distance. The instruments used are passive standoff chemical agent detectors (FTIRs). Each instrument individually can only measure the total of all the chemical in its line-of-site; the distance to the cloud is unknown. By merging data from multiple vantage points (either one instrument moving past the cloud or two or more instruments spaced so as to view the cloud from different directions) a map of the cloud locations can be generated using tomography. To improve the sensitivity and accuracy of the cloud map, chemical point sensors can be added to the sensor array being used. The equipment required for the CCTS is commercially available. Also, the data fusion techniques (tomography) have been demonstrated previously in the medical field. The Chemical Cloud Tracking System can monitor the movement of many chemical clouds of either military or industrial origin. Since the technique is standoff, the personnel are not exposed to toxic hazards while they follow the cloud. Also, the equipment works on-the-move which allows rapid response to emergency situations (plant explosions, tanker car accidents, chemical terrorism, etc.).

  10. 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.

  11. Establishing a Cloud Computing Success Model for Hospitals in Taiwan.

    Science.gov (United States)

    Lian, Jiunn-Woei

    2017-01-01

    The purpose of this study is to understand the critical quality-related factors that affect cloud computing success of hospitals in Taiwan. In this study, private cloud computing is the major research target. The chief information officers participated in a questionnaire survey. The results indicate that the integration of trust into the information systems success model will have acceptable explanatory power to understand cloud computing success in the hospital. Moreover, information quality and system quality directly affect cloud computing satisfaction, whereas service quality indirectly affects the satisfaction through trust. In other words, trust serves as the mediator between service quality and satisfaction. This cloud computing success model will help hospitals evaluate or achieve success after adopting private cloud computing health care services.

  12. Establishing a Cloud Computing Success Model for Hospitals in Taiwan

    Directory of Open Access Journals (Sweden)

    Jiunn-Woei Lian PhD

    2017-01-01

    Full Text Available The purpose of this study is to understand the critical quality-related factors that affect cloud computing success of hospitals in Taiwan. In this study, private cloud computing is the major research target. The chief information officers participated in a questionnaire survey. The results indicate that the integration of trust into the information systems success model will have acceptable explanatory power to understand cloud computing success in the hospital. Moreover, information quality and system quality directly affect cloud computing satisfaction, whereas service quality indirectly affects the satisfaction through trust. In other words, trust serves as the mediator between service quality and satisfaction. This cloud computing success model will help hospitals evaluate or achieve success after adopting private cloud computing health care services.

  13. Daytime warming has stronger negative effects on soil nematodes than night-time warming

    OpenAIRE

    Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

    2017-01-01

    Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatmen...

  14. Global Warming on Triton

    Science.gov (United States)

    Elliot, J. L.; Hammel, H. B.; Wasserman, L. H.; Franz, O. G.; McDonald, S. W.; Person, M. J.; Olkin, C. B.; Dunham, E. J.; Spencer, J. R.; Stansberry, J. A.; hide

    1998-01-01

    Triton, Neptune's largest moon, has been predicted to undergo significant seasonal changes that would reveal themselves as changes in its mean frost temperature. But whether this temperature should at the present time be increasing, decreasing or constant depends on a number of parameters (such as the thermal properties of the surface, and frost migration patterns) that are unknown. Here we report observations of a recent stellar occultation by Triton which, when combined with earlier results, show that Triton has undergone a period of global warming since 1989. Our most conservative estimates of the rate of temperature and surface-pressure increase during this period imply that the atmosphere is doubling in bulk every 10 years, significantly faster than predicted by any published frost model for Triton. Our result suggests that permanent polar caps on Triton play a c dominant role in regulating seasonal atmospheric changes. Similar processes should also be active on Pluto.

  15. Synergistic warm inflation

    International Nuclear Information System (INIS)

    Chimento, Luis P.; Jakubi, Alejandro S.; Zuccala, Norberto; Pavon, Diego

    2002-01-01

    We consider an alternative warm inflationary scenario in which n scalar fields coupled to a dissipative matter fluid cooperate to produce power-law inflation. The scalar fields are driven by an exponential potential and the bulk dissipative pressure coefficient is linear in the expansion rate. We find that the entropy of the fluid attains its asymptotic value in a characteristic time proportional to the square of the number of fields. This scenario remains nearly isothermal along the inflationary stage. The perturbations in energy density and entropy are studied in the long-wavelength regime and seen to grow roughly as the square of the scale factor. They are shown to be compatible with COBE measurements of the fluctuations in temperature of the CMB

  16. Interacting warm dark matter

    International Nuclear Information System (INIS)

    Cruz, Norman; Palma, Guillermo; Zambrano, David; Avelino, Arturo

    2013-01-01

    We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ m α ρ e β form, where ρ m and ρ e are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ,α,β) as well as w m and w e of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ,α,β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used

  17. New Classes of Applications in the Cloud. Evaluating Advantages and Disadvantages of Cloud Computing for Telemetry Applications

    Directory of Open Access Journals (Sweden)

    Anca APOSTU

    2014-05-01

    Full Text Available Nowadays companies are moving some parts of their businesses to the cloud. Industry predictions are that this trend will continue to grow and develop even further in the coming few years. While Cloud computing is undoubtedly beneficial for mid-size to large companies, it is not without its downsides, especially for smaller businesses. This paper's aim is to deliver an analysis based on advantages and disadvantages of Cloud computing technology, in order to help organizations fully understand and adopt this new computing technology. Finally, to prove the advantages that Cloud technology can have for this domain, we are presenting a cloud application for telemetry, with a focus on monitoring hydro-energy. We consider that the way to attain the benefits of Cloud technology is to understand its strengths and weaknesses and adapt to them accordingly.

  18. MAGIC Cloud Properties from Zenith Radiance Data Final Campaign Summary

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, J. -Y.C. [Univ. of Reading (United Kingdom); Gregory, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wagener, R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-01-01

    Cloud droplet size and optical depth are the most fundamental properties for understanding cloud formation, dissipation and interactions with aerosol and drizzle. They are also a crucial determinant of Earth’s radiative and water-energy balances. However, these properties are poorly predicted in climate models. As a result, the response of clouds to climate change is one of the major sources of uncertainty in climate prediction.

  19. Local warming: daily temperature change influences belief in global warming.

    Science.gov (United States)

    Li, Ye; Johnson, Eric J; Zaval, Lisa

    2011-04-01

    Although people are quite aware of global warming, their beliefs about it may be malleable; specifically, their beliefs may be constructed in response to questions about global warming. Beliefs may reflect irrelevant but salient information, such as the current day's temperature. This replacement of a more complex, less easily accessed judgment with a simple, more accessible one is known as attribute substitution. In three studies, we asked residents of the United States and Australia to report their opinions about global warming and whether the temperature on the day of the study was warmer or cooler than usual. Respondents who thought that day was warmer than usual believed more in and had greater concern about global warming than did respondents who thought that day was colder than usual. They also donated more money to a global-warming charity if they thought that day seemed warmer than usual. We used instrumental variable regression to rule out some alternative explanations.

  20. 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...

  1. Energy Aware Clouds

    Science.gov (United States)

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

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

  2. The sensitivities of in cloud and cloud top phase distributions to primary ice formation in ICON-LEM

    Science.gov (United States)

    Beydoun, H.; Karrer, M.; Tonttila, J.; Hoose, C.

    2017-12-01

    Mixed phase clouds remain a leading source of uncertainty in our attempt to quantify cloud-climate and aerosol-cloud climate interactions. Nevertheless, recent advances in parametrizing the primary ice formation process, high resolution cloud modelling, and retrievals of cloud phase distributions from satellite data offer an excellent opportunity to conduct closure studies on the sensitivity of the cloud phase to microphysical and dynamical processes. Particularly, the reliability of satellite data to resolve the phase at the top of the cloud provides a promising benchmark to compare model output to. We run large eddy simulations with the new ICOsahedral Non-hydrostatic atmosphere model (ICON) to place bounds on the sensitivity of in cloud and cloud top phase to the primary ice formation process. State of the art primary ice formation parametrizations in the form of the cumulative ice active site density ns are implemented in idealized deep convective cloud simulations. We exploit the ability of ICON-LEM to switch between a two moment microphysics scheme and the newly developed Predicted Particle Properties (P3) scheme by running our simulations in both configurations for comparison. To quantify the sensitivity of cloud phase to primary ice formation, cloud ice content is evaluated against order of magnitude changes in ns at variable convective strengths. Furthermore, we assess differences between in cloud and cloud top phase distributions as well as the potential impact of updraft velocity on the suppression of the Wegener-Bergeron-Findeisen process. The study aims to evaluate our practical understanding of primary ice formation in the context of predicting the structure and evolution of mixed phase clouds.

  3. Relationships between Convective Strength and Anvil Development based on AIRS-CloudSat Joint Dataset

    Science.gov (United States)

    Takahashi, H.; Protopapadaki, S.; Stubenrauch, C.; Luo, Z. J.; Stephens, G. L.

    2017-12-01

    This study is a follow-up to a previous publication by Protopapadaki et al (2017), which discovered an interesting tendency: during the mature stage of convective systems, stronger/deeper convective cores tend to have larger fractions of thin cirrus coverage. This tendency was found over continental, oceanic, single- and multi-core convective systems, which made the result robust. This tendency is a key to understanding atmospheric radiative budgets and climate feedbacks, since thin cirrus has a warming effect on the atmosphere. However, the analysis was limited to the Atmospheric Infrared Sounder (AIRS). For example, convective core, thick cirrus, and thin cirrus were categorized by AIRS emissivity, the proxy of convective strength/depth was based on AIRS minimum temperature within the convective core, and the definition of maturity stage was based on the fraction of convective core. Therefore, it is necessary to test if a similar tendency can be seen by other instruments such as CloudSat. In this study, different proxies of convective strength/depth, and a different definition of life stage of convective systems are introduced by the joint analysis of CloudSat, AIRS, and geostationary satellite observations, to investigate the relationship between convective depth/strength and the fraction of thin as well as thick cirrus. Finally, net heating rate is analyzed over convective cores, thick cirrus, and thin cirrus to understand what role they play in controlling the energy budget in the atmosphere.

  4. Evolution of surface sensible heat over the Tibetan Plateau under the recent global warming hiatus

    Science.gov (United States)

    Zhu, Lihua; Huang, Gang; Fan, Guangzhou; Qu, Xia; Zhao, Guijie; Hua, Wei

    2017-10-01

    Based on regular surface meteorological observations and NCEP/DOE reanalysis data, this study investigates the evolution of surface sensible heat (SH) over the central and eastern Tibetan Plateau (CE-TP) under the recent global warming hiatus. The results reveal that the SH over the CE-TP presents a recovery since the slowdown of the global warming. The restored surface wind speed together with increased difference in ground-air temperature contribute to the recovery in SH. During the global warming hiatus, the persistent weakening wind speed is alleviated due to the variation of the meridional temperature gradient. Meanwhile, the ground surface temperature and the difference in ground-air temperature show a significant increasing trend in that period caused by the increased total cloud amount, especially at night. At nighttime, the increased total cloud cover reduces the surface effective radiation via a strengthening of atmospheric counter radiation and subsequently brings about a clear upward trend in ground surface temperature and the difference in ground-air temperature. Cloud-radiation feedback plays a significant role in the evolution of the surface temperature and even SH during the global warming hiatus. Consequently, besides the surface wind speed, the difference in ground-air temperature becomes another significant factor for the variation in SH since the slowdown of global warming, particularly at night.

  5. Cloud Model Bat Algorithm

    OpenAIRE

    Yongquan Zhou; Jian Xie; Liangliang Li; Mingzhi Ma

    2014-01-01

    Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformati...

  6. Resilient Diffusive Clouds

    Science.gov (United States)

    2017-02-01

    RESILIENT DIFFUSIVE CLOUDS TRUSTEES OF DARTMOUTH COLLEGE FEBRUARY 2017 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC...To) SEP 2011 – SEP 2016 4. TITLE AND SUBTITLE RESILIENT DIFFUSIVE CLOUDS 5a. CONTRACT NUMBER FA8750-11-2-0257 5b. GRANT NUMBER N/A 5c. PROGRAM...diversified virtual machines. The concepts lead to a view of cloud computing in which vulnerabilities are different at every host, attackers cannot

  7. Cloud Oriented Applications

    Directory of Open Access Journals (Sweden)

    Razvan DINA

    2009-07-01

    Full Text Available Cloud computing is a paradigm that incorporates the concept of software as a service. The current cloud computing architecture involves the existence of data centers that are able to provide services to the clients located all over the world. The major players in field of the cloud computing are Google, Microsoft, Amazon, Yahoo, and some traditional hardware producers like HP, IBM, Intel.

  8. 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...

  9. 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.

  10. The observed influence of local anthropogenic pollution on northern Alaskan cloud properties

    Science.gov (United States)

    Maahn, Maximilian; de Boer, Gijs; Creamean, Jessie M.; Feingold, Graham; McFarquhar, Greg M.; Wu, Wei; Mei, Fan

    2017-12-01

    Due to their importance for the radiation budget, liquid-containing clouds are a key component of the Arctic climate system. Depending on season, they can cool or warm the near-surface air. The radiative properties of these clouds depend strongly on cloud drop sizes, which are governed in part by the availability of cloud condensation nuclei. Here, we investigate how cloud drop sizes are modified in the presence of local emissions from industrial facilities at the North Slope of Alaska. For this, we use aircraft in situ observations of clouds and aerosols from the 5th Department of Energy Atmospheric Radiation Measurement (DOE ARM) Program's Airborne Carbon Measurements (ACME-V) campaign obtained in summer 2015. Comparison of observations from an area with petroleum extraction facilities (Oliktok Point) with data from a reference area relatively free of anthropogenic sources (Utqiaġvik/Barrow) represents an opportunity to quantify the impact of local industrial emissions on cloud properties. In the presence of local industrial emissions, the mean effective radii of cloud droplets are reduced from 12.2 to 9.4 µm, which leads to suppressed drizzle production and precipitation. At the same time, concentrations of refractory black carbon and condensation nuclei are enhanced below the clouds. These results demonstrate that the effects of anthropogenic pollution on local climate need to be considered when planning Arctic industrial infrastructure in a warming environment.

  11. 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.

  12. Microbiologists search the clouds

    Science.gov (United States)

    Showstack, Randy

    On 22 May, a team of microbiologists used a prototype cloud-catcher mounted on a research plane to collect samples from low-lying cumulus clouds near Oxford, England. The researchers, from the University of East London (UEL), are investigating whether an active and self-sustaining ecosystem exists in clouds, and whether airborne microbes may play an active role in forming clouds and causing rainfall.While scientists have known that microorganisms, including bacteria, fungal spores, and algae, can survive and possibly reproduce in the atmosphere, the challenge, according to the UEL researchers, is to accurately detect, identify, and analyze microbial communities.

  13. 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.

  14. 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. 

  15. SparkClouds: visualizing trends in tag clouds.

    Science.gov (United States)

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

    2010-01-01

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

  16. The challenge of global warming

    International Nuclear Information System (INIS)

    Bryner, G.C.

    1992-01-01

    The chapter outlines the science of global warming, the likely consequences of global warming and some of the major challenges in dealing with global climate change. Some of the major international organisations concerned with environmental issues are listed. International agreements might be used to limit emissions of greenhouse gases. 32 refs., 2 tabs

  17. Climate feedback analysis of the GFDL IPCC AR4 global warming simulation

    Science.gov (United States)

    Castet, Christelle

    Both observed and modeled global warming pattern shows a large surface polar warming and a large upper atmospheric warming in the tropics. This pattern leads to an amplification (reduction) of the temperature gradient at upper levels (surface). Physical processes behind this temperature change are the external radiative forcing, and subsequent feedback processes that may amplify or dampen the climate response. This unique warming pattern suggests that high latitudes are very sensitive to climate change and also the area where the largest warming projection uncertainties occur. The objective of this study is to apply a new coupled atmosphere-surface climate feedback-response analysis method to quantify the contributions of the external forcing alone (doubling of carbon dioxide), and subsequent feedback processes to the 3-D global warming pattern in the GFDL_CM2.0 model. The feedbacks under consideration include the water vapor feedback, surface albedo feedback, surface turbulent heat flux feedback, and the sum of the change in cloud radiative forcing (CRF), vertical convective, and large-scale scale dynamical feedback. The partial temperature changes due to the external forcing and due to individual feedbacks are additive and their sum converges toward the temperature change produced by the original GFDL_CM2.0 global warming simulations. Therefore, our attributions of the global warming patter to individual thermodynamic and dynamical processes are mathematically robust and physically meaningful. The partial temperature change due to the water vapor feedback is found to be the largest contributor to the globally averaged surface warming. It is twice as large as the warming due to the external radiative forcing alone. The surface albedo feedback and change in surface cloud radiative forcing increase the surface temperature by a smaller amount. In addition, the changes in atmospheric cloud forcing and large-scale dynamics, as well as the surface turbulent heat flux

  18. Large Eddy Simulation of Cirrus Clouds

    Science.gov (United States)

    Wu, Ting; Cotton, William R.

    1999-01-01

    heating could be comparable in magnitude in the cloudy layer. This implies that latent heating cannot be neglected in the construction of a cirrus cloud model. The probability density function (PDF) of w was analyzed to assist in the parameterization of cloud-scale velocities in large-scale models. For the more radiatively-driven, thin cirrus case, the PDFs are approximately Gaussian. However, in the interior of the deep, convectively unstable case, the PDFs of w are multi-modal and very broad, indicating that parameterizing cloud-scale motions for such clouds can be very challenging. The results of this research are described in detail in a paper submitted to the Journal of Atmospheric Science (Wu and Cotton, 1999), which is enclosed as Appendix 2. Using soundings extracted from a mesoscale simulation of the November 26, 1991 cirrus event, the radiative effects on vapor deposition/sublimation of ice crystals was studied using a two-dimensional cloud-resolving model (CRM) version of RAMS, coupled to an explicit bin-resolving microphysics. The CRM simulations of the November 26, 1991 cirrus event demonstrate that the radiative impact on the diffusional growth (or sublimation) of ice crystals is significant. In this case, the ice particles experienced radiative warming. Model results show that radiative feedbacks in the diffusional growth of ice particles can be very complex. Radiative warming of an ice particle will restrict the particle's diffusional growth. In the case of radiative warming, ice particles larger than a certain size will experience so much radiative warming that surface ice saturation vapor pressures become large enough to cause sublimation of the larger crystals, while smaller crystals are growing by vapor deposition. However, ice mass production can be enhanced in the case of radiative cooling of an ice particle. For the November 26, 1991 cirrus event, radiative feedback results in significant reduction in the total ice mass, especially in the production

  19. Modeling of the cloud and radiation processes observed during SHEBA

    Science.gov (United States)

    Du, Ping; Girard, Eric; Bertram, Allan K.; Shupe, Matthew D.

    2011-09-01

    Six microphysics schemes implemented in the climate version of the Environment Canada's Global Multiscale Environmental (GEM) model are used to simulate the cloud and radiation processes observed during Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment. The simplest microphysics scheme (SUN) has one prognostic variable: the total cloud water content. The second microphysics scheme (MLO) has 12 prognostic variables. The four other microphysics schemes are modified versions of MLO. A new parameterization for heterogeneous ice nucleation based on laboratory experiments is included in these versions of MLO. One is for uncoated ice nuclei (ML-NAC) and another is for sulfuric acid coated ice nuclei (ML-AC). ML-AC and ML-NAC have been developed to distinguish non-polluted and polluted air masses, the latter being common over the Arctic during winter and spring. A sensitivity study, in which the dust concentration is reduced by a factor 5, is also performed to assess the sensitivity of the results to the dust concentration in ML-AC-test and ML-NAC-test. Results show that SUN, ML-AC and ML-AC-test reproduce quite well the downward longwave radiation and cloud radiative forcing during the cold season. The good results obtained with SUN are due to compensating errors. It overestimates cloud fraction and underestimates cloud liquid water path during winter. ML-AC and ML-AC-test reproduces quite well all these variables and their relationships. MLO, ML-NAC and ML-NAC-test underestimate the cloud liquid water path and cloud fraction during the cold season, which leads to an underestimation of the downward longwave radiation at surface. During summer, all versions of the model underestimate the downward shortwave radiation at surface. ML-AC and ML-NAC overestimate the total cloud water during the warm season, however, they reproduce relatively well the relationships between cloud radiative forcing and cloud microstructure, which is not the case for the most simple

  20. Global warming 2007. An update to global warming: the balance of evidence and its policy implications.

    Science.gov (United States)

    Keller, Charles F

    2007-03-09

    In the four years since my original review (Keller[25]; hereafter referred to as CFK03), research has clarified and strengthened our understanding of how humans are warming the planet. So many of the details highlighted in the IPCC's Third Assessment Report[21] and in CFK03 have been resolved that I expect many to be a bit overwhelmed, and I hope that, by treating just the most significant aspects of the research, this update may provide a road map through the expected maze of new information. In particular, while most of CFK03 remains current, there are important items that have changed: Most notable is the resolution of the conundrum that mid-tropospheric warming did not seem to match surface warming. Both satellite and radiosonde (balloon-borne sensors) data reduction showed little warming in the middle troposphere (4-8 km altitude). In the CFK03 I discussed potential solutions to this problem, but at that time there was no clear resolution. This problem has now been solved, and the middle troposphere is seen to be warming apace with the surface. There have also been advances in determinations of temperatures over the past 1,000 years showing a cooler Little Ice Age (LIA) but essentially the same warming during medieval times (not as large as recent warming). The recent uproar over the so-called "hockey stick" temperature determination is much overblown since at least seven other groups have made relatively independent determinations of northern hemisphere temperatures over the same time period and derived essentially the same results. They differ on how cold the LIA was but essentially agree with the Mann's hockey stick result that the Medieval Warm Period was not as warm as the last 25 years. The question of the sun's influence on climate continues to generate controversy. It appears there is a growing consensus that, while the sun was a major factor in earlier temperature variations, it is incapable of having caused observed warming in the past quarter

  1. 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.

  2. Recent Declines in Warming and Vegetation Greening Trends over Pan-Arctic Tundra

    Directory of Open Access Journals (Sweden)

    Igor V. Polyakov

    2013-08-01

    Full Text Available Vegetation productivity trends for the Arctic tundra are updated for the 1982–2011 period and examined in the context of land surface temperatures and coastal sea ice. Understanding mechanistic links between vegetation and climate parameters contributes to model advancements that are necessary for improving climate projections. This study employs remote sensing data: Global Inventory Modeling and Mapping Studies (GIMMS Maximum Normalized Difference Vegetation Index (MaxNDVI, Special Sensor Microwave Imager (SSM/I sea-ice concentrations, and Advanced Very High Resolution Radiometer (AVHRR radiometric surface temperatures. Spring sea ice is declining everywhere except in the Bering Sea, while summer open water area is increasing throughout the Arctic. Summer Warmth Index (SWI—sum of degree months above freezing trends from 1982 to 2011 are positive around Beringia but are negative over Eurasia from the Barents to the Laptev Seas and in parts of northern Canada. Eastern North America continues to show increased summer warmth and a corresponding steady increase in MaxNDVI. Positive MaxNDVI trends from 1982 to 2011 are generally weaker compared to trends from 1982–2008. So to better understand the changing trends, break points in the time series were quantified using the Breakfit algorithm. The most notable break points identify declines in SWI since 2003 in Eurasia and 1998 in Western North America. The Time Integrated NDVI (TI-NDVI, sum of the biweekly growing season values of MaxNDVI has declined since 2005 in Eurasia, consistent with SWI declines. Summer (June–August sea level pressure (slp averages from 1999–2011 were compared to those from 1982–1998 to reveal higher slp over Greenland and the western Arctic and generally lower pressure over the continental Arctic in the recent period. This suggests that the large-scale circulation is likely a key contributor to the cooler temperatures over Eurasia through increased summer cloud

  3. Global warming forecasts unreliability

    International Nuclear Information System (INIS)

    Baker, A.B.

    1993-01-01

    This paper reports the opinions of a series of experts who have recently commented on the reliability of predictions of global warning in relation to observed and forecasted increases in carbon dioxide emissions. One of the more difficult to explain observations, evidenced through the analysis of past meteorological data, was the rapid increase in global temperature that took place during the period preceding 1940 and which was followed by a gradual decrease, during a thirty year period of heightened industrialization and consumption of fossil fuels, up to 1970 when global temperatures began again to rise rapidly. Variations in solar activity was suggested to explain this apparently anomalous trend in global temperatures. This question as to the existence of a strict correlation between global warming and rises in carbon dioxide emissions, as well as, forecasted increases in concentrations of atmospheric carbon dioxide due to the expected population growth in China are putting a strain on attempts by OECD (Organization for Economic Co-operation and Development) environmental policy makers to gain support for energy tax proposals

  4. The governance of cloud based Supply Chain Collaborations

    NARCIS (Netherlands)

    Chandra, Dissa Riandaso; van Hillegersberg, Jos

    2015-01-01

    Despite of the promising benefits of cloud computing in enabling efficient, sustainable and agile Supply Chain Collaborations (SCCs), this service does not eliminate governance challenges in SCCs. Cloud based SCCs may flounder without a proper understanding of how to govern inter-organizational

  5. 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.

  6. 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, ...

  7. Assessment of aerosol-cloud interactions during southern African biomass burning activity, employing cloud parameterizations

    Science.gov (United States)

    Wiston, Modise; McFiggans, Gordon; Schultz, David

    2015-04-01

    In this study, we perform a simulation of the spatial distributions of particle and gas concentrations from a significantly large source of pollution event during a dry season in southern Africa and their interactions with cloud processes. Specific focus is on the extent to which cloud-aerosol interactions are affected by various inputs (i.e. emissions) and parameterizations and feedback mechanisms in a coupled mesoscale chemistry-meteorology model -herein Weather Research and Forecasting model with chemistry (WRF-Chem). The southern African dry season (May-Sep) is characterised by biomass burning (BB) type of pollution. During this period, BB particles are frequently observed over the subcontinent, at the same time a persistent deck of stratocumulus covers the south West African coast, favouring long-range transport over the Atlantic Ocean of aerosols above clouds. While anthropogenic pollutants tend to spread more over the entire domain, biomass pollutants are concentrated around the burning areas, especially the savannah and tropical rainforest of the Congo Basin. BB is linked to agricultural practice at latitudes south of 10° N. During an intense burning event, there is a clear signal of strong interactions of aerosols and cloud microphysics. These species interfere with the radiative budget, and directly affect the amount of solar radiation reflected and scattered back to space and partly absorbed by the atmosphere. Aerosols also affect cloud microphysics by acting as cloud condensation nuclei (CCN), modifying precipitation pattern and the cloud albedo. Key area is to understand the role of pollution on convective cloud processes and its impacts on cloud dynamics. The hypothesis is that an environment of potentially high pollution enables the probability of interactions between co-located aerosols and cloud layers. To investigate this hypothesis, we outline an approach to integrate three elements: i) focusing on regime(s) where there are strong indications of

  8. 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).

  9. 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.

  10. 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 ...

  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. On Cloud Nine

    Science.gov (United States)

    McCrea, Bridget; Weil, Marty

    2011-01-01

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

  13. 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.…

  14. Filament formation in wind-cloud interactions- II. Clouds with turbulent density, velocity, and magnetic fields

    Science.gov (United States)

    Banda-Barragán, W. E.; Federrath, C.; Crocker, R. M.; Bicknell, G. V.

    2018-01-01

    We present a set of numerical experiments designed to systematically investigate how turbulence and magnetic fields influence the morphology, energetics, and dynamics of filaments produced in wind-cloud interactions. We cover 3D, magnetohydrodynamic systems of supersonic winds impacting clouds with turbulent density, velocity, and magnetic fields. We find that lognormal density distributions aid shock propagation through clouds, increasing their velocity dispersion and producing filaments with expanded cross-sections and highly magnetized knots and subfilaments. In self-consistently turbulent scenarios, the ratio of filament to initial cloud magnetic energy densities is ∼1. The effect of Gaussian velocity fields is bound to the turbulence Mach number: Supersonic velocities trigger a rapid cloud expansion; subsonic velocities only have a minor impact. The role of turbulent magnetic fields depends on their tension and is similar to the effect of radiative losses: the stronger the magnetic field or the softer the gas equation of state, the greater the magnetic shielding at wind-filament interfaces and the suppression of Kelvin-Helmholtz instabilities. Overall, we show that including turbulence and magnetic fields is crucial to understanding cold gas entrainment in multiphase winds. While cloud porosity and supersonic turbulence enhance the acceleration of clouds, magnetic shielding protects them from ablation and causes Rayleigh-Taylor-driven subfilamentation. Wind-swept clouds in turbulent models reach distances ∼15-20 times their core radius and acquire bulk speeds ∼0.3-0.4 of the wind speed in one cloud-crushing time, which are three times larger than in non-turbulent models. In all simulations, the ratio of turbulent magnetic to kinetic energy densities asymptotes at ∼0.1-0.4, and convergence of all relevant dynamical properties requires at least 64 cells per cloud radius.

  15. Teaching Teaching & Understanding Understanding

    DEFF Research Database (Denmark)

    2006-01-01

    "Teaching Teaching & Understanding Understanding" is a 19-minute award-winning short-film about teaching at university and higher-level educational institutions. It is based on the "Constructive Alignment" theory developed by Prof. John Biggs. The film delivers a foundation for understanding what...

  16. Several thoughts for using new satellite remote sensing and global modeling for aerosol and cloud climate studies

    Science.gov (United States)

    Nakajima, Teruyuki; Hashimoto, Makiko; Takenaka, Hideaki; Goto, Daisuke; Oikawa, Eiji; Suzuki, Kentaroh; Uchida, Junya; Dai, Tie; Shi, Chong

    2017-04-01

    The rapid growth of satellite remote sensing technologies in the last two decades widened the utility of satellite data for understanding climate impacts of aerosols and clouds. The climate modeling community also has received the benefit of the earth observation and nowadays closed-collaboration of the two communities make us possible to challenge various applications for societal problems, such as for global warming and global-scale air pollution and others. I like to give several thoughts of new algorithm developments, model use of satellite data for climate impact studies and societal applications related with aerosols and clouds. Important issues are 1) Better aerosol detection and solar energy application using expanded observation ability of the third generation geostationary satellites, i.e. Himawari-8, GOES-R and future MTG, 2) Various observation functions by directional, polarimetric, and high resolution near-UV band by MISR, POLDER&PARASOL, GOSAT/CAI and future GOSAT2/CAI2, 3) Various applications of general purpose-imagers, MODIS, VIIRS and future GCOM-C/SGLI, and 4) Climate studies of aerosol and cloud stratification and convection with active and passive sensors, especially climate impact of BC aerosols using CLOUDSAT&CALIPSO and future Earth Explorer/EarthCARE.

  17. GRIP CLOUD MICROPHYSICS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Cloud Microphysics dataset was collected during the GRIP campaign from three probes: the Cloud, Aerosol, and Precipitation Spectrometer (CAPS), the...

  18. 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).

  19. Cloud model bat algorithm.

    Science.gov (United States)

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

    2014-01-01

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

  20. Cloud Model Bat Algorithm

    Directory of Open Access Journals (Sweden)

    Yongquan Zhou

    2014-01-01

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

  1. Toward Quantitative Understanding of the Atmospheric Heating over the Tibetan Plateau (Invited)

    Science.gov (United States)

    Koike, T.; Tamura, T.; Rasmy, M.; Seto, R.

    2010-12-01

    There are different ideas on the atmospheric heating over the Tibetan Plateau. Yanai et al. (1992) and Yanai and Li (1994) concluded this sensible heat flux from the surface is the major source of heating on the plateau before the summer rain commences. On the other hand, Ueda et al. (2003) also showed the importance of condensation heating in the heat balance during the pre-onset-phase of the summer monsoon over the western part of the Tibetan Plateau. The first intensive in situ observation in early spring was implemented on the plateau in April 2004 under the framework of the Coordinated Enhanced Observing Period (CEOP) (Koike, 2004). Taniguchi and Koike (2007) revealed the importance of cumulus activity in atmospheric temperature increases in the upper troposphere even in April by in situ and satellite observations and numerical simulations. They concluded that sensible heat transfer by dry convection is insufficient to warm the upper layer over the plateau and that the development of cloud convection is indispensable for atmospheric heating in the upper troposphere over the plateau during early spring. Then, Taniguchi and Koike (2008) investigated the seasonal variation in the cloud activity over the eastern part of the Tibetan Plateau, and the vertical profile of the atmosphere and moist condition causing the cloud. They showed cumulus convections easily occur under the adiabatically neutral condition of the first phase of the active convections in April. During a resting phase before the second active phase, the atmosphere is conditionally unstable but an unsaturated condition restrains cloud activity, while during second phase, the atmosphere is inclined to be saturated and cloud activity begins again. From early May to mid June, there is a resting period of cumulus convective activity. However, the tropospheric temperature at 200 hPa increases rapidly from late April. Such rapid tropospheric warming without significant cumulus convective activity is

  2. Cloud Computing and Its Applications in GIS

    Science.gov (United States)

    Kang, Cao

    2011-12-01

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

  3. Explicit prediction of ice clouds in general circulation models

    Science.gov (United States)

    Kohler, Martin

    1999-11-01

    Although clouds play extremely important roles in the radiation budget and hydrological cycle of the Earth, there are large quantitative uncertainties in our understanding of their generation, maintenance and decay mechanisms, representing major obstacles in the development of reliable prognostic cloud water schemes for General Circulation Models (GCMs). Recognizing their relative neglect in the past, both observationally and theoretically, this work places special focus on ice clouds. A recent version of the UCLA - University of Utah Cloud Resolving Model (CRM) that includes interactive radiation is used to perform idealized experiments to study ice cloud maintenance and decay mechanisms under various conditions in term of: (1) background static stability, (2) background relative humidity, (3) rate of cloud ice addition over a fixed initial time-period and (4) radiation: daytime, nighttime and no-radiation. Radiation is found to have major effects on the life-time of layer-clouds. Optically thick ice clouds decay significantly slower than expected from pure microphysical crystal fall-out (taucld = 0.9--1.4 h as opposed to no-motion taumicro = 0.5--0.7 h). This is explained by the upward turbulent fluxes of water induced by IR destabilization, which partially balance the downward transport of water by snowfall. Solar radiation further slows the ice-water decay by destruction of the inversion above cloud-top and the resulting upward transport of water. Optically thin ice clouds, on the other hand, may exhibit even longer life-times (>1 day) in the presence of radiational cooling. The resulting saturation mixing ratio reduction provides for a constant cloud ice source. These CRM results are used to develop a prognostic cloud water scheme for the UCLA-GCM. The framework is based on the bulk water phase model of Ose (1993). The model predicts cloud liquid water and cloud ice separately, and which is extended to split the ice phase into suspended cloud ice (predicted

  4. Using Updated Climate Accounting to Slow Global Warming Before 2035

    Science.gov (United States)

    Schultz, T.

    2015-12-01

    The current and projected worsening of climate impacts make clear the urgency of limiting the global mean temperature to 2°C over preindustrial levels. But while mitigation policy today may slow global warming at the end of the century, it will not keep global warming within these limits. This failure arises in large part from the climate accounting system used to inform this policy, which does not factor in several scientific findings from the last two decades, including: The urgent need to slow global warming before 2035. This can postpone the time the +1.5°C limit is passed, and is the only way to avoid the most serious long-term climate disruptions. That while it may mitigate warming by the end of the century, reducing emissions of CO2 alone, according to UNEP/WMO[1], will do "little to mitigate warming over the next 20-30 years," and "may temporarily enhance near-term warming as sulfate [cooling] is reduced." That the only emissions reductions that can slow warming before 2035 are focused on short-lived climate pollutants. A small increase in current mitigation funding could fund these projects, the most promising of which target emissions in regional climate "hot spots" like the Arctic and India.[2] To ensure policies can effectively slow global warming before 2035, a new climate accounting system is needed. Such an updated system is being standardized in the USA,[3] and has been proposed for use in ISO standards. The key features of this updated system are: consideration of all climate pollutants and their multi-faceted climate effects; use of time horizons which prioritize mitigation of near-term warming; a consistent and accurate accounting for "biogenic" CO2; protocols ensuring that new scientific findings are incorporated; and a distinct accounting for emissions affecting regional "hot spots". This accounting system also considers environmental impacts outside of climate change, a feature necessary to identify "win-win" projects with climate benefits

  5. Statistical Analyses of Satellite Cloud Object Data from CERES. Part II; Tropical Convective Cloud Objects During 1998 El Nino and Validation of the Fixed Anvil Temperature Hypothesis

    Science.gov (United States)

    Xu, Kuan-Man; Wong, Takmeng; Wielicki, Bruce a.; Parker, Lindsay; Lin, Bing; Eitzen, Zachary A.; Branson, Mark

    2006-01-01

    Characteristics of tropical deep convective cloud objects observed over the tropical Pacific during January-August 1998 are examined using the Tropical Rainfall Measuring Mission/ Clouds and the Earth s Radiant Energy System single scanner footprint (SSF) data. These characteristics include the frequencies of occurrence and statistical distributions of cloud physical properties. Their variations with cloud-object size, sea surface temperature (SST), and satellite precessing cycle are analyzed in detail. A cloud object is defined as a contiguous patch of the Earth composed of satellite footprints within a single dominant cloud-system type. It is found that statistical distributions of cloud physical properties are significantly different among three size categories of cloud objects with equivalent diameters of 100 - 150 km (small), 150 - 300 km (medium), and > 300 km (large), respectively, except for the distributions of ice particle size. The distributions for the larger-size category of cloud objects are more skewed towards high SSTs, high cloud tops, low cloud-top temperature, large ice water path, high cloud optical depth, low outgoing longwave (LW) radiation, and high albedo than the smaller-size category. As SST varied from one satellite precessing cycle to another, the changes in macrophysical properties of cloud objects over the entire tropical Pacific were small for the large-size category of cloud objects, relative to those of the small- and medium-size categories. This result suggests that the fixed anvil temperature hypothesis of Hartmann and Larson may be valid for the large-size category. Combining with the result that a higher percentage of the large-size category of cloud objects occurs during higher SST subperiods, this implies that macrophysical properties of cloud objects would be less sensitive to further warming of the climate. On the other hand, when cloud objects are classified according to SSTs where large-scale dynamics plays important roles

  6. Beam Measurements of a CLOUD (Cosmics Leaving OUtdoor Droplets) Chamber

    CERN Document Server

    Kirkby, Jasper

    2001-01-01

    A striking correlation has recently been observed between global cloud cover and the flux of incident cosmic rays. The effect of natural variations in the cosmic ray flux is large, causing estimated changes in the Earth's energy radiation balance that are comparable to those attributed to greenhouse gases from the burning of fossil fuels since the Industrial Revolution. However a direct link between cosmic rays and cloud formation has not been unambiguously established. We therefore propose to experimentally measure cloud (water droplet) formation under controlled conditions in a test beam at CERN with a CLOUD chamber, duplicating the conditions prevailing in the troposphere. These data, which have never been previously obtained, will allow a detailed understanding of the possible effects of cosmic rays on clouds and confirm, or otherwise, a direct link between cosmic rays, global cloud cover and the Earth's climate. The measurements will, in turn, allow more reliable calculations to be made of the residual e...

  7. 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, mole