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Sample records for experiment twp-ice cloud

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

    SciTech Connect

    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.

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

    SciTech Connect

    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. The microphysical and radiative properties of tropical cirrus from the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE)

    NASA Astrophysics Data System (ADS)

    Um, Jun Shik

    During the 2006 Tropical Warm Pool International Cloud Experiment conducted in the region near Darwin, Australia, the Scaled Composites Proteus aircraft executed spiral profiles and flew horizontal legs through aging cirrus, fresh anvils, and cirrus of unknown origin. Data from 27 Jan., 29 Jan., and 2 Feb., when all the microphysical probes a Cloud and Aerosol Spectrometer (CAS), a Cloud Droplet Probe (CDP), a Cloud Imaging Probe (CIP), and a Cloud Particle Imager (CPI) were working, are used to investigate whether a single parameterization can be used to characterize tropical cirrus in terms of prognostic variables used in large-scale models, to calculate the single-scattering properties (scattering phase function P11 and asymmetry parameter g) of aggregates and small ice crystals that more closely match observed ice crystals, and to quantify the influences of small ice crystals on the bulk scattering properties of tropical cirrus. A combination of CDP (D < 50 mum), fits (50 < D < 125 microm), and CIP (D > 125 mum) distributions is used to represent ice crystal size distributions. The CDP measurements are used for small ice crystals because comparison between the CAS and CDP suggested the CAS was artificially amplifying small ice crystal concentrations by detecting remnants of shattered large ice crystals. Artifacts in CIP images are removed or corrected and then CIP measurements are used to represent large ice crystals. Because of the uncertainties in both the CPI and CIP for 50 < D < 125 mum, the incomplete gamma fitting method with the CDP (D < 50 mum) and CIP (D > 125 mum) measurements as input is used to characterize these distributions. A new quasi-automatic habit classification scheme is developed. For all days, small quasi-spheres dominated the contributions from all ice crystal sizes (D > 0 mum, by number) for all 3 days. The areal fraction (D > 200 mum) from bullet rosettes and their aggregates was 48% and 60% for 27 and 29 Jan., respectively, but only 7

  4. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    NASA Astrophysics Data System (ADS)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2015-12-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

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

    SciTech Connect

    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.

  6. A Single-column Model Ensemble Approach Applied to the TWP-ICE Experiment

    NASA Technical Reports Server (NTRS)

    Davies, L.; Jakob, C.; Cheung, K.; DelGenio, A.; Hill, A.; Hume, T.; Keane, R. J.; Komori, T.; Larson, V. E.; Lin, Y.; Liu, X.; Nielsen, B. J.; Petch, J.; Plant, R. S.; Singh, M. S.; Shi, X.; Song, X.; Wang, W.; Whithall, M. A.; Wolf, A.; Xie, S.; Zhang, G.

    2013-01-01

    Single-column models (SCM) are useful test beds for investigating the parameterization schemes of numerical weather prediction and climate models. The usefulness of SCM simulations are limited, however, by the accuracy of the best estimate large-scale observations prescribed. Errors estimating the observations will result in uncertainty in modeled simulations. One method to address the modeled uncertainty is to simulate an ensemble where the ensemble members span observational uncertainty. This study first derives an ensemble of large-scale data for the Tropical Warm Pool International Cloud Experiment (TWP-ICE) based on an estimate of a possible source of error in the best estimate product. These data are then used to carry out simulations with 11 SCM and two cloud-resolving models (CRM). Best estimate simulations are also performed. All models show that moisture-related variables are close to observations and there are limited differences between the best estimate and ensemble mean values. The models, however, show different sensitivities to changes in the forcing particularly when weakly forced. The ensemble simulations highlight important differences in the surface evaporation term of the moisture budget between the SCM and CRM. Differences are also apparent between the models in the ensemble mean vertical structure of cloud variables, while for each model, cloud properties are relatively insensitive to forcing. The ensemble is further used to investigate cloud variables and precipitation and identifies differences between CRM and SCM particularly for relationships involving ice. This study highlights the additional analysis that can be performed using ensemble simulations and hence enables a more complete model investigation compared to using the more traditional single best estimate simulation only.

  7. Improvements in Representations of Cloud Microphysics for BBHRP and Models using Data Collected during M-PACE and TWP-ICE

    SciTech Connect

    Greg M. McFarquhar

    2010-02-22

    In our research we proposed to use data collected during the 2004 Mixed-Phase Arctic Cloud Experiment (MPACE) and the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) to improve retrievals of ice and mixed-phase clouds, to improve our understanding of how cloud and radiative processes affect cloud life cycles, and to develop and test methods for using ARM data more effectively in model. In particular, we proposed to: 1) use MPACE in-situ data to determine how liquid water fraction and cloud ice and liquid effective radius (r{sub ei} and r{sub ew}) vary with temperature, normalized cloud altitude and other variables for Arctic mixed-phase clouds, and to use these data to evaluate the performance of model parameterization schemes and remote sensing retrieval algorithms; 2) calculate rei and size/shape distributions using TWP-ICE in-situ data, investigate their dependence on cirrus type (oceanic or continental anvils or cirrus not directly traced to convection), and develop and test representations for MICROBASE; 3) conduct fundamental research enhancing our understanding of cloud/radiative interactions, concentrating on effects of small crystals and particle shapes and sizes on radiation; and 4) improve representations of microphysical processes for models (fall-out, effective density, mean scattering properties, rei and rew) and provide them to ARM PIs. In the course of our research, we made substantial progress on all four goals.

  8. Evaluation of Cloud-Resolving Model Intercomparison Simulations Using TWP-ICE Observations: Precipitation and Cloud Structure

    SciTech Connect

    Varble, Adam C.; Fridlind, Ann; Zipser, Ed; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben

    2011-06-24

    The Tropical Warm Pool - International Cloud Experiment (TWP-ICE) provided high quality model forcing and observational datasets through which detailed model and observational intercomparisons could be performed. In this first of a two part study, precipitation and cloud structures within nine cloud-resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Most simulations slightly overestimate volumetric convective rainfall. Overestimation of simulated convective area by 50% or more in several simulations is somewhat offset by underestimation of mean convective rain rates. Stratiform volumetric rainfall is underestimated by 13% to 53% despite overestimation of stratiform area by up to 65% because stratiform rain rates in every simulation are much lower than observed. Although simulations match the peaked convective radar reflectivity distribution at low levels, they do not reproduce the peaked distributions observed above the melting level. Simulated radar reflectivity aloft in convective regions is too high in most simulations. 29 In stratiform regions, there is a large spread in model results with none resembling 30 observed distributions. Above the melting level, observed radar reflectivity decreases 31 more gradually with height than simulated radar reflectivity. A few simulations produce 32 unrealistically uniform and cold 10.8-μm infrared brightness temperatures, but several 33 simulations produce distributions close to observed. Assumed ice particle size 34 distributions appear to play a larger role than ice water contents in producing incorrect 35 simulated radar reflectivity distributions aloft despite substantial differences in mean 36 graupel and snow water contents across models. 37

  9. Evaluation of Cloud-Resolving Model Intercomparison Simulations Using TWP-ICE Observations: Precipitation and Cloud Structure

    SciTech Connect

    Varble, Adam; Fridlind, Ann; Zipser, Edward J.; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben

    2011-10-04

    The Tropical Warm Pool – International Cloud Experiment (TWP-ICE) provided high quality model forcing and observational datasets through which detailed model and observational intercomparisons could be performed. In this first of a two part study, precipitation and cloud structures within nine cloud-resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Most simulations slightly overestimate volumetric convective rainfall. Overestimation of simulated convective area by 50% or more in several simulations is somewhat offset by underestimation of mean convective rain rates. Stratiform volumetric rainfall is underestimated by 13% to 53% despite overestimation of stratiform area by up to 65% because stratiform rain rates in every simulation are much lower than observed. Although simulations match the peaked convective radar reflectivity distribution at low levels, they do not reproduce the peaked distributions observed above the melting level. Simulated radar reflectivity aloft in convective regions is too high in most simulations. In stratiform regions, there is a large spread in model results with none resembling observed distributions. Above the melting level, observed radar reflectivity decreases more gradually with height than simulated radar reflectivity. A few simulations produce unrealistically uniform and cold 10.8-μm infrared brightness temperatures, but several simulations produce distributions close to observed. Assumed ice particle size distributions appear to play a larger role than ice water contents in producing incorrect simulated radar reflectivity distributions aloft despite substantial differences in mean graupel and snow water contents across models.

  10. Evaluation of Cloud-Resolving Model Intercomparison Simulations Using TWP-ICE Observations: Precipitation and Cloud Structure

    NASA Technical Reports Server (NTRS)

    Varble, Adam; Fridlind, Ann M.; Zipser, Edward J.; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; McFarlane, Sally A.; Pinty, Jean-Pierre; Shipway, Ben

    2011-01-01

    The Tropical Warm Pool.International Cloud Experiment (TWP ]ICE) provided extensive observational data sets designed to initialize, force, and constrain atmospheric model simulations. In this first of a two ]part study, precipitation and cloud structures within nine cloud ]resolving model simulations are compared with scanning radar reflectivity and satellite infrared brightness temperature observations during an active monsoon period from 19 to 25 January 2006. Seven of nine simulations overestimate convective area by 20% or more leading to general overestimation of convective rainfall. This is balanced by underestimation of stratiform rainfall by 5% to 50% despite overestimation of stratiform area by up to 65% because of a preponderance of very low stratiform rain rates in all simulations. All simulations fail to reproduce observed radar reflectivity distributions above the melting level in convective regions and throughout the troposphere in stratiform regions. Observed precipitation ]sized ice reaches higher altitudes than simulated precipitation ]sized ice despite some simulations that predict lower than observed top ]of ]atmosphere infrared brightness temperatures. For the simulations that overestimate radar reflectivity aloft, graupel is the cause with one ]moment microphysics schemes whereas snow is the cause with two ]moment microphysics schemes. Differences in simulated radar reflectivity are more highly correlated with differences in mass mean melted diameter (Dm) than differences in ice water content. Dm is largely dependent on the mass ]dimension relationship and gamma size distribution parameters such as size intercept (N0) and shape parameter (m). Having variable density, variable N0, or m greater than zero produces radar reflectivities closest to those observed.

  11. A Comparison of TWP-ICE Observational Data with Cloud-Resolving Model Results

    SciTech Connect

    Fridlind, A. M.; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Grabowski, Wojciech W.; Hill, A.; Jones, T. R.; Khaiyer, M. M.; Liu, G.; Minnis, Patrick; Morrison, H.; Nguyen, L.; Park, S.; Petch, Jon C.; Pinty, Jean-Pierre; Schumacher, Courtney; Shipway, Ben; Varble, A. C.; Wu, Xiaoqing; Xie, Shaocheng; Zhang, Minghua

    2012-03-13

    Observations made during the TWP-ICE campaign are used to drive and evaluate thirteen cloud-resolving model simulations with periodic lateral boundary conditions. The simulations employ 2D and 3D dynamics, one- and two-moment microphysics, several variations on large-scale forcing, and the use of observationally derived aerosol properties to prognose droplet numbers. When domain means are averaged over a 6-day active monsoon period, all simulations reproduce observed surface precipitation rate but not its structural distribution. Simulated fractional areas covered by convective and stratiform rain are uncorrelated with one another, and are both variably overpredicted by up to a factor of {approx}2. Stratiform area fractions are strongly anticorrelated with outgoing longwave radiation (OLR) but are negligibly correlated with ice water path (IWP), indicating that ice spatial distribution controls OLR more than mean IWP. Overpredictions of OLR tend to be accompanied by underpredictions of reflected shortwave radiation (RSR). When there are two simulations differing only in microphysics scheme or large-scale forcing, the one with smaller stratiform area tends to exhibit greater OLR and lesser RSR by similar amounts. After {approx}10 days, simulations reach a suppressed monsoon period with a wide range of mean precipitable water vapor, attributable in part to varying overprediction of cloud-modulated radiative flux divergence compared with observationally derived values. Differences across the simulation ensemble arise from multiple sources, including dynamics, microphysics, and radiation treatments. Close agreement of spatial and temporal averages with observations may not be expected, but the wide spreads of predicted stratiform fraction and anticorrelated OLR indicate a need for more rigorous observation-based evaluation of the underlying micro- and macrophysical properties of convective and stratiform structures.

  12. Evaluation of cloud-resolving and limited area model intercomparison simulations using TWP-ICE observations: 2. Precipitation microphysics

    NASA Astrophysics Data System (ADS)

    Varble, Adam; Zipser, Edward J.; Fridlind, Ann M.; Zhu, Ping; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher

    2014-12-01

    Ten 3-D cloud-resolving model (CRM) simulations and four 3-D limited area model (LAM) simulations of an intense mesoscale convective system observed on 23-24 January 2006 during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, colocated UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rainwater contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (μ) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes but lower RWCs. Two-moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and, thus, may have issues balancing raindrop formation, collision-coalescence, and raindrop breakup. Assuming a μ of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing μ to have values greater than 0 may improve excessive size sorting in two-moment schemes. Underpredicted stratiform rain rates are associated with underpredicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. A limited domain size also prevents a large, well-developed stratiform region like the one observed from developing in CRMs, although LAMs also fail to produce such a region.

  13. Evaluation of Cloud-resolving and Limited Area Model Intercomparison Simulations using TWP-ICE Observations. Part 2: Rain Microphysics

    SciTech Connect

    Varble, Adam; Zipser, Edward J.; Fridlind, Ann; Zhu, Ping; Ackerman, Andrew; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher R.

    2014-12-27

    Ten 3D cloud-resolving model (CRM) simulations and four 3D limited area model (LAM) simulations of an intense mesoscale convective system observed on January 23-24, 2006 during the Tropical Warm Pool – International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, co-located UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain published results showing a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rain water contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (μ) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes, but lower RWCs than observed. Two moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and thus, may have issues balancing raindrop formation, collision coalescence, and raindrop breakup. Assuming a μ of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing μ to have values greater than 0 may improve two-moment schemes. Under-predicted stratiform rain rates are associated with under-predicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. In addition to stronger convective updrafts than observed, limited domain size prevents a large, well-developed stratiform region from developing in CRMs, while a dry bias in ECMWF analyses does the same to the LAMs.

  14. Evaluation of Cloud-Resolving and Limited Area Model Intercomparison Simulations Using TWP-ICE Observations. Part 2 ; Precipitation Microphysics

    NASA Technical Reports Server (NTRS)

    Varble, Adam; Zipser, Edward J.; Fridland, Ann M.; Zhu, Ping; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher

    2014-01-01

    Ten 3-D cloud-resolving model (CRM) simulations and four 3-D limited area model (LAM) simulations of an intense mesoscale convective system observed on 23-24 January 2006 during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, colocated UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rainwater contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (mu) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes but lower RWCs. Two-moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and, thus, may have issues balancing raindrop formation, collision-coalescence, and raindrop breakup. Assuming a mu of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing mu to have values greater than 0 may improve excessive size sorting in two-moment schemes. Underpredicted stratiform rain rates are associated with underpredicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. A limited domain size also prevents a large, well-developed stratiform region like the one observed from developing in CRMs, although LAMs also fail to produce such a region.

  15. Final Report for "Improved Representations of Cloud Microphysics for Model and Remote Sensing Evaluation using Data Collected during ISDAC, TWP-ICE and RACORO

    SciTech Connect

    McFarquhar, Greg M.

    2003-06-11

    We were funded by ASR to use data collected during ISDAC and TWP-ICE to evaluate models with a variety of temporal and spatial scales, to evaluate ground-based remote sensing retrievals and to develop cloud parameterizations with the end goal of improving the modeling of cloud processes and properties and their impact on atmospheric radiation. In particular, we proposed to: 1) Calculate distributions of microphysical properties observed in arctic stratus during ISDAC for initializing and evaluating LES and GCMs, and for developing parameterizations of effective particle sizes, mean fall velocities, and mean single-scattering properties for such models; 2) Improve representations of particle sizes, fall velocities and scattering properties for tropical and arctic cirrus using TWP-ICE, ISDAC and M-PACE data, and to determine the contributions that small ice crystals, with maximum dimensions D less than 50 μm, make to mass and radiative properties; 3) Study fundamental interactions between clouds and radiation by improving representations of small quasi-spherical particles and their scattering properties. We were additionally funded 1-year by ASR to use RACORO data to develop an integrated product of cloud microphysical properties. We accomplished all of our goals.

  16. ARM/GCSS/SPARC TWP-ICE CRM Intercomparison Study

    NASA Technical Reports Server (NTRS)

    Fridlind, Ann; Ackerman, Andrew; Petch, Jon; Field, Paul; Hill, Adrian; McFarquhar, Greg; Xie, Shaocheng; Zhang, Minghua

    2010-01-01

    Specifications are provided for running a cloud-resolving model (CRM) and submitting results in a standardized format for inclusion in a n intercomparison study and archiving for public access. The simulated case study is based on measurements obtained during the 2006 Tropical Warm Pool - International Cloud Experiment (TWP-ICE) led by the U. S. department of Energy Atmospheric Radiation Measurement (ARM) program. The modeling intercomparison study is based on objectives developed in concert with the Stratospheric Processes And their Role in Climate (SPARC) program and the GEWEX cloud system study (GCSS) program. The Global Energy and Water Cycle Experiment (GEWEX) is a core project of the World Climate Research PRogramme (WCRP).

  17. Evaluation of cloud-resolving and limited area model intercomparison simulations using TWP-ICE observations: 1. Deep convective updraft properties

    NASA Astrophysics Data System (ADS)

    Varble, Adam; Zipser, Edward J.; Fridlind, Ann M.; Zhu, Ping; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Collis, Scott; Fan, Jiwen; Hill, Adrian; Shipway, Ben

    2014-12-01

    Ten 3-D cloud-resolving model simulations and four 3-D limited area model simulations of an intense mesoscale convective system observed on 23-24 January 2006 during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) are compared with each other and with observed radar reflectivity fields and dual-Doppler retrievals of vertical wind speeds in an attempt to explain published results showing a high bias in simulated convective radar reflectivity aloft. This high-bias results from ice water content being large, which is a product of large, strong convective updrafts, although hydrometeor size distribution assumptions modulate the size of this bias. Making snow mass more realistically proportional to D2 rather than D3 eliminates unrealistically large snow reflectivities over 40 dBZ in some simulations. Graupel, unlike snow, produces high biased reflectivity in all simulations, which is partly a result of parameterized microphysics but also partly a result of overly intense simulated updrafts. Peak vertical velocities in deep convective updrafts are greater than dual-Doppler-retrieved values, especially in the upper troposphere. Freezing of liquid condensate, often rain, lofted above the freezing level in simulated updraft cores greatly contributes to these excessive upper tropospheric vertical velocities. The strongest simulated updraft cores are nearly undiluted, with some of the strongest showing supercell characteristics during the multicellular (presquall) stage of the event. Decreasing horizontal grid spacing from 900 to 100 m slightly weakens deep updraft vertical velocity and moderately decreases the amount of condensate aloft but not enough to match observational retrievals. Therefore, overly intense simulated updrafts may additionally be a product of unrealistic interactions between convective dynamics, parameterized microphysics, and large-scale model forcing that promote different convective strengths than observed.

  18. Evaluation of Cloud-resolving and Limited Area Model Intercomparison Simulations using TWP-ICE Observations. Part 1: Deep Convective Updraft Properties

    SciTech Connect

    Varble, A. C.; Zipser, Edward J.; Fridlind, Ann; Zhu, Ping; Ackerman, Andrew; Chaboureau, Jean-Pierre; Collis, Scott M.; Fan, Jiwen; Hill, Adrian; Shipway, Ben

    2014-12-27

    Ten 3D cloud-resolving model (CRM) simulations and four 3D limited area model (LAM) simulations of an intense mesoscale convective system observed on January 23-24, 2006 during the Tropical Warm Pool – International Cloud Experiment (TWP-ICE) are compared with each other and with observed radar reflectivity fields and dual-Doppler retrievals of vertical wind speeds in an attempt to explain published results showing a high bias in simulated convective radar reflectivity aloft. This high bias results from ice water content being large, which is a product of large, strong convective updrafts, although hydrometeor size distribution assumptions modulate the size of this bias. Snow reflectivity can exceed 40 dBZ in a two-moment scheme when a constant bulk density of 100 kg m-3 is used. Making snow mass more realistically proportional to area rather than volume should somewhat alleviate this problem. Graupel, unlike snow, produces high biased reflectivity in all simulations. This is associated with large amounts of liquid water above the freezing level in updraft cores. Peak vertical velocities in deep convective updrafts are greater than dual-Doppler retrieved values, especially in the upper troposphere. Freezing of large rainwater contents lofted above the freezing level in simulated updraft cores greatly contributes to these excessive upper tropospheric vertical velocities. Strong simulated updraft cores are nearly undiluted, with some showing supercell characteristics. Decreasing horizontal grid spacing from 900 meters to 100 meters weakens strong updrafts, but not enough to match observational retrievals. Therefore, overly intense simulated updrafts may partly be a product of interactions between convective dynamics, parameterized microphysics, and large-scale environmental biases that promote different convective modes and strengths than observed.

  19. Analysis of Cloud-resolving Simulations of a Tropical Mesoscale Convective System Observed during TWP-ICE: Vertical Fluxes and Draft Properties in Convective and Stratiform Regions

    SciTech Connect

    Mrowiec, Agnieszka A.; Rio, Catherine; Fridlind, Ann; Ackerman, Andrew; Del Genio, Anthony D.; Pauluis, Olivier; Varble, Adam; Fan, Jiwen

    2012-10-02

    We analyze three cloud-resolving model simulations of a strong convective event observed during the TWP-ICE campaign, differing in dynamical core, microphysical scheme or both. Based on simulated and observed radar reflectivity, simulations roughly reproduce observed convective and stratiform precipitating areas. To identify the characteristics of convective and stratiform drafts that are difficult to observe but relevant to climate model parameterization, independent vertical wind speed thresholds are calculated to capture 90% of total convective and stratiform updraft and downdraft mass fluxes. Convective updrafts are fairly consistent across simulations (likely owing to fixed large-scale forcings and surface conditions), except that hydrometeor loadings differ substantially. Convective downdraft and stratiform updraft and downdraft mass fluxes vary notably below the melting level, but share similar vertically uniform draft velocities despite differing hydrometeor loadings. All identified convective and stratiform downdrafts contain precipitation below ~10 km and nearly all updrafts are cloudy above the melting level. Cold pool properties diverge substantially in a manner that is consistent with convective downdraft mass flux differences below the melting level. Despite differences in hydrometeor loadings and cold pool properties, convective updraft and downdraft mass fluxes are linearly correlated with convective area, the ratio of ice in downdrafts to that in updrafts is ~0.5 independent of species, and the ratio of downdraft to updraft mass flux is ~0.5-0.6, which may represent a minimum evaporation efficiency under moist conditions. Hydrometeor loading in stratiform regions is found to be a fraction of hydrometeor loading in convective regions that ranges from ~10% (graupel) to ~90% (cloud ice). These findings may lead to improved convection parameterizations.

  20. Joint ARM/GCSS/SPARC TWP-ICE CRM Intercomparison Study: Description, Preliminary Results, and Invitation to Participate

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Ackerman, A. S.; Allen, G.; Beringer, J.; Comstock, J. M.; Field, P. R.; Gallagher, M.; Hacker, J. M.; Hume, T.; Jakob, C.; Liu, G.; Long, C. N.; Mather, J. H.; May, P. T.; McCoy, R. F.; McFarlane, S. A.; McFarquhar, G. M.; Minnis, P.; Petch, J. C.; Schumacher, C.; Turner, D. D.; Whiteway, J. A.; Williams, C. R.; Williams, P. I.; Xie, S.; Zhang, M.

    2008-12-01

    The 2006 Tropical Warm Pool - International Cloud Experiment (TWP-ICE) is 'the first field program in the tropics that attempted to describe the evolution of tropical convection, including the large-scale heat, moisture, and momentum budgets at 3-hourly time resolution, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment' [May et al., 2008]. A cloud- resolving model (CRM) intercomparison based on TWP-ICE is now being undertaken by the Atmospheric Radiation Measurement (ARM), GEWEX Cloud Systems Study (GCSS), and Stratospheric Processes And their Role in Climate (SPARC) programs. We summarize the 16-day case study and the wealth of data being used to provide initial and boundary conditions, and evaluate some preliminary findings in the context of existing theories of moisture evolution in the tropical tropopause layer (TTL). Overall, simulated cloud fields evolve realistically by many measures. Budgets indicate that simulated convective flux convergence of water vapor is always positive or near zero at TTL elevations, except locally at lower levels during the driest suppressed monsoon conditions, while simulated water vapor deposition to hydrometeors always exceeds sublimation on average at all TTL elevations over 24-hour timescales. The next largest water vapor budget term is generally the nudging required to keep domain averages consistent with observations, which is at least partly attributable to large-scale forcing terms that cannot be derived from measurements. We discuss the primary uncertainties.

  1. Evaluating Deep Updraft Formulation in NCAR CAM3 with High-Resolution WRF Simulations During ARM TWP-ICE

    SciTech Connect

    Wang, Weiguo; Liu, Xiaohong

    2009-02-19

    The updraft formulation used in NCAR CAM3 deep convection parameterization assumes that the fractional entrainment rate for a single updraft is height-independent and the updraft mass flux increases monotonically with height to updraft top. These assumptions are evaluated against three-dimensional high-resolution simulations from the weather research and forecast (WRF) model during the monsoon period of the DOE ARM Tropical Warm Pool -- International Cloud Experiment (TWP-ICE). Analyses of the WRF-generated updrafts suggest that the fractional entrainment rate for a single updraft decreases with height and the updraft mass flux increases with height below the top of the conditionally unstable layer but decreases above. It is suggested that the assumed updraft mass flux profile in CAM3 might be unrealistic in many cases because the updraft acceleration is affected by other drag processes in addition to entrainment. Total convective cloud mass flux and detrainment rate over the TWP-ICE domain diagnosed from the CAM3 parameterization driven by WRF meteorological fields are smaller than those derived from WRF simulations. The total entrainment rate of CAM3 is smaller than that of WRF in the lower part of cloud and larger in the upper part of cloud. Compared with WRF simulations, the CAM3-parameterized convection is too active and, as a result, excess moisture and heat may be transported to the upper troposphere by the parameterized convection. Future improvement is envisioned.

  2. Microphysical characteristics of aging anvils and cirrus sampled during TWP- ICE

    NASA Astrophysics Data System (ADS)

    McFarquhar, G.; Freer, M.; Um, J.; Mace, G.; Kok, G.; McCoy, R.; Tooman, T.

    2006-12-01

    Observations of anvils at various stages in their life cycle and in generic cirrus were made during the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) using the Atmospheric Radiation Measurement Program's Uninhabited Aerospace Vehicle's (ARM UAV) payload of in-situ cloud microphysics probes on the Scaled Composites Proteus. The probes, including the Cloud and Aerosol Precipitation Spectrometer (CAPS), the Cloud Droplet Probe (CDP), the Cloud Particle Imager (CPI), the Cloud Spectrometer and Impactor Probe (CSI) and the Cloud Integrating Nephelometer (CIN), give number concentrations as a function of size, bulk parameters such as total water content and extinction, and information on ice crystal habits. Bulk measurements of total water content are also derived from co-located remote sensing measurements which are compared against the in-situ mass contents. In this presentation, data from the composite of probes are examined in an effort to determine the importance of ice crystals with maximum dimensions less than 100 micrometers to the total number, extinction and mass of the cirrus with varying ages. The variation of dominant ice crystal habit, median mass diameter and other bulk microphysical quantities with cirrus age and origin are also investigated. Implications of these results for cloud modeling studies are discussed.

  3. Experiment to Characterize Tropical Cloud Systems

    SciTech Connect

    May, Peter T.; Mather, Jim H.; Jakob, Christian

    2005-08-02

    A major experiment to study tropical convective cloud systems and their impacts will take place around Darwin, Northern Australia in early 2006. The Tropical Warm Pool International Cloud Experiment (TWP-ICE) is a collaboration including the DOE ARM (Atmospheric Radiation Measurement) and ARM-UAV programs, NASA centers, the Australian Bureau of Meteorology, CSIRO, and universities in the USA, Australia, Japan, the UK, and Canada. TWP-ICE will be preceded in November/December 2004 by a collaborating European aircraft campaign involving the EU SCOUT-O3 and UK NERC ACTIVE projects. Detailed atmospheric measurements will be made in the Darwin area through the whole Austral summer, giving unprecedented coverage through the pre-monsoon and monsoon periods.

  4. TWP-ICE Global Atmospheric Model Intercomparison: Convection Responsiveness and Resolution Impact

    SciTech Connect

    Lin, Yanluan; Donner, Leo J.; Petch, Jon C.; Bechtold, P.; Boyle, James; Klein, Stephen A.; Komori, T.; Wapler, K.; Willett, M.; Xie, X.; Zhao, M.; Xie, Shaocheng; McFarlane, Sally A.; Schumacher, Courtney

    2012-05-08

    Results are presented from an intercomparison of global atmospheric model (GAM) simulations of tropical convection during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). The distinct cloud properties, precipitation, radiation, and vertical diabatic heating profiles associated with three different monsoon regimes (wet, dry, and break) from available observations are used to evaluate 9 GAM forecasts initialized daily from realistic global analyses. All models well captured the evolution of large-scale circulation and the thermodynamic fields, but cloud properties differed substantially among models. For example, liquid water path and ice water path differed by up to two orders of magnitude. Compared with the relatively well simulated top-heavy heating structures during the wet and break period, most models had difficulty in depicting the bottom-heavy heating profiles associated with cumulus congestus. The best performing models during this period were the ones whose convection scheme was most responsive to the free tropospheric humidity. Compared with the large impact of cloud and convective parameterizations on model cloud and precipitation characteristics, resolution has relatively minor impact on simulated cloud properties. However, one feature that was influence by the resolution study in several models was the diurnal cycle of precipitation. Peaking at a different time from convective precipitation, large-scale precipitation generally increases in high resolution forecasts and modulates the total precipitation diurnal cycle. Overall, the study emphasizes the importance of more environmental responsive convective parameterizations to capture various types of convection and the substantial diversity among large-scale cloud and precipitation schemes in current GAMs. This experiment has also demonstrated itself to be a very useful testbed for those developing cloud and convection schemes in these models.

  5. Observed large-scale structures and diabatic heating and drying profiles during TWP-ICE

    SciTech Connect

    Xie, Shaocheng; Hume, Timothy; Jakob, Christian; Klein, Stephen A.; McCoy, Renata B.; Zhang, Minghua

    2010-01-01

    This study documents the characteristics of the large-scale structures and diabatic heating and drying profiles observed during the Tropical Warm Pool–International Cloud Experiment (TWP-ICE), which was conducted in January–February 2006 in Darwin during the northern Australian monsoon season. The examined profiles exhibit significant variations between four distinct synoptic regimes that were observed during the experiment. The active monsoon period is characterized by strong upward motion and large advective cooling and moistening throughout the entire troposphere, while the suppressed and clear periods are dominated by moderate midlevel subsidence and significant low- to midlevel drying through horizontal advection. The midlevel subsidence and horizontal dry advection are largely responsible for the dry midtroposphere observed during the suppressed period and limit the growth of clouds to low levels. During the break period, upward motion and advective cooling and moistening located primarily at midlevels dominate together with weak advective warming and drying (mainly from horizontal advection) at low levels. The variations of the diabatic heating and drying profiles with the different regimes are closely associated with differences in the large-scale structures, cloud types, and rainfall rates between the regimes. Strong diabatic heating and drying are seen throughout the troposphere during the active monsoon period while they are moderate and only occur above 700 hPa during the break period. The diabatic heating and drying tend to have their maxima at low levels during the suppressed periods. Furthermore, the diurnal variations of these structures between monsoon systems, continental/coastal, and tropical inland-initiated convective systems are also examined.

  6. Observed large-scale structures and diabatic heating and drying profiles during TWP-ICE

    DOE PAGESBeta

    Xie, Shaocheng; Hume, Timothy; Jakob, Christian; Klein, Stephen A.; McCoy, Renata B.; Zhang, Minghua

    2010-01-01

    This study documents the characteristics of the large-scale structures and diabatic heating and drying profiles observed during the Tropical Warm Pool–International Cloud Experiment (TWP-ICE), which was conducted in January–February 2006 in Darwin during the northern Australian monsoon season. The examined profiles exhibit significant variations between four distinct synoptic regimes that were observed during the experiment. The active monsoon period is characterized by strong upward motion and large advective cooling and moistening throughout the entire troposphere, while the suppressed and clear periods are dominated by moderate midlevel subsidence and significant low- to midlevel drying through horizontal advection. The midlevel subsidence andmore » horizontal dry advection are largely responsible for the dry midtroposphere observed during the suppressed period and limit the growth of clouds to low levels. During the break period, upward motion and advective cooling and moistening located primarily at midlevels dominate together with weak advective warming and drying (mainly from horizontal advection) at low levels. The variations of the diabatic heating and drying profiles with the different regimes are closely associated with differences in the large-scale structures, cloud types, and rainfall rates between the regimes. Strong diabatic heating and drying are seen throughout the troposphere during the active monsoon period while they are moderate and only occur above 700 hPa during the break period. The diabatic heating and drying tend to have their maxima at low levels during the suppressed periods. Furthermore, the diurnal variations of these structures between monsoon systems, continental/coastal, and tropical inland-initiated convective systems are also examined.« less

  7. Validation of Model Simulations of Anvil Cirrus Properties During TWP-ICE: Final Report

    SciTech Connect

    Zipser, Edward J.

    2013-05-20

    This 3-year grant, with two extensions, resulted in a successful 5-year effort, led by Ph.D. student Adam Varble, to compare cloud resolving model (CRM) simulations with the excellent database obtained during the TWP-ICE field campaign. The objective, largely achieved, is to undertake these comparisons comprehensively and quantitatively, informing the community in ways that goes beyond pointing out errors in the models, but points out ways to improve both cloud dynamics and microphysics parameterizations in future modeling efforts. Under DOE support, Adam Varble, with considerable assistance from Dr. Ann Fridlind and others, entrained scientists who ran some 10 different CRMs and 4 different limited area models (LAMs) using a variety of microphysics parameterizations, to ensure that the conclusions of the study will have considerable generality.

  8. Evaluation of Intercomparisons of Four Different Types of Model Simulating TWP-ICE

    NASA Technical Reports Server (NTRS)

    Petch, Jon; Hill, Adrian; Davies, Laura; Fridlind, Ann; Jakob, Christian; Lin, Yanluan; Xie, Shaoecheng; Zhu, Ping

    2013-01-01

    Four model intercomparisons were run and evaluated using the TWP-ICE field campaign, each involving different types of atmospheric model. Here we highlight what can be learnt from having single-column model (SCM), cloud-resolving model (CRM), global atmosphere model (GAM) and limited-area model (LAM) intercomparisons all based around the same field campaign. We also make recommendations for anyone planning further large multi-model intercomparisons to ensure they are of maximum value to the model development community. CRMs tended to match observations better than other model types, although there were exceptions such as outgoing long-wave radiation. All SCMs grew large temperature and moisture biases and performed worse than other model types for many diagnostics. The GAMs produced a delayed and significantly reduced peak in domain-average rain rate when compared to the observations. While it was shown that this was in part due to the analysis used to drive these models, the LAMs were also driven by this analysis and did not have the problem to the same extent. Based on differences between the models with parametrized convection (SCMs and GAMs) and those without (CRMs and LAMs), we speculate that that having explicit convection helps to constrain liquid water whereas the ice contents are controlled more by the representation of the microphysics.

  9. The Tropical Warm Pool International Cloud Experiment

    SciTech Connect

    May, Peter T.; Mather, James H.; Vaughan, Geraint; Jakob, Christian; McFarquhar, Greg; Bower, Keith; Mace, Gerald G.

    2008-05-01

    One of the most complete data sets describing tropical convection ever collected will result from the upcoming Tropical Warm Pool International Cloud Experiment (TWP-ICE) in the area around Darwin, Northern Australia in January and February 2006. The aims of the experiment, which will be operated in conjunction with the DOE Atmospheric Radiation Measurement (ARM) site in Darwin, will be to examine convective cloud systems from their initial stages through to the decay of the cirrus generated and to measure their impact on the environment. The experiment will include an unprecedented network of ground-based observations (soundings, active and passive remote sensors) combined with low, mid and high altitude aircraft for in-situ and remote sensing measurements. A crucial outcome of the experiment will be a data set suitable to provide the forcing and evaluation data required by cloud resolving and single column models as well as global climate models (GCMs) with the aim to contribute to parameterization development. This data set will provide the necessary link between the observed cloud properties and the models that are attempting to simulate them. The experiment is a large multi-agency experiment including substantial contributions from the United States DOE ARM program, ARM-UAV program, NASA, the Australian Bureau of Meteorology, CSIRO, EU programs and many universities.

  10. Ground-based observations of overshooting convection during the Tropical Warm Pool-International Cloud Experiment

    NASA Astrophysics Data System (ADS)

    Hassim, M. E. E.; Lane, T. P.; May, P. T.

    2014-01-01

    This study uses gridded radar data to investigate the properties of deep convective storms that penetrate the tropical tropopause layer (TTL) and overshoot the cold-point tropopause during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). Overshooting convection during the observed break period is relatively more intense and exhibits lesser diurnal variability than severe monsoonal storms in terms of mean overshooting area in the TTL (as covered by >20 dBZ echoes). However, ground-based radar has geometrical constraints and sampling gaps at high altitude that lead to biases in the final radar product. Using synthetic observations derived from model-based data, ground-based radar is shown to underestimate the mean overshooting area in the TTL across both TWP-ICE regimes. Differences range from ˜180 km2 (˜100 km2) to ˜14 km2 (˜8 km2) between 14 and 18 km for the active (break) period. This implies that the radar is underestimating the transport of water and ice mass into the TTL by convective overshoots during TWP-ICE. The synthetic data is also used to correct profiles of the mean observed overshooting area. These are shown to differ only marginally between the two sampled regimes once the influence of a large mesoscale convective system, considered as a departure from normal monsoon behavior, was removed from the statistics. The results of our study provide a useful cross-validation comparison for satellite-based detections of overshooting top areas over Darwin, Australia.

  11. Development and Evaluation of a Simple Algorithm to Find Cloud Optical Depth with Emphasis on Thin Ice Clouds

    SciTech Connect

    Barnard, James C.; Long, Charles N.; Kassianov, Evgueni I.; McFarlane, Sally A.; Comstock, Jennifer M.; Freer, Matthew; McFarquhar, Greg

    2008-04-14

    We present here an algorithm for determining cloud optical depth, τ, using data from shortwave broadband irradiances, focusing on the case of optically thin clouds. This method is empirical and consists of applying a one-line equation to the shortwave flux analysis described by Long and Ackerman (2000). We apply this method to cirrus clouds observed at the Atmospheric Radiation Measurement Program’s (ARM) Darwin, Australia site during the Tropical Warm Pool International Cloud Experiment (TWP-ICE) campaign and cirrus clouds observed at ARM’s Southern Great Plains (SGP) site. These cases were chosen because independent verification of cloud optical depth retrievals is possible. For the TWP-ICE case, the calculated optical depths compare favorably (to within about 1 unit) with a “first principles” τ calculated from a vertical profile of ice particle size distributions obtained from an aircraft sounding. For the SGP case, the results from the algorithm correspond reasonably well with τ values obtained from an average over other methods; some of which have been subject to independent verification. The medians of the two time series are 0.79 and 0.81, for the empirical and averaged values, respectively (although such close agreement is likely to be fortuitous). This tool may be applied wherever measurements of the three components of the shortwave broadband flux are available at 1- to 5-minute resolution. Because these measurements are made across the world, it then becomes possible to estimate optical depth at many locations.

  12. Characteristics of Mesoscale Organization in WRF Simulations of Convection during TWP-ICE

    NASA Technical Reports Server (NTRS)

    Del Genio, Anthony D.; Wu, Jingbo; Chen, Yonghua

    2013-01-01

    Compared to satellite-derived heating profiles, the Goddard Institute for Space Studies general circulation model (GCM) convective heating is too deep and its stratiform upper-level heating is too weak. This deficiency highlights the need for GCMs to parameterize the mesoscale organization of convection. Cloud-resolving model simulations of convection near Darwin, Australia, in weak wind shear environments of different humidities are used to characterize mesoscale organization processes and to provide parameterization guidance. Downdraft cold pools appear to stimulate further deep convection both through their effect on eddy size and vertical velocity. Anomalously humid air surrounds updrafts, reducing the efficacy of entrainment. Recovery of cold pool properties to ambient conditions over 5-6 h proceeds differently over land and ocean. Over ocean increased surface fluxes restore the cold pool to prestorm conditions. Over land surface fluxes are suppressed in the cold pool region; temperature decreases and humidity increases, and both then remain nearly constant, while the undisturbed environment cools diurnally. The upper-troposphere stratiform rain region area lags convection by 5-6 h under humid active monsoon conditions but by only 1-2 h during drier break periods, suggesting that mesoscale organization is more readily sustained in a humid environment. Stratiform region hydrometeor mixing ratio lags convection by 0-2 h, suggesting that it is strongly influenced by detrainment from convective updrafts. Small stratiform region temperature anomalies suggest that a mesoscale updraft parameterization initialized with properties of buoyant detrained air and evolving to a balance between diabatic heating and adiabatic cooling might be a plausible approach for GCMs.

  13. FIRE Arctic Clouds Experiment

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  14. Study of Multi-Scale Cloud Processes Over the Tropical Western Pacific Using Cloud-Resolving Models Constrained by Satellite Data

    SciTech Connect

    Dudhia, Jimy

    2013-03-12

    TWP-ICE using satellite and ground-based observations. -- Perform numerical experiments using WRF to investigate how convection over tropical islands in the Maritime Continent interacts with large-scale circulation and affects convection in nearby regions. -- Evaluate and apply WRF as a testbed for GCM cloud parameterizations, utilizing the ability of WRF to run on multiple scales (from cloud resolving to global) to isolate resolution and physics issues from dynamical and model framework issues. Key products will be disseminated to the ARM and larger community through distribution of data archives, including model outputs from the data assimilation products and cloud resolving simulations, and publications.

  15. Microphysics Parameterization in Convection and its Effects on Cloud Simulation in the NCAR CAM5

    NASA Astrophysics Data System (ADS)

    Zhang, G. J.; Song, X.

    2010-12-01

    Microphysical processes in convection are important to convection-cloud-climate interactions and atmospheric hydrological cycle. They are also essential to understanding aerosol-cloud interaction. However, their parameterization in GCMs is crude. As part of an effort to improve the convection parameterization scheme for the NCAR CAM using observations, we incorporate a cloud microphysics parameterization into the Zhang-McFarlane convection scheme. The scheme is then evaluated against observations of cloud ice and water from the TWP-ICE experiment and other sources using the NCAR SCAM. It is found that this physically-based treatment of convective microphysics yields more realistic vertical profiles of convective cloud ice and liquid water contents. Cloud water and ice budgets are calculated to estimate the role of cloud water and ice detrainment from convection as water and ice sources for large-scale clouds. The new microphysics treatment is further implemented into CAM5 to test its effect on GCM simulations of clouds. Results will be presented at the meeting, and the implications on the simulation of hydrological cycle will be discussed.

  16. Cloud/climate sensitivity experiments

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    SciTech Connect

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

    2012-08-01

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

  18. Determining Best Estimates and Uncertainties in Cloud Microphysical Parameters from ARM Field Data: Implications for Models, Retrieval Schemes and Aerosol-Cloud-Radiation Interactions

    SciTech Connect

    McFarquhar, Greg

    2015-12-28

    We proposed to analyze in-situ cloud data collected during ARM/ASR field campaigns to create databases of cloud microphysical properties and their uncertainties as needed for the development of improved cloud parameterizations for models and remote sensing retrievals, and for evaluation of model simulations and retrievals. In particular, we proposed to analyze data collected over the Southern Great Plains (SGP) during the Mid-latitude Continental Convective Clouds Experiment (MC3E), the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX), the Small Particles in Cirrus (SPARTICUS) Experiment and the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign, over the North Slope of Alaska during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) and the Mixed-Phase Arctic Cloud Experiment (M-PACE), and over the Tropical Western Pacific (TWP) during The Tropical Warm Pool International Cloud Experiment (TWP-ICE), to meet the following 3 objectives; derive statistical databases of single ice particle properties (aspect ratio AR, dominant habit, mass, projected area) and distributions of ice crystals (size distributions SDs, mass-dimension m-D, area-dimension A-D relations, mass-weighted fall speeds, single-scattering properties, total concentrations N, ice mass contents IWC), complete with uncertainty estimates; assess processes by which aerosols modulate cloud properties in arctic stratus and mid-latitude cumuli, and quantify aerosol’s influence in context of varying meteorological and surface conditions; and determine how ice cloud microphysical, single-scattering and fall-out properties and contributions of small ice crystals to such properties vary according to location, environment, surface, meteorological and aerosol conditions, and develop parameterizations of such effects.In this report we describe the accomplishments that we made on all 3 research objectives.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. The Role of Gravity Waves in the Formation and Organization of Clouds during TWPICE

    SciTech Connect

    Reeder, Michael J.; Lane, Todd P.; Hankinson, Mai Chi Nguyen

    2013-09-27

    All convective clouds emit gravity waves. While it is certain that convectively-generated waves play important parts in determining the climate, their precise roles remain uncertain and their effects are not (generally) represented in climate models. The work described here focuses mostly on observations and modeling of convectively-generated gravity waves, using the intensive observations from the DoE-sponsored Tropical Warm Pool International Cloud Experiment (TWP-ICE), which took place in Darwin, from 17 January to 13 February 2006. Among other things, the research has implications the part played by convectively-generated gravity waves in the formation of cirrus, in the initiation and organization of further convection, and in the subgrid-scale momentum transport and associated large-scale stresses imposed on the troposphere and stratosphere. The analysis shows two groups of inertia-gravity waves are detected: group L in the middle stratosphere during the suppressed monsoon period, and group S in the lower stratosphere during the monsoon break period. Waves belonging to group L propagate to the south-east with a mean intrinsic period of 35 h, and have vertical and horizontal wavelengths of about 5-6 km and 3000-6000 km, respectively. Ray tracing calculations indicate that these waves originate from a deep convective region near Indonesia. Waves belonging to group S propagate to the south-south-east with an intrinsic period, vertical wavelength and horizontal wavelength of about 45 h, 2 km and 2000-4000 km, respectively. These waves are shown to be associated with shallow convection in the oceanic area within about 1000 km of Darwin. The intrinsic periods of high-frequency waves are estimated to be between 20-40 minutes. The high-frequency wave activity in the stratosphere, defined by mass-weighted variance of the vertical motion of the sonde, has a maximum following the afternoon local convection indicating that these waves are generated by local convection

  1. Evaluation of microphysics and precipitation-type frequencies in long-term three-dimensional cloud-resolving model simulations using passive and active microwave sensors from the TRMM satellite

    NASA Astrophysics Data System (ADS)

    Matsui, T.; Zeng, X.; Tao, W.; Lang, S.; Zhang, M.; Masunaga, H.

    2007-12-01

    With significant improvements in computational power over the last decades, cloud-resolving model (CRM) simulations can now be conducted on larger scales for longer time periods to better understand cloud- precipitation systems. However, even after the decadal development of CRMs, there are many uncertainties in cloud microphysics processes and cloud-precipitation structures due to the lack of routine observations. Therefore, we need to establish a practical CRM evaluation framework using frequent observations from satellites. This evaluation framework consists of i) multi-satellite simulators and ii) the construction of statistical composites that can be used to effectively evaluate cloud-precipitation systems. First, simulated cloud- precipitation structures and microphysics processes are converted to satellite-consistent radar reflectivity and microwave brightness temperature using microwave and radar simulators in the Satellite Data Simulator Unit (SDSU). Second, the CRM-computed and satellite-observed radar reflectivities and microwave brightness temperatures are used to construct two statistical composites. One combines TRMM (Tropical Rainfall Measuring Mission) PR (precipitation radar) 13.8-GHz radar echo-top heights and TRMM VIRS (visible/infrared scanner) 10.8-micron brightness temperatures. This composite categorizes precipitating clouds into shallow warm, cumulus congestus, deep stratiform, and deep convective clouds. The other composite combines multi- frequency TMI (TRMM microwave imager) brightness temperatures. The combination of low- and high-frequency channels reveals the performance of the model cloud microphysics in terms of liquid and ice precipitation amounts. In this study, long-term CRM simulations are performed using the Goddard Cumulus Ensemble (GCE) model for three cases: ARM TWP-ICE (Tropical Warm Pool International Cloud Experiment), SCSMEX (South China Sea Monsoon Experiment), and KWAJEX (Kwajalein Experiment). Results from the proposed

  2. The Mixed-Phase Arctic Cloud Experiment.

    SciTech Connect

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

    2007-02-01

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

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

    SciTech Connect

    Phillips, Vaughan T. J.

    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 sedimentation. In addition

  4. Sensitivity of Cirrus and Mixed-phase Clouds to the Ice Nuclei Spectra in McRAS-AC: Single Column Model Simulations

    NASA Technical Reports Server (NTRS)

    Betancourt, R. Morales; Lee, D.; Oreopoulos, L.; Sud, Y. C.; Barahona, D.; Nenes, A.

    2012-01-01

    The salient features of mixed-phase and ice clouds in a GCM cloud scheme are examined using the ice formation parameterizations of Liu and Penner (LP) and Barahona and Nenes (BN). The performance of LP and BN ice nucleation parameterizations were assessed in the GEOS-5 AGCM using the McRAS-AC cloud microphysics framework in single column mode. Four dimensional assimilated data from the intensive observation period of ARM TWP-ICE campaign was used to drive the fluxes and lateral forcing. Simulation experiments where established to test the impact of each parameterization in the resulting cloud fields. Three commonly used IN spectra were utilized in the BN parameterization to described the availability of IN for heterogeneous ice nucleation. The results show large similarities in the cirrus cloud regime between all the schemes tested, in which ice crystal concentrations were within a factor of 10 regardless of the parameterization used. In mixed-phase clouds there are some persistent differences in cloud particle number concentration and size, as well as in cloud fraction, ice water mixing ratio, and ice water path. Contact freezing in the simulated mixed-phase clouds contributed to transfer liquid to ice efficiently, so that on average, the clouds were fully glaciated at T approximately 260K, irrespective of the ice nucleation parameterization used. Comparison of simulated ice water path to available satellite derived observations were also performed, finding that all the schemes tested with the BN parameterization predicted 20 average values of IWP within plus or minus 15% of the observations.

  5. Dust cloud manipulation in microgravity experiments

    NASA Astrophysics Data System (ADS)

    Vedernikov, Andrei; Blum, Jurgen; Ingo Von Borstel, Olaf; Schraepler, Rainer; Balapanov, Daniyar; Cecere, Anselmo

    The European Space Agency’s scientific program Interactions in Cosmic and Atmospheric Particle Systems (ICAPS) [1] attributed for the International Space Station is aimed at increasing our knowledge about dust agglomeration in astrophysical processes mostly related to proto-planetary matter formation. These processes are simulated experimentally in clouds initially composed of about micrometre-sized solid particles. Relatively low gas pressure provides intensive enough particle Brownian motion but considerably reduces the experimentation time at normal gravity. Microgravity removes this problem but long duration experiments result in cloud depletion due to grain diffusion to the chamber walls and particle number density decrease due to agglomeration. The main problem comes from the fact that residual forces quickly sweep away the cloud from the observation volume thus drastically reducing the experiment duration. We developed different cloud manipulation systems that solve these problems and provide additional research opportunities in investigation of dust clouds. Particularly, they counterbalance external perturbations and solve the most challenging task of the increase of particle number concentration (cloud squeezing). There are several driving forces that may be used separately or in combination. Thermophoresis and gas flows induced by thermal creep are most favourable for cloud manipulation because they are nearly independent from particle properties. Electrostatic force allows detect charged particles, while photophoresis is sensitive to particle dimensions. The system provides two main regimes - 1) cloud positioning or displacement and 2) dynamic trapping. In absence of repulsive forces between particles the latter regime leads to cloud squeezing and intensive forced particle agglomeration. The cloud manipulation system additionally provides temperature stabilization or, on the contrary, high temperature variation in the observation volume; formation of

  6. Magellan: experiences from a Science Cloud

    SciTech Connect

    Ramakrishnan, Lavanya; Zbiegel, Piotr; Campbell, Scott; Bradshaw, Rick; Canon, Richard; Coghlan, Susan; Sakrejda, Iwona; Desai, Narayan; Declerck, Tina; Liu, Anping

    2011-02-02

    Cloud resources promise to be an avenue to address new categories of scientific applications including data-intensive science applications, on-demand/surge computing, and applications that require customized software environments. However, there is a limited understanding on how to operate and use clouds for scientific applications. Magellan, a project funded through the Department of Energy?s (DOE) Advanced Scientific Computing Research (ASCR) program, is investigating the use of cloud computing for science at the Argonne Leadership Computing Facility (ALCF) and the National Energy Research Scientific Computing Facility (NERSC). In this paper, we detail the experiences to date at both sites and identify the gaps and open challenges from both a resource provider as well as application perspective.

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  8. Results from the CERN pilot CLOUD experiment

    NASA Astrophysics Data System (ADS)

    Duplissy, J.; Enghoff, M. B.; Aplin, K. L.; Arnold, F.; Aufmhoff, H.; Avngaard, M.; Baltensperger, U.; Bondo, T.; Bingham, R.; Carslaw, K.; Curtius, J.; David, A.; Fastrup, B.; Gagné, S.; Hahn, F.; Harrison, R. G.; Kellett, B.; Kirkby, J.; Kulmala, M.; Laakso, L.; Laaksonen, A.; Lillestol, E.; Lockwood, M.; Mäkelä, J.; Makhmutov, V.; Marsh, N. D.; Nieminen, T.; Onnela, A.; Pedersen, E.; Pedersen, J. O. P.; Polny, J.; Reichl, U.; Seinfeld, J. H.; Sipilä, M.; Stozhkov, Y.; Stratmann, F.; Svensmark, H.; Svensmark, J.; Veenhof, R.; Viisanen, Y.; Wagner, P. E.; Wehrle, G.; Weingartner, E.; Wex, H.; Wilhelmsson, M.; Winkler, P. M.

    2009-09-01

    During a 4-week run in October-November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the CLOUD1 experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm-3s-1, and growth rates between 2 and 37 nm h-1. The corresponding H2SO4 concentrations were typically around 106 cm-3 or less. The experimentally-measured formation rates and H2SO4 concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design

  9. Results from the CERN pilot CLOUD experiment

    NASA Astrophysics Data System (ADS)

    Duplissy, J.; Enghoff, M. B.; Aplin, K. L.; Arnold, F.; Aufmhoff, H.; Avngaard, M.; Baltensperger, U.; Bondo, T.; Bingham, R.; Carslaw, K.; Curtius, J.; David, A.; Fastrup, B.; Gagné, S.; Hahn, F.; Harrison, R. G.; Kellett, B.; Kirkby, J.; Kulmala, M.; Laakso, L.; Laaksonen, A.; Lillestol, E.; Lockwood, M.; Mäkelä, J.; Makhmutov, V.; Marsh, N. D.; Nieminen, T.; Onnela, A.; Pedersen, E.; Pedersen, J. O. P.; Polny, J.; Reichl, U.; Seinfeld, J. H.; Sipilä, M.; Stozhkov, Y.; Stratmann, F.; Svensmark, H.; Svensmark, J.; Veenhof, R.; Verheggen, B.; Viisanen, Y.; Wagner, P. E.; Wehrle, G.; Weingartner, E.; Wex, H.; Wilhelmsson, M.; Winkler, P. M.

    2010-02-01

    During a 4-week run in October-November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the Cosmics Leaving OUtdoor Droplets (CLOUD) experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm-3s-1, and growth rates between 2 and 37 nm h-1. The corresponding H2O concentrations were typically around 106 cm-3 or less. The experimentally-measured formation rates and htwosofour concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most

  10. The Mixed-Phase Arctic Cloud Experiment (M-PACE)

    NASA Technical Reports Server (NTRS)

    Verlinde, J.; Harrington, J. Y.; McFarquhar, G. M.; Yannuzzi, V. T.; Avramov, A.; Greenberg, S.; Johnson, N.; Zhang, G.; Poellot, M. R.; Mather, J. H.; Turner, D. D.; Eloranta, E. W.; Zak, B. D.; Prenni, A. J.; Daniel, J. S.; Kok, G. L.; Tobin, D. C.; Holz, R.; Sassen, K.; Spangenberg, D.; Minnis, P.; Tooman, T. P.; Ivey, M. D.; Richardson, S. J.; Bahramann, C. P.

    2007-01-01

    The Mixed-Phase Arctic Cloud Experiment (M-PACE) was conducted September 27 through October 22, 2004 on the North Slope of Alaska. The primary objective was to collect a data set suitable to study interactions between microphysics, dynamics and radiative transfer in mixed-phase Arctic clouds. Observations taken during the 1997/1998 Surface Heat and Energy Budget of the Arctic (SHEBA) experiment revealed that Arctic clouds frequently consist of one (or more) liquid layers precipitating ice. M-PACE sought to investigate the physical processes of these clouds utilizing two aircraft (an in situ aircraft to characterize the microphysical properties of the clouds and a remote sensing aircraft to constraint the upwelling radiation) over the Department of Energy s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) on the North Slope of Alaska. The measurements successfully documented the microphysical structure of Arctic mixed-phase clouds, with multiple in situ profiles collected in both single-layer and multi-layer clouds over two ground-based remote sensing sites. Liquid was found in clouds with temperatures down to -30 C, the coldest cloud top temperature below -40 C sampled by the aircraft. Remote sensing instruments suggest that ice was present in low concentrations, mostly concentrated in precipitation shafts, although there are indications of light ice precipitation present below the optically thick single-layer clouds. The prevalence of liquid down to these low temperatures could potentially be explained by the relatively low measured ice nuclei concentrations.

  11. Analytical study of the Atmospheric Cloud Physics Laboratory (ACPL) experiments

    NASA Technical Reports Server (NTRS)

    Davis, M. H.

    1977-01-01

    The design specifications of the research laboratory as a Spacelab facility are discussed along with the types of planned experiments. These include cloud formation, freezing and scavenging, and electrical phenomena. A summary of the program conferences is included.

  12. Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds

    NASA Astrophysics Data System (ADS)

    Schnaiter, M.; Järvinen, E.; Vochezer, P.; Abdelmonem, A.; Wagner, R.; Jourdan, O.; Mioche, G.; Shcherbakov, V. N.; Schmitt, C. G.; Tricoli, U.; Ulanowski, Z.; Heymsfield, A. J.

    2015-11-01

    This study reports on the origin of ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the -40 to -60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high ice crystal complexity is dominating the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapour during the crystal growth. Indications were found that the crystal complexity is influenced by unfrozen H2SO4/H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers; the Polar Nephelometer (PN) probe of LaMP and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side- and backward scattering directions resulting in low asymmetry parameters g around 0.78. It was found that these functions have a rather low sensitivity to the crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

  13. Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds

    NASA Astrophysics Data System (ADS)

    Schnaiter, Martin; Järvinen, Emma; Vochezer, Paul; Abdelmonem, Ahmed; Wagner, Robert; Jourdan, Olivier; Mioche, Guillaume; Shcherbakov, Valery N.; Schmitt, Carl G.; Tricoli, Ugo; Ulanowski, Zbigniew; Heymsfield, Andrew J.

    2016-04-01

    This study reports on the origin of small-scale ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the -40 to -60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Small-scale ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high crystal complexity dominates the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapor during the crystal growth. Indications were found that the small-scale crystal complexity is influenced by unfrozen H2SO4 / H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers: the polar nephelometer (PN) probe of Laboratoire de Métérologie et Physique (LaMP) and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side and backward scattering directions. It was found that these functions have a rather low sensitivity to the small-scale crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

  14. The Tropical Warm Pool International Cloud Experiment (TWPICE)

    SciTech Connect

    May, Peter T.; Mather, James H.; Vaughan, Geraint; Jakob, Christian; McFarquhar, Greg; Bower, Keith; Mace, Gerald G.

    2008-05-01

    One of the most comprehensive data sets of tropical cloud systems and their environmental setting and impacts ever sampled has been collected during the Tropical Warm Pool International Cloud Experiment in the area around Darwin, Northern Australia in January and February of 2006. The experiment design utilized permanent observational facilities in Darwin which include a polarimetric weather radar operated by the Australia Bureau of Meteorology (BOM) and a suite of cloud remote sensing instruments operated by the DOE Atmospheric Radiation Measurement (ARM) program. A dense network of observations added for the experiment included ocean observations and a dense balloon-borne sounding network. An integral factor in the design was to provide boundary conditions and validation data sets for a range of modelling activities and cloud retrieval development. A fleet of five research aircraft were deployed including two high altitude aircraft for characterizing cloud properties and the atmospheric state, a plane carrying airborne cloud radar and lidar and two aircraft sampling the boundary layer in great detail including fluxes, aerosols and chemistry.

  15. Electron cloud experiments at Fermilab: Formation and mitigation

    SciTech Connect

    Zwaska, R.; /Fermilab

    2011-06-01

    We have performed a series of experiments at Fermilab to explore the electron cloud phenomenon. The Main Injector will have its beam intensity increased four-fold in the Project X upgrade, and would be subject to instabilities from the electron cloud. We present measurements of the cloud formation in the Main Injector and experiments with materials for the mitigation of the Cloud. An experimental installation of Titanium-Nitride (TiN) coated beam pipes has been under study in the Main Injector since 2009; this material was directly compared to an adjacent stainless chamber through electron cloud measurement with Retarding Field Analyzers (RFAs). Over the long period of running we were able to observe the secondary electron yield (SEY) change and correlate it with electron fluence, establishing a conditioning history. Additionally, the installation has allowed measurement of the electron energy spectrum, comparison of instrumentation techniques, and energydependent behavior of the electron cloud. Finally, a new installation, developed in conjunction with Cornell and SLAC, will allow direct SEY measurement of material samples irradiated in the accelerator.

  16. Influence of Aerosols on the Shortwave Cloud Radiative Forcing from North Pacific Oceanic Clouds: Results from the Cloud Indirect Forcing Experiment (CIFEX)

    NASA Technical Reports Server (NTRS)

    Wilcox, Eric M.; Roberts, Greg; Ramanathan, V.

    2007-01-01

    Aerosols over the Northeastern Pacific Ocean enhance the cloud drop number concentration and reduce the drop size for marine stratocumulus and cumulus clouds. These microphysical effects result in brighter clouds, as evidenced by a combination of aircraft and satellite observations. In-situ measurements from the Cloud Indirect Forcing Experiment (CIFEX) indicate that the mean cloud drop number concentration in low clouds over the polluted marine boundary layer is greater by 53 cm(sup -3) compared to clean clouds, and the mean cloud drop effective radius is smaller by 4 micrometers. We link these in-situ measurements of cloud modification by aerosols, for the first time, with collocated satellite broadband radiative flux observations from the Clouds and the Earth s Radiant Energy System to show that these microphysical effects of aerosols enhance the top-of-atmosphere cooling by -.9.9 plus or minus 4.3 W m(sup -2) for overcast conditions.

  17. The Influence of Aerosols on the Shortwave Cloud Radiative Forcing from North Pacific Oceanic Clouds: Results from the Cloud Indirect Forcing Experiment (CIFEX)

    NASA Technical Reports Server (NTRS)

    Wilcox, Eric M.; Roberts, Greg; Ramanathan, V.

    2006-01-01

    Aerosols over the Northeastern Pacific Ocean enhance the cloud drop number concentration and reduce the drop size for marine stratocumulus and cumulus clouds. These microphysical effects result in brighter clouds, as evidenced by a combination of aircraft and satellite observations. In-situ measurements from the Cloud Indirect Forcing Experiment (CIFEX) indicate that the mean cloud drop number concentration in low clouds over the polluted marine boundary layer is greater by 53/cu cm compared to clean clouds, and the mean cloud drop effective radius is smaller by 4 microns. We link these in-situ measurements of cloud modification by aerosols, for the first time, with collocated satellite broadband radiative flux observations from the Clouds and the Earth's Radiant Energy System (CERES) to show that these microphysical effects of aerosols enhance the top-of-atmosphere cooling by -9.9+/-4.3 W/sq m for overcast conditions.

  18. Multiple scattering depolarization in marine stratus clouds: Lidar experiments

    NASA Technical Reports Server (NTRS)

    Sassen, K.; Petrilla, R. L.

    1986-01-01

    The depolarization of ruby lidar backscattering caused by multiple scattering in marine stratus clouds was examined systematically from a field site on the southern California coast. Investigated were the effects on the linear depolarization (delta) of lidar receiver field of view (FOV), elevation angle and laser beam pointing errors. An approximately linear increase in maximum delta values was observed with increasing receiver FOV, and the importance of accurate transmitter/receiver beam alignment was demonstrated during experiments in which the laser axis was deliberately misaligned. An elevation angle dependence to the delta values was observed as a consequence of the natural vertical inhomogeneity of water cloud content above the cloud base. Time histories of the depolarization characteristics of dissipating stratus clouds revealed significant spatial and temporal variability in delta values attributed to cloud composition variations. Employing a 1 mrad transmitter FOV, maximum delta values of 0.21 nd 0.33 were observed with 1 and 3 mrad receiver FOVs, respectively, from the low stratus clouds. The fundamental causes and effects on the lidar equation of multiple scattering are also discussed.

  19. Mesoscale Modeling During Mixed-Phase Arctic Cloud Experiment

    SciTech Connect

    Avramov, A.; Harringston, J.Y.; Verlinde, J.

    2005-03-18

    Mixed-phase arctic stratus clouds are the predominant cloud type in the Arctic (Curry et al. 2000) and through various feedback mechanisms exert a strong influence on the Arctic climate. Perhaps one of the most intriguing of their features is that they tend to have liquid tops that precipitate ice. Despite the fact that this situation is colloidally unstable, these cloud systems are quite long lived - from a few days to over a couple of weeks. It has been hypothesized that mixed-phase clouds are maintained through a balance between liquid water condensation resulting from the cloud-top radiative cooling and ice removal by precipitation (Pinto 1998; Harrington et al. 1999). In their modeling study Harrington et al. (1999) found that the maintenance of this balance depends strongly on the ambient concentration of ice forming nucleus (IFN). In a follow-up study, Jiang et al. (2002), using only 30% of IFN concentration predicted by Meyers et al. (1992) IFN parameterization were able to obtain results similar to the observations reported by Pinto (1998). The IFN concentration measurements collected during the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted in October 2004 over the North Slope of Alaska and the Beaufort Sea (Verlinde et al. 2005), also showed much lower values then those predicted (Prenne, pers. comm.) by currently accepted ice nucleation parameterizations (e.g. Meyers et al. 1992). The goal of this study is to use the extensive IFN data taken during M-PACE to examine what effects low IFN concentrations have on mesoscale cloud structure and coastal dynamics.

  20. Liquid Water Cloud Properties During the Polarimeter Definition Experiment (PODEX)

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Wasilewski, Andrzei P.; Ackerman, Andrew S.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Platnick, Steven; Arnold, George; Van Diedenhoven, Bastiaan; Chowdhary, Jacek; Ottaviani, Matteo; Knobelspiesse, Kirk D.

    2015-01-01

    We present retrievals of water cloud properties from the measurements made by the Research Scanning Polarimeter (RSP) during the Polarimeter Definition Experiment (PODEX) held between January 14 and February 6, 2013. The RSP was onboard the high-altitude NASA ER-2 aircraft based at NASA Dryden Aircraft Operation Facility in Palmdale, California. The retrieved cloud characteristics include cloud optical thickness, effective radius and variance of cloud droplet size distribution derived using a parameter-fitting technique, as well as the complete droplet size distribution function obtained by means of Rainbow Fourier Transform. Multi-modal size distributions are decomposed into several modes and the respective effective radii and variances are computed. The methodology used to produce the retrieval dataset is illustrated on the examples of a marine stratocumulus deck off California coast and stratus/fog over California's Central Valley. In the latter case the observed bimodal droplet size distributions were attributed to two-layer cloud structure. All retrieval data are available online from NASA GISS website.

  1. Experiments on Electron Cloud Mitigation at PEP-II

    SciTech Connect

    Ng, Johnny S.T.; Pivi, Mauro T.F.; /SLAC

    2011-11-22

    The electron cloud effect has been observed at many accelerator facilities. It has been the subject of many workshops and reviews. An electron cloud is formed when low energy photoelectrons released from the vacuum chamber surfaces and ionized residual gas molecules, driven by the beam fields of passing positively charged bunches, impinge on the chamber walls and create secondary emission. It is an important issue for many currently operating facilities and the damping rings of the proposed International Linear Collider (ILC) because beam-cloud interaction can severely impact the machines performance. Systematic studies on the electron cloud effect, and its possible remedies, have been carried out in many laboratories. At SLAC, the effort has been concentrated on theoretical understanding with the aid of computer simulations, and experimental measurements with high intensity positron beams at PEP-II. Computer simulation results have been presented at ECLOUD07 and in an earlier article in this journal. In this article, we present recent results from electron cloud experiments at the positron storage ring of PEP-II. In particular, we discuss the performance of various mitigation techniques.

  2. Cloud hole-boring with infrared lasers: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Caramana, E. J.; Morse, R. L.; Quigley, G. P.; Stephens, J. R.; Webster, R. B.; York, G. W.

    Results of experimental attempts to produce an optically clear channel in a water cloud by evaporating the cloud droplets with a CO2 laser are presented. Using scattered light it is possible to visualize the clear channel produced. Measurements of the fraction of power transmitted through the channel at visible wavelengths give insight into the clearing mechanisms. The present data suggest that the water droplets explode in the process of clearing. A theoretical explanation of why this should occur is presented and predictions of the onset of droplet explosions are made. The ability to clear an optical channel in a cloud has applications ranging from defense to ground based meteorological observation. The interior of many natural clouds cannot be probed by conventional optical means due to the large optical depths often encountered. By evaporating the liquid water in a cloud, it is possible to temporarily create an optically clear channel. The results are presented of laboratory experiments performed with the objectives of determining the conditions under which a high power pulsed CO2 laser can produce an optically clear channel and the physical mechanisms responsible for the cleaning and closure of such a channel are identified. In the present experiments, it appears that the droplets first explode resulting in an initial increase in turbidity. The smaller droplets formed by the explosion then evaporate leaving a partially cleared channel. This channel remains clear for a time period on the order of a second, finally closing by advection due to turbulence in the cloud. These findings are consistent with previous work using shorter and longer pulse lengths.

  3. Ionization, Charging and Electric Field Effects on Cloud Particles in the CLOUD Experiment

    NASA Astrophysics Data System (ADS)

    Nichman, L.; Järvinen, E.; Wagner, R.; Dorsey, J.; Dias, A. M.; Ehrhart, S.; Kirkby, J.; Gallagher, M. W.; Saunders, C. P.

    2015-12-01

    Ice crystals and frozen droplets play an important role in atmospheric charging and electrification processes, particularly by collision and aggregation. The dynamics of charged particles in the atmosphere can be modulated by Galactic Cosmic Rays (GCR). High electric fields also affect the alignment of charged particles, allowing more time for interactions. The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN has the ability to conduct ionization, charging and high electric field experiments on liquid or ice clouds created in the chamber by adiabatic pressure reductions. A pion secondary beam from the CERN Proton Synchrotron is used to ionize the molecules in the chamber, and Ar+ Corona Ion Generator for Atmospheric Research (CIGAR) is used to inject unipolar charged ions directly into the chamber. A pressurized airgun provides rapid pressure shocks inside the chamber and induces charged ice nucleation. The cloud chamber is accompanied by a variety of analysing instruments e.g. a 3View Cloud Particle Imager (3V-CPI) coupled with an induction ring, a Scattering Intensity Measurements for the Optical detection of icE (SIMONE) and a Nano-aerosol and Air Ion Spectrometer (NAIS). Using adiabatic expansion and high electric fields we can replicate the ideal conditions for adhesion, sintering and interlocking between ice crystals. Charged cloud particles produced measurable variations in the total induced current pulse on the induction ring. The most influential factors comprised initial temperature, lapse rate and charging mechanism. The ions produced in the chamber may deposit onto larger particles and form dipoles during ice nucleation and growth. The small ion concentration was monitored by the NAIS during these runs. Possible short-term aggregates or alignment of particles were observed in-situ with the SIMONE. These and future chamber measurements of charging and aggregation could shed more light on the ambient conditions and dynamics for electrification

  4. The VOCALS Regional Experiment: Aerosol-Cloud-Precipitation Interactions in Marine Boundary Layer Cloud

    NASA Astrophysics Data System (ADS)

    Wood, R.

    2012-12-01

    Robert Wood, C.S. Bretherton, C. R. Mechoso, R. A. Weller, B. J. Huebert, H. Coe, B. A. Albrecht, P. H. Daum, D. Leon, A. Clarke, P. Zuidema, C. W. Fairall, G. Allen, S. deSzoeke, G. Feingold, J. Kazil, S. Yuter, R. George, A. Berner, C. Terai, G. Painter, H. Wang, M. Wyant, D. Mechem The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) is an international field program designed to make observations of poorly understood but critical components of the coupled climate system of the southeast Pacific (SEP), a region dominated by strong coastal upwelling, extensive cold SSTs, and home to the largest subtropical stratocumulus deck on Earth. VOCALS-REx took place during October and November 2008 and involved five research aircraft, two ships and two surface sites in northen Chile. A central theme of VOCALS-REx is the improved understanding of links between aerosols, clouds and precipitation and their impacts on marine stratocumulus radiative properties. In this presentation, we will present a synthesis of results from VOCALS-REx focusing on the following questions: (a) how are aerosols, clouds and precipitation inter-related in the SEP region? (b) what microphysical-macrophysical interactions are necessary for the formation and maintenance of open cells? (c) how do cloud and MBL properties change across the strong microphysical gradients from the South American coast to the remote ocean?

  5. Midlatitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-10

    The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available.

  6. Arctic Boreal Vulnerability Experiment (ABoVE) Science Cloud

    NASA Astrophysics Data System (ADS)

    Duffy, D.; Schnase, J. L.; McInerney, M.; Webster, W. P.; Sinno, S.; Thompson, J. H.; Griffith, P. C.; Hoy, E.; Carroll, M.

    2014-12-01

    The effects of climate change are being revealed at alarming rates in the Arctic and Boreal regions of the planet. NASA's Terrestrial Ecology Program has launched a major field campaign to study these effects over the next 5 to 8 years. The Arctic Boreal Vulnerability Experiment (ABoVE) will challenge scientists to take measurements in the field, study remote observations, and even run models to better understand the impacts of a rapidly changing climate for areas of Alaska and western Canada. The NASA Center for Climate Simulation (NCCS) at the Goddard Space Flight Center (GSFC) has partnered with the Terrestrial Ecology Program to create a science cloud designed for this field campaign - the ABoVE Science Cloud. The cloud combines traditional high performance computing with emerging technologies to create an environment specifically designed for large-scale climate analytics. The ABoVE Science Cloud utilizes (1) virtualized high-speed InfiniBand networks, (2) a combination of high-performance file systems and object storage, and (3) virtual system environments tailored for data intensive, science applications. At the center of the architecture is a large object storage environment, much like a traditional high-performance file system, that supports data proximal processing using technologies like MapReduce on a Hadoop Distributed File System (HDFS). Surrounding the storage is a cloud of high performance compute resources with many processing cores and large memory coupled to the storage through an InfiniBand network. Virtual systems can be tailored to a specific scientist and provisioned on the compute resources with extremely high-speed network connectivity to the storage and to other virtual systems. In this talk, we will present the architectural components of the science cloud and examples of how it is being used to meet the needs of the ABoVE campaign. In our experience, the science cloud approach significantly lowers the barriers and risks to organizations

  7. Retrieval of Cloud Phase Using the Moderate Resolution Imaging Spectroradiometer Data during the Mixed-Phase Arctic Cloud Experiment

    SciTech Connect

    Spangenberg, D.; Minnis, P.; Shupe, M.; Uttal, T.; Poellot, M.

    2005-03-18

    Improving climate model predictions over Earth's polar regions requires a comprehensive knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface, making it difficult to detect clouds and retrieve their phase from space. Snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds make it even more difficult to determine cloud phase. Also, since determining cloud phase is the first step toward analyzing cloud optical depth, particle size, and water content, it is vital that the phase be correct in order to obtain accurate microphysical and bulk properties. Changes in these cloud properties will, in turn, affect the Arctic climate since clouds are expected to play a critical role in the sea ice albedo feedback. In this paper, the IR trispectral technique (IRTST) is used as a starting point for a WV and 11-{micro}m brightness temperature (T11) parameterization (WVT11P) of cloud phase using MODIS data. In addition to its ability to detect mixed-phase clouds, the WVT11P also has the capability to identify thin cirrus clouds overlying mixed or liquid phase clouds (multiphase ice). Results from the Atmospheric Radiation Measurement (ARM) MODIS phase model (AMPHM) are compared to the surface-based cloud phase retrievals over the ARM North Slope of Alaska (NSA) Barrow site and to in-situ data taken from University of North Dakota Citation (CIT) aircraft which flew during the Mixed-Phase Arctic Cloud Experiment (MPACE). It will be shown that the IRTST and WVT11P combined to form the AMPHM can achieve a relative high accuracy of phase discrimination compared to the surface-based retrievals. Since it only uses MODIS WV and IR channels, the AMPHM is robust in the sense that it can be applied to daytime, twilight, and nighttime scenes with no discontinuities in the output phase.

  8. A New Look at the Israeli Cloud Seeding Experiments.

    NASA Astrophysics Data System (ADS)

    Rangno, Arthur L.; Robbs, Peter V.

    1995-05-01

    Two statistical experiments, carried out in Israel, appeared for a time to have provided a unique demonstration of the ability of cloud seeding to increase rainfall. In this paper the authors examine the possibility that both experiments were compromised by type I statistical errors (i.e., `lucky draws' or false positives). It is concluded that in the first Israeli experiment a type I statistical error produced the appearance of statistically significant effects of artificial seeding on rainfall 1) in the buffer zone and the center target area, 2) in the coastal region of Israel, a few kilometers downwind of the seeding, and 3) in portions of Lebanon, Syria, and Jordan.Analysis of the second Israeli experiment using the original crossover design produced a null result. However, when the two target areas were evaluated separately, naturally heavier rainfall over a wide region on days when the north target area was seeded produced the appearance of increases in rainfall due to seeding in the north target area, and when the south target area was seeded, the appearance of decreases in rainfall due to seeding was produced.Target-control (as contrasted with crossover) evaluations of the second Israeli experiment for the north target area alone foundered when control stations were selected from a relatively small region of anomalously low seed/no-seed ratios that was situated within a much larger region of high seed/no-seed ratios, which included Lebanon, Jordan, and most of Israel. Thus, the north target area seed/no-seed ratios are not an isolated, seeding-induced anomaly. On the contrary, it is the low seed/no-seed ratios of the northern coastal control stations, selected after the experiment began, that are anomalous in a regional context and are virtually the only stations that yield an apparently statistically significant effect due to seeding in the north target area.It is concluded that neither of the Israeli experiments demonstrated statistically significant

  9. Review study and evaluation of possible flight experiments relating to cloud physics experiments in space

    NASA Technical Reports Server (NTRS)

    Hunt, R. J.; Wu, S. T.

    1976-01-01

    The general objectives of the Zero-Gravity Atmospheric Cloud Physics Laboratory Program are to improve the level of knowledge in atmospheric cloud research by placing at the disposal of the terrestrial-bound atmospheric cloud physicist a laboratory that can be operated in the environment of zero-gravity or near zero-gravity. This laboratory will allow studies to be performed without mechanical, aerodynamic, electrical, or other techniques to support the object under study. The inhouse analysis of the Skylab 3 and 4 experiments in dynamics of oscillations, rotations, collisions and coalescence of water droplets under low gravity-environment is presented.

  10. Re-evaluation of the Arizona cloud-seeding experiment.

    PubMed

    Neyman, J; Osborn, H B; Scott, E L; Wells, M A

    1972-06-01

    The apparent effect of cloud seeding on the average 24-hr precipitation in the Santa Catalina Mountains during the two programs of the 7-year-long Arizona experiment was found to be a 30% loss of rain (P = 0.06). Considering rainy days only, the apparent effect is a 34% loss of rain (P = 0.03). On South-East days the apparent loss was 40% (P = 0.03). The analysis of the diurnal variation in the amounts of hourly precipitation brought out two suggestions: (i) more active silver iodide enters the clouds through seeding at their bases than at the -6 degrees C level; (ii) the population of experimental days includes two categories with opposite responses to seeding: augmentations of rain in one case and losses in the other. These suggestions require independent confirmation. PMID:16591991

  11. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. II: Multi layered cloud

    SciTech Connect

    Morrison, H.; McCoy, Renata; Klein, Stephen A.; Xie, Shaocheng; Luo, Yali; Avramov, Alexander; Chen, Mingxuan; Cole, Jason N.; Falk, Michael; Foster, Mike; Del Genio, Anthony D.; Harrington, Jerry Y.; Hoose, Corinna; Khrairoutdinov, Marat; Larson, Vince; Liu, Xiaohong; McFarquhar, Greg; Poellot, M. R.; Von Salzen, Knut; Shipway, Ben; Shupe, Matthew D.; Sud, Yogesh C.; Turner, David D.; Veron, Dana; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey; Xu, Kuan-Man; Yang, Fanglin; Zhang, G.

    2009-05-21

    Results are presented from an intercomparison of single-column and cloud resolving model simulations of a deep, multi-layered, mixed-phase cloud system observed during the ARM Mixed-Phase Arctic Cloud Experiment. This cloud system was associated with strong surface turbulent sensible and latent heat fluxes as cold air flowed over the open Arctic Ocean, combined with a low pressure system that supplied moisture at mid-level. The simulations, performed by 13 single-column and 4 cloud-resolving models, generally overestimate the liquid water path and strongly underestimate the ice water path, although there is a large spread among the models. This finding is in contrast with results for the single-layer, low-level mixed-phase stratocumulus case in Part I of this study, as well as previous studies of shallow mixed-phase Arctic clouds, that showed an underprediction of liquid water path. The overestimate of liquid water path and underestimate of ice water path occur primarily when deeper mixed-phase clouds extending into the mid-troposphere were observed. These results suggest important differences in the ability of models to simulate Arctic mixed-phase clouds that are deep and multi-layered versus shallow and single-layered. In general, the cloud-resolving models and models with a more sophisticated, two-moment treatment of the cloud microphysics produce a somewhat smaller liquid water path that is closer to observations. The cloud-resolving models also tend to produce a larger cloud fraction than the single column models. The liquid water path and especially the cloud fraction have a large impact on the cloud radiative forcing at the surface, which is dominated by the longwave flux for this case.

  12. Smoke, Clouds, and Radiation-Brazil (SCAR-B) Experiment

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Hobbs, P. V.; Kirchoff, V. W. J. H.; Artaxo, P.; Remer, L. A.; Holben, B. N.; King, M. D.; Ward, D. E.; Prins, E. M.; Longo, K. M.; Mattos, L. F.; Nobre, C. A.; Spinhirne, J. D.; Ji, Q.; Thompson, A. M.; Gleason, J. F.; Christopher, S. A.; Tsay, S.-C.

    1998-01-01

    The Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project took place in the Brazilian Amazon and cerrado regions in August-September 1995 as a collaboration between Brazilian and American scientists. SCAR-B, a comprehensive experiment to study biomass burning, emphasized measurements of surface biomass, fires, smoke aerosol and trace gases, clouds, and radiation. their climatic effects, and remote sensing from aircraft and satellites. It included aircraft and ground-based in situ measurements of smoke emission factors and the compositions, sizes, and optical properties of the smoke particles; studies of the formation of ozone; the transport and evolution of smoke; and smoke interactions with water vapor and clouds. This overview paper introduces SCAR-B and summarizes some of the main results obtained so far. (1) Fires: measurements of the size distribution of fires, using the 50 m resolution MODIS Airborne Simulator, show that most of the fires are small (e.g. 0.005 square km), but the satellite sensors (e.g., AVHRR and MODIS with I km resolution) can detect fires in Brazil which are responsible for 60-85% of the burned biomass: (2) Aerosol: smoke particles emitted from fires increase their radius by as much as 60%, during their first three days in the atmosphere due to condensation and coagulation, reaching a mass median radius of 0.13-0.17 microns: (3) Radiative forcing: estimates of the globally averaged direct radiative forcing due to smoke worldwide, based on the properties of smoke measured in SCAR-B (-O.l to -0.3 W m(exp -2)), are smaller than previously modeled due to a lower single-scattering albedo (0.8 to 0.9), smaller scattering efficiency (3 square meters g(exp -2) at 550 nm), and low humidification factor; and (4) Effect on clouds: a good relationship was found between cloud condensation nuclei and smoke volume concentrations, thus an increase in the smoke emission is expected to affect cloud properties. In SCAR-B, new techniques were developed

  13. Wind estimates from cloud motions: Phase 1 of an in situ aircraft verification experiment

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Shenk, W. E.; Skillman, W.

    1974-01-01

    An initial experiment was conducted to verify geostationary satellite derived cloud motion wind estimates with in situ aircraft wind velocity measurements. Case histories of one-half hour to two hours were obtained for 3-10km diameter cumulus cloud systems on 6 days. Also, one cirrus cloud case was obtained. In most cases the clouds were discrete enough that both the cloud motion and the ambient wind could be measured with the same aircraft Inertial Navigation System (INS). Since the INS drift error is the same for both the cloud motion and wind measurements, the drift error subtracts out of the relative motion determinations. The magnitude of the vector difference between the cloud motion and the ambient wind at the cloud base averaged 1.2 m/sec. The wind vector at higher levels in the cloud layer differed by about 3 m/sec to 5 m/sec from the cloud motion vector.

  14. Midlatitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-01

    Convective processes play a critical role in the Earth’s energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earth’s climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical “parameterizations” that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States

  15. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part II: Multi-layered cloud

    SciTech Connect

    Morrison, H; McCoy, R B; Klein, S A; Xie, S; Luo, Y; Avramov, A; Chen, M; Cole, J; Falk, M; Foster, M; Genio, A D; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; McFarquhar, G; Poellot, M; Shipway, B; Shupe, M; Sud, Y; Turner, D; Veron, D; Walker, G; Wang, Z; Wolf, A; Xu, K; Yang, F; Zhang, G

    2008-02-27

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a deep, multi-layered, mixed-phase cloud system observed during the ARM Mixed-Phase Arctic Cloud Experiment. This cloud system was associated with strong surface turbulent sensible and latent heat fluxes as cold air flowed over the open Arctic Ocean, combined with a low pressure system that supplied moisture at mid-level. The simulations, performed by 13 single-column and 4 cloud-resolving models, generally overestimate the liquid water path and strongly underestimate the ice water path, although there is a large spread among the models. This finding is in contrast with results for the single-layer, low-level mixed-phase stratocumulus case in Part I of this study, as well as previous studies of shallow mixed-phase Arctic clouds, that showed an underprediction of liquid water path. The overestimate of liquid water path and underestimate of ice water path occur primarily when deeper mixed-phase clouds extending into the mid-troposphere were observed. These results suggest important differences in the ability of models to simulate Arctic mixed-phase clouds that are deep and multi-layered versus shallow and single-layered. In general, models with a more sophisticated, two-moment treatment of the cloud microphysics produce a somewhat smaller liquid water path that is closer to observations. The cloud-resolving models tend to produce a larger cloud fraction than the single-column models. The liquid water path and especially the cloud fraction have a large impact on the cloud radiative forcing at the surface, which is dominated by the longwave flux for this case.

  16. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. I: Single layer cloud

    SciTech Connect

    Klein, Stephen A.; McCoy, Renata; Morrison, H.; Ackerman, Andrew; Avramov, Alexander; DeBoer, GIJS; Chen, Mingxuan; Cole, Jason N.; DelGenio, Anthony D.; Falk, Michael; Foster, Mike; Fridlind, Ann; Golaz, Jean-Christophe; Hashino, Tempei; Harrington, Jerry Y.; Hoose, Corinna; Khairoutdinov, Marat; Larson, Vince; Liu, Xiaohong; Luo, Yali; McFarquhar, Greg; Menon, Surabi; Neggers, Roel; Park, Sungsu; Poellot, M. R.; Schmidt, Jerome M.; Sednev, Igor; Shipway, Ben; Shupe, Matthew D.; Spangenberg, D.; Sud, Yogesh; Turner, David D.; Veron, Dana; Von Salzen, Knut; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey; Xie, Shaocheng; Xu, Kuan-Man; Yang, Fanglin; Zhang, G.

    2009-05-21

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the ARM Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of –15°C. While the cloud was water dominated, ice precipitation appears to have lowered the liquid water path to about 2/3 of the adiabatic value. The simulations, which were performed by seventeen single column and nine cloud-resolving models, generally underestimate the liquid water path with the median single-column and cloud-resolving model liquid water path a factor of 3 smaller than observed. While the simulated ice water path is in general agreement with the observed values, results from a sensitivity study in which models removed ice microphysics indicate that in many models the interaction between liquid and ice phase microphysics is responsible for the strong model underestimate of liquid water path. Although no single factor is found to lead to a good simulation, these results emphasize the need for care in the model treatment of mixed-phase microphysics. This case study, which has been well observed from both aircraft and ground-based remote sensors, could be benchmark for model simulations of mixed-phase clouds.

  17. Comparison of Electron Cloud Simulation and Experiments in the High-Current Experiment

    SciTech Connect

    Cohen, R H; Friedman, A; Covo, M K; Lund, S M; Molvik, A W; Bieniosek, F M; Seidl, P A; Vay, J; Stoltz, P; Veitzer, S

    2004-11-11

    Contaminating clouds of electrons are a common concern for accelerators of positive-charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly, weakly, and un-magnetized. We describe our approach to such self-consistency, and in particular a scheme for interpolating between full-orbit (Boris) and drift-kinetic particle pushes that enables electron time steps long compared to the typical gyro period in the magnets. We present tests and applications: simulation of electron clouds produced by three different kinds of sources indicates the sensitivity of the cloud shape to the nature of the source; first-of-a-kind self-consistent simulation of electron-cloud experiments on the High-Current Experiment (HCX) at LBNL, in which the machine can be flooded with electrons released by impact of the ion beam on an end plate, demonstrate the ability to reproduce key features of the ion-beam phase space; and simulation of a two-stream instability of thin beams in a magnetic field demonstrate the ability of the large-timestep mover to accurately calculate the instability.

  18. The Midlatitude Continental Convective Clouds Experiment (MC3E)

    DOE PAGESBeta

    Jensen, M. P.; Petersen, W. A.; Bansemer, A.; Bharadwaj, N.; Carey, L. D.; Cecil, D. J.; Collis, S. M.; DelGenio, A. D.; Dolan, B.; Gerlach, J.; et al

    2015-12-18

    The Midlatitude Continental Convective Clouds Experiment (MC3E), a field program jointly led by the U.S. Department of Energy’s Atmospheric Radiation Measurement program and the NASA Global Precipitation Measurement (GPM) Mission, was conducted in south-central Oklahoma during April – May 2011. MC3E science objectives were motivated by the need to improve understanding of midlatitude continental convective cloud system lifecycles, microphysics, and GPM precipitation retrieval algorithms. To achieve these objectives a multi-scale surface- and aircraft-based in situ and remote sensing observing strategy was employed. A variety of cloud and precipitation events were sampled during the MC3E, of which results from three deepmore » convective events are highlighted. Vertical structure, air motions, precipitation drop-size distributions and ice properties were retrieved from multi-wavelength radar, profiler, and aircraft observations for an MCS on 11 May. Aircraft observations for another MCS observed on 20 May were used to test agreement between observed radar reflectivities and those calculated with forward-modeled reflectivity and microwave brightness temperatures using in situ particle size distributions and ice water content. Multi-platform observations of a supercell that occurred on 23 May allowed for an integrated analysis of kinematic and microphysical interactions. A core updraft of 25 ms-1 supported growth of hail and large rain drops. As a result, data collected during the MC3E campaign is being used in a number of current and ongoing research projects and is available through the DOE ARM and NASA data archives.« less

  19. The Midlatitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect

    Jensen, M. P.; Petersen, W. A.; Bansemer, A.; Bharadwaj, N.; Carey, L. D.; Cecil, D. J.; Collis, S. M.; DelGenio, A. D.; Dolan, B.; Gerlach, J.; Giangrande, S. E.; Heymsfield, A.; Heymsfield, G.; Kollias, P.; Lang, T. J.; Nesbitt, S. W.; Neumann, A.; Poellot, M.; Rutledge, S. A.; Schwaller, M.; Tokay, A.; Williams, C. R.; Wolff, D. B.; Xie, S.; Zipser, E. J.

    2015-12-18

    The Midlatitude Continental Convective Clouds Experiment (MC3E), a field program jointly led by the U.S. Department of Energy’s Atmospheric Radiation Measurement program and the NASA Global Precipitation Measurement (GPM) Mission, was conducted in south-central Oklahoma during April – May 2011. MC3E science objectives were motivated by the need to improve understanding of midlatitude continental convective cloud system lifecycles, microphysics, and GPM precipitation retrieval algorithms. To achieve these objectives a multi-scale surface- and aircraft-based in situ and remote sensing observing strategy was employed. A variety of cloud and precipitation events were sampled during the MC3E, of which results from three deep convective events are highlighted. Vertical structure, air motions, precipitation drop-size distributions and ice properties were retrieved from multi-wavelength radar, profiler, and aircraft observations for an MCS on 11 May. Aircraft observations for another MCS observed on 20 May were used to test agreement between observed radar reflectivities and those calculated with forward-modeled reflectivity and microwave brightness temperatures using in situ particle size distributions and ice water content. Multi-platform observations of a supercell that occurred on 23 May allowed for an integrated analysis of kinematic and microphysical interactions. A core updraft of 25 ms-1 supported growth of hail and large rain drops. As a result, data collected during the MC3E campaign is being used in a number of current and ongoing research projects and is available through the DOE ARM and NASA data archives.

  20. A Robust Multi-Scale Modeling System for the Study of Cloud and Precipitation Processes

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2012-01-01

    During the past decade, numerical weather and global non-hydrostatic models have started using more complex microphysical schemes originally developed for high resolution cloud resolving models (CRMs) with 1-2 km or less horizontal resolutions. These microphysical schemes affect the dynamic through the release of latent heat (buoyancy loading and pressure gradient) the radiation through the cloud coverage (vertical distribution of cloud species), and surface processes through rainfall (both amount and intensity). Recently, several major improvements of ice microphysical processes (or schemes) have been developed for cloud-resolving model (Goddard Cumulus Ensemble, GCE, model) and regional scale (Weather Research and Forecast, WRF) model. These improvements include an improved 3-ICE (cloud ice, snow and graupel) scheme (Lang et al. 2010); a 4-ICE (cloud ice, snow, graupel and hail) scheme and a spectral bin microphysics scheme and two different two-moment microphysics schemes. The performance of these schemes has been evaluated by using observational data from TRMM and other major field campaigns. In this talk, we will present the high-resolution (1 km) GeE and WRF model simulations and compared the simulated model results with observation from recent field campaigns [i.e., midlatitude continental spring season (MC3E; 2010), high latitude cold-season (C3VP, 2007; GCPEx, 2012), and tropical oceanic (TWP-ICE, 2006)].

  1. Results of magnetospheric barium ion cloud experiment of 1971

    NASA Technical Reports Server (NTRS)

    Adamson, D.; Fricke, C. L.; Long, S. A. T.

    1975-01-01

    The barium ion cloud experiment involved the release of about 2 kg of barium at an altitude of 31 482 km, a latitude of 6.926 N., and a longitude of 74.395 W. Significant erosion of plasma from the main ion core occurred during the initial phase of the ion cloud expansion. From the motion of the outermost striational filaments, the electric field components were determined to be 0.19 mV/m in the westerly direction and 0.68 mV/m in the inward direction. The differences between these components and those measured from balloons flown in the proximity of the extremity of the field line through the release point implied the existence of potential gradients along the magnetic field lines. The deceleration of the main core was greater than theoretically predicted. This was attributed to the formation of a polarization wake, resulting in an increase of the area of interaction and resistive dissipation at ionospheric levels. The actual orientation of the magnetic field line through the release point differed by about 10.5 deg from that predicted by magnetic field models that did not include the effect of ring current.

  2. Zero-gravity cloud physics laboratory: Experiment program definition and preliminary laboratory concept studies

    NASA Technical Reports Server (NTRS)

    Eaton, L. R.; Greco, E. V.

    1973-01-01

    The experiment program definition and preliminary laboratory concept studies on the zero G cloud physics laboratory are reported. This program involves the definition and development of an atmospheric cloud physics laboratory and the selection and delineations of a set of candidate experiments that must utilize the unique environment of zero gravity or near zero gravity.

  3. Exploiting Cloud Radar Doppler Spectra of Mixed-Phase Clouds during ACCEPT Field Experiment to Identify Microphysical Processes

    NASA Astrophysics Data System (ADS)

    Kalesse, H.; Myagkov, A.; Seifert, P.; Buehl, J.

    2015-12-01

    Clouds with Extended Polarization Techniques (ACCEPT) field experiment in Cabauw, Netherlands in Fall 2014. There, another MIRA-35 was operated in simultaneous transmission and simultaneous reception (STSR) mode for obtaining measurements of differential reflectivity (ZDR) and correlation coefficient ρhv.

  4. Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment - Part 1: Distributions and variability

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L.

    2016-07-01

    Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study describes and discusses the properties and variations of aerosol, cloud, and precipitation associated with shallow marine cumulus clouds observed in the North Atlantic trades during a field campaign (Barbados Aerosol Cloud Experiment- BACEX, March-April 2010), which took place off Barbados where African dust periodically affects the region. The principal observing platform was the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft, which was equipped with standard meteorological instruments, a zenith pointing cloud radar and probes that measured aerosol, cloud, and precipitation characteristics.The temporal variation and vertical distribution of aerosols observed from the 15 flights, which included the most intense African dust event during all of 2010 in Barbados, showed a wide range of aerosol conditions. During dusty periods, aerosol concentrations increased substantially in the size range between 0.5 and 10 µm (diameter), particles that are large enough to be effective giant cloud condensation nuclei (CCN). The 10-day back trajectories showed three distinct air masses with distinct vertical structures associated with air masses originating in the Atlantic (typical maritime air mass with relatively low aerosol concentrations in the marine boundary layer), Africa (Saharan air layer), and mid-latitudes (continental pollution plumes). Despite the large differences in the total mass loading and the origin of the aerosols, the overall shapes of the aerosol particle size distributions were consistent, with the exception of the transition period.The TO was able to sample many clouds at various phases of growth. Maximum cloud depth observed was less than ˜ 3 km, while most clouds were less than 1 km

  5. The Cloud Detection and UV Monitoring Experiment (CLUE)

    NASA Technical Reports Server (NTRS)

    Barbier, L.; Loh, E.; Sokolsky, P.; Streitmatter, R.

    2004-01-01

    We propose a large-area, low-power instrument to perform CLoud detection and Ultraviolet monitoring, CLUE. CLUE will combine the W detection capabilities of the NIGHTGLOW payload, with an array of infrared sensors to perform cloud slicing measurements. Missions such as EUSO and OWL which seek to measure UHE cosmic-rays at 1W20 eV use the atmosphere as a fluorescence detector. CLUE will provide several important correlated measurements for these missions, including: monitoring the atmospheric W emissions &om 330 - 400 nm, determining the ambient cloud cover during those W measurements (with active LIDAR), measuring the optical depth of the clouds (with an array of narrow band-pass IR sensors), and correlating LIDAR and IR cloud cover measurements. This talk will describe the instrument as we envision it.

  6. Dynamics of molecular clouds: observations, simulations, and NIF experiments

    NASA Astrophysics Data System (ADS)

    Kane, Jave O.; Martinez, David A.; Pound, Marc W.; Heeter, Robert F.; Casner, Alexis; Mancini, Roberto C.

    2015-02-01

    For over fifteen years astronomers at the University of Maryland and theorists and experimentalists at LLNL have investigated the origin and dynamics of the famous Pillars of the Eagle Nebula, and similar parsec-scale structures at the boundaries of HII regions in molecular hydrogen clouds. Eagle Nebula was selected as one of the National Ignition Facility (NIF) Science programs, and has been awarded four NIF shots to study the cometary model of pillar formation. These experiments require a long-duration drive, 30 ns or longer, to drive deeply nonlinear ablative hydrodynamics. The NIF shots will feature a new long-duration x-ray source prototyped at the Omega EP laser, in which multiple hohlraums are driven with UV light in series for 10 ns each and reradiate the energy as an extended x-ray pulse. The new source will be used to illuminate a science package with directional radiation mimicking a cluster of stars. The scaled Omega EP shots tested whether a multi-hohlraum concept is viable — whether earlier time hohlraums would degrade later time hohlraums by preheat or by ejecting ablated plumes that would deflect the later beams. The Omega EP shots illuminated three 2.8 mm long by 1.4 mm diameter Cu hohlraums for 10 ns each with 4.3 kJ per hohlraum. At NIF each hohlraum will be 4 mm long by 3 mm in diameter and will be driven with 80 kJ per hohlraum.

  7. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud

    SciTech Connect

    Klein, S A; McCoy, R B; Morrison, H; Ackerman, A; Avramov, A; deBoer, G; Chen, M; Cole, J; DelGenio, A; Golaz, J; Hashino, T; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; Luo, Y; McFarquhar, G; Menon, S; Neggers, R; Park, S; Poellot, M; von Salzen, K; Schmidt, J; Sednev, I; Shipway, B; Shupe, M; Spangenberg, D; Sud, Y; Turner, D; Veron, D; Falk, M; Foster, M; Fridlind, A; Walker, G; Wang, Z; Wolf, A; Xie, S; Xu, K; Yang, F; Zhang, G

    2008-02-27

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics indicate that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is some evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics. This case study, which has been well observed from both aircraft and ground-based remote sensors, could be a benchmark for model simulations of mixed-phase clouds.

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

    SciTech Connect

    Marchand, RT; Protat, A; Alexander, SP

    2015-12-01

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

  9. Catastrophic Collapse of Particulate Clouds: Implications From Aggregation Experiments in the USML-1 and USML-2 Glovebox. Experiment 35

    NASA Technical Reports Server (NTRS)

    Marshall, John; Freund, Friedemann; Sauke, Todd; Freund, Minoru

    1998-01-01

    Experiments with electrostatic aggregation of well-dispersed (nominally, mono-dispersed), freely suspended particles in the United States Microgravity Laboratory (USML) Glovebox have determined that filamentary aggregates are a universal product of grain interactions in relatively dense particulate clouds. Aggregate growth from the experimental particle clouds primarily involves dipole-dipole interactions for nonconducting materials; dipole interactions account for both attraction between grains as well as the cohesive force that maintains the integrity of the filamentary structures. When a cloud undergoes a turbulent-to-quiescent transition after damping of fluid and ballistic grain motions, aggregation occurs almost instantaneously and the cloud is transformed into a population of "heavier" clusters of material with organized electrical structures. This abrupt transformation could initiate catastrophic gravitational collapse of certain regions of particulate clouds, thus controlling the longevity and fate of cloud systems as diverse as protoplanetary dust disks and volcanic eruption plumes.

  10. LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment

    SciTech Connect

    Greenberg, S.D.; Harrington, J.Y.; Prenni, A.; DeMott, P.

    2005-03-18

    Roll clouds, and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Bruemmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds. In an effort to examine the influences of mixed-phase microphysics on the boundary layer evolution of roll clouds during off-ice flow, Olsson and Harrington (2000) used a 2D mesoscale model coupled to a bulk microphysical scheme (see Section 2). Their results showed that mixed-phase clouds produced more shallow boundary layers with weaker turbulence than liquid-phase cases. Furthermore, their results showed that because of th e reduced turbulent drag on the atmosphere in the mixed-phase case, regions of mesoscale divergence in the marginal ice-zone were significantly affected. A follow-up 2D study (Harrington and Olsson 2001) showed that the reduced turbulent intensity in mixed-phase cases was due to precipitation. Ice precipitation caused downdraft stabilization which fed back and caused a reduction in the surface heat fluxes. In this work, we extend the work of Olsson and Harrington (2000) and Harrington and Olsson (2001) by examining the impacts of ice microphysics on roll convection. We will present results that illustrate how microphysics alters roll cloud structure and dynamics.

  11. The Physical Properties of the Midcourse Space Experiment Galactic Infrared-dark Clouds

    NASA Astrophysics Data System (ADS)

    Carey, Sean J.; Clark, F. O.; Egan, M. P.; Price, S. D.; Shipman, R. F.; Kuchar, T. A.

    1998-12-01

    The SPIRIT III infrared telescope on the Midcourse Space Experiment (MSX) satellite has provided an unprecedented view of the mid-infrared emission (8-25 μm) of the Galactic plane. An initial analysis of images from MSX Galactic plane survey data reveals dark clouds seen in silhouette against the bright emission from the Galactic plane (Egan et al.). These clouds have mid-infrared extinctions in excess of 2 mag at 8 μm. We probed the physical properties of 10 of these MSX dark clouds using millimeter-wave molecular rotational lines as an indicator of dense molecular gas. All 10 clouds were detected in millimeter spectral lines of H2CO, which confirms the presence of dense gas. The distances to these clouds range from 1 to 8 kiloparsecs and their diameters from 0.4 to 15.0 pc. Excitation analysis of the observed lines indicates that the clouds are cold (T < 20 K) and dense [n(H2) > 105 cm-3]. Some of the clouds have nearby H II regions, H2O masers, and other tracers of star formation at comparable spectral line velocities; however, only one cloud contains embedded centimeter or infrared sources. The lack of mid- to far-infrared emission associated with these clouds suggests that they are not currently forming high-mass stars. If star formation is present in these clouds, it is clearly protostellar class 0 or earlier.

  12. The Deep Convective Clouds and Chemistry (DC3) Field Experiment

    NASA Astrophysics Data System (ADS)

    Barth, M. C.; Brune, W. H.; Cantrell, C. A.; Rutledge, S. A.; Crawford, J. H.; Huntrieser, H.; Homeyer, C. R.; Nault, B.; Cohen, R. C.; Pan, L.; Ziemba, L. D.

    2014-12-01

    The Deep Convective Clouds and Chemistry (DC3) field experiment took place in the central U.S. in May and June 2012 and had the objectives of characterizing the effect of thunderstorms on the chemical composition of the lower atmosphere and determining the chemical aging of upper troposphere (UT) convective outflow plumes. DC3 employed ground-based radars, lightning mapping arrays, and weather balloon soundings in conjunction with aircraft measurements sampling the composition of the inflow and outflow of a variety of thunderstorms in northeast Colorado, West Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the UT convective plume. The DC3 data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, and chemistry in the UT that is affected by the convection. In this presentation, we give an overview of the DC3 field campaign and highlight results from the campaign that are relevant to the upper troposphere and lower stratosphere region. These highlights include stratosphere-troposphere exchange in connection with thunderstorms, the 0-12 hour chemical aging and new particle formation in the UT outflow of a dissipating mesoscale convective system observed on June 21, 2012, and UT chemical aging in convective outflow as sampled the day after convection occurred and modeled in the Weather Research and Forecasting coupled with Chemistry model.

  13. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud

    SciTech Connect

    Klein, Stephen A.; McCoy, Renata B.; Morrison, Hugh; Ackerman, Andrew S.; Avramov, Alexander; de Boer, Gijs; Chen, Mingxuan; Cole, Jason N.S.; Del Genio, Anthony D.; Falk, Michael; Foster, Michael J.; Fridlind, Ann; Golaz, Jean-Christophe; Hashino, Tempei; Harrington, Jerry Y.; Hoose, Corinna; Khairoutdinov, Marat F.; Larson, Vincent E.; Liu, Xiaohong; Luo, Yali; McFarquhar, Greg M.; Menon, Surabi; Neggers, Roel A. J.; Park, Sungsu; Poellot, Michael R.; Schmidt, Jerome M.; Sednev, Igor; Shipway, Ben J.; Shupe, Matthew D.; Spangenberg, Douglas A.; Sud, Yogesh C.; Turner, David D.; Veron, Dana E.; von Salzen, Knut; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey B.; Xie, Shaocheng; Xu, Kuan-Man; Yang, Fanglin; Zhang, Gong

    2009-02-02

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed average liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the average mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics suggest that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics.

  14. X-RAY SHADOWING EXPERIMENTS TOWARD INFRARED DARK CLOUDS

    SciTech Connect

    Anderson, L. D.; Bania, T. M.; Snowden, S. L.

    2010-10-01

    We searched for X-ray shadowing toward two infrared dark clouds (IRDCs) using the MOS detectors on XMM-Newton to learn about the Galactic distribution of X-ray emitting plasma. IRDCs make ideal X-ray shadowing targets of 3/4 keV photons due to their high column densities, relatively large angular sizes, and known kinematic distances. Here we focus on two clouds near 30{sup 0} Galactic longitude at distances of 2 and 5 kpc from the Sun. We derive the foreground and background column densities of molecular and atomic gas in the direction of the clouds. We find that the 3/4 keV emission must be distributed throughout the Galactic disk. It is therefore linked to the structure of the cooler material of the interstellar medium and to the birth of stars.

  15. X-Ray Shadowing Experiments Toward Infrared Dark Clouds

    NASA Technical Reports Server (NTRS)

    Anderson, L. E.; Snowden, S.; Bania, T. M.

    2009-01-01

    We searched for X-ray shadowing toward two infrared dark clouds (IRDCs) using the MOS detectors on XMM-Newton to learn about the Galactic distribution of X-ray emitting plasma. IRDCs make ideal X-ray shadowing targets of 3/4 keY photons due to their high column densities, relatively large angular sizes, and known kinematic distances. Here we focus on two clouds near 30 deg Galactic longitude at distances of 2 and 5 kpc from the Sun. We derive the foreground and background column densities of molecular and atomic gas in the direction of the clouds. We find that the 3/4 ke V emission must be distributed throughout the Galactic disk. It is therefore linked to the structure of the cooler material of the ISM, and to the birth of stars.

  16. IMPROVED PREDICTION OF IN-CLOUD BIOGENIC SOA: EXPERIMENTS AND CMAQ MODEL REFINEMENTS

    EPA Science Inventory

    Laboratory experiments and modeling will be performed to enable better prediction of secondary organic aerosol formation through cloud processing and to facilitate the development of more effective air quality management strategies.

  17. Feasibility study of a zero-gravity (orbital) atmospheric cloud physics experiments laboratory

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    A feasibility and concepts study for a zero-gravity (orbital) atmospheric cloud physics experiment laboratory is discussed. The primary objective was to define a set of cloud physics experiments which will benefit from the near zero-gravity environment of an orbiting spacecraft, identify merits of this environment relative to those of groundbased laboratory facilities, and identify conceptual approaches for the accomplishment of the experiments in an orbiting spacecraft. Solicitation, classification and review of cloud physics experiments for which the advantages of a near zero-gravity environment are evident are described. Identification of experiments for potential early flight opportunities is provided. Several significant accomplishments achieved during the course of this study are presented.

  18. Comparison of electron cloud simulation and experiments in the high-current experiment

    SciTech Connect

    Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Verboncoeur, J.; Stoltz, P.; Veitzer, S.

    2004-08-27

    A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.

  19. Comparison of Electron Cloud Simulation and Experiments in the High-Current Experiment

    SciTech Connect

    Cohen, R; Friedman, A; Covo, M K; Lund, S; Molvik, A; Bieniosek, F; Seidl, P; Vay, J; Verboncoeur, J; Stoltz, P; Veitzer, S

    2004-10-07

    A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.

  20. Model analysis of radar echo split observed in an artificial cloud seeding experiment

    NASA Astrophysics Data System (ADS)

    Masaki, Shimada; Kikuro, Tomine; Koji, Nishiyama

    2016-06-01

    An artificial cloud seeding experiment was performed over the Japan Sea in winter to show how massive seeding could be effective to mitigate heavy snowfall damage. The results showed that 20 min after cloud seeding, a portion of the radar echo beneath the seeding track was weakened to divide the radar echo into two parts. In order to analyze the results, a numerical simulation was conducted by using the Weather Research and Forecasting model verion 3.5.1. In this simulation, the seeding effects were represented as phenomena capable of changing rain particles by accreting cloud ice and snow to form graupel particles and by changing cloud liquid water to snow particles. The graupel particles fell rapidly, thus temporarily intensifying the rainfall, which subsequently decreased. Therefore, the weakened radar echo in the field experiment is deemed to have been caused by the increase in rapidly falling graupel particles.

  1. Lxcloud: a prototype for an internal cloud in HEP. Experiences and lessons learned

    NASA Astrophysics Data System (ADS)

    Goasguen, Sebastien; Moreira, Belmiro; Roche, Ewan; Schwickerath, Ulrich

    2012-12-01

    Born out of the desire to virtualize our batch compute farm CERN has developed an internal cloud known as lxcloud. Since December 2010 it has been used to run a small but sufficient part of our batch workload thus allowing operational and development experience to be gained. Recently, this service has evolved to a public cloud allowing selected physics users an alternate way of accessing resources.

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

    SciTech Connect

    Leung, L. R.; Prather, K.; Ralph, R.; Rosenfeld, D.; Spackman, R.; DeMott, P.; Fairall, C.; Fan, J.; Hagos, S.; Hughes, M.; Long, C.; Rutledge, S.; Waliser, D.; Wang, H.

    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.

  3. Experiment on mass-stripping of interstellar cloud following shock passage

    SciTech Connect

    Hansen, J F; Robey, H F; Klein, R I; Miles, A R

    2006-10-17

    The interaction of supernova shocks and interstellar clouds is an important astrophysical phenomenon which can lead to mass-stripping (transfer of material from cloud to surrounding flow, ''mass-loading'' the flow) and possibly increase the compression in the cloud to high enough densities to trigger star formation. Our experiments attempt to simulate and quantify the mass-stripping as it occurs when a shock passes through interstellar clouds. We drive a strong shock using 5 kJ of the 30 kJ Omega laser into a cylinder filled with low-density foam with an embedded 120 {micro}m Al sphere simulating an interstellar cloud. The density ratio between Al and foam is {approx} 9. Time-resolved x-ray radiographs show the cloud getting compressed by the shock (t {approx} 5 ns), undergoing a classical Kelvin-Helmholtz roll-up (12 ns) followed by a Widnall instability (30 ns), an inherently 3d effect that breaks the 2d symmetry of the experiment. Material is continuously being stripped from the cloud at a rate which is shown to be inconsistent with laminar models for mass-stripping (the cloud is fully stripped by 80 ns-100 ns, ten times faster than the laminar model). We present a new model for turbulent mass-stripping that agrees with the observed rate and which should scale to astrophysical conditions, which occur at even higher Reynolds numbers than the current experiment. The new model combines the integral momentum equations, potential flow past a sphere, flat plate skin friction coefficients, and Spalding's law of the wall for turbulent boundary layers.

  4. From Clusters to Atmospheric Aerosol Particles: Nucleation in the CLOUD Experiment at CERN

    NASA Astrophysics Data System (ADS)

    Baltensperger, Urs

    2015-03-01

    Globally, a significant source of cloud condensation nuclei for cloud formation is thought to originate from new particle formation (aerosol nucleation). Despite extensive research, many questions remain about the dominant nucleation mechanisms. Specifically, a quantitative understanding of the dependence of the nucleation rate on the concentration of the nucleating substances such as gaseous sulfuric acid, ammonia, water vapor and others has not been reached. This is of relevance for climate as the atmospheric concentrations of sulfuric acid, ammonia and other nucleating agents are strongly influenced by anthropogenic emissions. By providing extremely well controlled and essentially contaminant free conditions in the CLOUD chamber, we were able to show that indeed sulfuric acid is an important component for such new particle formation, however, for the typical temperatures encountered in the planetary boundary layer the concentrations of sulfuric acid are not high enough to explain the atmospheric observations. Moreover, the effect of ammonia, amines and oxidized organic molecules on the nucleation rate of sulfuric acid has been investigated in CLOUD so far. Recent developments in instrument technology such as the Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometer have allowed us to investigate the chemical composition of charged as well as neutral clusters during such nucleation experiments. The CLOUD (Cosmics Leaving OUtdoor Droplets) collaboration consists of 20 institutions from Europe and the United States and is funded by national funding institutions as well as the EU training network CLOUD-TRAIN (http://www.cloud-train.eu/).

  5. Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions

    NASA Astrophysics Data System (ADS)

    Möhler, O.; Georgakopoulos, D. G.; Morris, C. E.; Benz, S.; Ebert, V.; Hunsmann, S.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2008-10-01

    The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of Snomax™ were investigated in the temperature range between -5 and -15°C. Water suspensions of these bacteria were directly sprayed into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of -5.7°C. At this temperature, about 1% of the Snomax™ cells induced immersion freezing of the spray droplets before the droplets evaporated in the cloud chamber. The living cells didn't induce any detectable immersion freezing in the spray droplets at -5.7°C. After evaporation of the spray droplets the bacterial cells remained as aerosol particles in the cloud chamber and were exposed to typical cloud formation conditions in experiments with expansion cooling to about -11°C. During these experiments, the bacterial cells first acted as cloud condensation nuclei to form cloud droplets. Then, only a minor fraction of the cells acted as heterogeneous ice nuclei either in the condensation or the immersion mode. The results indicate that the bacteria investigated in the present study are mainly ice active in the temperature range between -7 and -11°C with an ice nucleation (IN) active fraction of the order of 10-4. In agreement to previous literature results, the ice nucleation efficiency of Snomax™ cells was much larger with an IN active fraction of 0.2 at temperatures around -8°C.

  6. Constructing a Merged Cloud-Precipitation Radar Dataset for Tropical Convective Clouds during the DYNAMO/AMIE Experiment at Addu Atoll

    SciTech Connect

    Feng, Zhe; McFarlane, Sally A.; Schumacher, Courtney; Ellis, Scott; Comstock, Jennifer M.; Bharadwaj, Nitin

    2014-05-16

    To improve understanding of the convective processes key to the Madden-Julian-Oscillation (MJO) initiation, the Dynamics of the MJO (DYNAMO) and Atmospheric Radiation Measurement MJO Investigation Experiment (AMIE) collected four months of observations from three radars, the S-band Polarization Radar (S-Pol), the C-band Shared Mobile Atmospheric Research & Teaching Radar (SMART-R), and Ka-band Zenith Radar (KAZR) on Addu Atoll in the tropical Indian Ocean. This study compares the measurements from the S-Pol and SMART-R to those from the more sensitive KAZR in order to characterize the hydrometeor detection capabilities of the two scanning precipitation radars. Frequency comparisons for precipitating convective clouds and non-precipitating high clouds agree much better than non-precipitating low clouds for both scanning radars due to issues in ground clutter. On average, SMART-R underestimates convective and high cloud tops by 0.3 to 1.1 km, while S-Pol underestimates cloud tops by less than 0.4 km for these cloud types. S-Pol shows excellent dynamic range in detecting various types of clouds and therefore its data are well suited for characterizing the evolution of the 3D cloud structures, complementing the profiling KAZR measurements. For detecting non-precipitating low clouds and thin cirrus clouds, KAZR remains the most reliable instrument. However, KAZR is attenuated in heavy precipitation and underestimates cloud top height due to rainfall attenuation 4.3% of the time during DYNAMO/AMIE. An empirical method to correct the KAZR cloud top heights is described, and a merged radar dataset is produced to provide improved cloud boundary estimates, microphysics and radiative heating retrievals.

  7. AIDA experiments on heterogeneous ice nucleation in warm mixed-phase clouds

    NASA Astrophysics Data System (ADS)

    Möhler, Ottmar; Benz, Stefan; Leisner, Thomas; Niemand, Monika; Oehm, Caroline; Saathoff, Harald; Schnaiter, Martin; Wagner, Robert

    2010-05-01

    Clouds are important regulators of the Earth's temperature, because they scatter shortwave radiation from the sun back to space (cooling effect) and absorb long wave terrestrial radiation from the Earth surface (warming effect). About 60% of the Earth's surface is covered with clouds at any time. The response of cloud characteristics and precipitation processes to changing natural and anthropogenic aerosol sources is one of the largest uncertainties in the current understanding of climate change. Cloud development and precipitation are related to a complex chain of microphysical processes which in many cases starts with the formation of the ice phase. The occurrence and abundance of the ice phase in tropospheric clouds is strongly linked to the freezing properties of cloud droplets and aerosol solution particles as well as the abundance and properties of insoluble aerosol particles which selectively act as heterogeneous ice nuclei. Field and laboratory work have demonstrated that in particular mineral dust and bological particles can act as heterogeneous ice nuclei in mixed-phase clouds. Little is known however about the ice nucleation impact of organic matter, which has been found as a prominent compound of tropospheric aerosol particles and has the potential to form surface coatings to other aerosol particles during their transport through the atmosphere. The AIDA (Aerosol Interaction and Dynamics in the Atmosphere) facility at the Karlsruhe Institute of Technology has been used to investigate the heterogeneous ice nucleation efficiency of various dust and biological particles. The temperature, pressure and humidity conditions in the cloud chamber can be varied in a wide range of natural cloud systems. This is achieved by expansion cooling induced by strong pumping to the chamber volume. This talk will summarise AIDA experiments and results on the ice nucleation behaviour of bacteria, mineral dust particles, and dust particles coated with sulphuric acid and

  8. Evaluation of liquid water measuring instruments in cold clouds sampled during FIRE. [First ISCCP Research Experiment

    NASA Technical Reports Server (NTRS)

    Heymsfield, Andrew J.; Miloshevich, Larry M.

    1989-01-01

    Airborne liquid water content (LWC) measurements were conducted with an icing detector and a forward-scattering spectrometer probe during 10 flights into cold clouds, as part of the First ISCCP Research Experiment (FIRE). The LWC measurements thus obtained compare favorably with those from the hot-wire probes in the range where LWC is above the detection limits of the latter; the hot-wire probes have detection thresholds about one order of magnitude higher than is possible with the icing detector and spectrometer probe. FIRE experiment data indicate that LWC should be taken into consideration in cloud studies at temperatures down to at least 35 C.

  9. Multiphase chemical processing by clouds: Modelling the HCCT-2010 hill cap cloud experiment with SPACCIM/CAPRAM4.0α

    NASA Astrophysics Data System (ADS)

    Tilgner, Andreas; Bräuer, Peter; Wolke, Ralf; Herrmann, Hartmut

    2014-05-01

    Tropospheric clouds are a complex multiphase and multi-component environment with simultaneously occurring gas and aqueous phase chemical transformations. Such multiphase cloud processes can proceed very efficient on short timescales and can potentially alter the physical and chemical composition and the deduced physical properties on a global scale. Further, chemical aerosol-cloud interactions have significant effects on the whole multiphase oxidation budget. In order to improve the still limited understanding of the aerosol-cloud interactions, Lagrangian-type field experiments, where an orographic cloud is used as a natural flow-through reactor, are used for studying such processes in more detail by means of field measurements and associated multiphase modelling. In Sept./Oct. 2010, the Lagrangian-type cloud experiment HCCT-2010 (Hill Cap Cloud Thuringia 2010) was conducted at Mt. Schmücke in Thuringia, Germany to investigate aerosol cloud interactions. The main aim of the present model simulations was to investigate the multiphase chemical processing of aerosol constituents during real orographic clouds and to compare of the modelled and measured data. In detail, the model study focuses on the multiphase chemistry of important oxidants and organic compounds by means of the multiphase chemistry model SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model). The air parcel model SPACCIM combines a complex cloud microphysical and a detailed multiphase chemistry model with 11381 gas phase and 7118 aqueous phase reactions. The chemical multiphase mechanism (MCMv3.1 (Master Chemical Mechanism)/ CAPRAM4.0α (Chemical Aqueous Phase RAdical Mechanism)) incorporates a detailed near-explicit description of the inorganic and organic multiphase chemistry. The measured physical and chemical data at the upwind site provided the basis for the model initialisation under real environmental conditions. SPACCIM simulations have been carried out for selected cloud events (FCEs

  10. Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions

    NASA Astrophysics Data System (ADS)

    Möhler, O.; Georgakopoulos, D. G.; Morris, C. E.; Benz, S.; Ebert, V.; Hunsmann, S.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2008-04-01

    The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of SnomaxTM were investigated in the temperature range between -5 and -15°C. Water suspensions of these bacteria were directly spray into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of -5.7°. At this temperature, about 1% of the SnomaxTM cells induced freezing of the spray droplets before they evaporated in the cloud chamber. The other suspensions of living cells didn't induce any measurable ice concentration during spray formation at -5.7°. The remaining aerosol was exposed to typical cloud activation conditions in subsequent experiments with expansion cooling to about -11°C. During these experiments, the bacterial cells first acted as cloud condensation nuclei to form cloud droplets and then eventually acted as ice nuclei to freeze the droplets. The results indicate that the bacteria investigated in the present study are mainly ice active in the temperature range between -7 and -11°C with an INA fraction of the order of 10-4. The ice nucleation efficiency of SnomaxTM cells was much larger with an INA fraction of 0.2 at temperatures around -8°C.

  11. Elemental composition of aerosols in fourteen experiments of the Cloud Condensation Nuclei Workshop

    NASA Technical Reports Server (NTRS)

    Mach, W. H.; Hucek, R. R.

    1981-01-01

    Aeosols were collected with two Ci impactors and analyzed with proton induced X-ray emission (PIXE) for chemical composition and to detect if contamination was present. One of the impactors sampled the generated aerosols; the other impactor sampled droplets from a diffusion cloud chamber. The purpose of the experiments was to test the feasibility of a study of the transfer of chemical elements from the fine particle sizes to the coarse particle sizes, after CCN are activated and cloud droplets are formed. The data indicated that sulfur-containing aerosols did exhibit the expected transfer.

  12. Zero-Gravity Atmospheric Cloud Physics Experiment Laboratory engineering concepts/design tradeoffs. Volume 1: Study results

    NASA Technical Reports Server (NTRS)

    Greco, R. V.; Eaton, L. R.; Wilkinson, H. C.

    1974-01-01

    The work is summarized which was accomplished from January 1974 to October 1974 for the Zero-Gravity Atmospheric Cloud Physics Laboratory. The definition and development of an atmospheric cloud physics laboratory and the selection and delineation of candidate experiments that require the unique environment of zero gravity or near zero gravity are reported. The experiment program and the laboratory concept for a Spacelab payload to perform cloud microphysics research are defined. This multimission laboratory is planned to be available to the entire scientific community to utilize in furthering the basic understanding of cloud microphysical processes and phenomenon, thereby contributing to improved weather prediction and ultimately to provide beneficial weather control and modification.

  13. Flame propagation experiment of PMMA particle cloud in a microgravity environment

    SciTech Connect

    Kobayashi, Hideaki; Ono, Naomichi; Okuyama, Yozo; Niioka, Takashi

    1994-12-31

    The flame propagation experiments on clouds of purely spherical PMMA particles in a microgravity environment were conducted by using the Japan Microgravity Center (JAMIC) drop shaft, where a microgravity condition of 10{sup {minus}4} g for 10 s is available. The exact measurement of the burning velocity of the particle cloud was impossible due to the particle sedimentation in normal gravity up to now. The particle cloud was created using a fluidized-bed-type device and suspended in the flame propagation tube. The cloud was ignited at the open end of the tube, and the flame speed was measured by charge coupled device (CCD) video camera images. The flame speed in normal gravity was also measured, and the two groups of results were compared. The results showed that the flame speed in normal gravity was considerably larger than for ordinary gaseous flames, since turbulent combustion occurred due to the residual turbulence of the flow and the turbulence generated by the particle sedimentation. On the other hand, in the microgravity environment, when the cloud was ignited 6 s after the release of the capsule, the particles were quiescent and dispersed with sufficient uniformity, indicating the effectiveness of the long duration microgravity environment on the decay of turbulence. The flame speed decreased drastically in comparison with normal gravity cases, but the dependence of the flame speed on the particle concentration was similar to that in normal gravity.

  14. Remote sensing of smoke, clouds, and radiation using AVIRIS during SCAR experiments

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Remer, Lorraine; Kaufman, Yorman J.

    1995-01-01

    During the past two years, researchers from several institutes joined together to take part in two SCAR experiments. The SCAR-A (Sulfates, Clouds And Radiation - Atlantic) took place in the mid-Atlantic region of the United States in July, 1993. remote sensing data were acquired with the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), the MODIS Airborne Simulator (MAS), and a RC-10 mapping camera from an ER-2 aircraft at 20 km. In situ measurements of aerosol and cloud microphysical properties were made with a variety of instruments equipped on the University of Washington's C-131A research aircraft. Ground based measurements of aerosol optical depths and particle size distributions were made using a network of sunphotometers. The main purpose of SCAR-A experiment was to study the optical, physical and chemical properties of sulfate aerosols and their interaction with clouds and radiation. Sulfate particles are believed to affect the energy balance of the earth by directly reflecting solar radiation back to space and by increasing the cloud albedo. The SCAR-C (Smoke, Clouds And Radiation - California) took place on the west coast areas during September - October of 1994. Sets of aircraft and ground-based instruments, similar to those used during SCAR-A, were used during SCAR-C. Remote sensing of fires and smoke from AVIRIS and MAS imagers on the ER-2 aircraft was combined with a complete in situ characterization of the aerosol and trace gases from the C-131A aircraft of the University of Washington and the Cesna aircraft from the U.S. Forest Service. The comprehensive data base acquired during SCAR-A and SCAR-C will contribute to a better understanding of the role of clouds and aerosols in global change studies. The data will also be used to develop satellite remote sensing algorithms from MODIS on the Earth Observing System.

  15. Multi-Layer Arctic Mixed-Phase Clouds Simulated by a Cloud-Resolving Model: Comparison with ARM Observations and Sensitivity Experiments

    NASA Technical Reports Server (NTRS)

    Luo, Yali; Xu, Kuan-Man; Morrison, Hugh; McFarquhar, Greg M.; Wang, Zhien; Zhang, Gong

    2007-01-01

    A cloud-resolving model (CRM) is used to simulate the multiple-layer mixed-phase stratiform (MPS) clouds that occurred during a three-and-a-half day subperiod of the Department of Energy-Atmospheric Radiation Measurement Program s Mixed-Phase Arctic Cloud Experiment (M-PACE). The CRM is implemented with an advanced two-moment microphysics scheme, a state-of-the-art radiative transfer scheme, and a complicated third-order turbulence closure. Concurrent meteorological, aerosol, and ice nucleus measurements are used to initialize the CRM. The CRM is prescribed by time-varying large-scale advective tendencies of temperature and moisture and surface turbulent fluxes of sensible and latent heat. The CRM reproduces the occurrences of the single- and double-layer MPS clouds as revealed by the M-PACE observations. However, the simulated first cloud layer is lower and the second cloud layer thicker compared to observations. The magnitude of the simulated liquid water path agrees with that observed, but its temporal variation is more pronounced than that observed. As in an earlier study of single-layer cloud, the CRM also captures the major characteristics in the vertical distributions and temporal variations of liquid water content (LWC), total ice water content (IWC), droplet number concentration and ice crystal number concentration (nis) as suggested by the aircraft observations. However, the simulated mean values differ significantly from the observed. The magnitude of nis is especially underestimated by one order of magnitude. Sensitivity experiments suggest that the lower cloud layer is closely related to the surface fluxes of sensible and latent heat; the upper cloud layer is probably initialized by the large-scale advective cooling/moistening and maintained through the strong longwave (LW) radiative cooling near the cloud top which enhances the dynamical circulation; artificially turning off all ice-phase microphysical processes results in an increase in LWP by a

  16. Wind estimates from cloud motions: Preliminary results from phases 1, 2, and 3 of an in situ aircraft verification experiment

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Shenk, W. E.; Skillman, W. C.

    1975-01-01

    Low level aircraft equipped with Inertial Navigation Systems (INS) were used to define the vertical extent and horizontal motion of a cloud and to measure the ambient wind field. A high level aircraft, also equipped with an INS, took photographs to describe the horizontal extent of the cloud field and to measure cloud motion. The aerial photographs were also used to make a positive identification in a satellite picture of the cloud observed by the low level aircraft. The experiment was conducted over the tropical oceans in the vicinity of Florida, Puerto Rico, Panama and in the Western Gulf of Mexico. Results for tropical cumulus clouds indicate excellent agreement between the cloud motion and the wind at the cloud base. The magnitude of the vector difference between the cloud motion and the cloud base wind is less than 1.3 m/sec for 67% of the cases with track lengths of 1 hour or longer. The cirrus cloud motions agreed best with the mean wind in the cloud layer with a vector difference of about 1.6 m/sec.

  17. Cirrus cloud occurrence as function of ambient relative humidity: a comparison of observations obtained during the INCA experiment

    NASA Astrophysics Data System (ADS)

    Ström, J.; Seifert, M.; Kärcher, B.; Ovarlez, J.; Minikin, A.; Gayet, J.-F.; Krejci, R.; Petzold, A.; Auriol, F.; Haag, W.; Busen, R.; Schumann, U.; Hansson, H. C.

    2003-10-01

    Based on in-situ observations performed during the Interhemispheric differences in cirrus properties from anthropogenic emissions (INCA) experiment, we introduce and discuss the cloud presence fraction (CPF) defined as the ratio between the number of data points determined to represent cloud at a given ambient relative humidity over ice (RHI) divided by the total number of data points at that value of RHI. The CPFs are measured with four different cloud probes. Within similar ranges of detected particle sizes and concentrations, it is shown that different cloud probes yield results that are in good agreement with each other. The CPFs taken at Southern Hemisphere (SH) and Northern Hemisphere (NH) midlatitudes differ from each other. Above ice saturation, clouds occurred more frequently during the NH campaign. Local minima in the CPF as a function of RHI are interpreted as a systematic underestimation of cloud presence when cloud particles become invisible to cloud probes. Based on this interpretation, we find that clouds during the SH campaign formed preferentially at RHIs between 140 and 155%, whereas clouds in the NH campaign formed at RHIs somewhat below 130%. The data show that interstitial aerosol and ice particles coexist down to RHIs of 70-90%, demonstrating that the ability to distinguish between different particle types in cirrus conditions depends on the sensors used to probe the aerosol/cirrus system. Observed distributions of cloud water content differ only slightly between the NH and SH campaigns and seem to be only weakly, if at all, affected by the freezing aerosols.

  18. The CalWater 2 - ARM Cloud Aerosol Precipitation Experiment (ACAPEX)

    NASA Astrophysics Data System (ADS)

    Leung, L. Y.; Prather, K. A.; Ralph, F. M.; Rosenfeld, D.; Spackman, J. R.; Fairall, C. W.; DeMott, P. J.; Fan, J.; Zhao, C.

    2014-12-01

    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. 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. While ARs are responsible for a large fraction of heavy precipitation in the western U.S. 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. In January - March 2015, the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) field campaign will take place in northern California. Joined with CalWater 2, the field campaign aims to improve understanding and modeling of large-scale dynamics and cloud and precipitation processes associated with ARs and aerosol-cloud interactions that influence precipitation variability and extremes in the western U.S. We will implement an observational strategy consisting of the use of land and offshore assets to monitor (1) the evolution and structure of ARs from near their regions of development, (2) long range transport of aerosols in eastern North Pacific and potential interactions with ARs, and (3) how aerosols from long-range transport and local sources influence cloud and precipitation in the U.S. West Coast where ARs make landfall and post-frontal clouds are frequent. This presentation will provide an overview of the science questions and hypotheses to be addressed by CalWater 2/ACAPEX, review key results from prior studies, and discuss recent findings from

  19. Artificial nest experiments in a fragmented neotropical cloud forest

    USGS Publications Warehouse

    Trujillo, G.; Ahumada, J.A.

    2005-01-01

    We conducted artificial nest experiments in a Neotropical montane forest in the eastern Andes, Colombia, in order to test the effect of placing the nests in forest fragments or continuous forests, at two nest heights and for two different climatic seasons. Predation was not consistently different between nests placed in fragments and controls. However, we found that nests on the ground had a higher daily probability of being predated than nests in the understory. Also, daily nest mortality rate (DNM) was higher in the wet season than in the dry season. Most of the predated nests were attributed to mammals (56%), and predation occurred mostly on the ground (78%). Our estimates of DNM are quite low (= 0.023) and similar to another Neotropical montane forest and other Neotropical sites. Comparisons of DNM between Neotropical and temperate sites suggests that predation rates are similar. Our results suggest that fragmentation may not have a large negative impact in nest predation for bird populations breeding in fragments compared to other sites in tropical and temperate regions. ?? The Neotropical Ornithological Society.

  20. Study to perform preliminary experiments to evaluate particle generation and characterization techniques for zero-gravity cloud physics experiments

    NASA Technical Reports Server (NTRS)

    Katz, U.

    1982-01-01

    Methods of particle generation and characterization with regard to their applicability for experiments requiring cloud condensation nuclei (CCN) of specified properties were investigated. Since aerosol characterization is a prerequisite to assessing performance of particle generation equipment, techniques for characterizing aerosol were evaluated. Aerosol generation is discussed, and atomizer and photolytic generators including preparation of hydrosols (used with atomizers) and the evaluation of a flight version of an atomizer are studied.

  1. Feasibility of reduced gravity experiments involving quiescent, uniform particle cloud combustion

    NASA Technical Reports Server (NTRS)

    Ross, Howard D.; Facca, Lily T.; Berlad, Abraham L.; Tangirala, Venkat

    1989-01-01

    The study of combustible particle clouds is of fundamental scientific interest as well as a practical concern. The principal scientific interests are the characteristic combustion properties, especially flame structure, propagation rates, stability limits, and the effects of stoichiometry, particle type, transport phenomena, and nonadiabatic processes on these properties. The feasibility tests for the particle cloud combustion experiment (PCCE) were performed in reduced gravity in the following stages: (1) fuel particles were mixed into cloud form inside a flammability tube; (2) when the concentration of particles in the cloud was sufficiently uniform, the particle motion was allowed to decay toward quiescence; (3) an igniter was energized which both opened one end of the tube and ignited the suspended particle cloud; and (4) the flame proceeded down the tube length, with its position and characteristic features being photographed by high-speed cameras. Gravitational settling and buoyancy effects were minimized because of the reduced gravity enviroment in the NASA Lewis drop towers and aircraft. Feasibility was shown as quasi-steady flame propagation which was observed for fuel-rich mixtures. Of greatest scientific interest is the finding that for near-stoichiometric mixtures, a new mode of flame propagation was observed, now called a chattering flame. These flames did not propagate steadily through the tube. Chattering modes of flame propagation are not expected to display extinction limits that are the same as those for acoustically undisturbed, uniform, quiescent clouds. A low concentration of fuel particles, uniformly distributed in a volume, may not be flammable but may be made flammable, as was observed, through induced segregation processes. A theory was developed which showed that chattering flame propagation was controlled by radiation from combustion products which heated the successive discrete laminae sufficiently to cause autoignition.

  2. Results of the South African Cloud-Seeding Experiments Using Hygroscopic Flares.

    NASA Astrophysics Data System (ADS)

    Mather, G. K.; Terblanche, D. E.; Steffens, F. E.; Fletcher, L.

    1997-11-01

    A new method of seeding convective clouds for the purpose of augmenting rainfall is being developed in South Africa. Flares that produce small salt particles (0.5-m mean diameter) are attached to the trailing edge of the wings of seeding aircraft and ignited in updrafts below the cloud base of convective storms. This method of delivery overcomes most of the difficulties encountered in the handling and the use of hygroscopic materials, difficulties that made seeding with ice nuclei (AgI) a more attractive option.The research that has led to the development of this new technique was prompted by an encounter with a storm with dramatically altered microphysics that was growing over a Kraft paper mill in the research area. Hygroscopic seeding flares were subsequently developed, and seeding trials began in October 1990. Successful seeding trials quickly led to the design and execution of a randomized convective cloud-seeding experiment, the results of which show convincing evidence of increases in the radar-measured rain mass from seeded storms when compared to the control or unseeded storms.Heightened reflectivities aloft seen by the real-time storm-tracking software and observed in the exploratory analysis raises the possibility of developing a radar-measured seeding algorithm that can recognize in almost real time a successful convective seeding event. The implications of such a development would have far-reaching effects on the conduct of future convective cloud-seeding experiments and operations.The authors' seeding hypothesis postulates that the hygroscopic seeding at cloud base accelerates the growth of large hydrometeors in the treated clouds, which harvest more of the available supercooled water before it is expelled into the anvils by the strong updrafts that are a characteristic of the local storms, thereby increasing the efficiency of the rainfall process. The validity of this hypothesis is supported by microphysical measurements made from an instrumented

  3. Our World: Cool Clouds

    NASA Video Gallery

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

  4. STORMVEX: The Storm Peak Lab Cloud Property Validation Experiment Science and Operations Plan

    SciTech Connect

    Mace, J; Matrosov, S; Shupe, M; Lawson, P; Hallar, G; McCubbin, I; Marchand, R; Orr, B; Coulter, R; Sedlacek, A; Avallone, L; Long, C

    2010-09-29

    During the Storm Peak Lab Cloud Property Validation Experiment (STORMVEX), a substantial correlative data set of remote sensing observations and direct in situ measurements from fixed and airborne platforms will be created in a winter season, mountainous environment. This will be accomplished by combining mountaintop observations at Storm Peak Laboratory and the airborne National Science Foundation-supported Colorado Airborne Multi-Phase Cloud Study campaign with collocated measurements from the second ARM Mobile Facility (AMF2). We describe in this document the operational plans and motivating science for this experiment, which includes deployment of AMF2 to Steamboat Springs, Colorado. The intensive STORMVEX field phase will begin nominally on 1 November 2010 and extend to approximately early April 2011.

  5. Interactions between spacecraft motions and the atmospheric cloud physics laboratory experiments

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.

    1981-01-01

    In evaluating the effects of spacecraft motions on atmospheric cloud physics laboratory (ACPL) experimentation, the motions of concern are those which will result in the movement of the fluid or cloud particles within the experiment chambers. Of the various vehicle motions and residual forces which can and will occur, three types appear most likely to damage the experimental results: non-steady rotations through a large angle, long-duration accelerations in a constant direction, and vibrations. During the ACPL ice crystal growth experiments, the crystals are suspended near the end of a long fiber (20 cm long by 200 micron diameter) of glass or similar material. Small vibrations of the supported end of the fiber could cause extensive motions of the ice crystal, if care is not taken to avoid this problem.

  6. Aerosol-Cloud Interactions Evaluated with Aircraft Measurements during the Marine Stratus Experiment (MASE)"

    NASA Astrophysics Data System (ADS)

    Conant, W. C.; Arnott, P.; Bucholtz, A.; Buzorius, G.; Chuang, P. Y.; Jonsson, H. H.; Murphy, S. M.; Rissman, T. A.; Small, J. D.; Sorooshian, A.; Varutbangkul, V.; Flagan, R. C.; Seinfeld, J. H.

    2005-12-01

    In this presentation we explore how aerosols influence the microphysical, dynamical, and radiative properties of marine stratocumulus clouds. We address these aerosol-cloud interactions using data collected by the CIRPAS Twin Otter aircraft during the MASE (Marine Stratus Experiment) campaign, which was conducted off the coast of northern California in July of this year. The otter was instrumented to measure aerosol number concentration, size distribution from 15 nm - 2500 nm, composition (TOF-AMS; PILS), and light absorption. Furthermore, an array of optical probes on the aircraft provided detailed information on the cloud microphysics, including droplet concentration, size distribution, liquid water content and precipitation size distribution. Pyranometers measuring upwelling and downwelling solar irradiance (0.3 μm - 3.5 μm) mounted on a stabilized radiometer platform were used to obtain cloud albedo immediately above the region that was being profiled. Localized (2-20 km wide) regions of high aerosol concentration in the marine boundary layer (MBL) were found and identified as "ship tracks", although no coincident features were immediately apparent in the visible satellite images. Vertical profiles were conducted by the Twin Otter within and on both sides of each ship track to obtain the contrast in aerosol and cloud properties. The ship emissions enhanced aerosol number concentration by factors ranging from 2 to more than 10. They contribute almost entirely to sulfate aerosol -- there was virtually no change in organic aerosol concentration measured by the Aerodyne TOF-AMS or light absorption measured by a photoacoustic instrument within the tracks. The ship emissions are found to have a significant impact on the cloud microphysics, including nearly a doubling of droplet concentration and a reduction in effective radius. The change in droplet dispersion is found to be important in understanding the indirect effect. Cloud albedo tended to be slightly enhanced

  7. Microwave Transmission Through the Electron Cloud at the Fermilab Main Injector: Simulation and Comparison with Experiment

    SciTech Connect

    Lebrun, Paul L.G.; Veitzer, Seth Andrew; /Tech-X, Boulder

    2009-04-01

    Simulations of the microwave transmission properties through the electron cloud at the Fermilab Main Injector have been implemented using the plasma simulation code 'VORPAL'. Phase shifts and attenuation curves have been calculated for the lowest frequency TE mode, slightly above the cutoff frequency, in field free regions, in the dipoles and quadrupoles. Preliminary comparisons with experimental results for the dipole case are showed and will guide the next generation of experiments.

  8. EXPERIENCE IN REDUCING ELECTRON CLOUD AND DYNAMIC PRESSURE RISE IN WARM AND COLD REGIONS IN RHIC.

    SciTech Connect

    ZHANG, S.Y.; AHRENS,L.; ALLESI, J.; BAI, M.; BLASKIEWICZ, M.; CAMERON, P.; CONNOLLY, R.; DREES, A.; FISCHER, W.; GULLOTTA, J.; HE, P.; HSEUH, H.C.; HUANG, H.; LEE, R.; LITVINENKO, V.; MACKAY, W.W.; MONTAG, C.; NICOLETTI, A.; OERTER, B.; PILAT, F.; PTITSYN, V.; ROSER, T.; SATOGATA, T.; SMART, L.; SYNDSTRUP, L.; TEPIKIAN, S.; THIEBERGER, P.; TRBOJEVIC, D.; WEI, J.; ZENO, K.

    2006-06-23

    The large scale application of non-evaporable getter coating in RHIC has been effective in reducing the electron cloud. Since beams with higher intensity and smaller bunch spacing became possible in operation, the emittance growth is of concern. Study results are reported together with experiences of machine improvements: saturated NEG coatings, anti-grazing ridges in warm sections, and the pre-pumping in cryogenic regions.

  9. Nature of Convective Instabilities in Explosive Volcanic Clouds Inferred by Analog Experiments

    NASA Astrophysics Data System (ADS)

    Carazzo, G.; Jellinek, M.

    2009-12-01

    Understanding the mechanisms controlling the dynamics of a volcanic cloud generated by the rise and spread of an explosive eruption is a central issue in volcanology for the assessment of associated hazards. The last decades have seen the development of sophisticated numerical simulations and particle-tracking models with the aim of better understanding and forecasting the transport and sedimentation of the solid fraction in the cloud. In these models, the lateral spreading of an umbrella cloud is strongly influenced by stratospheric winds and its loss of mass with time is assumed be controlled by the opposing effects of particles settling and turbulent diffusion. However, recent observations suggest that additional spatially complex and time-dependent phenomena may govern the dynamics in a volcanic cloud. Here we investigate the mechanisms governing the lateral transport and residence time of ash in the atmosphere using analog experiments. In these experiments, a mixture of small particles and fresh water is injected upwards at a fixed rate into a chamber containing a salt water layer beneath a fresh water layer. Our results show that the formation of a thin particle-rich layer at the base of the cloud (a particle boundary layer) can dramatically modify its dynamics and lead to a variety of behaviors not detected previously. Depending on the conditions imposed at the source and on the magnitude of the density gradient in the environment, the cloud may either break up into discrete layers or release material as dense batches of particle-laden fluid. In natural eruptions the formation of this dense layer is found to be mainly controlled by the grain size distribution and to a lesser extent the altitude reached by the plume. An exhaustive review of field data available in the literature suggests that several past eruptions meet the required conditions to form a particle boundary layer. This study shows that large convective instabilities induced by the presence of a

  10. Clouds and the Earth`s radiant energy system (CERES): An Earth observing system experiment

    SciTech Connect

    Wielicki, B.A.; Barkstrom, B.R.; Harrison, E.F.

    1996-05-01

    Clouds and the Earth`s Radiant Energy System (CERES) is an investigation to examine the role of cloud/radiation feedback on the Earth`s climate system. The CERES broadband scanning radiometers are an improved version of the Earth`s Radiation Budget Experiment (ERBE) radiometers. The CERES instruments will fly on several National Aeronautics and Space Administration Earth Observing System (EOS) satellites starting in 1998 and extending over at least 15 years. The CERES science investigations will provide data to extend the ERBE climate record of top-of-atmosphere shortwave (SW) and longwave (LW) radiative fluxes. CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data, including SW and LW radiative fluxes at the surface and at several selected levels within the atmosphere. CERES data are expected to provide top-of-atmosphere radiative fluxes with a factor of 2 to 3 less error than the ERBE data. Estimates of radiative fluxes at the surface and especially within the atmosphere will be a much greater challenge but should also show significant improvements over current capabilities. 62 refs., 10 figs., 3 tabs.

  11. Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Barkstrom, Bruce R.; Harrison, Edwin F.; Lee, Robert B., III; Smith, G. Louis; Cooper, John E.

    1996-01-01

    Clouds and the Earth's Radiant Energy System (CERES) is an investigation to examine the role of cloud/radiation feedback in the Earth's climate system. The CERES broadband scanning radiometers are an improved version of the Earth Radiation Budget Experiment (ERBE) radiometers. The CERES instruments will fly on several National Aeronautics and Space Administration Earth Observing System (EOS) satellites starting in 1998 and extending over at least 15 years. The CERES science investigations will provide data to extend the ERBE climate record of top-of-atmosphere shortwave (SW) and longwave (LW) radiative fluxes CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data, including SW and LW radiative fluxes at the surface and at several selected levels within the atmosphere. CERES data are expected to provide top-of-atmosphere radiative fluxes with a factor of 2 to 3 less error than the ERBE data Estimates of radiative fluxes at the surface and especially within the atmosphere will be a much greater challenge but should also show significant improvements over current capabilities.

  12. Aerosol and cloud chemistry of amines from CCS - reactivity experiments and numerical modeling

    NASA Astrophysics Data System (ADS)

    Weller, Christian; Tilgner, Andreas; Herrmann, Hartmut

    2013-04-01

    Capturing CO2 from the exhaust of power plants using amine scrubbing is a common technology. Therefore, amines can be released during the carbon capture process. To investigate the tropospheric chemical fate of amines from CO2 capturing processes and their oxidation products, the impact of aqueous aerosol particles and cloud droplets on the amine chemistry has been considered. Aqueous phase reactivity experiments of NO3 radicals and ozone with relevant amines and their corresponding nitrosamines were performed. Furthermore, nitrosamine formation and nitrosamine photolysis was investigated during laboratory experiments. These experiments implicated that aqueous phase photolysis can be an effective sink for nitrosamines and that ozone is unreactive towards amines and nitrosamines. Multiphase phase oxidation schemes of amines, nitrosamines and amides were developed, coupled to the existing multiphase chemistry mechanism CAPRAM and built into the Lagrangian parcel model SPACCIM using published and newly measured data. As a result, both deliquescent particles and cloud droplets are important compartments for the multiphase processing of amines and their products. Amines can be readily oxidised by OH radicals in the gas and cloud phase during daytime summer conditions. However, amine oxidation is restricted during winter conditions with low photochemical activity leading to long lifetimes of amines. The importance of the gas and aqueous phase depends strongly on the partitioning of the different amines. Furthermore, the simulations revealed that the aqueous formation of nitrosamines in aerosol particles and could droplets is not a relevant process under tropospheric conditions.

  13. Solar radiation absorption in the atmosphere due to water and ice clouds: Sensitivity experiments with plane-parallel clouds

    SciTech Connect

    Gautier, C.

    1995-09-01

    One cloud radiation issue that has been troublesome for several decades is the absorption of solar radiation by clouds. Many hypotheses have been proposed to explain the discrepancies between observations and modeling results. A good review of these often-competing hypotheses has been provided by Stephens and Tsay. They characterize the available hypotheses as failing into three categories: (1) those linked to cloud microphysical and consequent optical properties; (2) those linked to the geometry and heterogeneity of clouds; and (3) those linked to atmospheric absorption.Current modeling practice is seriously inconsistent with new observational inferences concerning absorption of solar radiation in the atmosphere. The author and her colleagues contend that an emphasis on R may, therefore, not be the optimal way of addressing the cloud solar absorption issue. 4 refs., 1 fig.

  14. Moisture dynamics in the cloudy and polluted tropical atmosphere: The Cloud Aerosol Radiative Forcing Dynamics Experiment (CARDEX)

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.; Thomas, R. M.; Praveen, P. S.; Pistone, K.; Bender, F.; Feng, Y.; Ramanathan, V.

    2012-12-01

    Aerosols are well known to modify the microphysical properties of clouds. This modification is expected to yield brighter clouds that cover a greater area. However, observations from satellites show little inter-hemispheric difference in cloud optical thickness and liquid water path in spite of the clear inter-hemispheric difference in aerosol optical thickness. Furthermore, comparisons of observations with global atmospheric models suggest that models that parameterize the mechanisms of aerosol nucleation of cloud drops but do not resolve cloud-scale dynamics may be overestimating the magnitude of aerosol effects on cloud radiative forcing. Resolving these discrepancies requires a deeper understanding of the factors determining the transport of moisture to the cloud layer and the effects of aerosols on that transport. Towards this goal, we have conducted a new field experiment to study the moisture dynamics in the boundary layer and lower troposphere of the polluted and cloudy tropical atmosphere. The Cloud Aerosol Radiative Forcing Dynamics Experiment (CARDEX) was conducted during the winter of 2012 at the Maldives Climate Observatory - Hanimaadhoo in the tropical northern Indian Ocean during the period of extensive outflow of the South Asian pollution. Pollution in the CARDEX region has been well documented to both modify the microphysical properties of low clouds and strongly absorb solar radiation with significant consequences for the lower atmosphere and surface radiative energy budgets. Three unmanned aerial vehicles (UAVs) flew nearly 60 research flights instrumented to measure turbulent latent and sensible heat fluxes, aerosol concentrations, and cloud microphysical properties. Airborne measurements were enhanced with continuous surface monitoring of surface turbulent heat fluxes, aerosol concentrations and physical properties, surface remote sensing of cloud water amount and aerosol profiles, and model analyses of aerosols and dynamics with WRFchem. This

  15. Using High-Resolution Satellite Observations for Evaluation of Cloud and Precipitation Statistics from Cloud-Resolving Model Simulations. Part I: South China Sea Monsoon Experiment

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Hou, A.; Lau, W. K.; Shie, C.; Tao, W.; Lin, X.; Chou, M.; Olson, W. S.; Grecu, M.

    2006-05-01

    The cloud and precipitation statistics simulated by 3D Goddard Cumulus Ensemble (GCE) model during the South China Sea Monsoon Experiment (SCSMEX) is compared with Tropical Rainfall Measuring Mission (TRMM) TMI and PR rainfall measurements and the Earth's Radiant Energy System (CERES) single scanner footprint (SSF) radiation and cloud retrievals. It is found that GCE is capable of simulating major convective system development and reproducing total surface rainfall amount as compared with rainfall estimated from the soundings. Mesoscale organization is adequately simulated except when environmental wind shear is very weak. The partitions between convective and stratiform rain are also close to TMI and PR classification. However, the model simulated rain spectrum is quite different from either TMI or PR measurements. The model produces more heavy rains and light rains (less than 0.1 mm/hr) than the observations. The model also produces heavier vertical hydrometer profiles of rain, graupel when compared with TMI retrievals and PR radar reflectivity. Comparing GCE simulated OLR and cloud properties with CERES measurements found that the model has much larger domain averaged OLR due to smaller total cloud fraction and a much skewed distribution of OLR and cloud top than CERES observations, indicating that the model's cloud field is not wide spread, consistent with the model's precipitation activity. These results will be used as guidance for improving the model's microphysics.

  16. The Mid-Latitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect

    Petersen,W.; Jensen,M.; Genio, A. D.; Giangrande, S.; Heymsfield, A.; Heymsfield, G.; Hou, A.; Kollias, P.; Orr, B.; Rutledge, S.; Schwaller, M.; Zipser, E.

    2010-03-15

    The Midlatitude Continental Convective Cloud Experiment (MC3E) will take place in central Oklahoma during the April-May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy Atmospheric Radition Measurement Program and the National Aeronautics and Space Administration's (NASA) Global Precipitation Measurement (GPM) mission Ground Validation program. The Intensive Observation Period leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall observations over land that have never before been available. Several different components of convective processes tangible to the convective parameterization problem are targeted such as, pre-convective environment and convective initiation, updraft / downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, influence on the environment and radiation and a detailed description of the large-scale forcing. MC3E will use a new multi-scale observing strategy with the participation of a network of distributed sensors (both passive and active). The approach is to document in 3-D not only the full spectrum of precipitation rates, but also clouds, winds and moisture in an attempt to provide a holistic view of convective clouds and their feedback with the environment. A goal is to measure cloud and precipitation transitions and environmental quantities that are important for satellite retrieval algorithms, convective parameterization in large-scale models

  17. The Wisconsin Snow and Cloud-Terra 2000 Experiment (WISC-T2000)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Atmospheric scientists take to the skies this winter for the Wisconsin Snow and Cloud-Terra 2000 experiment, Feb. 25 through March 13. Scientists in WISC-T2000 will use instruments on board NASA's ER-2, a high-altitude research plane, to validate new science products from NASA's earth-observing satellite Terra, which began its five-year mission on Dec. 18, 1999. Contact Terri Gregory Public Information Coordinator Space Science and Engineering Center University of Wisconsin-Madison (608) 263-3373; fax (608) 262-5974 terri.gregory@ssec.wisc.edu Science Goals: WISC-T2000 is the third in a series of field experiments sponsored by the University of Wisconsin-Madison's Space Science and Engineering Center. The center helped develop one of the five science instruments on Terra, the Moderate-Resolution Imaging Spectroradiometer (MODIS). MODIS will make global measurements of clouds, oceans, land, and atmospheric properties in an effort to monitor and predict global climate change. Infrastructure: The ER-2 will be based at Madison's Truax Field and will fly over the upper Midwest and Oklahoma. ER-2 measurements will be coordinated with observations at the Department of Energy's Cloud and Radiation Testbed site in Oklahoma (http://www.arm.gov/), which will be engaged in a complementary cloud experiment. The center will work closely with NASA's Goddard Space Flight Center, which will collect and distribute MODIS data and science products. Additional information on the WISC-T2000 field campaign is available at the project's Web site http://cimss.ssec.wisc.edu/wisct2000/

  18. Chemical Composition and Cloud Condensation Nuclei Properties of Marine Aerosols during the 2005 Marine Stratus Experiment

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Hudson, J.; Daum, P.; Springston, S.; Wang, J.; Senum, G.; Alexander, L.; Jayne, J.; Hubbe, J.

    2006-12-01

    Marine aerosol chemical composition and cloud condensation nuclei (CCN) spectrum were determined on board the DOE G1 aircraft during the Marine Stratus Experiment conducted over the coastal waters between Point Reyes National Seashore and Monterey Bay, California, in July 2005. Aerosol components, including sea-salt- (sodium, chloride, magnesium, methansulfonate) and terrestrial/pollution-derived (ammonium, sulfate, nitrate, organics, potassium, and calcium) were measured using the particle-into-liquid sampler-ion chromatography technique and an Aerodyne AMS at a time resolution of 4 min and 30 s, respectively, both covering the size range of ~0.08 to 1.5 micrometers. The CCN spectrum was determined at a 1-s time resolution covering a supersaturation range between 0.02% and 1%. The accumulation mode particle size- number distribution was measured using a passive cavity aerosol spectrometer probe; the cloud droplet size- number distribution was determined using a Cloud Aerosol Probe. During the campaign sulfate/organic aerosols were always present, sea-salt aerosols were observed on half of the flights, and no dust or biomass burning contribution was noted as calcium and potassium were always below their limits-of-detection. Based on CCN spectra and cloud droplet number concentrations, the typical supersaturation of the marine stratus clouds was ~0.06%, corresponding to a CCN critical diameter between 0.1 and 0.2 micrometer. This large critical diameter makes the aerosol chemical composition measured appropriate for investigating the CCN properties and marine stratus clouds. We note that while sea-salt aerosols and sulfate aerosols were most likely externally mixed, the ensemble exhibits similar CCN properties irrespective of the relative mass concentrations of these two types of aerosols, owing partly to the similar activation properties of NaCl and (NH4)2SO4 aerosols, and that sea-salt particles were larger but fewer, accounting for a small fraction of cloud

  19. The Mid-latitude Continental Convective Clouds (MC3E) Experiment Final Campaign Report

    SciTech Connect

    Jensen, Michael; Kollias, Pavlos; Giangrande, Scott

    2014-04-01

    The Mid-latitude Continental Convective Clouds Experiment (MC3E) took place from April 22 through June 6, 2011, centered at the ARM Southern Great Plains site (http://www.arm.gov/sites/sgp) in northcentral Oklahoma. MC3E was a collaborative effort between the ARM Climate Research Facility and the National Aeronautics and Space Administration’s (NASA’s) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The campaign leveraged the largest ground-based observing infrastructure available in the central United States, including recent upgrades through the American Recovery and Reinvestment Act of 2009, combined with an extensive sounding array, remote sensing and in situ aircraft observations, and additional radar and in situ precipitation instrumentation. The overarching goal of the campaign was to provide a three-dimensional characterization of convective clouds and precipitation for the purpose of improving the representation of convective lifecycle in atmospheric models and the reliability of satellite-based retrievals of precipitation.

  20. Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) 2011: Design and Highlights

    NASA Astrophysics Data System (ADS)

    Russell, L. M.; Sorooshian, A.; Seinfeld, J.; Albrecht, B. A.; Nenes, A.; Ahlm, L.; Chen, Y.; Craven, J. S.; Coggon, M.; Frossard, A. A.; Jung, E.; Lin, J. J.; Metcalf, A. R.; Modini, R.; Muelmenstaedt, J.; Shingler, T.; Song, S.; Wang, Z.; Wonaschuetz, A.

    2011-12-01

    Aerosol-cloud-radiation interactions are widely held to be the largest single source of uncertainty in climate model projections of future climate change due to increasing anthropogenic emissions. The underlying causes of this uncertainty among modeled predictions of climate are the gaps in our fundamental understanding of cloud processes. There has been significant progress with both observations and models on these important questions. However, while the qualitative aspects of the indirect effects of aerosols on clouds are well known, the quantitative representation of these processes is nontrivial and limits our ability to represent them in global climate models. The Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) 2011 was a targeted aircraft campaign with embedded modeling studies, using the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft and the R/V Point Sur in July 2011 off the coast of Monterey, California, with a full payload of instruments to measure particle and cloud number, mass, composition, and water uptake distributions. To date, the global models lack (i) accurate aerosol particle activation, with the resulting implications for the profiles of supersaturation, vertical velocity, liquid water content, and drop distribution; (ii) realistic microphysical growth and precipitation processes that control the formation and impacts of drizzle on cloud structure, lifetime, and particle concentration; and (iii) eddy-based transport processes that control the effects of entrainment on cloud thickness and lifetime as well as the dispersion of aerosol plumes. These are basic scientific issues that have not been addressed by climate models or by geoengineering proposals that involve perturbing marine stratocumulus. In this talk, we summarize three central aspects of the collaborative E-PEACE design and the resulting highlights: 1. Controlled particle sources were used to separate particle-induced feedbacks

  1. Effect of ions on the measurement of sulphuric acid in the CLOUD experiment at CERN

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Kürten, A.; Ehrhart, S.; Schobesberger, S.; Franchin, A.; Junninen, H.; Petäjä, T.; Sipilä, M.; Worsnop, D. R.; Curtius, J.

    2014-07-01

    Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e., with and without the presence of ions, were carried out under precisely controlled conditions. The sulphuric acid concentration was measured with a Chemical Ionization Mass Spectrometer (CIMS) during the new particle formation experiments. The added ternary trace gases were ammonia (NH3), dimethylamine (DMA, C2H7N) or oxidised products of pinanediol (PD, C10H18O2). When pinanediol was introduced into the chamber, an increase in the mass spectrometric signal used to determine the sulphuric acid concentration (m/z 97, i.e., HSO4-) was observed due to ions from the CLOUD chamber. The enhancement was only observed during ion-induced nucleation measurements by using either galactic cosmic rays (GCR) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically involved an increase in the apparent sulphuric acid concentration by a factor of ~2 to 3 and was qualitatively verified by the ion measurements by an Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometer. By applying a high voltage (HV) clearing field inside the CLOUD chamber the ion effect on the CIMS measurement was completely eliminated since, under these conditions, small ions are swept from the chamber in about one second. In order to exclude the ion effect and to provide corrected sulphuric acid concentrations during the GCR and PS beam nucleation experiments, a parameterisation was derived that utilizes the trace gas concentrations and the UV light intensity as input parameters. Atmospheric sulphuric acid measurements with a CIMS showed an insignificant ion effect.

  2. Effect of ions on the measurement of sulfuric acid in the CLOUD experiment at CERN

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Kürten, A.; Ehrhart, S.; Schobesberger, S.; Franchin, A.; Junninen, H.; Petäjä, T.; Sipilä, M.; Worsnop, D. R.; Curtius, J.

    2014-11-01

    Ternary aerosol nucleation experiments were conducted in the CLOUD chamber at CERN in order to investigate the influence of ions on new particle formation. Neutral and ion-induced nucleation experiments, i.e. without and with the presence of ions, respectively, were carried out under precisely controlled conditions. The sulfuric acid concentration was measured with a chemical ionisation mass spectrometer (CIMS) during the new particle formation experiments. The added ternary trace gases were ammonia (NH3), dimethylamine (DMA, C2H7N) or oxidised products of pinanediol (PD, C10H18O2). When pinanediol was introduced into the chamber, an increase in the mass spectrometric signal used to determine the sulfuric acid concentration (m/z 97, i.e. HSO4-) was observed due to ions from the CLOUD chamber. The enhancement was only observed during ion-induced nucleation measurements by using either galactic cosmic rays (GCRs) or the proton synchrotron (PS) pion beam for the ion generation, respectively. The ion effect typically involved an increase in the apparent sulfuric acid concentration by a factor of ~ 2 to 3 and was qualitatively verified by the ion measurements with an atmospheric-pressure interface-time of flight (APi-TOF) mass spectrometer. By applying a high-voltage (HV) clearing field inside the CLOUD chamber, the ion effect on the CIMS measurement was completely eliminated since, under these conditions, small ions are swept from the chamber in about 1 s. In order to exclude the ion effect and to provide corrected sulfuric acid concentrations during the GCR and PS beam nucleation experiments, a parameterisation was derived that utilises the trace gas concentrations and the UV light intensity as input parameters. Atmospheric sulfuric acid measurements with a CIMS showed an insignificant ion effect.

  3. First Look at Results from the Metal Oxide Space Cloud (MOSC) Experiment

    NASA Astrophysics Data System (ADS)

    Caton, R. G.; Pedersen, T. R.; Parris, R. T.; Groves, K. M.; Bernhardt, P. A.; Cannon, P. S.

    2013-12-01

    During the moon down period from 28 April to 10 May 2013, the NASA Sounding Rocket Program successfully completed a series of two launches from the Kwajalein Atoll for the Air Force Research Laboratory's Metal Oxide Space Cloud (MOSC) experiment. Payloads on both Terrier Improved Orion rockets flown during the mission included two 5 kg of canisters of Samarium (Sm) powder in a thermite mix for immediate expulsion and vaporization and a two-frequency Coherent Electromagnetic Radio Tomography (CERTO) beacon provided by the Naval Research Laboratory. The launches were carefully timed for dusk releases of Sm vapor at preselected altitudes creating artificially generated layers lasting several hours. A host of ground sensors were deployed to fully probe and characterize the localized plasma cloud produced as a result of charge exchange with the background oxygen (Sm + O → SmO+ + e-). In addition to incoherent scatter probing of the ionization cloud with the ALTAIR radar, ground diagnostics included GPS and CERTO beacon receivers at five locations in the Marshall Islands. Researchers from QinetiQ and the UK MOD participated in the MOSC experiment with the addition of an HF transmitting system and an array of receivers distributed across multiple islands to examine the response of the HF propagation environment to the artificially generated layer. AFRL ground equipment included a pair of All-Sky Imagers, optical spectrographs, and two DPS-4D digisondes spaced ~200 km apart providing vertical and oblique soundings. As the experimental team continues to evaluate the data, this paper will present a first look at early results from the MOSC experiment. Data collected will be used to improve existing models and tailor future experiments targeted at demonstrating the ability to temporarily control the RF propagation environment through an on-demand modification of the ionosphere. Funding for the launch was provided by the DoD Space Test Program.

  4. Aerosol and Cloud Properties during the Cloud Cheju ABC Plume -Asian Monsoon Experiment (CAPMEX) 2008: Linking between Ground-based and UAV Measurements

    NASA Astrophysics Data System (ADS)

    Kim, S.; Yoon, S.; Venkata Ramana, M.; Ramanathan, V.; Nguyen, H.; Park, S.; Kim, M.

    2009-12-01

    Cheju Atmospheric Brown Cloud (ABC) Plume-Monsoon Experiment (CAPMEX), comprehsensive ground-based measurements and a series of data-gathering flights by specially equipped autonomous unmanned aerial vehicles (AUAVs) for aerosol and cloud, had conducted at Jeju (formerly, Cheju), South Korea during August-September 2008, to improve our understanding of how the reduction of anthropogenic emissions in China (so-called “great shutdown” ) during and after the Summer Beijing Olympic Games 2008 effcts on the air quliaty and radiation budgets and how atmospheric brown clouds (ABCs) influences solar radiation budget off Asian continent. Large numbers of in-situ and remote sensing instruments at the Gosan ABC observatory and miniaturized instruments on the aircraft measure a range of properties such as the quantity of soot, size-segregated aerosol particle numbers, total particle numbers, size-segregated cloud droplet numbers (only AUAV), aerosol scattering properties (only ground), aerosol vertical distribution, column-integrated aerosol properties, and meteorological variables. By integrating ground-level and high-elevation AUAV measurements with NASA-satellite observations (e.g., MODIS, CALIPSO), we investigate the long range transport of aerosols, the impact of ABCs on clouds, and the role of biogenic and anthropogenic aerosols on cloud condensation nuclei (CCN). In this talk, we will present the results from CAPMEX focusing on: (1) the characteristics of aerosol optical, physical and chemical properties at Gosan observatory, (2) aerosol solar heating calculated from the ground-based micro-pulse lidar and AERONET sun/sky radiometer synergy, and comparison with direct measurements from UAV, and (3) aerosol-cloud interactions in conjunction with measurements by satellites and Gosan observatory.

  5. Island based radar and microwave radiometer measurements of stratus cloud parameters during the Atlantic Stratocumulus Transition Experiment (ASTEX)

    SciTech Connect

    Frisch, A.S.; Fairall, C.W.; Snider, J.B.; Lenshow, D.H.; Mayer, S.D.

    1996-04-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, simultaneous measurements were made with a vertically pointing cloud sensing radar and a microwave radiometer. The radar measurements are used to estimate stratus cloud drizzle and turbulence parameters. In addition, with the microwave radiometer measurements of reflectivity, we estimated the profiles of cloud liquid water and effective radius. We used radar data for computation of vertical profiles of various drizzle parameters such as droplet concentration, modal radius, and spread. A sample of these results is shown in Figure 1. In addition, in non-drizzle clouds, with the radar and radiometer we can estimate the verticle profiles of stratus cloud parameters such as liquid water concentration and effective radius. This is accomplished by assuming a droplet distribution with droplet number concentration and width constant with height.

  6. Study of the effect of cloud inhomogeneity on the earth radiation budget experiment

    NASA Technical Reports Server (NTRS)

    Smith, Phillip J.

    1988-01-01

    The Earth Radiation Budget Experiment (ERBE) is the most recent and probably the most intensive mission designed to gather precise measurements of the Earth's radiation components. The data obtained from ERBE is of great importance for future climatological studies. A statistical study reveals that the ERBE scanner data are highly correlated and that instantaneous measurements corresponding to neighboring pixels contain almost the same information. Analyzing only a fraction of the data set when sampling is suggested and applications of this strategy are given in the calculation of the albedo of the Earth and of the cloud-forcing over ocean.

  7. Dual-Polarised Doppler X-band Radar Observations of Mixed Phased Clouds from the UK's Ice in Clouds Experiment-Dust (ICE-D)

    NASA Astrophysics Data System (ADS)

    Neely, Ryan; Blyth, Alan; Bennett, Lindsay; Dufton, David; Cui, Zhiqiang; McQuaid, Jim; Price, Hannah; Murray, Benjamin; Huang, Yahui

    2016-04-01

    Here we present dual-polarised X-band radar and in situ observations of convective, altocumulus and altostratus clouds relatively close to the Sahara desert in order to examine the impact of dust on the formation of ice and precipitation. These initial results come the UK's Ice in Clouds Experiment - Dust (UK ICE-D). UK ICE-D was an aircraft and ground-based project based in Cape Verde off the coast of Senegal, Africa during August 2015. The overall goal of this experiment was to determine how desert dust affects primary nucleation of ice particles in convective and layer clouds as well as the subsequent development of precipitation and glaciation of the clouds. This was accomplished by making focused observations when dust was present in high concentrations and when almost no dust was present. Here we focus on examining the differences in hydrometeor types derived from the dual-polarised X-band radar observations observed in the high and low dust loadings with specific emphasis on the role of supercooled rain drops in these two situations.

  8. Dual-Polarised Doppler X-band Radar Observations of Mixed Phased Clouds from the UK's Ice in Clouds Experiment-Dust (ICE-D)

    NASA Astrophysics Data System (ADS)

    Neely, R. R., III; Blyth, A. M.; Bennett, L.; Dufton, D.; Cui, Z.; Huang, Y.

    2015-12-01

    Here we present dual-polarised Doppler X-band radar observations of convective, altocumulus and altostratus clouds relatively close to the Sahara desert in order to examine the impact of dust on the formation of ice and precipitation. These initial results come the UK's Ice in Clouds Experiment - Dust (UK ICE-D). UK ICE-D was an aircraft and ground-based project based in Cape Verde off the coast of Senegal, Africa during August 2015. The overall goal of this experiment was to determine how desert dust affects primary nucleation of ice particles in convective and layer clouds as well as the subsequent development of precipitation and glaciation of the clouds. This was accomplished by making focused observations when dust was present in high concentrations and when almost no dust was present. Here we focus on examining the differences in hydrometeor types derived from the dual-polarised X-band radar observations observed in the high and low dust loadings with specific emphasis on the role of supercooled rain drops in these two situations.

  9. Evaluation of Mixed-Phase Cloud Parameterizations in Short-Range Weather Forecasts with CAM3 and AM2 for Mixed-Phase Arctic Cloud Experiment

    SciTech Connect

    Xie, S; Boyle, J; Klein, S; Liu, X; Ghan, S

    2007-06-01

    By making use of the in-situ data collected from the recent Atmospheric Radiation Measurement Mixed-Phase Arctic Cloud Experiment, we have tested the mixed-phase cloud parameterizations used in the two major U.S. climate models, the National Center for Atmospheric Research Community Atmosphere Model version 3 (CAM3) and the Geophysical Fluid Dynamics Laboratory climate model (AM2), under both the single-column modeling framework and the U.S. Department of Energy Climate Change Prediction Program-Atmospheric Radiation Measurement Parameterization Testbed. An improved and more physically based cloud microphysical scheme for CAM3 has been also tested. The single-column modeling tests were summarized in the second quarter 2007 Atmospheric Radiation Measurement metric report. In the current report, we document the performance of these microphysical schemes in short-range weather forecasts using the Climate Chagne Prediction Program Atmospheric Radiation Measurement Parameterizaiton Testbest strategy, in which we initialize CAM3 and AM2 with realistic atmospheric states from numerical weather prediction analyses for the period when Mixed-Phase Arctic Cloud Experiment was conducted.

  10. Atmospheric Radiation Measurement (ARM) Data from Steamboat Springs, Colorado, for the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX)

    DOE Data Explorer

    In October 2010, the initial deployment of the second ARM Mobile Facility (AMF2) took place at Steamboat Springs, Colorado, for the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX). The objective of this field campaign was to obtain data about liquid and mixed-phase clouds using AMF2 instruments in conjunction with Storm Peak Laboratory (located at an elevation of 3220 meters on Mt. Werner), a cloud and aerosol research facility operated by the Desert Research Institute. STORMVEX datasets are freely available for viewing and download. Users are asked to register with the ARM Archive; the user's email address is used from that time forward as the login name.

  11. Zero-gravity cloud physics laboratory: Candidate experiments definition and preliminary concept studies

    NASA Technical Reports Server (NTRS)

    Eaton, L. R.; Greco, R. V.; Hollinden, A. B.

    1973-01-01

    The candidate definition studies on the zero-g cloud physics laboratory are covered. This laboratory will be an independent self-contained shuttle sortie payload. Several critical technology areas have been identified and studied to assure proper consideration in terms of engineering requirements for the final design. Areas include chambers, gas and particle generators, environmental controls, motion controls, change controls, observational techniques, and composition controls. This unique laboratory will allow studies to be performed without mechanical, aerodynamics, electrical, or other type techniques to support the object under study. This report also covers the candidate experiment definitions, chambers and experiment classes, laboratory concepts and plans, special supporting studies, early flight opportunities and payload planning data for overall shuttle payload requirements assessments.

  12. Radiative effects of polar stratospheric clouds during the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    1992-01-01

    Results are presented of a study of the radiative effects of polar stratospheric clouds during the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASE) in which daily 3D Type I nitric acid trihydrate (NAT) and Type II water ice polar stratospheric clouds (PSCs) were generated in the polar regions during AAOE and the AASE aircraft missions. Mission data on particular composition and size, together with NMC-analyzed temperatures, are used. For AAOE, both Type I and Type II clouds were formed for the time period August 23 to September 17, after which only Type I clouds formed. During AASE, while Type I clouds were formed for each day between January 3 and February 10, Type II clouds formed on only two days, January 24 and 31. Mie theory and a radiative transfer model are used to compute the radiative heating rates during the mission periods, for clear and cloudy lower sky cases. Only the Type II water ice clouds have a significant radiative effect, with the Type I NATO PSCs generating a net heating or cooling of 0.1 K/d or less.

  13. H I ZEEMAN EXPERIMENTS OF SHOCKED ATOMIC GAS IN TWO SUPERNOVA REMNANTS INTERACTING WITH MOLECULAR CLOUDS

    SciTech Connect

    Koo, Bon-Chul; Heiles, Carl; Stanimirovic, Snezana; Troland, Tom

    2010-07-15

    We have carried out observations of Zeeman splitting of the H I 21 cm emission line from shocked atomic gas in the supernova remnants (SNRs) IC 443 and W51C using the Arecibo telescope. The observed shocked atomic gas is expanding at {approx}100 km s{sup -1} and this is the first Zeeman experiment of such fast-moving, shocked atomic gas. The emission lines, however, are very broad and the systematic error due to baseline curvature hampers an accurate measurement of field strengths. We derive an upper limit of 100-150 {mu}G on the strength of the line-of-sight field component. These two SNRs are interacting with molecular clouds, but the derived upper limits are considerably smaller than the field strengths expected from a strongly shocked dense cloud. We discuss the implications and conclude that either the magnetic field within the telescope beam is mostly randomly oriented or the high-velocity H I emission is from a shocked interclump medium of relatively low density.

  14. Flight performance and first results from the sub-orbital local interstellar cloud experiment (SLICE)

    NASA Astrophysics Data System (ADS)

    France, Kevin; Nell, Nicholas; Hoadley, Keri; Kane, Robert; Burgh, Eric B.; Beasley, Matthew; Bushinksy, Rachel; Schultz, Ted B.; Kaiser, Michael; Moore, Christopher; Kulow, Jennifer; Green, James C.

    2013-09-01

    We present the flight performance and preliminary science results from the first flight of the Sub-orbital Local Interstellar Cloud Experiment (SLICE). SLICE is a rocket-borne far-ultraviolet instrument designed to study the diffuse interstellar medium. The SLICE payload comprises a Cassegrain telescope with LiF-coated aluminum optics feeding a Rowland Circle spectrograph operating at medium resolution (R ~ 5000) over the 102 - 107 nm bandpass. We present a novel method for cleaning LiF-overcoated Al optics and the instrumental wavelength calibration, while the details of the instrument design and assembly are presented in a companion proceeding (Kane et al. 2013). We focus primarily on first results from the spring 2013 launch of SLICE in this work. SLICE was launched aboard a Terrier-Black Brant IX sounding rocket from White Sands Missile Range to observe four hot stars sampling different interstellar sightlines. The instrument acquired approximately 240 seconds of on-target time for the science spectra. We observe atomic and molecular transitions (HI, OI, CII, OVI, H2) tracing a range of temperatures, ionization states, and molecular fractions in diffuse interstellar clouds. Initial spectral synthesis results and future plans are discussed.

  15. Experience of the JPL Exploratory Data Analysis Team at validating HIRS2/MSU cloud parameters

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Haskins, Robert D.; Granger-Gallegos, Stephanie; Pursch, Andrew; Delgenio, Anthony

    1992-01-01

    Validation of the HIRS2/MSU cloud parameters began with the cloud/climate feedback problem. The derived effective cloud amount is less sensitive to surface temperature for higher clouds. This occurs because as the cloud elevation increases, the difference between surface temperature and cloud temperature increases, so only a small change in cloud amount is needed to effect a large change in radiance at the detector. By validating the cloud parameters it is meant 'developing a quantitative sense for the physical meaning of the measured parameters', by: (1) identifying the assumptions involved in deriving parameters from the measured radiances, (2) testing the input data and derived parameters for statistical error, sensitivity, and internal consistency, and (3) comparing with similar parameters obtained from other sources using other techniques.

  16. A Review of Cloud Seeding Experiments to Enhance Precipitation and Some New Prospects.

    NASA Astrophysics Data System (ADS)

    Bruintjes, Roelof T.

    1999-05-01

    Water is one of the most basic commodities on earth sustaining human life. In many regions of the world, traditional sources and supplies of ground water, rivers and reservoirs, are either inadequate or under threat from ever-increasing demands on water from changes in land use and growing populations. This has prompted scientists and engineers to explore the possibility of augmenting water supplies by means of cloud seeding.This paper provides an overview of the current scientific status of weather modification activities to enhance precipitation for both glaciogenic and hygroscopic seeding experiments. It is important to emphasize that although funding for scientific studies has decreased substantially during the past decade, operational programs have actually increased.During the last 10 years there has been a thorough scrutiny of past experiments involving experiments using glaciogenic seeding. Although there still exist indications that seeding can increase precipitation, a number of recent studies have questioned many of the positive results, weakening the scientific credibility. As a result, considerable skepticism exists as to whether these methods provides a cost-effective means for increasing precipitation for water resources.Recent results from hygroscopic seeding experiments provided for some renewed optimism in the field of precipitation enhancement. Although promising results have been obtained to date, some fundamental questions remain that need to be answered in order to provide a sound scientific basis for this technology.

  17. Evidence of Widespread Effects of Cloud Seeding at Two Arizona Experiments

    PubMed Central

    Neyman, Jerzy; Osborn, Herbert B.

    1971-01-01

    The average effect of two cloud seeding experiments (1957-1960; 1961, 1962, and 1964) over the Santa Catalina Mountains, Arizona, on the 24-hr precipitation at Walnut Gulch, 65 miles away, was an apparent 40% loss of rainfall (P = 0.025) on seeded, as opposed to not-seeded, experimental days. Larger apparent losses, some highly significant, were found for experimental days on which Walnut Gulch was downwind from the seeding site (but not on upwind days), and also on “second days” of the randomized pairs (but not on “first days”). The timing of significant apparent effects indicated that the afternoon maximum of precipitation, which is very pronounced on days without seeding, is either absent or weakened on days with seeding. This phenomenon was observed earlier in a study of the Whitetop Project. PMID:16591914

  18. A statistical data analysis and plotting program for cloud microphysics experiments

    NASA Technical Reports Server (NTRS)

    Jordan, A. J.

    1981-01-01

    The analysis software developed for atmospheric cloud microphysics experiments conducted in the laboratory as well as aboard a KC-135 aircraft is described. A group of four programs was developed and implemented on a Hewlett Packard 1000 series F minicomputer running under HP's RTE-IVB operating system. The programs control and read data from a MEMODYNE Model 3765-8BV cassette recorder, format the data on the Hewlett Packard disk subsystem, and generate statistical data (mean, variance, standard deviation) and voltage and engineering unit plots on a user selected plotting device. The programs are written in HP FORTRAN IV and HP ASSEMBLY Language with the graphics software using the HP 1000 Graphics. The supported plotting devices are the HP 2647A graphics terminal, the HP 9872B four color pen plotter, and the HP 2608A matrix line printer.

  19. Experience in Grid Site Testing for ATLAS, CMS and LHCb with HammerCloud

    NASA Astrophysics Data System (ADS)

    Elmsheuser, Johannes; Medrano Llamas, Ramón; Legger, Federica; Sciabà, Andrea; Sciacca, Gianfranco; Úbeda García, Mario; van der Ster, Daniel

    2012-12-01

    Frequent validation and stress testing of the network, storage and CPU resources of a grid site is essential to achieve high performance and reliability. HammerCloud was previously introduced with the goals of enabling VO- and site-administrators to run such tests in an automated or on-demand manner. The ATLAS, CMS and LHCb experiments have all developed VO plugins for the service and have successfully integrated it into their grid operations infrastructures. This work will present the experience in running HammerCloud at full scale for more than 3 years and present solutions to the scalability issues faced by the service. First, we will show the particular challenges faced when integrating with CMS and LHCb offline computing, including customized dashboards to show site validation reports for the VOs and a new API to tightly integrate with the LHCbDIRAC Resource Status System. Next, a study of the automatic site exclusion component used by ATLAS will be presented along with results for tuning the exclusion policies. A study of the historical test results for ATLAS, CMS and LHCb will be presented, including comparisons between the experiments’ grid availabilities and a search for site-based or temporal failure correlations. Finally, we will look to future plans that will allow users to gain new insights into the test results; these include developments to allow increased testing concurrency, increased scale in the number of metrics recorded per test job (up to hundreds), and increased scale in the historical job information (up to many millions of jobs per VO).

  20. Measurements of Isoprene and its Oxidation Products during the CLOUD9 Experiment

    NASA Astrophysics Data System (ADS)

    Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Coburn, Sean; Volkamer, Rainer; Hansel, Armin

    2015-04-01

    Isoprene (C5H8), being produced and emitted by the biosphere, is by far the dominant biogenic volatile organic compound (BVOC) in the atmosphere. Its complex reaction pathways with OH radicals, O3 and NO3, lead to compounds with lower volatilities and increasing water solubility. The high hydrophilicity allows for easy partitioning between the gas and liquid phase making those compounds good candidates for aqueous phase droplet chemistry that may contribute to particle growth. (Ervens et al., 2008). The CLOUD experiment (Cosmics Leaving Outdoor Droplets) at CERN allows the studying the evolution of particles originating from precursor gases in, in our case isoprene, in an ultraclean and very well controlled environmental chamber. Gas phase concentrations of isoprene and its first reaction products were measured in real-time with a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS, Graus et al., 2010) and Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS, Thalman and Volkamer, 2010). PTR-ToF-MS was calibrated using gas standards with known VOC concentrations. The PTR-ToF-MS was operated with H3O+ and NO+ as primary ions, continuously switching between both operating modes throughout the experiments. The use of different primary ions allows the discrimination of isomeric compounds like the main high NOx oxidation products methyl vinyl ketone (MVK) and methacroleine (MACR). The experiment was conducted at high isoprene concentrations and a constant level of O3. The highly water soluble gas phase oxidation products from the reaction of isoprene with O3 and OH radicals (from isoprene ozonolysis) were investigated and compared for two temperatures (+10 °C and -10 °C) and different NOx concentrations during cloud formation experiments. Here we will present first results of isoprene oxidation products observed with PTR-ToF-MS and CE-DOAS. References Ervens et al. (2008), Geophys. Res. Lett., 35, L02816 Graus et al. (2010), J. Am

  1. Single particle analysis of ice crystal residuals observed in orographic wave clouds over Scandinavia during INTACC experiment

    NASA Astrophysics Data System (ADS)

    Targino, A. C.; Krejci, R.; Noone, K. J.; Glantz, P.

    2006-06-01

    Individual ice crystal residual particles collected over Scandinavia during the INTACC (INTeraction of Aerosol and Cold Clouds) experiment in October 1999 were analyzed by Scanning Electron Microscopy (SEM) equipped with Energy-Dispersive X-ray Analysis (EDX). Samples were collected onboard the British Met Office Hercules C-130 aircraft using a Counterflow Virtual Impactor (CVI). This study is based on six samples collected in orographic clouds. The main aim of this study is to characterize cloud residual elemental composition in conditions affected by different airmasses. In total 609 particles larger than 0.1 μm diameter were analyzed and their elemental composition and morphology were determined. Thereafter a hierarchical cluster analysis was performed on the signal detected with SEM-EDX in order to identify the major particle classes and their abundance. A cluster containing mineral dust, represented by aluminosilicates, Fe-rich and Si-rich particles, was the dominating class of particles, accounting for about 57.5% of the particles analyzed, followed by low-Z particles, 23.3% (presumably organic material) and sea salt (6.7%). Sulfur was detected often across all groups, indicating ageing and in-cloud processing of particles. A detailed inspection of samples individually unveiled a relationship between ice crystal residual composition and airmass origin. Cloud residual samples from clean airmasses (that is, trajectories confined to the Atlantic and Arctic Oceans and/or with source altitude in the free troposphere) were dominated primarily by low-Z and sea salt particles, while continentally-influenced airmasses (with trajectories that originated or traveled over continental areas and with source altitude in the continental boundary layer) contained mainly mineral dust residuals. Comparison of residual composition for similar cloud ambient temperatures around -27°C revealed that supercooled clouds are more likely to persist in conditions where low-Z particles

  2. Single particle analysis of ice crystal residuals observed in orographic wave clouds over Scandinavia during INTACC experiment

    NASA Astrophysics Data System (ADS)

    Targino, A. C.; Krejci, R.; Noone, K. J.; Glantz, P.

    2005-09-01

    Individual ice crystal residual particles collected over Scandinavia during the INTACC (INTeraction of Aerosol and Cold Clouds) experiment in October 1999 were analyzed by Scanning Electron Microscopy (SEM) equipped with Energy-Dispersive X-ray Analysis (EDX). Samples were collected onboard the British Met Office Hercules C-130 aircraft using a Counterflow Virtual Impactor (CVI). This study is based on six samples collected in orographic clouds. The main aim of this study is to characterize cloud residual elemental composition in conditions affected by different airmasses. In total 609 particles larger than 0.1 µm diameter were analyzed and their elemental composition and morphology were determined. Thereafter a hierarchical cluster analysis was performed on the signal detected with SEM-EDX in order to identify the major particle classes and their abundance. A cluster containing mineral dust, represented by aluminosilicates, Fe-rich and Si-rich particles, was the dominating class of particles, accounting for about 57.5% of the particles analyzed, followed by low-Z particles, 23.3% (presumably organic material) and sea salt (6.7%). Sulfur was detected often across all groups, indicating ageing and in-cloud processing of particles. A detailed inspection of samples individually unveiled a relationship between ice crystal residual composition and airmass origin. Cloud residual samples from clean airmasses (that is, trajectories confined to the Atlantic and Arctic Oceans and/or with source altitude in the free troposphere) were dominated primarily by low-Z and sea salt particles, while continentally-influenced airmasses (with trajectories that originated or traveled over continental areas and with source altitude in the continental boundary layer) contained mainly mineral dust residuals. Comparison of residual composition for similar cloud ambient temperatures around -27°C revealed that supercooled clouds are more likely to persist in conditions where low-Z particles

  3. Discrimination of water, ice and aerosols by light polarisation in the CLOUD experiment

    NASA Astrophysics Data System (ADS)

    Nichman, L.; Fuchs, C.; Järvinen, E.; Ignatius, K.; Höppel, N. F.; Dias, A.; Heinritzi, M.; Simon, M.; Tröstl, J.; Wagner, A. C.; Wagner, R.; Williamson, C.; Yan, C.; Bianchi, F.; Connolly, P. J.; Dorsey, J. R.; Duplissy, J.; Ehrhart, S.; Frege, C.; Gordon, H.; Hoyle, C. R.; Kristensen, T. B.; Steiner, G.; Donahue, N. M.; Flagan, R.; Gallagher, M. W.; Kirkby, J.; Möhler, O.; Saathoff, H.; Schnaiter, M.; Stratmann, F.; Tomé, A.

    2015-11-01

    Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather and General Circulation Models (GCMs). The simultaneous detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud-particle size range below 50 μm, remains challenging in mixed phase, often unstable ice-water phase environments. The Cloud Aerosol Spectrometer with Polarisation (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure their effects on the backscatter polarisation state. Here we operate the versatile Cosmics-Leaving-OUtdoor-Droplets (CLOUD) chamber facility at the European Organisation for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water and ice particles. In this paper, optical property measurements of mixed phase clouds and viscous Secondary Organic Aerosol (SOA) are presented. We report observations of significant liquid - viscous SOA particle polarisation transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarisation ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulphate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentration and mixtures with respect to the CLOUD 8-9 campaigns and its potential contribution to Tropical Troposphere Layer (TTL) analysis.

  4. Phase transition observations and discrimination of small cloud particles by light polarization in expansion chamber experiments

    NASA Astrophysics Data System (ADS)

    Nichman, Leonid; Fuchs, Claudia; Järvinen, Emma; Ignatius, Karoliina; Florian Höppel, Niko; Dias, Antonio; Heinritzi, Martin; Simon, Mario; Tröstl, Jasmin; Wagner, Andrea Christine; Wagner, Robert; Williamson, Christina; Yan, Chao; Connolly, Paul James; Dorsey, James Robert; Duplissy, Jonathan; Ehrhart, Sebastian; Frege, Carla; Gordon, Hamish; Hoyle, Christopher Robert; Bjerring Kristensen, Thomas; Steiner, Gerhard; McPherson Donahue, Neil; Flagan, Richard; Gallagher, Martin William; Kirkby, Jasper; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Stratmann, Frank; Tomé, António

    2016-03-01

    Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud particle-size range below 50 μm, remains challenging in mixed phase, often unstable environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water, and ice particles. In this paper, optical property measurements of mixed-phase clouds and viscous secondary organic aerosol (SOA) are presented. We report observations of significant liquid-viscous SOA particle polarization transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarization ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulfate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentrations and mixtures with respect to the CLOUD 8-9 campaigns and its potential contribution to tropical troposphere layer analysis.

  5. Developing large-scale forcing data for single-column and cloud-resolving models from the Mixed-Phase Arctic Cloud Experiment

    SciTech Connect

    Xie, Shaocheng; Klein, Stephen A.; Zhang, Minghua; Yio, John J.; Cederwall, Richard T.; McCoy, Renata

    2006-10-05

    [1] This study represents an effort to develop Single-Column Model (SCM) and Cloud-Resolving Model large-scale forcing data from a sounding array in the high latitudes. An objective variational analysis approach is used to process data collected from the Atmospheric Radiation Measurement Program (ARM) Mixed-Phase Arctic Cloud Experiment (M-PACE), which was conducted over the North Slope of Alaska in October 2004. In this method the observed surface and top of atmosphere measurements are used as constraints to adjust the sounding data from M-PACE in order to conserve column-integrated mass, heat, moisture, and momentum. Several important technical and scientific issues related to the data analysis are discussed. It is shown that the analyzed data reasonably describe the dynamic and thermodynamic features of the Arctic cloud systems observed during M-PACE. Uncertainties in the analyzed forcing fields are roughly estimated by examining the sensitivity of those fields to uncertainties in the upper-air data and surface constraints that are used in the analysis. Impacts of the uncertainties in the analyzed forcing data on SCM simulations are discussed. Results from the SCM tests indicate that the bulk features of the observed Arctic cloud systems can be captured qualitatively well using the forcing data derived in this study, and major model errors can be detected despite the uncertainties that exist in the forcing data as illustrated by the sensitivity tests. Lastly, the possibility of using the European Center for Medium-Range Weather Forecasts analysis data to derive the large-scale forcing over the Arctic region is explored.

  6. Developing large-scale forcing data for single-column and cloud-resolving models from the Mixed-Phase Arctic Cloud Experiment

    DOE PAGESBeta

    Xie, Shaocheng; Klein, Stephen A.; Zhang, Minghua; Yio, John J.; Cederwall, Richard T.; McCoy, Renata

    2006-10-05

    [1] This study represents an effort to develop Single-Column Model (SCM) and Cloud-Resolving Model large-scale forcing data from a sounding array in the high latitudes. An objective variational analysis approach is used to process data collected from the Atmospheric Radiation Measurement Program (ARM) Mixed-Phase Arctic Cloud Experiment (M-PACE), which was conducted over the North Slope of Alaska in October 2004. In this method the observed surface and top of atmosphere measurements are used as constraints to adjust the sounding data from M-PACE in order to conserve column-integrated mass, heat, moisture, and momentum. Several important technical and scientific issues related tomore » the data analysis are discussed. It is shown that the analyzed data reasonably describe the dynamic and thermodynamic features of the Arctic cloud systems observed during M-PACE. Uncertainties in the analyzed forcing fields are roughly estimated by examining the sensitivity of those fields to uncertainties in the upper-air data and surface constraints that are used in the analysis. Impacts of the uncertainties in the analyzed forcing data on SCM simulations are discussed. Results from the SCM tests indicate that the bulk features of the observed Arctic cloud systems can be captured qualitatively well using the forcing data derived in this study, and major model errors can be detected despite the uncertainties that exist in the forcing data as illustrated by the sensitivity tests. Lastly, the possibility of using the European Center for Medium-Range Weather Forecasts analysis data to derive the large-scale forcing over the Arctic region is explored.« less

  7. Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments

    NASA Astrophysics Data System (ADS)

    Kim, J.; Ahlm, L.; Yli-Juuti, T.; Lawler, M.; Keskinen, H.; Tröstl, J.; Schobesberger, S.; Duplissy, J.; Amorim, A.; Bianchi, F.; Donahue, N. M.; Flagan, R. C.; Hakala, J.; Heinritzi, M.; Jokinen, T.; Kürten, A.; Laaksonen, A.; Lehtipalo, K.; Miettinen, P.; Petäjä, T.; Rissanen, M. P.; Rondo, L.; Sengupta, K.; Simon, M.; Tomé, A.; Williamson, C.; Wimmer, D.; Winkler, P. M.; Ehrhart, S.; Ye, P.; Kirkby, J.; Curtius, J.; Kulmala, M.; Lehtinen, K. E. J.; Smith, J. N.; Riipinen, I.; Virtanen, A.

    2015-07-01

    Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e. particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake constrains their chemical composition. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) experiments performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size indicating decreasing acidity of particles. No clear effect of the sulfuric acid monomer concentrations on the hygroscopicities of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid monomer concentrations. In particular, when the concentrations of sulfuric acid was 5.1 × 106 molecules cm-3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01 close to the value reported for dimethylamine sulfate (DMAS) (κDMAS ~ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid-dimethylamine experiments increased with increasing particle size. The κ values of particles in the presence of sulfuric acid and organics were

  8. Overview of the Field Phase of the NASA Tropical Cloud Systems and Processes (TCSP)Experiment

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Zipser, Edward; Heymsfield, Gerald M.; Kakar, Ramesh; Halverson Jeffery; Rogers, Robert; Black, Michael

    2006-01-01

    The Tropical Cloud Systems and Processes experiment is sponsored by the National Aeronautics and Space Administration (NASA) to investigate characteristics of tropical cyclone genesis, rapid intensification and rainfall using a three-pronged approach that emphasizes satellite information, suborbital observations and numerical model simulations. Research goals include demonstration and assessment of new technology, improvements to numerical model parameterizations, and advancements in data assimilation techniques. The field phase of the experiment was based in Costa Rica during July 2005. A fully instrumented NASA ER-2 high altitude airplane was deployed with Doppler radar, passive microwave instrumentation, lightning and electric field sensors and an airborne simulator of visible and infrared satellite sensors. Other assets brought to TCSP were a low flying uninhabited aerial vehicle, and a surface-based radiosonde network. In partnership with the Intensity Forecasting Experiment of the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division, two NOAA P-3 aircraft instrumented with radar, passive microwave, microphysical, and dropsonde instrumentation were also deployed to Costa Rica. The field phase of TCSP was conducted in Costa Rica to take advantage of the geographically compact tropical cyclone genesis region of the Eastern Pacific Ocean near Central America. However, the unusual 2005 hurricane season provided numerous opportunities to sample tropical cyclone development and intensification in the Caribbean Sea and Gulf of Mexico as well. Development of Hurricane Dennis and Tropical Storm Gert were each investigated over several days in addition to Hurricane Emily as it was close to Saffir-Simpson Category 5 intensity. An overview of the characteristics of these storms along with the pregenesis environment of Tropical Storm Eugene in the Eastern Pacific will be presented.

  9. Cloud fraction, layer, and direction of movement results from sky cameras during the FIRE IFO, Coffeyville, Kansas, experiment for the period Nov. 12 through Dec. 9, 1991

    NASA Technical Reports Server (NTRS)

    Purgold, Gerald C.; Wheeler, Robert J.; Whitlock, Charles H.

    1992-01-01

    Tables and figures are presented which show local site observations of cloud fractions, the number of cloud layers, direction of movement, and precipitation data collected during the FIRE (First ISCCP Regional Experiment) Phase 2 Cirrus Intensive Field Observations (IFO) conducted in Coffeyville, Kansas during November and December, 1991. Selected data are also presented at the times of the TIROS Operational Vertical Sounder (TOVS) satellite overpass. Several major scientific projects have used surface-based observations of clouds to compare directly with those being observed from satellites. Characterizing the physical properties of clouds is extremely useful in obtaining a more accurate analysis of the effect of clouds and their movements on weather and climate. It is the purpose of this paper to report data collected during the FIRE Phase 2 IFO experiment and to provide a brief history of such a surface-based system and the technical information required for recording local cloud parameters.

  10. The Midlatitude Continental Convective Clouds Experiment (MC3E) sounding network: operations, processing and analysis

    DOE PAGESBeta

    Jensen, M. P.; Toto, T.; Troyan, D.; Ciesielski, P. E.; Holdridge, D.; Kyrouac, J.; Schatz, J.

    2014-09-12

    The Midlatitude Continental Convective Clouds Experiment (MC3E) took place during the spring of 2011 centered in north-central Oklahoma, USA. The main goal of this field campaign was to capture the dynamical and microphysical characteristics of precipitating convective systems in the Central Plains. A major component of the campaign was a 6-site radiosonde array designed to capture the large-scale variability of the atmospheric state with the intent of deriving model forcing datasets. Over the course of the 46 day MC3E campaign, a total of 1362 radiosondes were launched from the enhanced sonde network. This manuscript describes the details of the instrumentationmore » used as part of the sounding array, the data processing activities including quality checks and humidity bias corrections and an analysis of the impacts of bias correction and algorithm assumptions on the determination of convective levels and indices. It is found that corrections for known radiosonde humidity biases and assumptions regarding the characteristics of the surface convective parcel result in significant differences in the derived values of convective levels and indices in many soundings.« less

  11. The Midlatitude Continental Convective Clouds Experiment (MC3E) sounding network: operations, processing and analysis

    DOE PAGESBeta

    Jensen, M. P.; Toto, T.; Troyan, D.; Ciesielski, P. E.; Holdridge, D.; Kyrouac, J.; Schatz, J.; Zhang, Y.; Xie, S.

    2015-01-27

    The Midlatitude Continental Convective Clouds Experiment (MC3E) took place during the spring of 2011 centered in north-central Oklahoma, USA. The main goal of this field campaign was to capture the dynamical and microphysical characteristics of precipitating convective systems in the US Central Plains. A major component of the campaign was a six-site radiosonde array designed to capture the large-scale variability of the atmospheric state with the intent of deriving model forcing data sets. Over the course of the 46-day MC3E campaign, a total of 1362 radiosondes were launched from the enhanced sonde network. This manuscript provides details on the instrumentationmore » used as part of the sounding array, the data processing activities including quality checks and humidity bias corrections and an analysis of the impacts of bias correction and algorithm assumptions on the determination of convective levels and indices. It is found that corrections for known radiosonde humidity biases and assumptions regarding the characteristics of the surface convective parcel result in significant differences in the derived values of convective levels and indices in many soundings. In addition, the impact of including the humidity corrections and quality controls on the thermodynamic profiles that are used in the derivation of a large-scale model forcing data set are investigated. The results show a significant impact on the derived large-scale vertical velocity field illustrating the importance of addressing these humidity biases.« less

  12. Aerosol and cloud sensing with the lidar in-space technology experiment (LITE)

    NASA Astrophysics Data System (ADS)

    Winker, David M.; McCormick, Michael P.

    1994-12-01

    The Lidar In-space Technology Experiment (LITE) is a multi-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. The LITE instrument is built around a three-wavelength Nd:YAG laser and a 1-meter diameter telescope. The laser operates at 10 Hz and produces about 500 mJ per pulse at 1064 nm and 532 nm, and 150 mJ per pulse at 355 nm. The objective of the LITE program is to develop the engineering processes required for space lidar and to demonstrate applications of space-based lidar to remote sensing of the atmosphere. The LITE instrument was designed to study a wide range of cloud and aerosol phenomena. To this end, a comprehensive program of scientific investigations has been planned for the upcoming mission. Simulations of on-orbit performance show the instrument has sufficient sensitivity to detect even thin cirrus on a single-shot basis. Signal averaging provides the capability of measuring the height and structure of the planetary boundary layer, aerosols in the free troposphere, the stratospheric aerosol layer, and density profiles to an altitude of 40 km. The instrument has successfully completed a ground-test phase and is scheduled to fly on the Space Shuttle Discovery for a 9- day mission in September 1994.

  13. Aerosol and cloud sensing with the Lidar In-space Technology Experiment (LITE)

    NASA Technical Reports Server (NTRS)

    Winker, D. M.; McCormick, M. P.

    1994-01-01

    The Lidar In-space Technology Experiment (LITE) is a multi-wavelength backscatter lidar developed by NASA Langley Research Center to fly on the Space Shuttle. The LITE instrument is built around a three-wavelength ND:YAG laser and a 1-meter diameter telescope. The laser operates at 10 Hz and produces about 500 mJ per pulse at 1064 nm and 532 nm, and 150 mJ per pulse at 355 nm. The objective of the LITE program is to develop the engineering processes required for space lidar and to demonstrate applications of space-based lidar to remote sensing of the atmosphere. The LITE instrument was designed to study a wide range of cloud and aerosol phenomena. To this end, a comprehensive program of scientific investigations has been planned for the upcoming mission. Simulations of on-orbit performance show the instrument has sufficient sensitivity to detect even thin cirrus on a single-shot basis. Signal averaging provides the capability of measuring the height and structure of the planetary boundary layer, aerosols in the free troposphere, the stratospheric aerosol layer, and density profiles to an altitude of 40 km. The instrument has successfully completed a ground-test phase and is scheduled to fly on the Space Shuttle Discovery for a 9-day mission in September 1994.

  14. Cirrus Clouds Optical, Microphysical and Radiative Properties Observed During Crystal-Face Experiment: I. A Radar-Lidar Retrieval System

    NASA Technical Reports Server (NTRS)

    Mitrescu, C.; Haynes, J. M.; Stephens, G. L.; Heymsfield, G. M.; McGill, M. J.

    2004-01-01

    A method of retrieving cloud microphysical properties using combined observations from both cloud radar and lidar is introduced. This retrieval makes use of an improvement to the traditional optimal estimation retrieval method, whereby a series of corrections are applied to the state vector during the search for an iterative solution. This allows faster convergence to a solution and is less processor intensive. The method is first applied to a synthetic cloud t o demonstrate its validity, and it is shown that the retrieval reliably reproduces vertical profiles of ice water content. The retrieval method is then applied to radar and lidar observations from the CRYSTAL-FACE experiment, and vertical profiles of ice crystal diameter, number concentration, and ice water content are retrieved for a cirrus cloud layers observed one day of that experiment. The validity of the relationship between visible extinction coefficient and radar reflectivity was examined. While synthetic tests showed such a functional relationship, the measured data only partially supported such a conclusion. This is due to errors in the forward model (as explained above) as well as errors in the data sets, including possible mismatch between lidar and radar profiles or errors in the optical depth. Empirical relationships between number concentrations and mean particle diameter were also examined. The results indicate that a distinct and robust relationship exists between these retrieved quantities and it is argued that such a relationship is more than an artifact of the retrieval process offering insight into the nature of the microphysical processes taking place in cirrus.

  15. Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments

    NASA Astrophysics Data System (ADS)

    Kim, J.; Ahlm, L.; Yli-Juuti, T.; Lawler, M.; Keskinen, H.; Tröstl, J.; Schobesberger, S.; Duplissy, J.; Amorim, A.; Bianchi, F.; Donahue, N. M.; Flagan, R. C.; Hakala, J.; Heinritzi, M.; Jokinen, T.; Kürten, A.; Laaksonen, A.; Lehtipalo, K.; Miettinen, P.; Petäjä, T.; Rissanen, M. P.; Rondo, L.; Sengupta, K.; Simon, M.; Tomé, A.; Williamson, C.; Wimmer, D.; Winkler, P. M.; Ehrhart, S.; Ye, P.; Kirkby, J.; Curtius, J.; Baltensperger, U.; Kulmala, M.; Lehtinen, K. E. J.; Smith, J. N.; Riipinen, I.; Virtanen, A.

    2016-01-01

    Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106 molecules cm-3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01: close to the value reported for dimethylaminium sulfate (DMAS) (κDMAS ˜ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid-imethylamine experiments increased with increasing particle size. The κ values of particles in the presence of

  16. The NASA CloudSat/GPM Light Precipitation Validation Experiment (LPVEx)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; L'Ecuyer, Tristan; Moisseev, Dmitri

    2011-01-01

    Ground-based measurements of cool-season precipitation at mid and high latitudes (e.g., above 45 deg N/S) suggest that a significant fraction of the total precipitation volume falls in the form of light rain, i.e., at rates less than or equal to a few mm/h. These cool-season light rainfall events often originate in situations of a low-altitude (e.g., lower than 2 km) melting level and pose a significant challenge to the fidelity of all satellite-based precipitation measurements, especially those relying on the use of multifrequency passive microwave (PMW) radiometers. As a result, significant disagreements exist between satellite estimates of rainfall accumulation poleward of 45 deg. Ongoing efforts to develop, improve, and ultimately evaluate physically-based algorithms designed to detect and accurately quantify high latitude rainfall, however, suffer from a general lack of detailed, observationally-based ground validation datasets. These datasets serve as a physically consistent framework from which to test and refine algorithm assumptions, and as a means to build the library of algorithm retrieval databases in higher latitude cold-season light precipitation regimes. These databases are especially relevant to NASA's CloudSat and Global Precipitation Measurement (GPM) ground validation programs that are collecting high-latitude precipitation measurements in meteorological systems associated with frequent coolseason light precipitation events. In an effort to improve the inventory of cool-season high-latitude light precipitation databases and advance the physical process assumptions made in satellite-based precipitation retrieval algorithm development, the CloudSat and GPM mission ground validation programs collaborated with the Finnish Meteorological Institute (FMI), the University of Helsinki (UH), and Environment Canada (EC) to conduct the Light Precipitation Validation Experiment (LPVEx). The LPVEx field campaign was designed to make detailed measurements of

  17. Validating a large geophysical data set: Experiences with satellite-derived cloud parameters

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Haskins, Robert D.; Knighton, James E.; Pursch, Andrew; Granger-Gallegos, Stephanie

    1992-01-01

    We are validating the global cloud parameters derived from the satellite-borne HIRS2 and MSU atmospheric sounding instrument measurements, and are using the analysis of these data as one prototype for studying large geophysical data sets in general. The HIRS2/MSU data set contains a total of 40 physical parameters, filling 25 MB/day; raw HIRS2/MSU data are available for a period exceeding 10 years. Validation involves developing a quantitative sense for the physical meaning of the derived parameters over the range of environmental conditions sampled. This is accomplished by comparing the spatial and temporal distributions of the derived quantities with similar measurements made using other techniques, and with model results. The data handling needed for this work is possible only with the help of a suite of interactive graphical and numerical analysis tools. Level 3 (gridded) data is the common form in which large data sets of this type are distributed for scientific analysis. We find that Level 3 data is inadequate for the data comparisons required for validation. Level 2 data (individual measurements in geophysical units) is needed. A sampling problem arises when individual measurements, which are not uniformly distributed in space or time, are used for the comparisons. Standard 'interpolation' methods involve fitting the measurements for each data set to surfaces, which are then compared. We are experimenting with formal criteria for selecting geographical regions, based upon the spatial frequency and variability of measurements, that allow us to quantify the uncertainty due to sampling. As part of this project, we are also dealing with ways to keep track of constraints placed on the output by assumptions made in the computer code. The need to work with Level 2 data introduces a number of other data handling issues, such as accessing data files across machine types, meeting large data storage requirements, accessing other validated data sets, processing speed

  18. Aerosol and nucleation research in support of NASA cloud physics experiments in space. [ice nuclei generator for the atmospheric cloud physics laboratory on Spacelab

    NASA Technical Reports Server (NTRS)

    Vali, G.; Rogers, D.; Gordon, G.; Saunders, C. P. R.; Reischel, M.; Black, R.

    1978-01-01

    Tasks performed in the development of an ice nucleus generator which, within the facility concept of the ACPL, would provide a test aerosol suitable for a large number and variety of potential experiments are described. The impact of Atmospheric Cloud Physics Laboratory scientific functional requirements on ice nuclei generation and characterization subsystems was established. Potential aerosol generating systems were evaluated with special emphasis on reliability, repeatability and general suitability for application in Spacelab. Possible contamination problems associated with aerosol generation techniques were examined. The ice nucleating abilities of candidate test aerosols were examined and the possible impact of impurities on the nucleating abilities of those aerosols were assessed as well as the relative merits of various methods of aerosol size and number density measurements.

  19. The 27-28 October 1986 FIRE cirrus case study - Meteorology and clouds. [First International Satellite Cloud Climatology Project Regional Experiment

    NASA Technical Reports Server (NTRS)

    Starr, David O'C.; Wylie, Donald P.

    1990-01-01

    A detailed case study is conducted of cirrus clouds that were observed intensely over a 36-h period from 1200 UTC October 27 to 0000 UTC October 29, 1986. The clouds varied in density and structure as synoptic and mesoscale features passed through the region. The study seeks to provide a meteorological overview including a synoptic and regional perspective; to document the rawinsonde-resolved atmospheric structure and large-scale forcing associated with the observed cloud systems; and to provide understanding of the relationship between atmospheric structure and the character of the corresponding cloud fields. Regional analyses of the static stability structure and vertical motion are presented and interpreted with respect to the characteristics of the corresponding cloud fields as deduced from satellite and lidar observations. It is suggested that mesoscale organization must be taken into account in parametric treatments of cirrus for large-scale atmospheric models. It is shown that cloud generation typically occurred at multiple levels.

  20. Ice clouds optical properties in the Far Infrared from the ECOWAR-COBRA Experiment

    NASA Astrophysics Data System (ADS)

    Rizzi, Rolando; Tosi, Ennio

    ECOWAR-COBRA (Earth COoling by WAter vapouR emission -Campagna di Osservazioni della Banda Rotazionale del vapor d'Acqua) field campaign took place in Italy from 3 to 17 March 2007 with the main goal of studying the scarcely sensed atmospheric emission occurring beyond 17 microns. Instrumentation involved in the campaign included two different Fourier Transforms Spectrometers (FTS) : REFIR-PAD (at Testa Grigia Station, 3500 m a.s.l.) and FTIR-ABB (at Cervinia Station, 1990 m a.s.l.). In this work cloudy sky data have been ana-lyzed. A cloud properties retrieval methodology (RT-RET), based on high spectral resolution measurements in the atmospheric window (800-1000 cm-1), is applied to both FTS sensors. Cloud properties determined from the infrared retrievals are compared with those obtained from Raman lidar taken by the BASIL Lidar system that was operating at Cervinia station. Cloud microphysical and optical properties retrieved by RT-RET are used to perform forward simulations over the entire FTSs measurements spectral interval. Results are compared to FTS data to test the ability of single scattering ice crystals models to reproduce cloudy sky radiances in the Far Infra-Red (FIR) part of the spectrum. New methods to retrieve cloud optical and microphysical properties exploiting high spectral resolution FIR measurements are also investigated.

  1. Current and future advances in optical multiangle remote sensing of aerosols and clouds based on Terra/MISR experience

    NASA Astrophysics Data System (ADS)

    Diner, David J.; Davies, Roger; Kahn, Ralph; Martonchik, John; Gaitley, Barbara; Davis, Ab

    2006-12-01

    Through acquisition of well-calibrated near-nadir and oblique-angle imagery (0° - 70° zenith angles) at moderately high spatial resolution (275 m - 1.1 km), the Multi-angle Imaging SpectroRadiometer (MISR) experiment aboard NASA's Terra satellite has taken atmospheric remote sensing in new directions. Retrieval algorithms that were largely conceptual prior to Terra launch in 1999 have led to publicly available aerosol and cloud products with direct application to global climate and particulate air quality research. Automated algorithms making use of stereoscopic parallax, time lapse among the nine angular views, and the variation in radiance with view angle, scattering angle, and wavelength (446-866 nm) make possible unique data sets including geometric cloud and aerosol plume heights derived independently of emissivity or temperature assumptions; height-resolved cloud-tracked winds; and aerosol optical depth and particle type over a wide variety of surfaces including bright desert source regions. To illustrate these capabilities, examples of regional and global MISR data products, quantitative evaluations of product accuracies based on comparisons with independent data sources, and time series showing seasonal and interannual variations are presented here. Future sensor improvements aimed at building upon MISR heritage, including expanding the spectral coverage to ultraviolet and shortwave infrared wavelengths, adding polarization channels, and widening the sensor swath, are also discussed.

  2. High Frequency Propagation modeling in a disturbed background ionosphere: Results from the Metal Oxide Space Cloud (MOSC) experiment

    NASA Astrophysics Data System (ADS)

    Joshi, D. R.; Groves, K. M.

    2015-12-01

    The Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud. A host of diagnostic instruments were used to probe and characterize the cloud including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. Data from ALTAIR incoherent scatter radar and HF radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. During the first release the ionosphere was disturbed, rising rapidly and spread F formed within minutes after the release. To address the disturbed conditions present during the first release, we have developed a new method of assimilating oblique ionosonde data to generate the background ionosphere that can have numerous applications for HF systems. The link budget analysis of the received signals from the HF transmitters explains the missing low frequencies in the received signals along the great circle path. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural propagation environment.

  3. Wind sets from SMS images - An assessment of quality for GATE. [Synchronous Meteorological Satellite cloud monitoring for GARP Atlantic Tropical Experiment

    NASA Technical Reports Server (NTRS)

    Suchman, D.; Martin, D. W.

    1976-01-01

    The paper analyzes the accuracy, representativeness, and reproducibility of tracer winds in the 1974 GARP Atlantic Tropical Experiment whose data are used as ground truth. The tracer winds were generated by tracking clouds in SMS (Synchronous Meteorological Satellite) images. Data availability limits comparisons to satellite winds with ship winds at the surface and at 250 mb. Attention is focused on how accurately the cloud displacements can be measured and on the extent to which the cloud displacements represent the wind field. Operator errors in obtaining the cloud displacements are examined in a series of reproducibility tests and wind sets. Differences between proximate satellite and ship winds were all under 3 m/sec. Representativeness of cloud tracers for cumulus and cirrus level flow is found to be good within the accuracy of currently available ground truth data.

  4. Biomass Smoke Influences on Deep Convection during the 2011 Midlatitude Continental Convective Clouds Experiment (MC3E)

    NASA Astrophysics Data System (ADS)

    Dong, X.; Logan, T.; Xi, B.

    2015-12-01

    Three deep convective cloud cases were selected during the 2011 Mid-Latitude Continental Convective Clouds Experiment (MC3E). Although biomass burning smoke advected from Mexico and Central America was the dominant source of cloud condensation nuclei (CCN) for deep convective cloud formation, the 11 May, 20 May, and 23 May cases exhibited different convective characteristics. The convection in the 11 May and 23 May cases formed in smoke laden environments in the presence of convective available potential energy (CAPE) values exceeding 1000 m2 s-2 and 3000 m2 s-2 along with low-level (0-1 km) shear of 10.3 m s-1 and 5.1 m s-1, respectively. The 11 May case had linear convection while the 23 May case featured discrete supercells. The 20 May case featured elevated linear convection that formed in a more moist environment with cleaner aerosol conditions, weak CAPE (<50 m2 s-2), and stronger low-level shear (25.6 m s-1). Though the 20 May case had the highest precipitation amount and duration, the 23 May case had the highest ice water content (IWC) in the upper levels of the convection (>9 km) suggesting a warm rain suppression mechanism caused by a combination of strong aerosol loading, large CAPE, and weak low-level wind shear. The observed results for the 20 May and 23 May cases agree well with recent modeling studies that simulated the convection and precipitation in these cases. Furthermore, the modeling of the 11 May case is suggested since the abundant amount of smoke CCN did not greatly enhance the overall precipitation amount and could be a possible aerosol-induced precipitation suppression case.

  5. Testing ice microphysics parameterizations in the NCAR Community Atmospheric Model Version 3 using Tropical Warm Pool-International Cloud Experiment data

    DOE PAGESBeta

    Wang, Weiguo; Liu, Xiaohong; Xie, Shaocheng; Boyle, Jim; McFarlane, Sally A.

    2009-07-23

    Here, cloud properties have been simulated with a new double-moment microphysics scheme under the framework of the single-column version of NCAR Community Atmospheric Model version 3 (CAM3). For comparison, the same simulation was made with the standard single-moment microphysics scheme of CAM3. Results from both simulations compared favorably with observations during the Tropical Warm Pool–International Cloud Experiment by the U.S. Department of Energy Atmospheric Radiation Measurement Program in terms of the temporal variation and vertical distribution of cloud fraction and cloud condensate. Major differences between the two simulations are in the magnitude and distribution of ice water content within themore » mixed-phase cloud during the monsoon period, though the total frozen water (snow plus ice) contents are similar. The ice mass content in the mixed-phase cloud from the new scheme is larger than that from the standard scheme, and ice water content extends 2 km further downward, which is in better agreement with observations. The dependence of the frozen water mass fraction on temperature from the new scheme is also in better agreement with available observations. Outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from the simulation with the new scheme is, in general, larger than that with the standard scheme, while the surface downward longwave radiation is similar. Sensitivity tests suggest that different treatments of the ice crystal effective radius contribute significantly to the difference in the calculations of TOA OLR, in addition to cloud water path. Numerical experiments show that cloud properties in the new scheme can respond reasonably to changes in the concentration of aerosols and emphasize the importance of correctly simulating aerosol effects in climate models for aerosol-cloud interactions. Further evaluation, especially for ice cloud properties based on in-situ data, is needed.« less

  6. Testing ice microphysics parameterizations in the NCAR Community Atmospheric Model Version 3 using Tropical Warm Pool-International Cloud Experiment data

    SciTech Connect

    Wang, Weiguo; Liu, Xiaohong; Xie, Shaocheng; Boyle, Jim; McFarlane, Sally A.

    2009-07-23

    Here, cloud properties have been simulated with a new double-moment microphysics scheme under the framework of the single-column version of NCAR Community Atmospheric Model version 3 (CAM3). For comparison, the same simulation was made with the standard single-moment microphysics scheme of CAM3. Results from both simulations compared favorably with observations during the Tropical Warm Pool–International Cloud Experiment by the U.S. Department of Energy Atmospheric Radiation Measurement Program in terms of the temporal variation and vertical distribution of cloud fraction and cloud condensate. Major differences between the two simulations are in the magnitude and distribution of ice water content within the mixed-phase cloud during the monsoon period, though the total frozen water (snow plus ice) contents are similar. The ice mass content in the mixed-phase cloud from the new scheme is larger than that from the standard scheme, and ice water content extends 2 km further downward, which is in better agreement with observations. The dependence of the frozen water mass fraction on temperature from the new scheme is also in better agreement with available observations. Outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) from the simulation with the new scheme is, in general, larger than that with the standard scheme, while the surface downward longwave radiation is similar. Sensitivity tests suggest that different treatments of the ice crystal effective radius contribute significantly to the difference in the calculations of TOA OLR, in addition to cloud water path. Numerical experiments show that cloud properties in the new scheme can respond reasonably to changes in the concentration of aerosols and emphasize the importance of correctly simulating aerosol effects in climate models for aerosol-cloud interactions. Further evaluation, especially for ice cloud properties based on in-situ data, is needed.

  7. Cloud Infrastructure & Applications - CloudIA

    NASA Astrophysics Data System (ADS)

    Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

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

  8. Tomographic retrieval of cloud liquid water fields from a single scanning microwave radiometer aboard a moving platform – Part 1: Field trial results from the Wakasa Bay experiment

    SciTech Connect

    Huang, D.; Gasiewski, A.; Wiscombe, W.

    2010-07-22

    Tomographic methods offer great potential for retrieving three-dimensional spatial distributions of cloud liquid water from radiometric observations by passive microwave sensors. Fixed tomographic systems require multiple radiometers, while mobile systems can use just a single radiometer. Part 1 (this paper) examines the results from a limited cloud tomography trial with a single-radiometer airborne system carried out as part of the 2003 AMSR-E validation campaign over Wakasa Bay of the Sea of Japan. During this trial, the Polarimetric Scanning Radiometer (PSR) and Microwave Imaging Radiometer (MIR) aboard the NASA P-3 research aircraft provided a useful dataset for testing the cloud tomography method over a system of low-level clouds. We do tomographic retrievals with a constrained inversion algorithm using three configurations: PSR, MIR, and combined PSR and MIR data. The liquid water paths from the PSR retrieval are consistent with those from the MIR retrieval. The retrieved cloud field based on the combined data appears to be physically plausible and consistent with the cloud image obtained by a cloud radar. We find that some vertically-uniform clouds appear at high altitudes in the retrieved field where the radar shows clear sky. This is likely due to the sub-optimal data collection strategy. This sets the stage for Part 2 of this study that aims to define optimal data collection strategies using observation system simulation experiments.

  9. Airborne LIDAR Measurements of Water Vapor, Ozone, Clouds, and Aerosols in the Tropics Near Central America During the TC4 Experiment

    NASA Technical Reports Server (NTRS)

    Kooi, Susan; Fenn, Marta; Ismail, Syed; Ferrare, Richard; Hair, John; Browell, Edward; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Simpson, Steven

    2008-01-01

    Large scale distributions of ozone, water vapor, aerosols, and clouds were measured throughout the troposphere by two NASA Langley lidar systems on board the NASA DC-8 aircraft as part of the Tropical Composition, Cloud, and Climate Coupling Experiment (TC4) over Central and South America and adjacent oceans in the summer of 2007. Special emphasis was placed on the sampling of convective outflow and transport, sub-visible cirrus clouds, boundary layer aerosols, Saharan dust, volcanic emissions, and urban and biomass burning plumes. This paper presents preliminary results from this campaign, and demonstrates the value of coordinated measurements by the two lidar systems.

  10. Alabama Ground Operations during the Deep Convective Clouds and Chemistry Experiment

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence; Blakeslee, Richard; Koshak, William; Bain, Lamont; Rogers, Ryan; Kozlowski, Danielle; Sherrer, Adam; Saari, Matt; Bigelbach, Brandon; Scott, Mariana; Schultz, Elise; Schultz, Chris; Gatlin, Patrick; Wingo, Matt; Phillips, Dustin; Phillips, Chris; Peterson, Harold; Bailey, Jeff; Frederickson, Terryn; Hall, John; Bart, Nicole; Becker, Melissa; Pinkney, Kurtis; Rowe, Scott; Starzec, Mariusz

    2013-01-01

    The Deep Convective Clouds and Chemistry (DC3) field campaign investigates the impact of deep, midlatitude convective clouds, including their dynamical, physical and lighting processes, on upper tropospheric composition and chemistry. DC3 science operations took place from 14 May to 30 June 2012. The DC3 field campaign utilized instrumented aircraft and ground ]based observations. The NCAR Gulfstream ]V (GV) observed a variety of gas ]phase species, radiation and cloud particle characteristics in the high ]altitude outflow of storms while the NASA DC ]8 characterized the convective inflow. Groundbased radar networks were used to document the kinematic and microphysical characteristics of storms. In order to study the impact of lightning on convective outflow composition, VHF ]based lightning mapping arrays (LMAs) provided detailed three ]dimensional measurements of flashes. Mobile soundings were utilized to characterize the meteorological environment of the convection. Radar, sounding and lightning observations were also used in real ]time to provide forecasting and mission guidance to the aircraft operations. Combined aircraft and ground ]based observations were conducted at three locations, 1) northeastern Colorado, 2) Oklahoma/Texas and 3) northern Alabama, to study different modes of deep convection in a variety of meteorological and chemical environments. The objective of this paper is to summarize the Alabama ground operations and provide a preliminary assessment of the ground ]based observations collected over northern Alabama during DC3. The multi ] Doppler, dual ]polarization radar network consisted of the UAHuntsville Advanced Radar for Meteorological and Operational Research (ARMOR), the UAHuntsville Mobile Alabama X ]band (MAX) radar and the Hytop (KHTX) Weather Surveillance Radar 88 Doppler (WSR ]88D). Lightning frequency and structure were observed in near real ]time by the NASA MSFC Northern Alabama LMA (NALMA). Pre ]storm and inflow proximity

  11. Analysis and forecast experiments incorporating satellite soundings and cloud and water vapor drift wind information

    NASA Technical Reports Server (NTRS)

    Goodman, Brian M.; Diak, George R.; Mills, Graham A.

    1986-01-01

    A system for assimilating conventional meteorological data and satellite-derived data in order to produce four-dimensional gridded data sets of the primary atmospheric variables used for updating limited area forecast models is described. The basic principles of a data assimilation scheme as proposed by Lorenc (1984) are discussed. The design of the system and its incremental assimilation cycles are schematically presented. The assimilation system was tested using radiosonde, buoy, VAS temperature, dew point, gradient wind data, cloud drift, and water vapor motion data. The rms vector errors for the data are analyzed.

  12. Hydroxyl (OH) and hydroperoxyl (HO2) in and out of clouds during the Deep Convective Clouds and Chemistry (DC3) experiment

    NASA Astrophysics Data System (ADS)

    Brune, W. H.; Mao, J.; Ren, X.; Zhang, L.; Miller, D.

    2013-12-01

    Atmospheric hydroxyl (OH) and hydroperoxyl (HO2) are readily taken up into cloud drops and if HO2 is consumed in the aqueous phase, as evidence suggests, then aqueous phase chemistry can significantly affect the gas-phase amounts of OH and HO2, particularly HO2. Testing these effects is best done by comparing in situ measurements to models that are constrained by the simultaneous measurements of environmental factors and other chemical species. However, in addition to changes in OH and HO2, many environmental and chemical conditions can change, some dramatically, when the aircraft goes into a cloud. A further complication is that the measurement capability of some instruments is not well characterized in clouds. For DC3, the NASA DC-8 had extensive measurement suite for constraining box models that can be compared to the OH and HO2 measurements made by the Airborne Tropospheric Hydrogen Oxides Sensor. In addition, the DC-8 was frequently flying in and around clouds, thus giving many case studies in clouds of different types and densities. For this presentation, we analyze high-resolution HO2 measurements compared to a box model in the presence and absence of clouds in order to examine the potential effects of OH and HO2 uptake on gas-phase OH and HO2 abundances.

  13. VOC Source and Inflow Characterization during the Deep Convective Cloud and Chemistry (DC3) experiment

    NASA Astrophysics Data System (ADS)

    Blake, N. J.; Hartt, G.; Barletta, B.; Simpson, I. J.; Schroeder, J.; Hung, Y.; Marrero, J.; Gartner, A.; Hirsch, C.; Meinardi, S.; Blake, D. R.; Zhang, Y.; Apel, E. C.; Hornbrook, R. S.; Campos, T. L.; Emmons, L. K.

    2013-12-01

    More than 50 volatile organic compounds (VOCs) were measured during the Deep Convective Clouds and Chemistry Project (DC3) field campaign, which was based out of Salina, KS May 10 - June 30, 2012. DC3 investigated the impact of deep, mid-latitude continental convective clouds on upper tropospheric composition and chemistry. The UCI Whole Air Sampler (WAS) measured VOCs on board the NASA DC-8 aircraft and the NCAR Trace Organic Gas Analyzer (TOGA) measured VOCs on board the NSF GV. Coordinated flights between the two aircraft produced a rich dataset with which to characterize the inflow and outflow of convective events. While probing storm inflow, numerous natural and anthropogenic sources were encountered, including oil and gas wells in Colorado, Texas, and Oklahoma, biomass burning, biogenic VOC emissions, and other anthropogenic sources (urban, feedlots, etc). The significant and widespread influence of oil and gas activities dominated VOC alkane distributions during DC3, in both inflow and outflow, effectively illustrating the connection between emission and fast vertical transport of VOCs into the free troposphere. We present a mass balance analysis of a flight over TX and OK, which allowed us to estimate oil and gas emissions in that region. The results from this analysis will be compared to previous work in the same area, as well as to emissions from other oil and gas regions and to model simulations from the Community Atmosphere Model with Chemistry (CAM-chem).

  14. Integrated framework for retrievals in a networked radar environment: Application to the Mid-latitude Continental Convective Clouds Experiment

    NASA Astrophysics Data System (ADS)

    Hardin, J. C.; Chandrasekar, C. V.; Yoshikawa, E.; Ushio, T.

    2012-12-01

    The Mid-Latitude Continental Convective Clouds Experiment (MC3E), was a joint DOE Atmospheric Radiation Measurement (ARM) and NASA Global Precipitation Measurements (GPM) field campaign that took place from April - June 2011 in Central Oklahoma centered at the ARM Southern Great Plains site. The experiment was a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign involved a large suite of observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation. The overarching goal was to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that had never before been available. The experiment consisted of a large number of ground radars, including NASA scanning dual-polarization radar systems (NPOL) at S-band, wind profilers, and a dense network of surface disdrometers. In addition to these special MC3E instruments, there were three networked scanning X-band radar systems, four wind profilers, a C-band scanning radar, a dual-wavelength (Ka/W) scanning cloud radar. There is extensive literature on the retrieval algorithms for precipitation and cloud parameters from single frequency, dual-polarization radar systems. With the cost of instruments such as radars becoming more affordable, multiple radar deployments are becoming more common in special programs, and the MC3E is a text book example of such a deployment. Networked deployments are becoming more common popularized by the

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

    SciTech Connect

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

    2005-03-18

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

  16. A New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

    SciTech Connect

    Pivi, M.T.F.; Ng, J.S.T.; Arnett, D.; Cooper, F.; Kharakh, D.; King, F.K.; Kirby, R.E.; Kuekan, B.; Lipari, J.J.; Munro, M.; Olszewski, J.; Raubenheimer, T.O.; Seeman, J.; Smith, B.; Spencer, C.M.; Wang, L.; Wittmer, W.; Celata, C.M.; Furman, M.A.; /SLAC /LBL, Berkeley

    2008-07-03

    Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.

  17. A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

    SciTech Connect

    Pivi, M. T.; Pivi, M.T.F.; Ng, J.S.T.; Arnett, D.; Cooper, F.; Kharakh, D.; King, F.K.; Kirby, R.E.; Kuekan, B.; Lipari, J.J.; Munro, M.; Olszewski, J.; Raubenheimer, T.O.; Seeman, J.; Spencer, C.M.; Wang, L.; Wittmer, W.; Celata, C.M.; Furman, M.A.; Smith, B.

    2008-06-11

    Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.

  18. CernVM Co-Pilot: a Framework for Orchestrating Virtual Machines Running Applications of LHC Experiments on the Cloud

    NASA Astrophysics Data System (ADS)

    Harutyunyan, A.; Aguado Sánchez, C.; Blomer, J.; Buncic, P.

    2011-12-01

    CernVM Co-Pilot is a framework for the delivery and execution of the workload on remote computing resources. It consists of components which are developed to ease the integration of geographically distributed resources (such as commercial or academic computing clouds, or the machines of users participating in volunteer computing projects) into existing computing grid infrastructures. The Co-Pilot framework can also be used to build an ad-hoc computing infrastructure on top of distributed resources. In this paper we present the architecture of the Co-Pilot framework, describe how it is used to execute the jobs of the ALICE and ATLAS experiments, as well as to run the Monte-Carlo simulation application of CERN Theoretical Physics Group.

  19. The Optical Gravitational Lensing Experiment. Ellipsoidal Variability of Red Giants in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszynski, I.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Zebrun, K.; Szewczyk, O.; Wyrzykowski, L.; Dziembowski, W. A.

    2004-12-01

    We used the OGLE-II and OGLE-III photometry of red giants in the Large Magellanic Cloud to select and study objects revealing ellipsoidal variability. We detected 1546 candidates for long period ellipsoidal variables and 121 eclipsing binary systems with clear ellipsoidal modulation. The ellipsoidal red giants follow a period--luminosity (PL) relationship (sequence E), and the scatter of the relation is correlated with the amplitude of variability: the larger the amplitude, the smaller the scatter. We note that some of the ellipsoidal candidates exhibit simultaneously OGLE Small Amplitude Red Giants pulsations. Thus, in some cases the Long Secondary Period (LSP) phenomenon can be explained by the ellipsoidal modulation. We also select about 1600 red giants with distinct LSP, which are not ellipsoidal variables. We discover that besides the sequence D in the PL diagram known before, the LSP giants form additional less numerous sequence for longer periods. We notice that the PL sequence of the ellipsoidal candidates is a direct continuation of the LSP sequence toward fainter stars, what might suggest that the LSP phenomenon is related to binarity but there are strong arguments against such a possibility. About 10% of the presented light curves reveal clear deformation by the eccentricity of the system orbits. The largest estimated eccentricity in our sample is about 0.4. All presented data, including individual BVI observations and finding charts are available from the OGLE Internet archive.

  20. The Optical Gravitational Lensing Experiment. Miras and Semiregular Variables in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszynski, I.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Pietrzynski, G.; Zebrun, K.; Szewczyk, O.; Wyrzykowski, L.; Ulaczyk, K.

    2005-12-01

    We use the OGLE-II and OGLE-III data in conjunction with the 2MASS near-infrared (NIR) photometry to identify and study Miras and Semiregular Variables (SRVs) in the Large Magellanic Cloud. We found in total 3221 variables of both types, populating two of the series of NIR period--luminosity (PL) sequences. The majority of these objects are double periodic pulsators, with periods belonging to both PL ridges. We indicate that in the period -- Wesenheit index plane the oxygen-rich and carbon-rich AGB stars from the NIR PL sequences C, C' and D split into well separated ridges. Thus, we discover an effective method of distinguishing between O-rich and C-rich Miras, SRVs and stars with Long Secondary Periods using their V and I-band photometry. We present an empirical method of estimating the mean K_s magnitudes of the Long Period Variables using single-epoch K_s measurements and complete light curves in the I-band. We utilize these corrected magnitudes to show that the O-rich and C-rich Miras and SRVs follow somewhat different K_s-band PL relations.

  1. Search Cloud

    MedlinePlus

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

  2. Search Cloud

    MedlinePlus

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

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

    NASA Astrophysics Data System (ADS)

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

    2002-06-01

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

  4. The Metal Oxide Space Clouds (MOSC) Experiment: High Frequency (HF) Signatures and Interactions with the Ambient Ionosphere

    NASA Astrophysics Data System (ADS)

    Groves, K. M.; Caton, R. G.; Pedersen, T. R.; Parris, R. T.; Su, Y.; Cannon, P. S.; Jackson-booth, N. K.; Angling, M. J.; Retterer, J. M.

    2013-12-01

    With support from the NASA sounding rocket team, AFRL performed two separate 5 kg releases of samarium metal vapor in the lower F-region near Kwajalein Atoll in May 2013. A fraction of the samarium subsequently ionized forming a plasma cloud that persisted for tens of minutes to hours in the post-sunset period. Numerous sensors were used to characterize the clouds including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. The primary objectives of the experiments were to understand the dynamics, evolution and chemistry of Sm atoms in the earth's upper atmosphere. Sm is predicted to both photo-ionize and chemi-ionize through charge exchange with neutral oxygen (O). Ionization rates and loss reactions are not well known. A secondary objective was to understand the interaction of an artificial plasma cloud with the low latitude ionosphere during the pre-reversal enhancement period leading up to the post-sunset development of large-scale Rayleigh-Taylor instability. It was initially hoped that the introduction of the artificial plasma might be sufficient to quench the development of the instability by maintaining high conductivity within the affected flux tubes. Modeling results showed that this result was unlikely due to the relatively small amount of material being released. However, it appeared possible that the presence of SmO+ near the bottomside of the F-region might be capable of reducing the formation of short-scale irregularities within the larger Rayleigh-Taylor 'bubbles'. Indeed, preliminary results indicate that the artificial layers, positioned at 170 and 180 km respectively, did interact with the overlying F region and in at least one case, cause a decrease in the short-scale component of the natural irregularity spectrum. The results suggest that it may be possible to mitigate the formation of low-latitude irregularities responsible for radio

  5. Cloud radiative forcing sensitivity to Arctic synoptic regimes, surface type, cloud phase and cloud properties during the Fall 2014 Arctic Radiation, IceBridge and Sea-Ice Experiment (ARISE)

    NASA Astrophysics Data System (ADS)

    Segal-Rosenheimer, Michal; Redemann, Jens; Shinozuka, Yohei; Flynn, Connor; LeBanc, Samuel; Schmidt, Sebastian; Song, Shi; Bucholtz, Anthony; Reid, Elizabeth; Anderson, Bruce; Corr, Chelsea; Smith, William L.; Kato, Seiji; Spangenberg, Douglas A.; Hofton, Michelle; Moore, Richard; Winstead, Edward; Thornhill, Lee K.

    2015-04-01

    Surface cloud radiative forcing (CRF) estimates in the Arctic cover a wide range of values when comparing various datasets (e.g. MERRA, CERES), and show high bias when compared to in-situ ground-based flux measurement stations (e.g. in Greenland) [Wenshan and Zender, 2014]. These high variations and biases result from an intricate relationship between the prevailing synoptic regimes, surface types (open ocean versus sea-ice), and cloud properties [e.g. Barton et al., 2012; Bennartz et al., 2013]. To date, analyses are focused on large-scale or inter-annual comparisons [e.g. Barton et al., 2012; Taylor et al., 2014], or on several specific ground-based sites [Shupe et al., 2004; Sedlar et al., 2012]. Nevertheless, smaller scale CRF variations related to the sharp changes in sea-ice cover, cloud type and synoptic regimes in autumn are still not well understood. Here, we are focusing on assessing the CRF sensitivity to a composite variable matrix of atmospheric stability regimes, cloud profiles and properties and surface type changes during the NASA ARISE campaign conducted in the Fall of 2014 during the Arctic sea-ice minimum in the Beaufort Sea. We are interested in answering the following questions: (1) what are the combinations of distinct synoptic regimes, surface types, and cloud properties that result in the lowest or highest simulated CRF values over the Arctic Beaufort Sea during the autumn 2014 sea-ice growth period?, and (2) can we relate these simulated extremes to the observations made during the ARISE campaign? We are using the libRadtran radiative transfer modeling package to calculate the CRF sensitivity matrix, with daily gridded atmospheric profiles input from MERRA re-analysis, cloud fields and properties from CALIPSO, MODIS, AVHRR, daily variations in sea-ice margins from AMSR-2, and complementary airborne measurements collected on the C-130 during the campaign. In performing sensitivity analysis, we examine CRF extremes sorted by atmospheric

  6. Clouds and silver linings: training experiences of psychodynamically oriented mental health trainees.

    PubMed

    Rouff, L C

    2000-01-01

    This paper discusses the experiences of today's psychodynamically oriented mental health trainees. Recent changes in the training environment, such as the increase in managed care, rise in use of psychotropic medication, the waning popularity of psychodynamic thinking, and reduced funding for psychotherapy training, in general, have all affected current trainees' professional development. In particular, trainees struggle with problems of demoralization, professional isolation, and reduced financial opportunities. Advantages that current trainees experience, as well as suggestions for training directors and trainees, will also be discussed. PMID:11109138

  7. A study of the response of deep tropical clouds to mesoscale processes - Three-dimensional numerical experiments

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Soong, Su-Tzai

    1986-01-01

    A three-dimensional numerical cloud model is utilized to study the collective feedback effects of cloud systems on the large-scale environment. The characteristic features of the cloud ensemble model are described. The model is applied to a case of a well-defined ITCZ rainband over the eastern tropical Atlantic ocean. The location, number, and configuration of the clouds that formed in the model during the simulations are examined. The cloud heating and moistening, environmental wind shear, and vertical transports of momentum are analyzed. The collective feedbacks of cloud systems on the large-scale temperature, moisture, and horizontal momentum fields are computed after each simulation. The effect of the pressure gradient force on the v-momentum flux is investigated. It is observed that there is good correlation between the model simulations and the observed data.

  8. Determination of Large-Scale Cloud Ice Water Concentration by Combining Surface Radar and Satellite Data in Support of ARM SCM Activities

    SciTech Connect

    Liu, Guosheng

    2013-03-15

    water contents in support of cloud modeling activities. The approach of the study is to expand a (surface) point measurement to an (satellite) area measurement. That is, the study takes the advantage of the high quality cloud measurements (particularly cloud radar and microwave radiometer measurements) at the point of the ARM sites. We use the cloud ice water characteristics derived from the point measurement to guide/constrain a satellite retrieval algorithm, then use the satellite algorithm to derive the 3-D cloud ice water distributions within an 10° (latitude) x 10° (longitude) area. During the research period, we have developed, validated and improved our cloud ice water retrievals, and have produced and archived at ARM website as a PI-product of the 3-D cloud ice water contents using combined satellite high-frequency microwave and surface radar observations for SGP March 2000 IOP and TWP-ICE 2006 IOP over 10 deg. x 10 deg. area centered at ARM SGP central facility and Darwin sites. We have also worked on validation of the 3-D ice water product by CloudSat data, synergy with visible/infrared cloud ice water retrievals for better results at low ice water conditions, and created a long-term (several years) of ice water climatology in 10 x 10 deg. area of ARM SGP and TWP sites and then compared it with GCMs.

  9. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

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

  10. LDEF Interplanetary Dust Experiment - Techniques for identification and study of long-lived orbital debris clouds

    NASA Technical Reports Server (NTRS)

    Singer, S. F.; Oliver, J. P.; Weinberg, J. L.; Cooke, W. J.; Montague, N. L.; Mulholland, J. D.; Wortman, J. J.; Kassel, P. C.; Kinard, W. H.

    1991-01-01

    The Long Duration Exposure Facility (LDEF) is a 12-sided, 4.3-m-diameter, 9.1-m-long cylinder designed and built by NASA Langley to carry experiments for extended periods in space. The LDEF was first placed in orbit by the Shuttle Challenger on 7 April 1984 and recovered by the Shuttle Columbia in January 1990, only days before it was expected to burn up in the earth's atmosphere. The Interplanetary Dust Experiment (IDE) was designed to detect impacts of extra-terrestrial particles and orbital debris. The IDE detectors (which covered about 1 sq m of the surface of LDEF) were sensitive to particles ranging in size from about 0.2 to 100 microns. Data were recorded for 11.5 months before the supply of magnetic tape was exhausted. Examination of the LDEF IDE dataset shows that impacts often occurred in 'bursts', during which numerous impacts occurred in a short time (typically 3-5 min) at a rate much greater than the average impact rate. In several cases, such events reoccurred each time the LDEF returned to the same point in its orbit. Such multi-orbit event sequences were found to extend for as many as 25 or more orbits.

  11. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Parcivel Disdrometer (williams-disdro)

    DOE Data Explorer

    Williams, Christopher; Jensen, Mike

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  12. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Surface Meteorology (williams-surfmet)

    DOE Data Explorer

    Williams, Christopher; Jensen, Mike

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  13. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, 449 MHz Profiler(williams-449_prof)

    DOE Data Explorer

    Williams, Christopher; Jensen, Mike

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  14. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, Vertical Air Motion (williams-vertair)

    DOE Data Explorer

    Williams, Christopher; Jensen, Mike

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  15. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  16. An Overview of the Lightning - Atmospheric Chemistry Aspects of the Deep Convective Clouds and Chemistry (DC3) Experiment

    NASA Technical Reports Server (NTRS)

    Pickering, K. E.; Barth, M. C.; Koshak, W.; Bucsela, E. J.; Allen, D. J.; Weinheimer, A.; Ryerson, T.; Huntrieser, H.; Bruning, E.; MacGorman, D.; Krehbiel, P.; Thomas, R.; Carey, L.

    2012-01-01

    Some of the major goals of the DC3 experiment are to determine the contribution of lightning to NO(x) in the anvils of observed thunderstorms, examine the relationship of lightning NO(x) production to flash rates and to lightning channel lengths, and estimate the relative production per flash for cloud-to-ground flashes and intracloud flashes. In addition, the effects of lightning NO(x) production on photochemistry downwind of thunderstorms is also being examined. The talk will survey the observation types that were conducted during DC3 relevant to these goals and provide an overview of the analysis and modeling techniques which are being used to achieve them. NO(x) was observed on three research aircraft during DC3 (the NCAR G-V, the NASA DC-8, and the DLR Falcon) in flights through storm anvils in three study regions (NE Colorado, Central Oklahoma to West Texas, and northern Alabama) where lightning mapping arrays (LMAs) and radar coverage were available. Initial comparisons of the aircraft NOx observations in storm anvils relative to flash rates have been conducted, which will be followed with calculations of the flux of NO(x) through the anvils, which when combined with observed flash rates can be used to estimate storm-average lightning NOx production per flash. The WRF-Chem model will be run for cloud-resolved simulations of selected observed storms during DC3. Detailed lightning information from the LMAs (flash rates and flash lengths as a function of time and vertical distributions of flash channel segments) will be input to the model along with assumptions concerning NO(x) production per CG flash and per IC flash. These assumptions will be tested through comparisons with the aircraft NOx data from anvil traverses. A specially designed retrieval method for lightning NO2 column amounts from the OMI instrument on NASA fs Aura satellite has been utilized to estimate NO2 over the region affected by selected DC3 storms. Combined with NO(x) to NO2 ratios from the

  17. Ion Clusters in Nucleation Experiments in the CERN Cloud Chamber: Sulfuric Acid + Ammonia + Dimethyl Amine + Oxidized Organics

    NASA Astrophysics Data System (ADS)

    Worsnop, D. R.; Schobesberger, S.; Bianchi, F.; Ehrhart, S.; Junninen, H.; Kulmala, M. T.

    2012-12-01

    Nucleation from gaseous precursors is an important source of aerosol particles in the atmosphere. The CLOUD experiment at CERN provides exceptionally clean and well-defined experimental conditions for studies of atmospheric nucleation and initial growth, in a 26 m3 stainless-steel chamber. In addition, the influence of cosmic rays on nucleation and nanoparticle growth can be simulated by exposing the chamber to a pion beam produced by the CERN Proton Synchrotron. A key to understanding the mechanism by which nucleation proceeds in the CLOUD chamber is the use of state-of-the-art instrumentation, including the Atmospheric Pressure interface Time-Of-Flight (APi-TOF) mass spectrometer. The APi-TOF is developed by Tofwerk AG, and Aerodyne Research, Inc., and typically obtains resolutions between 4000 and 6000 Th/Th and mass accuracies < 10 ppm. Sampling occurs directly from atmospheric pressure through a critical orifice. Ions are then focused and guided to the time-of-flight mass spectrometer, while passing through differentially pumped chambers. No ionization of the sampled aerosol is performed; only ions charged in the chamber are detected in the current configuration. For all studied chemical systems, the APi-TOF detected ion clusters that could directly be linked to nucleation. The composition of these ion clusters could be determined based on their exact masses and isotopic patterns. Aided by the chamber's cleanliness and the possibility of enhancing ion concentrations by using CERN's pion beam, a remarkably large fraction of the ion spectra could be identified, even for more complex chemical systems studied. For the ammonia-sulfuric acid-water system, for instance, growing clusters containing ammonia (NH3) and sulfuric acid (H2SO4) were observed up to 3300 Th. Adding dimethyl amine and/or pinanediol into the CLOUD chamber, altered the chemical compositions of the observed ion clusters accordingly. Cluster growth then included mixtures of sulfuric acid and

  18. Study of the ammonia ice cloud layer in the Equatorial Region of Jupiter from the infrared interferometric experiment on Voyager

    NASA Technical Reports Server (NTRS)

    Marten, A.; Rouan, D.; Baluteau, J. P.; Gautier, D.; Conrath, B. J.; Hanel, R. A.; Kunde, V.; Samuelson, R.; Chedin, A.; Scott, N.

    1981-01-01

    Spectra from the Voyager 1 infrared interferometer spectrometer (IRIS) obtained near the time of closest approach to Jupiter were analyzed for the purpose of inferring ammonia cloud properties associated with the Equatorial Region. Comparisons of observed spectra with synthetic spectra computed from a radiative transfer formulation, that includes multiple scattering, yielded the following conclusions: (1) very few NH3 ice particles with radii less than 3 microns contribute to the cloud opacity; (2) the major source of cloud opacity arises from particles with radii in excess of 30 microns; (3) column particle densities are between 1 and 2 orders of magnitude smaller than those derived from thermochemical considerations alone, implying the presence of important atmospheric motion; and (4) another cloud system is confirmed to exist deeper in the Jovian troposphere.

  19. Weather Fundamentals: Clouds. [Videotape].

    ERIC Educational Resources Information Center

    1998

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

  20. An overview of the Ice Nuclei Research Unit Jungfraujoch/Cloud and Aerosol Characterization Experiment 2013 (INUIT-JFJ/CLACE-2013)

    NASA Astrophysics Data System (ADS)

    Schneider, Johannes

    2014-05-01

    Ice formation in mixed phase tropospheric clouds is an essential prerequisite for the formation of precipitation at mid-latitudes. Ice formation at temperatures warmer than -35°C is only possible via heterogeneous ice nucleation, but up to now the exact pathways of heterogeneous ice formation are not sufficiently well understood. The research unit INUIT (Ice NUcleation research unIT), funded by the Deutsche Forschungsgemeinschaft (DFG FOR 1525) has been established in 2012 with the objective to investigate heterogeneous ice nucleation by combination of laboratory studies, model calculation and field experiments. The main field campaign of the INUIT project (INUIT-JFJ) was conducted at the High Alpine Research Station Jungfraujoch (Swiss Alps, 3580 m asl) during January and February 2013, in collaboration with several international partners in the framework of CLACE2013. The instrumentation included a large set of aerosol chemical and physical analysis instruments (particle counters, particle sizers, particle mass spectrometers, cloud condensation nuclei counters, ice nucleus counters etc.), that were operated inside the Sphinx laboratory and sampled in mixed phase clouds through two ice selective inlets (Ice-CVI, ISI) as well as through a total aerosol inlet that was used for out-of-cloud aerosol measurements. Besides the on-line measurements, also samples for off-line analysis (ESEM, STXM) have been taken in and out of clouds. Furthermore, several cloud microphysics instruments were operated outside the Sphinx laboratory. First results indicate that a large fraction of ice residues sampled from mixed phase clouds contain organic material, but also mineral dust. Soot and lead were not found to be enriched in ice residues. The concentration of heterogeneous ice nuclei was found to be variable (ranging between < 1 and > 100 per liter) and to be strongly dependent on the operating conditions of the respective IN counter. The number size distribution of ice residues

  1. Cloud Computing for Astronomers on Top of EGI Federated Cloud

    NASA Astrophysics Data System (ADS)

    Taffoni, G.; Vuerli, C.; Pasian, F.

    2015-09-01

    EGI Federated Cloud offers a general academic Cloud Infrastructure. We exploit EGI functionalities to address the needs of representative Astronomy and Astrophysics communities through clouds and gateways while respecting commonly used standards. The vision is to offer a novel environment empowering scientists to focus more on experimenting and pitching new ideas to service their needs for scientific discovery.

  2. Cloud Detection and Clearing for the Earth Observing System Terra Satellite Measurements of Pollution in the Troposphere (MOPITT) Experiment.

    PubMed

    Warner, J X; Gille, J C; Edwards, D P; Ziskin, D C; Smith, M W; Bailey, P L; Rokke, L

    2001-03-10

    The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to measure tropospheric CO and CH(4) by use of a nadir-viewing geometry. The measurements are taken at 4.7 mum in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 mum in the reflected solar region for the total CO column amount and CH(4) column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected ?10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5-10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH(4). PMID:18357114

  3. Utilizing clouds for Belle II

    NASA Astrophysics Data System (ADS)

    Sobie, R. J.

    2015-12-01

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

  4. Polarization of clouds

    NASA Astrophysics Data System (ADS)

    Goloub, Philippe; Herman, Maurice; Parol, Frederic

    1995-12-01

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

  5. Physical Validation of GPM Retrieval Algorithms Over Land: An Overview of the Mid-Latitude Continental Convective Clouds Experiment (MC3E)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Jensen, Michael P.

    2011-01-01

    The joint NASA Global Precipitation Measurement (GPM) -- DOE Atmospheric Radiation Measurement (ARM) Midlatitude Continental Convective Clouds Experiment (MC3E) was conducted from April 22-June 6, 2011, centered on the DOE-ARM Southern Great Plains Central Facility site in northern Oklahoma. GPM field campaign objectives focused on the collection of airborne and ground-based measurements of warm-season continental precipitation processes to support refinement of GPM retrieval algorithm physics over land, and to improve the fidelity of coupled cloud resolving and land-surface satellite simulator models. DOE ARM objectives were synergistically focused on relating observations of cloud microphysics and the surrounding environment to feedbacks on convective system dynamics, an effort driven by the need to better represent those interactions in numerical modeling frameworks. More specific topics addressed by MC3E include ice processes and ice characteristics as coupled to precipitation at the surface and radiometer signals measured in space, the correlation properties of rainfall and drop size distributions and impacts on dual-frequency radar retrieval algorithms, the transition of cloud water to rain water (e.g., autoconversion processes) and the vertical distribution of cloud water in precipitating clouds, and vertical draft structure statistics in cumulus convection. The MC3E observational strategy relied on NASA ER-2 high-altitude airborne multi-frequency radar (HIWRAP Ka-Ku band) and radiometer (AMPR, CoSMIR; 10-183 GHz) sampling (a GPM "proxy") over an atmospheric column being simultaneously profiled in situ by the University of North Dakota Citation microphysics aircraft, an array of ground-based multi-frequency scanning polarimetric radars (DOE Ka-W, X and C-band; NASA D3R Ka-Ku and NPOL S-bands) and wind-profilers (S/UHF bands), supported by a dense network of over 20 disdrometers and rain gauges, all nested in the coverage of a six-station mesoscale rawinsonde

  6. [Proposal of a cloud chamber experiment using diagnostic X-ray apparatus and an analysis assisted by a simulation code].

    PubMed

    Hayashi, Hiroaki; Hanamitsu, Hiroki; Nishihara, Sadamitsu; Ueno, Junji; Miyoshi, Hirokazu

    2013-04-01

    A cloud chamber is a radiation detector that can visualize the tracks of charged particles. In this study, we developed a middle-type cloud chamber for use in practical training using a diagnostic X-ray apparatus. Because our cloud chamber has a heater to vaporize ethanol and features antifogging glass, it is possible to observe the vapor trails for a long time without the need for fine adjustments. X-rays with a tube voltage of 40 kV or of 120 kV (with a 21-mm aluminum filter) were irradiated at the chamber and the various phenomena were observed. We explain these phenomena in terms of the range of electrons and/or interactions between X-rays and matter and conclude that our analysis is consistent with analysis using the Monte Carlo simulation code EGS5. PMID:23609860

  7. Triangulation Error Analysis for the Barium Ion Cloud Experiment. M.S. Thesis - North Carolina State Univ.

    NASA Technical Reports Server (NTRS)

    Long, S. A. T.

    1973-01-01

    The triangulation method developed specifically for the Barium Ion Cloud Project is discussed. Expression for the four displacement errors, the three slope errors, and the curvature error in the triangulation solution due to a probable error in the lines-of-sight from the observation stations to points on the cloud are derived. The triangulation method is then used to determine the effect of the following on these different errors in the solution: the number and location of the stations, the observation duration, east-west cloud drift, the number of input data points, and the addition of extra cameras to one of the stations. The pointing displacement errors, and the pointing slope errors are compared. The displacement errors in the solution due to a probable error in the position of a moving station plus the weighting factors for the data from the moving station are also determined.

  8. Using unmanned aircraft to measure the impact of pollution plumes on atmospheric heating rates and cloud properties during the Cheju ABC Plume-Asian Monsoon Experiment (CAPMEX)

    NASA Astrophysics Data System (ADS)

    Venkata Ramana, M.; Ramanathan, V.; Nguyen, H.; Xu, Y.; Pistone, K.; Corrigan, C.; Feng, Y.; Zhu, A.; Kim, S.; Yoon, S.; Carmichael, G. R.; Schauer, J. J.

    2009-12-01

    The CAPMEX (Cheju ABC Plume-Asian Monsoon Experiment) campaign took place off the Coast of Cheju Island in South Korea to take advantage of the unique event associated with the shutdown of anthropogenic emissions surrounding Beijing during the Olympics in summer 2008. CAPMEX studied pollution plumes before, during, and after the Beijing reductions using ground-level and high-elevation measurements, i.e., from unmanned aircrafts. Additionally, the campaign documented the effect on solar heating and clouds due to aerosols carried by the long range transport of pollution plumes. The unmanned aerial vehicle (UAV) measurement component of this campaign took place during Aug 9 to Sept 30, 2008. The AUAV payload was mission-specific and was outfitted to perform a particular set of measurements. These measurements include aerosol concentration, aerosol size distribution, aerosol absorption, cloud drop size distribution, solar radiation fluxes (visible and broadband), and spectral radiative fluxes. Throughout the CAPMEX experiment, long-range transport of aerosols from Beijing, Shanghai and Marine plumes were sampled in aerosol layers up to 3-4 km above sea level. During this period, we captured both heavy and light pollution events and witnessed air masses from both pristine oceanic sources and from major cities including Beijing and Shanghai. Analysis of specific plumes allowed us to quantify the impact of anthropogenic pollution on heating rates and cloud properties.

  9. On the role of thermodynamics and cloud-aerosol-precipitation interactions over thunderstorm activity during GoAmazon and ACRIDICON-CHUVA field experiments

    NASA Astrophysics Data System (ADS)

    Albrecht, R. I.; Morales, C. A.; Hoeller, H.; Braga, R. C.; Machado, L.; Wendisch, M.; Andreae, M. O.; Rosenfeld, D.; Poeschl, U.; Biscaro, T.; Lima, W.; Eichholz, C.; Oliveira, R. A. J.; Sperling, V.; Carvalho, I.; Calheiros, A. J. P.; Amaral, L. F.; Cecchin, M.; Saraiva, J.; Saraiva, I.; Schumacher, C.; Funk, A. B.

    2015-12-01

    Based on satellite data, total (intracloud and cloud-to-ground) lightning activity climatological annual cycle over the GoAmazon area of interest (from T0 to T3 sites) shows that lightning activity is moderate (up to 10 flashes per day - fl day-1) throughout the wet (December-March) and dry (April-August) seasons, with T3 always being a little greater than T1 and T0 sites, respectively. During the dry-to-wet transition season (September-October), however, lightning activity peaks up to 25 fl day-1 at T1, followed by T3 (20 fl day-1) and T0 (15 fl day-1). The diurnal cycle reveals that the onset of deep convection during this same season starts one hour and peaks two hours earlier than the wet season. In the Amazon, cloud updrafts are primarily controlled by the local environment thermodynamics. During the dry-to-wet transition season, thermodynamics is significantly changed by land cover land cover where cloud base heights are elevated over deforested areas potentially increasing the strength of updrafts due to a better processing of the convective available potential energy, and therefore also increasing cloud electrification. The total (intracloud and cloud-to-ground) LIghtning NET(LINET - Nowcast) installed in September-October 2014 for GoAmazon IOP2 and ACRIDICON-CHUVA field experiments and the set of weather radars revealed that the thunderstorm enhancement over T1 (Manaus) during the dry-to-wet season is driven by the interaction between river breeze and the main easterly winds over Amazon basin, resulting in a locally forced convergent flow on the east side of Rio Negro which drives deep afternoon convection. In terms of atmospheric pollution, the dry-to-wet season is also marked by increased biomass burning, and the city of Manaus (T1) is a local polluted heat island. We will also present quantified thermodynamical and microphysical differences between the thunderstorms that developed over T0, T1 and T2. Our hypothesis is that cloud charge centers, total

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  12. Cloud Computing

    SciTech Connect

    Pete Beckman and Ian Foster

    2009-12-04

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

  13. Arctic Clouds

    Atmospheric Science Data Center

    2013-04-19

    ...     View Larger Image Stratus clouds are common in the Arctic during the summer months, and are ... formats available at JPL August 23, 2000 - Stratus clouds help modulate the arctic climate. project:  ...

  14. Dimensions and aspect ratios of natural ice crystals

    NASA Astrophysics Data System (ADS)

    Um, J.; McFarquhar, G. M.; Hong, Y. P.; Lee, S.-S.; Jung, C. H.; Lawson, R. P.; Mo, Q.

    2015-04-01

    During the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) in the tropics, the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) in the Arctic, and the 2010 Small PARTicles In CirrUS (SPARTICUS) campaign at mid-latitudes, high-resolution images of ice crystals were recorded by a Cloud Particle Imager at temperatures (T) between -87 and 0 °C. The projected maximum dimension (D'), length (L'), and width (W') of pristine columns, plates, and component bullets of bullet rosettes were measured using newly developed software, the Ice Crystal Ruler. The number of bullets in each bullet rosette was also measured. Column crystals were further distinguished as either horizontally oriented columns or columns with other orientations to eliminate any orientation effect on the measured dimensions. The dimensions and aspect ratios (AR, the dimension of the major axis divided by the dimension of the minor axis) of crystals were determined as functions of temperature, geophysical location, and type of cirrus. Dimensions of crystals generally increased with temperature. Columns and bullets had larger dimensions (i.e., W') of the minor axis (i.e., a axis) for a given dimension (i.e., D' orL') of the major axis (i.e., c axis), and thus smaller AR, as T increased, whereas this trend did not occur for plate crystals. The average number of branches in bullet rosettes was 5.50 ± 1.35 during three campaigns and 6.32 ± 1.34 (5.46 ± 1.34; 4.95 ± 1.01) during TWP-ICE (SPARTICUS; ISDAC). The AR of bullets increased with the number of branches in bullet rosettes. Most dimensions of crystals and ARs of columnar crystals measured during SPARTICUS were larger than those measured during TWP-ICE and ISDAC at -67 < T < -35 °C and at -40 < T < -15 °C, respectively. The relative occurrence of varying pristine habits depended strongly on cirrus type (i.e., anvil or non-anvil clouds), with plates especially occurring more frequently in anvils. The L-W relationships of columns

  15. Dimensions and aspect ratios of natural ice crystals

    DOE PAGESBeta

    Um, J.; McFarquhar, G. M.; Hong, Y. P.; Lee, S. -S.; Jung, C. H.; Lawson, R. P.; Mo, Q.

    2015-04-15

    During the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) in the tropics, the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) in the Arctic, and the 2010 Small PARTicles In CirrUS (SPARTICUS) campaign at mid-latitudes, high-resolution images of ice crystals were recorded by a Cloud Particle Imager at temperatures (T) between -87 and 0 °C. The projected maximum dimension (D'), length (L'), and width (W') of pristine columns, plates, and component bullets of bullet rosettes were measured using newly developed software, the Ice Crystal Ruler. The number of bullets in each bullet rosette was also measured. Column crystals were furthermore » distinguished as either horizontally oriented columns or columns with other orientations to eliminate any orientation effect on the measured dimensions. The dimensions and aspect ratios (AR, the dimension of the major axis divided by the dimension of the minor axis) of crystals were determined as functions of temperature, geophysical location, and type of cirrus. Dimensions of crystals generally increased with temperature. Columns and bullets had larger dimensions (i.e., W') of the minor axis (i.e., a axis) for a given dimension (i.e., D' orL') of the major axis (i.e., c axis), and thus smaller AR, as T increased, whereas this trend did not occur for plate crystals. The average number of branches in bullet rosettes was 5.50 ± 1.35 during three campaigns and 6.32 ± 1.34 (5.46 ± 1.34; 4.95 ± 1.01) during TWP-ICE (SPARTICUS; ISDAC). The AR of bullets increased with the number of branches in bullet rosettes. Most dimensions of crystals and ARs of columnar crystals measured during SPARTICUS were larger than those measured during TWP-ICE and ISDAC at −67 < T < -35 °C and at −40 < T < −15 °C, respectively. The relative occurrence of varying pristine habits depended strongly on cirrus type (i.e., anvil or non-anvil clouds), with plates especially occurring more frequently in anvils. The L

  16. Dimensions and aspect ratios of natural ice crystals

    DOE PAGESBeta

    Um, J.; McFarquhar, G. M.; Hong, Y. P.; Lee, S. -S.; Jung, C. H.; Lawson, R. P.; Mo, Q.

    2014-12-10

    During the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) in the Tropics, the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) in the Arctic, and the 2010 Small PARTicles In CirrUS (SPARTICUS) campaign in mid-latitudes, high-resolution images of ice crystals were recorded by a Cloud Particle Imager at temperatures (T) between -87 and 0 °C. The projected maximum dimension (D'), length (L'), and width (W') of pristine columns, plates, and component bullets of bullet rosettes were measured using newly developed software, the Ice Crystal Ruler. The number of bullets in each bullet rosette was also measured. Column crystals were furthermore » distinguished as either horizontally oriented columns or columns with other orientations to eliminate any orientation effect on the measured dimensions. Dimensions and aspect ratios (AR, dimension of major axis divided by dimension of minor axis) of crystals were determined as functions of temperature, geophysical location, and type of cirrus. Dimensions of crystals generally increased as temperature increased. Columns and bullets had larger dimensions (i.e., W') of the minor axis (i.e., a axis) for a given dimension (i.e., D' or L') of the major axis (i.e., c axis), and thus smaller AR, as T increased, whereas this trend did not occur for plate crystals. The average number of branches in bullet rosettes was 5.50±1.35 during three campaigns and 6.32±1.34 (5.46±1.34; 4.95±1.01) during TWP-ICE (SPARTICUS; ISDAC). The AR of bullets increased with the number of branches in bullet rosettes. Most dimensions of crystals and ARs of columnar crystals measured during SPARTICUS were larger than those measured during TWP-ICE and ISDAC at −67 < T < −35 °C and at −40 < T < −15 °C, respectively. The relative occurrence of varying pristine habits depended strongly on cirrus type (i.e., anvil or non-anvil clouds), with plates especially occurring more frequently in anvils. The L–W relationships of columns

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  19. The Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) Experiment: Scientific Basis, New Analysis Tools and Some Ongoing Results

    NASA Astrophysics Data System (ADS)

    Montgomery, M. T.

    2012-12-01

    The principal hypotheses of a new model of tropical cyclogenesis, known as the marsupial paradigm, were tested in the context of Atlantic tropical disturbances during the National Science Foundation-sponsored Pre-Depression Investigation of Cloud systems in the Tropics (PREDICT) experiment in 2010. PREDICT was part of a tri-agency collaboration, with the National Aeronautics and Space Administration's Genesis and Rapid Intensification Processes (NASA GRIP) experiment and the National Oceanic and Atmospheric Administration's Intensity Forecasting Experiment (NOAA IFEX), intended to examine both developing and non-developing tropical disturbances. In this talk, some scientific products and examples of data collected by the PREDICT science team will be highlighted for several of the disturbances and an example of some of the recent research by PREDICT team members will be summarized.

  20. Silicon photonics cloud (SiCloud)

    NASA Astrophysics Data System (ADS)

    DeVore, Peter T. S.; Jiang, Yunshan; Lynch, Michael; Miyatake, Taira; Carmona, Christopher; Chan, Andrew C.; Muniam, Kuhan; Jalali, Bahram

    2015-02-01

    We present SiCloud (Silicon Photonics Cloud), the first free, instructional web-based research and education tool for silicon photonics. SiCloud's vision is to provide a host of instructional and research web-based tools. Such interactive learning tools enhance traditional teaching methods by extending access to a very large audience, resulting in very high impact. Interactive tools engage the brain in a way different from merely reading, and so enhance and reinforce the learning experience. Understanding silicon photonics is challenging as the topic involves a wide range of disciplines, including material science, semiconductor physics, electronics and waveguide optics. This web-based calculator is an interactive analysis tool for optical properties of silicon and related material (SiO2, Si3N4, Al2O3, etc.). It is designed to be a one stop resource for students, researchers and design engineers. The first and most basic aspect of Silicon Photonics is the Material Parameters, which provides the foundation for the Device, Sub-System and System levels. SiCloud includes the common dielectrics and semiconductors for waveguide core, cladding, and photodetection, as well as metals for electrical contacts. SiCloud is a work in progress and its capability is being expanded. SiCloud is being developed at UCLA with funding from the National Science Foundation's Center for Integrated Access Networks (CIAN) Engineering Research Center.

  1. Project Fog Drops 5. Task 1: A numerical model of advection fog. Task 2: Recommendations for simplified individual zero-gravity cloud physics experiments

    NASA Technical Reports Server (NTRS)

    Rogers, C. W.; Eadie, W. J.; Katz, U.; Kocmond, W. C.

    1975-01-01

    A two-dimensional numerical model was used to investigate the formation of marine advection fog. The model predicts the evolution of potential temperature, horizontal wind, water vapor content, and liquid water content in a vertical cross section of the atmosphere as determined by vertical turbulent transfer and horizontal advection, as well as radiative cooling and drop sedimentation. The model is designed to simulate the formation, development, or dissipation of advection fog in response to transfer of heat and moisture between the atmosphere and the surface as driven by advection over horizontal discontinuities in the surface temperature. Results from numerical simulations of advection fog formation are discussed with reference to observations of marine fog. A survey of candidate fog or cloud microphysics experiments which might be performed in the low gravity environment of a shuttle-type spacecraft in presented. Recommendations are given for relatively simple experiments which are relevent to fog modification problems.

  2. Clouds in GEOS-5

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  3. Cloud Technology May Widen Genomic Bottleneck - TCGA

    Cancer.gov

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

  4. H{sub 2} EXCITATION STRUCTURE ON THE SIGHTLINES TO {delta} SCORPII AND {zeta} OPHIUCI: FIRST RESULTS FROM THE SUB-ORBITAL LOCAL INTERSTELLAR CLOUD EXPERIMENT

    SciTech Connect

    France, Kevin; Nell, Nicholas; Kane, Robert; Green, James C.; Burgh, Eric B.

    2013-07-20

    We present the first science results from the Sub-orbital Local Interstellar Cloud Experiment (SLICE): moderate resolution 1020-1070 A spectroscopy of four sightlines through the local interstellar medium. High signal-to-noise (S/N) spectra of {eta} Uma, {alpha} Vir, {delta} Sco, and {zeta} Oph were obtained during a 2013 April 21 rocket flight. The SLICE observations constrain the density, molecular photoexcitation rates, and physical conditions present in the interstellar material toward {delta} Sco and {zeta} Oph. Our spectra indicate a factor of two lower total N(H{sub 2}) than previously reported for {delta} Sco, which we attribute to higher S/N and better scattered light control in the new SLICE observations. We find N(H{sub 2}) = 1.5 Multiplication-Sign 10{sup 19} cm{sup -2} on the {delta} Sco sightline, with kinetic and excitation temperatures of 67 and 529 K, respectively, and a cloud density of n{sub H} = 56 cm{sup -3}. Our observations of the bulk of the molecular sightline toward {zeta} Oph are consistent with previous measurements (N(H{sub 2}) Almost-Equal-To 3 Multiplication-Sign 10{sup 20} cm{sup -2} at T{sub 01}(H{sub 2}) = 66 K and T{sub exc} = 350 K). However, we detect significantly more rotationally excited H{sub 2} toward {zeta} Oph than previously observed. We infer a cloud density in the rotationally excited component of n{sub H} Almost-Equal-To 7600 cm{sup -3} and suggest that the increased column densities of excited H{sub 2} are a result of the ongoing interaction between {zeta} Oph and its environment; also manifest as the prominent mid-IR bowshock observed by WISE and the presence of vibrationally excited H{sub 2} molecules observed by the Hubble Space Telescope.

  5. A data assimilation experiment of RASTA airborne cloud radar data during HyMeX IOP16

    NASA Astrophysics Data System (ADS)

    Saussereau, Gaël; Caumont, Olivier; Delanoë, Julien

    2015-04-01

    The main goal of HyMeX first special observing period (SOP1), which took place from 5 September to 5 November 2012, was to document the heavy precipitation events and flash floods that regularly affect the north-western Mediterranean coastal areas. In the two-month campaign, around twenty rainfall events were documented in France, Italy, and Spain. Among the instrumental platforms that were deployed during SOP1, the Falcon 20 of the Safire unit (http://www.safire.fr/) made numerous flights in storm systems so as to document their thermodynamic, microphysical, and dynamical properties. In particular, the RASTA cloud radar (http://rali.projet.latmos.ipsl.fr/) was aboard this aircraft. This radar measures vertical profiles of reflectivity and Doppler velocity above and below the aircraft. This unique instrument thus allows us to document the microphysical properties and the speed of wind and hydrometeors in the clouds, quasi-continuously in time and at a 60-m vertical resolution. For this field campaign, a special version of the numerical weather prediction (NWP) Arome system was developed to cover the whole north-western Mediterranean basin. This version, called Arome-WMed, ran in real time during the SOP in order to, notably, schedule the airborne operations, especially in storm systems. Like the operational version, Arome-WMed delivers forecasts at a horizontal resolution of 2.5 km with a one-moment microphysical scheme that predicts the evolution of six water species: water vapour, cloud liquid water, rainwater, pristine ice, snow, and graupel. Its three-dimensional variational (3DVar) data assimilation (DA) system ingests every three hours (at 00 UTC, 03 UTC, etc.) numerous observations (radiosoundings, ground automatic weather stations, radar, satellite, GPS, etc.). In order to provide improved initial conditions to Arome-WMed, especially for heavy precipitation events, RASTA data were assimilated in Arome-WMed 3DVar DA system for IOP16 (26 October 2012), to

  6. ATLAS Cloud R&D

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  7. Contrasting sea-ice and open-water boundary layers during melt and freeze-up seasons: Some result from the Arctic Clouds in Summer Experiment.

    NASA Astrophysics Data System (ADS)

    Tjernström, Michael; Sotiropoulou, Georgia; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara; Brooks, Ian; Persson, Ola; Prytherch, John; Salsbury, Dominic; Shupe, Matthew; Johnston, Paul; Wolfe, Dan

    2016-04-01

    With more open water present in the Arctic summer, an understanding of atmospheric processes over open-water and sea-ice surfaces as summer turns into autumn and ice starts forming becomes increasingly important. The Arctic Clouds in Summer Experiment (ACSE) was conducted in a mix of open water and sea ice in the eastern Arctic along the Siberian shelf during late summer and early autumn 2014, providing detailed observations of the seasonal transition, from melt to freeze. Measurements were taken over both ice-free and ice-covered surfaces, offering an insight to the role of the surface state in shaping the lower troposphere and the boundary-layer conditions as summer turned into autumn. During summer, strong surface inversions persisted over sea ice, while well-mixed boundary layers capped by elevated inversions were frequent over open-water. The former were often associated with advection of warm air from adjacent open-water or land surfaces, whereas the latter were due to a positive buoyancy flux from the warm ocean surface. Fog and stratus clouds often persisted over the ice, whereas low-level liquid-water clouds developed over open water. These differences largely disappeared in autumn, when mixed-phase clouds capped by elevated inversions dominated in both ice-free and ice-covered conditions. Low-level-jets occurred ~20-25% of the time in both seasons. The observations indicate that these jets were typically initiated at air-mass boundaries or along the ice edge in autumn, while in summer they appeared to be inertial oscillations initiated by partial frictional decoupling as warm air was advected in over the sea ice. The start of the autumn season was related to an abrupt change in atmospheric conditions, rather than to the gradual change in solar radiation. The autumn onset appeared as a rapid cooling of the whole atmosphere and the freeze up followed as the warm surface lost heat to the atmosphere. While the surface type had a pronounced impact on boundary

  8. Cloud Control

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  9. Cloud Cover

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

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

  10. Cloud Control

    ERIC Educational Resources Information Center

    Weinstein, Margery

    2012-01-01

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

  11. Early time evolution of negative ion clouds and electron density depletions produced during electron attachment chemical release experiments

    NASA Technical Reports Server (NTRS)

    Scales, W. A.; Bernhardt, P. A.; Ganguli, G.

    1994-01-01

    Two-dimensional electrostatic particle-in-cell simulations are used to study the early time evolution of electron depletions and negative ion clouds produced during electron attachment chemical releases in the ionosphere. The simulation model considers the evolution in the plane perpendicular to the magnetic field and a three-species plasma that contains electrons, positive ions, and also heavy negative ions that result as a by-product of the electron attachment reaction. The early time evolution (less than the negative ion cyclotron period) of the system shows that a negative charge surplus initially develops outside of the depletion boundary as the heavy negative ions move across the boundary. The electrons are initially restricted from moving into the depletion due to the magnetic field. An inhomogenous electric field develops across the boundary layer due to this charge separation. A highly sheared electron flow velocity develops in the depletion boundary due to E x B and Delta-N x B drifts that result from electron density gradients and this inhomogenous electric field. Structure eventually develops in the depletion boundary layer due to low-frequency electrostatic waves that have growth times shorter than the negative ion cyclotron period. It is proposed that these waves are most likely produced by the electron-ion hybrid instability that results from sufficiently large shears in the electron flow velocity.

  12. Marine Cloud Brightening

    SciTech Connect

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

    2012-09-07

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

  13. The Sensitivity of the Cloud Imaging and Particle Size Experiment to Gravity Wave Density Perturbations near the Stratopause

    NASA Astrophysics Data System (ADS)

    Carstens, J. N.; Bailey, S. M.; Alexander, M. J.; Randall, C. E.

    2014-12-01

    Nadir images of Rayleigh scattered UV sunlight (265 nm) from the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite contain many periodic structures. These structures are believed to be the result of Gravity Waves (GW). In this work, we investigate the theoretical impact of GWs on the albedo imagery. We show that GWs are indeed capable of producing the observed structures. The sensitivity to GW perturbations peaks at an altitude of ~50 km with a FWHM of ~15 km with images taken at mid to polar latitudes. For vertical wavelengths greater than 15 km, this corresponds to GWs with momentum fluxes greater than ~0.1-0.01 mPa. Vertical wavelengths less than ~10 km require amplitudes larger than static stability considerations allow, so these GWs are not observable. Observable horizontal wavelengths range from approximately 20 to 300 km. These wavelength ranges correspond to a sensitivity to GWs with an intrinsic period shorter than ~2.5 hrs. Existing satellite GW studies in this altitude region use limb scanners or microwave nadir imagers, which are sensitive to much longer horizontal wavelengths. This tends to limit the sensitivity to longer period waves. Therefore, the addition of CIPS imagery to the existing coverage of GW measurements is complimentary - significantly expanding the spectral coverage of GWs near the stratopause. Short period GWs observed by CIPS carry significantly larger momentum flux than the climatological averages seen for longer period GWs, so important differences may exist. GWs are critically important to middle atmosphere dynamics, and their representation in global climate models is not well constrained by observations.

  14. Introducing Cloud Computing Topics in Curricula

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  15. Simple Cloud Chambers Using Gel Ice Packs

    ERIC Educational Resources Information Center

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  17. Cloud formation in substellar atmospheres

    NASA Astrophysics Data System (ADS)

    Helling, Christiane

    2009-02-01

    Clouds seem like an every-day experience. But-do we know how clouds form on brown dwarfs and extra-solar planets? How do they look like? Can we see them? What are they composed of? Cloud formation is an old-fashioned but still outstanding problem for the Earth atmosphere, and it has turned into a challenge for the modelling of brown dwarf and exo-planetary atmospheres. Cloud formation imposes strong feedbacks on the atmospheric structure, not only due to the clouds own opacity, but also due to the depletion of the gas phase, possibly leaving behind a dynamic and still supersaturated atmosphere. I summarise the different approaches taken to model cloud formation in substellar atmospheres and workout their differences. Focusing on the phase-non-equilibrium approach to cloud formation, I demonstrate the inside we gain from detailed microphysical modelling on for instance the material composition and grain size distribution inside the cloud layer on a Brown Dwarf atmosphere. A comparison study on four different cloud approaches in Brown Dwarf atmosphere simulations demonstrates possible uncertainties in interpretation of observational data.

  18. Marine cloud brightening

    PubMed Central

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

    2012-01-01

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

  19. Radiative Closure Experiments at a Cloud-Free Desert Site, Nevada, as Part of MISR Algorithm Validation

    NASA Technical Reports Server (NTRS)

    Conel, J. E.; Abdou, W. A.; Bruegge, C. J.; Gaitley, B. J.; Helmlinger, M. C.; Ledeboer, W. C.; Pilorz, S. H.; Martonchik, J. V.

    1997-01-01

    Radiative closure experiments involving a comparison between surface-measured spectral irradiance and the surface irradiance calculated according to a radiative transfer code at a desert site in Nevada under clear skies, yield the result that agreement between the two requires presence of an absorbing aerosol component with an imaginary refractive index equal to 0.03 and a 50:50 mix by optical depth of small and large particles with log-normal size distributions.

  20. CLOUD CONDENSATION NUCLEI MEASUREMENTS WITHIN CLOUDS

    EPA Science Inventory

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

  1. 27-day solar forcing of mesospheric temperature, water vapor and polar mesospheric clouds from the AIM SOFIE and CIPS satellite experiments

    NASA Astrophysics Data System (ADS)

    Thomas, Gary; Thurairajah, Brentha; von Savigny, Christian; Hervig, Mark; Snow, Martin

    2016-04-01

    Solar cycle variations of ultraviolet radiation have been implicated in the 11-year and 27-day variations of Polar Mesospheric Cloud (PMC) properties. Both of these variations have been attributed to variable solar ultraviolet heating and photolysis, but no definitive studies of the mechanisms are available. The solar forcing issue is critical toward answering the broader question of whether PMC's have undergone long-term changes, and if so, what is the nature of the responsible long-term climate forcings? One of the principal goals of the Aeronomy of Ice in the Mesosphere satellite mission was to answer the question: "How does changing solar irradiance affect PMCs and the environment in which they form?" We describe an eight-year data set from the AIM Solar Occultation for Ice Experiment (SOFIE) and the AIM Cloud Imaging and Particle Size (CIPS) experiment. Together, these instruments provide high-precision measurements of high-latitude summertime temperature (T), water vapor (H2O), and PMC ice properties for the period 2007-present. The complete temporal coverage of the summertime polar cap region for both the primary atmospheric forcings of PMC (T and H2O), together with a continually updated time series of Lyman-alpha solar irradiance, allows an in-depth study of the causes and effects of 27-day PMC variability. The small responses of these variables, relative to larger day-to-day changes from gravity waves, tides, inter-hemispheric coupling, etc. require a careful statistical analysis to isolate the solar influence. We present results for the 27-day responses of T, H2O and PMC for a total of 15 PMC seasons, (30 days before summer solstice to 60 days afterward, for both hemispheres). We find that the amplitudes and phase relationships are not consistent with the expected mechanisms of solar UV heating and photolysis - instead we postulate a primarily dynamical response, in which a periodic vertical wind heats/cools the upper mesosphere, and modulates PMC

  2. Cloud albedo control by cloud-top entrainment

    NASA Technical Reports Server (NTRS)

    Hanson, Howard P.

    1991-01-01

    Marine stratus and stratocumulus clouds exert a considerable influence on the earth's heat budget, mainly due to their high albedos relative to the ocean surface. It is therefore important to understand the processes that control the radiative properties of these extensive cloud systems, particularly during daylight hours. Aircraft measurements of a stratocumulus cloud deck taken around local noon during the 1987 field phase of the First International Satellite Cloud Climatology Project Regional Experiment are the topic of this paper. A mixing line analysis of data from a series of flight tracks across a strong gradient in cloud albedo provides evidence that variations in the water vapor content of the air above the marine inversion can be responsible for the albedo change. The implications of this unexpected result for climate modeling are discussed.

  3. Survalytics: An Open-Source Cloud-Integrated Experience Sampling, Survey, and Analytics and Metadata Collection Module for Android Operating System Apps

    PubMed Central

    Mackey, Sean

    2016-01-01

    Background We describe here Survalytics, a software module designed to address two broad areas of need. The first area is in the domain of surveys and app analytics: developers of mobile apps in both academic and commercial environments require information about their users, as well as how the apps are being used, to understand who their users are and how to optimally approach app development. The second area of need is in the field of ecological momentary assessment, also referred to as experience sampling: researchers in a wide variety of fields, spanning from the social sciences to psychology to clinical medicine, would like to be able to capture daily or even more frequent data from research subjects while in their natural environment. Objective Survalytics is an open-source solution for the collection of survey responses as well as arbitrary analytic metadata from users of Android operating system apps. Methods Surveys may be administered in any combination of one-time questions and ongoing questions. The module may be deployed as a stand-alone app for experience sampling purposes or as an add-on to existing apps. The module takes advantage of free-tier NoSQL cloud database management offered by the Amazon Web Services DynamoDB platform to package a secure, flexible, extensible data collection module. DynamoDB is capable of Health Insurance Portability and Accountability Act compliant storage of personal health information. Results The provided example app may be used without modification for a basic experience sampling project, and we provide example questions for daily collection of blood glucose data from study subjects. Conclusions The module will help researchers in a wide variety of fields rapidly develop tailor-made Android apps for a variety of data collection purposes. PMID:27261155

  4. Comparisons of cloud ice mass content retrieved from the radar-infrared radiometer method with aircraft data during the second international satellite cloud climatology project regional experiment (FIRE-II)

    SciTech Connect

    Matrosov, S.Y. |; Heymsfield, A.J.; Kropfli, R.A.; Snider, J.B.

    1996-04-01

    Comparisons of remotely sensed meteorological parameters with in situ direct measurements always present a challenge. Matching sampling volumes is one of the main problems for such comparisons. Aircraft usually collect data when flying along a horizontal leg at a speed of about 100 m/sec (or even greater). The usual sampling time of 5 seconds provides an average horizontal resolution of the order of 500 m. Estimations of vertical profiles of cloud microphysical parameters from aircraft measurements are hampered by sampling a cloud at various altitudes at different times. This paper describes the accuracy of aircraft horizontal and vertical coordinates relative to the location of the ground-based instruments.

  5. Zero-gravity cloud physics.

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  6. CLOUD CHEMISTRY.

    SciTech Connect

    SCHWARTZ,S.E.

    2001-03-01

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

  7. Neptune's clouds

    NASA Technical Reports Server (NTRS)

    1999-01-01

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

  8. Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

    SciTech Connect

    Tao, Wei-Kuo; Houze, Robert, A., Jr.; Zeng, Xiping

    2013-03-14

    This three-year project, in cooperation with Professor Bob Houze at University of Washington, has been successfully finished as planned. Both ARM (the Atmospheric Radiation Measurement Program) data and cloud-resolving model (CRM) simulations were used to identify the water budgets of clouds observed in two international field campaigns. The research results achieved shed light on several key processes of clouds in climate change (or general circulation models), which are summarized below. 1. Revealed the effect of mineral dust on mesoscale convective systems (MCSs) Two international field campaigns near a desert and a tropical coast provided unique data to drive and evaluate CRM simulations, which are TWP-ICE (the Tropical Warm Pool International Cloud Experiment) and AMMA (the African Monsoon Multidisciplinary Analysis). Studies of the two campaign data were contrasted, revealing that much mineral dust can bring about large MCSs via ice nucleation and clouds. This result was reported as a PI presentation in the 3rd ASR Science Team meeting held in Arlington, Virginia in March 2012. A paper on the studies was published in the Journal of the Atmospheric Sciences (Zeng et al. 2013). 2. Identified the effect of convective downdrafts on ice crystal concentration Using the large-scale forcing data from TWP-ICE, ARM-SGP (the Southern Great Plains) and other field campaigns, Goddard CRM simulations were carried out in comparison with radar and satellite observations. The comparison between model and observations revealed that convective downdrafts could increase ice crystal concentration by up to three or four orders, which is a key to quantitatively represent the indirect effects of ice nuclei, a kind of aerosol, on clouds and radiation in the Tropics. This result was published in the Journal of the Atmospheric Sciences (Zeng et al. 2011) and summarized in the DOE/ASR Research Highlights Summaries (see http://www.arm.gov/science/highlights/RMjY5/view). 3. Used radar

  9. FAR-ULTRAVIOLET DUST ALBEDO MEASUREMENTS IN THE UPPER SCORPIUS CLOUD USING THE SPINR SOUNDING ROCKET EXPERIMENT

    SciTech Connect

    Lewis, N. K.; Cook, T. A.; Wilton, K. P.; Chakrabarti, S.; France, K.; Gordon, K. D. E-mail: Kevin.France@colorado.ed

    2009-11-20

    The Spectrograph for Photometric Imaging with Numeric Reconstruction sounding rocket experiment was launched on 2000 August 4 to record far-ultraviolet (912-1450 A) spectral and spatial information for the giant reflection nebula in the Upper Scorpius region. The data were divided into three arbitrary bandpasses (912-1029 A, 1030-1200 A, and 1235-1450 A) for which stellar and nebular flux levels were derived. These flux measurements were used to constrain a radiative transfer model and to determine the dust albedo for the Upper Scorpius region. The resulting albedos were 0.28 +- 0.07 for the 912-1029 A bandpass, 0.33 +- 0.07 for the 1030-1200 A bandpass, and 0.77 +- 0.13 for the 1235-1450 A bandpass.

  10. Alterations of Cloud Microphysics Due to Cloud Processed CCN

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  11. ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, S-band Radar (williams-s_band)

    DOE Data Explorer

    Williams, Christopher

    2012-11-06

    This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

  12. Development of methods for inferring cloud thickness and cloud-base height from satellite radiance data

    NASA Technical Reports Server (NTRS)

    Smith, William L., Jr.; Minnis, Patrick; Alvarez, Joseph M.; Uttal, Taneil; Intrieri, Janet M.; Ackerman, Thomas P.; Clothiaux, Eugene

    1993-01-01

    Cloud-top height is a major factor determining the outgoing longwave flux at the top of the atmosphere. The downwelling radiation from the cloud strongly affects the cooling rate within the atmosphere and the longwave radiation incident at the surface. Thus, determination of cloud-base temperature is important for proper calculation of fluxes below the cloud. Cloud-base altitude is also an important factor in aircraft operations. Cloud-top height or temperature can be derived in a straightforward manner using satellite-based infrared data. Cloud-base temperature, however, is not observable from the satellite, but is related to the height, phase, and optical depth of the cloud in addition to other variables. This study uses surface and satellite data taken during the First ISCCP Regional Experiment (FIRE) Phase-2 Intensive Field Observation (IFO) period (13 Nov. - 7 Dec. 1991, to improve techniques for deriving cloud-base height from conventional satellite data.

  13. Status and Operations at the Clouds and the Earth's Radiant Energy System (CERES) Ocean Validation Experiment (COVE) - Also a Baseline Surface Radiation Network (BSRN) Station

    NASA Astrophysics Data System (ADS)

    Fabbri, B. E.; Schuster, G. L.; Denn, F. M.; Rutan, D. A.; Madigan, J. J.; Arduini, R. F.

    2012-12-01

    25 km off the coast of Virginia, a lighthouse structure has been used for scientific measurements for over a decade. The CERES Ocean Validation Experiment (COVE) at Chesapeake Light is involved in several projects and networks. This report focuses on measurements and analysis made over the last 5 years at COVE. Being part of the BSRN network, most of the instruments at COVE are radiometers that measure both downwelling and upwelling flux at visible and infrared wavelengths. Basic meteorological parameters are also monitored. A table will show all the instrumentation and measurements being collected at COVE for the BSRN network as well as other data collections for aerosol, black carbon, total column water vapor and more. The initial motivation for COVE was to serve as a surface validation site for satellites. We compare modeled and actual downwelling shortwave and longwave measurements into 3 different sky scenarios (clear, partly cloudy and cloudy) over a number of years. Results show the best agreement for the clear sky model in both shortwave and longwave, with downwelling longwave correlating and having less mean bias than downwelling shortwave. COVE provides a wide range of measurements over an ocean environment with other examinations including aerosol studies, black carbon analysis and determination of spectral albedos from Multi-Filter Rotating Shadowband Radiometers (MFRSRs). One example displays how we can use these studies and analysis to trace smoke over the COVE site and how it affects our measurements.Chesapeake Light. Home of the Clouds and the Earth's Radiant Energy System (CERES) Ocean Validation Experiment (COVE) ` Location of Chesapeake Light. Home of COVE. 25 kilometers East of Virginia. Coordinates: 36.90 North, 75.71 West

  14. Ash cloud aviation advisories

    SciTech Connect

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

    1992-06-25

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

  15. Complex Clouds

    Atmospheric Science Data Center

    2013-04-16

    ...     View Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired ... Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously from pole to pole, and every 9 days views the entire globe ...

  16. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  17. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

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

  18. Microphysical And Macrophysical Characteristics Of Non-Precipitating Morning Shallow Clouds In Central Amazonia Using One-Year Of Data From GOAMAZON 2014/15 Experiment

    NASA Astrophysics Data System (ADS)

    Pauliquevis, T.; Barbosa, H. M.; Rosario, N. M. E. D.; Rizzo, L. V.; Correia, A. L.; Adams, D. K.; Calheiros, A. J. P.; Alves, C. F.

    2015-12-01

    Shallow cumulus cloud fields in Amazonia are typical of the morning hours. They play a critical role in the mean observed diurnal cycle of precipitation in the Amazon Basin, which is characterized by the occurrence of heavy precipitation events in the afternoon. Shallow clouds act both to reduce incident shortwave radiation at the surface and in the transport of humidity from the lowest portions of the troposphere to higher levels. These two processes are poorly represented in numerical models, but are critical in the transition to deep convection and associated precipitation. Numerical models have problems in properly representing shallow cumulus fields and their transition to deep precipitating convection, the net result of which is producing rainfall to early in the diurnal cycle. Due to their importance, detailed characterization of morning shallow clouds is critical for understanding the shallow-to-deep transition as well as providing for model validation purposes. In this study we report 16 month data of observations of shallow cumulus with respect to cloud cover (CC), cloud base height (CBH), liquid water path (LWP), precipitable water vapor (PWV) and GOES (Visible and IR)analysis. Results showed a consistent pattern of evolution in the cloud field throughout the morning period. After sunrise the cloud field starts to move from a random cloud field to an organized shallow clouds field. In fact, there is an absence of any pattern in CBH from 6LT to 7LT. Once some amount of radiation reaches the surface shallow convection is established around 8:00LT, when a mode of CBH at 100 m is established and rises to 900 m at noon. During this time interval, CC grows up to 50% (mean), however with significant variability and oscillations. With respect to microphysical properties, both LWP and PWV were remarkably stable for single mornings and for shallow clouds, with LWP/PWV ~ 6.10-4. All of these results are being compared with GOES observations of cloud fields (Visible

  19. Transitioning ISR architecture into the cloud

    NASA Astrophysics Data System (ADS)

    Lash, Thomas D.

    2012-06-01

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

  20. Nectar secretion on fern fronds associated with lower levels of herbivore damage: field experiments with a widespread epiphyte of Mexican cloud forest remnants

    PubMed Central

    Koptur, Suzanne; Palacios-Rios, Mónica; Díaz-Castelazo, Cecilia; Mackay, William P.; Rico-Gray, Víctor

    2013-01-01

    Background and Aims The oldest group of plants in which nectar secretions have been observed are the Polypodiopsida (ferns sensu lato). Nectaries have been reported in a dozen extant genera. The function of these nectaries has been investigated in several fern species, and in some circumstances has been demonstrated to have an antiherbivore role, attracting and maintaining biotic defence (ants and/or other predatory arthropods). This study documents foliar nectaries in Pleopeltis crassinervata, a widespread Central American epiphyte growing on a variety of trees in cloud forest areas of Veracruz, Mexico. This is a new record for this genus and species. Methods As previous experimental work on epiphytic species of Polypodium has demonstrated a protective role of ants for developing fronds, we conducted similar experiments (using nylon nail polish to cover nectaries rather than excluding ants with bands of sticky resin as in earlier work). The fronds of Pl. crassinervata developed over 6 weeks, at which time damage was assessed. The experiment was simultaneously conducted on a sympatric species lacking nectaries, Polypodium furfuraceum. Herbivore placement experiments were conducted with large and small caterpillars on both of these ferns. Key Results Fronds with nectaries covered suffered greater damage from herbivores over the course of their development, compared with fronds that had uncovered nectaries functioning normally. The parallel experiment on Po. furfuraceum showed no difference between manipulated and control fronds. Six species of ants (Brachymyrmex minutus, Crematogaster formosa, Paratrechina longicornis, Solenopsis geminata, S. picea and Wasmannia auropunctata) were observed visiting nectaries of Pl. crassinervata; most were effective in removing herbivore larvae placed on the fronds. Conclusions The long evolutionary history of ferns may explain why some previous studies of fern nectaries have shown little or no benefit to ferns from nectary visitors

  1. Cloud Statistics for NASA Climate Change Studies

    NASA Technical Reports Server (NTRS)

    Wylie, Donald P.

    1999-01-01

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

  2. Liquid Cloud Responses to Soot

    NASA Astrophysics Data System (ADS)

    Koch, D. M.

    2010-12-01

    Although soot absorption warms the atmosphere, soot may cause climate cooling due to its effects on liquid clouds, including contribution to cloud condensation nuclei (CCN) and semi-direct effects. Six global models that include aerosol microphysical schemes conducted three soot experiments. The average model cloud radiative response to biofuel soot (black and organic carbon), including both indirect and semi-direct effects, is -0.12 Wm-2, comparable in size but opposite in sign to the respective direct atmospheric warming. In a more idealized fossil fuel black carbon only experiment, some models calculated a positive cloud response because the soot provided a deposition sink for sulfate, decreasing formation of more viable CCN. Biofuel soot particles were typically assumed to be larger and more hygroscopic than for fossil fuel soot and therefore caused more negative forcing, as also found in previous studies. Diesel soot (black and organic carbon) experiments had relatively smaller cloud impacts with five of the models < ±0.06 Wm-2 from clouds. The net semi-direct effect alone may also be negative in global models, as found by several previous studies. The soot-cloud effects are quite uncertain. The range of model responses was large and interrannual variability for each model can also be large. Furthermore the aerosol microphysical schemes are poorly constrained, and the non-linearities resulting from the competition of opposing effects on the CCN population make it difficult to extrapolate from idealized experiments to likely impacts of realistic potential emission changes. However, results so far suggest that soot-induced cloud-cooling effects are comparable in magnitude to the direct warming effects from soot absorption.

  3. Insitu aircraft verification of the quality of satellite cloud winds over oceanic regions

    NASA Technical Reports Server (NTRS)

    Hasler, A. F.; Skillman, W. C.

    1979-01-01

    A five year aircraft experiment to verify the quality of satellite cloud winds over oceans using in situ aircraft inertial navigation system wind measurements is presented. The final results show that satellite measured cumulus cloud motions are very good estimators of the cloud base wind for trade wind and subtropical high regions. The average magnitude of the vector differences between the cloud motion and the cloud base wind is given. For cumulus clouds near frontal regions, the cloud motion agreed best with the mean cloud layer wind. For a very limited sample, cirrus cloud motions also most closely followed the mean wind in the cloud layer.

  4. Validation of cloud forcing simulated by the National Center for Atmospheric Research Community Climate Model using observations from the Earth Radiation Budget Experiment

    NASA Technical Reports Server (NTRS)

    Soden, B. J.

    1992-01-01

    Satellite measurements of the effect of clouds on the top of atmosphere radiative energy budget are used to validate model simulations from the National Center for Atmospheric Research Community Climate Model (NCAR CCM). The ability of the NCAR CCM to reproduce the monthly mean global distribution and temporal variability on both daily and seasonal time scales is assessed. The comparison reveals several deficiencies in the CCM cloud representation. Most notable are the difficulties in properly simulating the effect of clouds on the planetary albedo. This problem arises from discrepancies in the model's portrayal of low-level cloudiness and leads to significant errors in the absorbed solar radiation simulated by the model. The CCM performs much better in simulating the effect of clouds on the longwave radiation emitted to space, indicating its relative success in capturing the vertical distribution of cloudiness. The daily variability of the radiative effects of clouds in both the shortwave and longwave spectral regions is systematically overestimated. Analysis of the seasonal variations illustrates a distinct lack of coupling in the seasonal changes in the radiative effects of cloudiness between the tropics and mid-latitudes and between the Northern and Southern Hemisphere. Much of this problem also arises from difficulties in simulating low-level cloudiness, placing further emphasis on the need for better model parameterizations of boundary layer clouds.

  5. Accessing commercial cloud resources within the European Helix Nebula cloud marketplace

    NASA Astrophysics Data System (ADS)

    Cordeiro, C.; De Salvo, A.; Di Girolamo, A.; Field, L.; Giordano, D.; Jones, R.; Villazon, L.

    2015-12-01

    Helix Nebula - the Science Cloud Initiative - is a public-private partnership between Europe's leading scientific research organisations and European IT cloud providers. CERN contributed to this initiative by providing a flagship use case: the workloads from the ATLAS experiment. Aiming to gain experience in managing and monitoring large-scale deployments, as well as in benchmarking the cloud resources, a sizable Monte Carlo production was performed using the Helix Nebula platform. This contribution describes the Helix Nebula initiative and summarizes the experience and the lessons learned from deploying ATLAS experiment application within large cloud setups involving several commercial providers.

  6. The Evolution of Cloud Computing in ATLAS

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  7. Cloud supersaturations from CCN spectra Hoppel minima

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Global aerosol effects on convective clouds

    NASA Astrophysics Data System (ADS)

    Wagner, Till; Stier, Philip

    2013-04-01

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

  9. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. I. Classical Cepheids in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszynski, I.; Poleski, R.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Szewczyk, O.; Ulaczyk, K.

    2008-09-01

    We present the first part of a new catalog of variable stars (OIII-CVS) compiled from the data collected in the course of the third phase of the Optical Gravitational Lensing Experiment (OGLE-III). In this paper we describe the catalog of 3361 classical Cepheids detected in the approx 40 square degrees area in the Large Magellanic Cloud. The sample consists of 1848 fundamental-mode (F), 1228 first-overtone (1O), 14 second-overtone (2O), 61 double-mode F/1O, 203 double-mode 1O/2O, 2 double-mode 1O/3O, and 5 triple-mode classical Cepheids. This sample is supplemented by the list of 23 ultra-low amplitude variable stars which may be Cepheids entering or exiting instability strip. The catalog data include VI high-quality photometry collected since 2001, and for some stars supplemented by the OGLE-II photometry obtained between 1997 and 2000. We provide basic parameters of the stars: coordinates, periods, mean magnitudes, amplitudes and parameters of the Fourier light curve decompositions. Our sample of Cepheids is cross-identified with previously published catalogs of these variables in the LMC. Individual objects of particular interest are discussed, including single-mode second-overtone Cepheids, multiperiodic pulsators with unusual period ratios or Cepheids in eclipsing binary systems. We discuss the variations of the Fourier coefficients with periods and point out on the sharp feature for periods around 0.35 days of first-overtone Cepheids, which can be explained by the occurrence of 2:1 resonance between the first and fifth overtones. Similar behavior at P approx 3 days for 1O Cepheids and P approx 10 days for F Cepheids are also interpreted as an effect of resonances between two radial modes. We fit the period-luminosity relations to our sample of Cepheids and compare these functions with previous determinations.

  10. Solar-induced 27-day variations of mesospheric temperature and water vapor from the AIM SOFIE experiment: Drivers of polar mesospheric cloud variability

    NASA Astrophysics Data System (ADS)

    Thomas, Gary E.; Thurairajah, Brentha; Hervig, Mark E.; von Savigny, Christian; Snow, Martin

    2015-11-01

    Polar Mesospheric Clouds (PMCs) are known to be influenced by changes in water vapor and temperature in the cold summertime mesopause. Solar variability of these constituents has been held responsible for 11-year and 27-day variability of PMC activity, although the detailed mechanisms are not yet understood. It is also known that the solar influence on PMC variability is a minor contributor to the overall day-to-day variability, which is dominated by effects of gravity waves, planetary waves, and inter-hemispheric coupling. To address this issue, we have analyzed 15 seasons of data taken from the Solar Occultation for Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE data contain precise measurements of water vapor, temperature and ice water content (among other quantities). These high-latitude measurements are made during the PMC season at the terminator, and therefore directly relate to the simultaneous measurements of mesospheric ice. Using a composite data set of Lyman-α irradiance, we correlated the time variation of the atmospheric variables with the 27-day variability of solar ultraviolet irradiance. We used a combination of time-lagged linear regression and Superposed Epoch Analysis to extract the solar contribution as sensitivity values (response/forcing) vs. height. We compare these results to previously published results, and show that the temperature sensitivity is somewhat higher, whereas the water sensitivity is nearly the same as published values. The time lags are shorter than that expected from direct solar heating and photodissociation, suggesting that the responses are due to 27-day variations of vertical winds. An analytic solution for temperature changes forced by solar irradiance variations suggests that if the response is due purely to Lyman-α heating and Newtonian cooling, the response should vary throughout the summertime season and depend primarily upon the height-dependent column density of

  11. Linear Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  12. Enabling Earth Science Through Cloud Computing

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  13. Summertime Arctic Mixed-Phase Clouds

    NASA Astrophysics Data System (ADS)

    Zuidema, P.

    2005-12-01

    3 mixed-phase clouds observed during July of the Surface Heat Budget of the Arctic experiment are discussed. The analysis relies on a combination of surface-based remote sensing measurements and aircraft data. The clouds were multi-layered ice clouds with liquid layers either embedded within the ice phase (July 8) or overlying the ice phase (July 15 and 23). The liquid layers have temperatures ranging between -20 to -5 Celsius. Thin boundary layer clouds or fog underlie the mixed-phase clouds. The boundary layer clouds are liquid but possess temperatures close to the surface temperature of near zero Celsius. The 3 cases all coincide with meltpond-ice surfaces with albedos of approximately 0.5. The cloud microphysical characteristics, radiative impact, and lifecycles will be discussed.

  14. Climate Effects of Cloud Modified CCN-Cloud Interactions

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. Cloud Interactions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

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

  16. VERTICAL TRANSPORT BY CUMULUS CLOUDS

    EPA Science Inventory

    The exchange process between the mixed layer and the free troposphere by non precipitating cumulus convective clouds is examined based on results of two field experiments conducted in Lexington, Kentucky. The first experiment utilized SF6 tracer gas released from one aircraft and...

  17. Biomass burning layers measured with an airborne Single Particle Soot Photometer (SP2) during the Deep Convective Clouds and Chemistry (DC3) experiment

    NASA Astrophysics Data System (ADS)

    Heimerl, K.; Weinzierl, B.; Minikin, A.; Sauer, D. N.; Fütterer, D.; Lichtenstern, M.; Schlager, H.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.; Fahey, D. W.; Huntrieser, H.

    2013-12-01

    The 2012 wildfire season in the U.S. was one of the worst in the past decade. Coinciding with the period of intense wildfires in the western U.S., the Deep Convective Clouds and Chemistry (DC3) experiment took place in the central U.S. in May and June of 2012. Although the main goal of this experiment was to characterize chemical processes in and around thunderstorms, biomass burning plumes from wildfires were also measured during almost every flight. Measurements were performed with three different research aircraft (NCAR GV, NASA DC8 and DLR Falcon 20E), accompanied by ground based measurements with radars and radiosondes, and measurements of meteorological parameters and lightning. The instrumentation aboard the DLR Falcon included measurements of the trace gases NO, CO, O3, CO2, CH4, SO2, volatile organic compounds, and a variety of aerosol microphysical parameters. To cover a wide range of aerosol particle sizes, the DLR Falcon payload included optical particle counters (UHSAS-A, FSSP-300, FSSP-100, PCASP-100X/SPP-200 and Sky-OPC 1.129), a multi-channel CPC system for measuring total and non-volatile particle concentrations and, for absorbing particles, a three-wavelength PSAP and a Single Particle Soot Photometer (SP2). We will focus on the latter in this presentation. The SP2 measures both the mass of refractory black carbon (rBC) particles as well as their optical size, providing information about the mixing state of particles in the biomass burning layers. Most biomass burning layers were found between 3 and 8 km altitude. We will discuss measurements of plumes originating from New Mexico wildfires (Little Bear wildfire on June 11th of 2012 and Whitewater-Baldy wildfire on May 29th and 30th of 2012). Peaks of the rBC mass concentration in the plumes were as high as 2μg/m3, the fraction of rBC particles with thick coatings was higher than what is usually found in the boundary layer. During the Falcon transfer flights from Germany to the U.S. and back

  18. New cloud chamber experiments on the heterogeneous ice nucleation ability of oxalic acid in the deposition nucleation and immersion freezing modes

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Wagner, R.; Saathoff, H.; Schnaiter, M.; Leisner, T.

    2010-12-01

    Dicarboxylic acids are ubiquitous components of the water-soluble organic fraction of the tropospheric aerosol. Their contribution to the total particulate organic carbon typically ranges from 1 - 3 wt% in urban and semi-urban areas to up to 10 wt% in remote marine atmospheres [1,2]. Oxalic acid, malonic acid, and succinic acid are usually the most abundant species, partly comprising more than 80% of the total diacid mass concentrations [3]. Several recent studies have addressed the ice nucleation potential of solid low-molecular weight dicarboxylic acids. On the one hand, the dicarboxylic acids can act as deposition mode ice nuclei provided that they are directly exposed to an ice supersaturated environment, e.g. in form of a coating layer that was formed by physical and chemical processing on prevalent particulates such as mineral dust and soot. At typical tropospheric relative humidities, diacids of low water solubility like oxalic and succinic acid may, on the other hand, also be present as solids that are immersed in aqueous inorganic and/or organic solution droplets [4,5]. These embedded crystals can act as ice nuclei in the immersion mode. Here we present new results from recent experiments at the aerosol and cloud chamber facility of the Karlsruhe Institute of Technology. The ice nucleation ability of aqueous and crystalline oxalic acid aerosol particles was investigated at expansion cooling conditions in the temperature range between 244 and 228 K [6]. Oxalic acid dihydrate particles with diameters between 0.03 to 0.8 μm, that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets, showed a high deposition mode ice activity at temperatures around 244 K. The ice onset humidity was below 110 % with respect to ice, and the ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles

  19. Estimating Cloud Cover

    ERIC Educational Resources Information Center

    Moseley, Christine

    2007-01-01

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

  20. Instrument measures cloud cover

    NASA Technical Reports Server (NTRS)

    Laue, E. G.

    1981-01-01

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

  1. SAGE II (Stratospheric Aerosol and Gas Experiment) observations of polar stratospheric clouds near 50 degree N January 31-February 2, 1989

    SciTech Connect

    Pitts, M.C. ); Poole, L.R.; McCormick, M.P. )

    1990-03-01

    Polar stratospheric clouds (PSCs) form at very cold temperatures which typically occur only at high latitudes during local winter. However, meteorological circumstances in the Arctic during late January 1989 led to PSC formation unusually far to the south, at latitudes (near 50{degree}N) being sampled during the period (January 31-February 2) by the orbiting SAGE II instrument. These unusual PSC sightings and the evolution of meteorological conditions which produced the episode are described. Profiles of SAGE II extinction measurements at 0.525 and 1.02 {mu}m show clear signatures of PSCs and indicate that the cloud particles were considerably larger than the background aerosol. It is most important to note that the clouds were sighted at a latitude where there was extensive sunlight, thus increasing the likelihood of ozone loss both locally and downstream due to enhancements in reactive chlorine expected from heterogeneous chemical processing within the PSCs.

  2. Anatomy of a Cirrus Cloud

    NASA Astrophysics Data System (ADS)

    Cook, C. R.; Whiteway, J.; Choularton, T.; Gallagher, M.; Bower, K.; Flynn, M.; Green, P.; Busen, R.; Hacker, J.

    2003-04-01

    An airborne measurement campaign was conducted during September 2001 to study cirrus clouds above Adelaide, Australia. The campaign was called EMERALD: Egrett Microphysical Experiment with Radiation, Lidar, and Dynamics. It involved the use of two aircraft. One, the King Air, carried a lidar system for mapping the structure of the clouds from below. The second aircraft was the Egrett, a unique aircraft in its ability to fly at relatively slow speeds at altitudes of up to 15 km. The Egrett carried instrumentation for the measurement of cloud particles, water vapour, temperature, turbulence, and ozone. A poster will display a combination of lidar measurements of cloud structure and simultaneous in-situ sampling of ice crystals, thermodynamics, and turbulence.

  3. Thermodynamic and cloud parameter retrieval using infrared spectral data

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Smith, William L., Sr.; Liu, Xu; Larar, Allen M.; Huang, Hung-Lung A.; Li, Jun; McGill, Matthew J.; Mango, Stephen A.

    2005-01-01

    High-resolution infrared radiance spectra obtained from near nadir observations provide atmospheric, surface, and cloud property information. A fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. The retrieval algorithm is presented along with its application to recent field experiment data from the NPOESS Airborne Sounding Testbed - Interferometer (NAST-I). The retrieval accuracy dependence on cloud properties is discussed. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with an accuracy of approximately 1.0 km. Preliminary NAST-I retrieval results from the recent Atlantic-THORPEX Regional Campaign (ATReC) are presented and compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar (CPL).

  4. Underestimation of Deep Convective Cloud Tops by Thermal Imagery

    NASA Technical Reports Server (NTRS)

    Sherwood, Steven C.; Chae, Jung-Hyo; Minnis, Patrick; McGill, Matthew

    2004-01-01

    The most common method of ascertaining cloud heights from space is from thermal brightness temperatures. Deep cumulus clouds of high water content are expected to radiate as black bodies. Here, cloud tops are estimated from several sensors: GOES-8, the Moderate Resolution Imaging Spectroradiometer (MODIS), the Moderate resolution Imaging Sensor (MISR), and the Goddard Cloud Physics Lidar (CPL), all collected during the CRYSTAL Florida Area Cirrus Experiment (CRYSTAL-FACE). Thermally derived cloud tops are consistently approx. 1km too low compared with independent measurements, no matter how thick the clouds are, even when the finite optical extinctions near cloud top and in thin overlying cirrus are taken into account. The bias appears to get worse for the tallest clouds. Cloud material is often present 2 km or more above the apparent cloud top. This mysterious discrepancy appears to be satellite-independent.

  5. Coupling of the microphysical and optical properties of an Arctic nimbostratus cloud during the ASTAR 2004 experiment: Implications for light-scattering modeling

    NASA Astrophysics Data System (ADS)

    Jourdan, Olivier; Mioche, Guillaume; Garrett, Timothy J.; SchwarzenböCk, Alfons; Vidot, JéRôMe; Xie, Yu; Shcherbakov, Valery; Yang, Ping; Gayet, Jean-FrançOis

    2010-12-01

    Airborne measurements in an Arctic mixed-phase nimbostratus cloud were conducted in Spitsbergen on 21 May 2004 during the international Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign. The in situ instrument suite aboard the Alfred Wegener Institute Polar 2 aircraft included a polar nephelometer (PN), a cloud particle imager (CPI), a Nevzorov probe, and a standard PMS 2DC probe to measure the cloud particle single-scattering properties (at a wavelength of 0.8 μm), and the particle morphology and size, as well as the in-cloud partitioning of ice/water content. The main objective of this work is to present a technique based on principal component analysis and light-scattering modeling to link the microphysical properties of cloud particles to their optical characteristics. The technique is applied to the data collected during the 21 May case study where a wide variety of ice crystal shapes and liquid water fractions were observed at temperatures ranging from -1°C to -12°C. CPI measurements highlight the presence of large supercooled water droplets with diameters close to 500 μm. Although the majority of ice particles were found to have irregular shapes, columns and needles were the prevailing regular habits between -3°C and -6°C while stellars and plates were observed at temperatures below -8°C. The implementation of the principal component analysis of the PN scattering phase function measurements revealed representative optical patterns that were consistent with the particle habit classification derived from the CPI. This indicates that the synergy between the CPI and the PN can be exploited to link the microphysical and shape properties of cloud particles to their single-scattering characteristics. Using light-scattering modeling, we have established equivalent microphysical models based on a limited set of free parameters (roughness, mixture of idealized particle habits, and aspect ratio of ice crystals) that reproduce the main

  6. Martian Clouds

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

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

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

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

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

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

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

  7. Effects of Cloud-Processed CCN on Warm Clouds

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Microphysics and Southern Ocean Cloud Feedback

    NASA Astrophysics Data System (ADS)

    McCoy, Daniel T.

    strong indirect control of global cloud fraction by the mixed-phase cloud parameterization. As discussed above, ice crystals are so much larger than liquid droplets that a transition from ice to liquid results in a robust increase in albedo, but this effect is modulated by variations in the size of cloud droplets. Cloud droplet size is determined by the prevalence and efficacy of cloud condensation nuclei (CCN). We present observational and modeling data showing that the sources of CCN in the SO are natural and that biogenic sources account for half of the cloud droplet number concentration in summer when biological productivity and sunlight are strongest. This makes it important to accurately represent biogenic CCN sources, especially their depletion as ocean acidification destroys the calcareous marine organisms that generate the majority of CCN. Despite confirming a natural and substantially biogenic source of CCN, both the source terms of CCN and interaction of CCN with liquid clouds are still uncertain. To help validate the cloud-aerosol indirect effect in GCMs we present a recent natural experiment that occurred when the Bartharbunga-Veithivotn fissure erupted suddenly releasing several times the total sulfur emission from Europe into the Atlantic. Substantial cloud aerosol indirect effects were observed during the eruption. This natural experiment offers a scenario that may be used in GCMs to validate their modeled cloud-aerosol indirect effect. Overall, accurate representations of liquid and mixed-phase cloud microphysics in the SO are required if we want to model the Earth's climate sensitivity. Further, efforts to tune around unreasonable portrayals of SO clouds result in long-ranging biases in global cloud properties and feedbacks.

  9. Simulation and Interpretation of the Genesis of Tropical Storm Gert (2005) as Part of the NASA Tropical Cloud Systems and Processes Experiment

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.; Montgomery, Michael T.; Mallen, Kevin

    2009-01-01

    Several hypotheses have been put forward for the how tropical cyclones (tropical storms and hurricanes in the Atlantic) first develop circulation at the surface, a key event that needs to occur before a storm can begin to draw energy from the warm ocean. One hypothesis suggests that the surface circulation forms from a "top-down" approach in which a storm s rotating circulation begins at middle levels of the atmosphere and builds down to the surface through processes related to light "stratiform" (horizontally extensive) precipitation. Another hypothesis suggests a bottom-up approach in which deep thunderstorm towers (convection) play the major role in spinning up the flow at the surface. These "hot towers" form in the area of the mid-level circulation and strongly concentrate this rotation at low levels within their updrafts. Merger of several of these hot towers then intensifies the surface circulation to the point in which a storm forms. This paper examines computer simulations of Tropical Storm Gert (2005), which formed in the Gulf of Mexico during the National Aeronautics and Space Administration s (NASA) Tropical Cloud Systems and Processes (TCSP) Experiment, to investigate the development of low-level circulation and, in particular, whether stratiform or hot tower processes were responsible for the storm s formation. Data from NASA satellites and from aircraft were used to show that the model did a good job of reproducing the formation and evolution of Gert. The simulation shows that a mix of both stratiform and convective rainfall occurred within Gert. While the stratiform rainfall clearly acted to increase rotation at middle levels, the diverging outflow beneath the stratiform rain worked against spinning up the low-level winds. The hot towers appeared to dominate the low-level flow, producing intense rotation within their cores and often being associated with significant pressure falls at the surface. Over time, many of these hot towers merged, with each

  10. Crater Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

  11. Study of the ammonia ice cloud layer in the north tropical zone of Jupiter from the infrared interferometric experiment on Voyager

    NASA Technical Reports Server (NTRS)

    Shaffer, William A.; Samuelson, Robert E.; Conrath, Barney J.

    1986-01-01

    An average of 51 Voyager 1 IRIS spectra of Jupiter's North Tropical Zone was analyzed to infer the abundance, vertical extent, and size distribution of the particles making up the ammonia cloud in this region. It is assumed that the cloud base coincides with the level at which 100% saturation of ammonia vapor occurs. The vertical distribution of particulates above this level is determined by assuming a constant total ammonia mixing ratio and adjusting the two phases so that the vapor is saturated throughout the cloud. A constant scaling factor then adjusts the base number density. A radiative transfer program is used that includes the effects of absorption and emission of all relevant gases as well as anisotropic scattering by cloud particles. Mie scattering from a gaussian particle size distribution is assumed. The vertical thermal structure is inferred from a temperature retrieval program that utilizes the collision induced S(0) and S(1) molecular hydrogen lines between 300 and 700.cm, and the 1304.cm methane band.

  12. Tropical cirrus cloud radiative forcing: Sensitivity studies

    SciTech Connect

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

    1994-09-01

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

  13. Uniform-Temperature Walls for Cloud Chambers

    NASA Technical Reports Server (NTRS)

    Fleischman, G.

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  15. Lidar cloud studies for FIRE and ECLIPS

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  16. Coherent forward broadening in cold atom clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, F.

    2016-02-01

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

  17. Coherent Forward Broadening in Cold Atom Clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, Francis

    2016-05-01

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

  18. The effect of clouds on the earth's radiation budget

    NASA Technical Reports Server (NTRS)

    Ziskin, Daniel; Strobel, Darrell F.

    1991-01-01

    The radiative fluxes from the Earth Radiation Budget Experiment (ERBE) and the cloud properties from the International Satellite Cloud Climatology Project (ISCCP) over Indonesia for the months of June and July of 1985 and 1986 were analyzed to determine the cloud sensitivity coefficients. The method involved a linear least squares regression between co-incident flux and cloud coverage measurements. The calculated slope is identified as the cloud sensitivity. It was found that the correlations between the total cloud fraction and radiation parameters were modest. However, correlations between cloud fraction and IR flux were improved by separating clouds by height. Likewise, correlations between the visible flux and cloud fractions were improved by distinguishing clouds based on optical depth. Calculating correlations between the net fluxes and either height or optical depth segregated cloud fractions were somewhat improved. When clouds were classified in terms of their height and optical depth, correlations among all the radiation components were improved. Mean cloud sensitivities based on the regression of radiative fluxes against height and optical depth separated cloud types are presented. Results are compared to a one-dimensional radiation model with a simple cloud parameterization scheme.

  19. Martian Clouds Data Workshop

    NASA Technical Reports Server (NTRS)

    Lee, Steven (Editor)

    1987-01-01

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

  20. Observational and Modeling Studies of Clouds and the Hydrological Cycle

    NASA Technical Reports Server (NTRS)

    Somerville, Richard C. J.

    1997-01-01

    Our approach involved validating parameterizations directly against measurements from field programs, and using this validation to tune existing parameterizations and to guide the development of new ones. We have used a single-column model (SCM) to make the link between observations and parameterizations of clouds, including explicit cloud microphysics (e.g., prognostic cloud liquid water used to determine cloud radiative properties). Surface and satellite radiation measurements were used to provide an initial evaluation of the performance of the different parameterizations. The results of this evaluation will then used to develop improved cloud and cloud-radiation schemes, which were tested in GCM experiments.

  1. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XIII. Long-Period Variables in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Kozłowski, S.; Pietrukowicz, P.

    2011-09-01

    The thirteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains 19 384 long-period variables (LPVs) detected in the Small Magellanic Cloud. The sample is composed of 352 Mira stars, 2222 semiregular variables (SRVs) and 16 810 OGLE Small Amplitude Red Giants (OSARGs). Sources are divided into oxygen-rich and carbon-rich stars. The catalog includes time-series VI photometry obtained between 1997 and 2009. Methods used to select and classify variable stars are described. We show some statistical properties of the sample, and compare it with LPVs in the Large Magellanic Cloud. Additionally, we present objects of particular interest, e.g., a SRV with outbursts, and a Mira star with the longest known pulsation period P=1860 days.

  2. Comparison of surface-derived and ISCCP cloud optical properties

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Poole, L. R.; Lecroy, S. R.; Rossow, W. B.; Bell, K. L.; Robinson, David A.; Grund, Christian J.

    1990-01-01

    One objective of the FIRE Project is to validate the cloud parameters given on ISCCP tapes. ISCCP first defines whether or not a region is clear or has clouds based on two threshold algorithms. If the region has clouds, then a cloud optical depth is given as well as a cloud height. Special high resolution ISCCP CX tapes were created for the time period of the Wisconsin FIRE experiment. These tapes did not include the cloud height product, however, other parameters used to make up the standard ISCCP Cl products were available. The ISCCP cloud/no cloud and cloud depth parameters are compared with surface derived values for the Wisconsin FIRE region during the October 27 and 28 case study days.

  3. Contrasting ice microphysical properties of wintertime frontal clouds and summertime convective clouds

    NASA Astrophysics Data System (ADS)

    Wu, W.; McFarquhar, G. M.

    2015-12-01

    The microphysical and optical properties of ice clouds were derived from measurements collected during the Colorado Airborne Multi-phase Cloud Study (CAMPS) and the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX) conducted in the winter of 2010-2011 over the Rocky Mountains and during the Midlatitude Continental Convective Clouds Experiment (MC3E) conducted in the summer of 2011 over Oklahoma. A two-dimensional cloud (2DC) probe, two-dimensional precipitation (2DP) probe and Fast 2DC probe were installed on the University of Wyoming King Air aircraft during CAMPS and a Cloud Imaging Probe (CIP) and Precipitation Imaging Probe were operated on the ground at the Storm Peak Laboratory during STORMVEX. A 2DC, CIP and a high volume precipitation spectrometer were installed in the University of North Dakota Citation aircraft during MC3E. The distributions of particle habits, number distribution functions, total number concentrations, ice water contents, precipitation rates, extinction and effective radius from four cases of wintertime frontal clouds sampled during CAMPS/STORMVEX and from four cases of the stratiform region of summer convective systems from MC3E are compared. It is found that there is higher percentage of pristine ice particles, such as dendrites and columns, in the wintertime frontal clouds than in the summertime convective clouds, where the dominant habits are rimed particles. The number distribution functions are generally broader in the summertime clouds than in the wintertime frontal clouds. In addition, the number concentrations and ice water contents are generally lower in the wintertime frontal clouds than in the summertime convective clouds when comparing the same temperature ranges. Implications about the potential microphysical processes that are acting in these two types of ice clouds are discussed. The results in this study are also compared with previous studies using data from other field campaigns.

  4. Parameterization of cloud effects on the absorption of solar radiation

    NASA Technical Reports Server (NTRS)

    Davies, R.

    1983-01-01

    A radiation parameterization for the NASA Goddard climate model was developed, tested, and implemented. Interactive and off-hire experiments with the climate model to determine the limitations of the present parameterization scheme are summarized. The parameterization of Cloud absorption in terms of solar zeith angle, column water vapors about the cloud top, and cloud liquid water content is discussed.

  5. Recent progress in cloud physics research in China

    NASA Astrophysics Data System (ADS)

    Ma, Jianzhong; Guo, Xueliang; Zhao, Chunsheng; Zhang, Yijun; Hu, Zhijin

    2007-11-01

    A review of China cloud physics research during 2003 2006 is made in this paper. The studies on cloud field experiments and observation, cloud physics and precipitation, including its theoretical applications in hail suppression and artificial rain enhancement, cloud physics and lightning, and clouds and climate change are included. Due primarily to the demand from weather modification activities, the issue of cloud physics and weather modification has been addressed in China with many field experiments and model studies. While cloud physics and weather modification is still an important research field, the interaction between aerosol, cloud and radiation processes, which is the key issue of current climate change research, has become a new research direction in China over the past four years.

  6. The clouds of Venus - A synthesis report

    NASA Technical Reports Server (NTRS)

    Knollenberg, R.; Travis, L.; Tomasko, M.; Smith, P.; Ragent, B.; Esposito, L.; Mccleese, D.; Martonchik, J.; Beer, R.

    1980-01-01

    The results presented represent a synthesis of data from those Pioneer Venus experiments directed toward studying cloud problems. These orbiter and multiprobe experiments show the cloud system to consist of three altitude regions populated by cloud particles and smaller haze particles which extend above and below as well as coexist with the cloud particles. The optical properties derived are only consistent with the largest particles, having platelike morphology. The smallest particles are shown to require changes in chemical composition to explain observed behavior. The medium-sized H2SO4 droplets of 2 micrometers diameter appear to be the least volatile and are the best understood. The role of the cloud particles in precipitation dynamical processes, lightning, and radiation are all discussed.

  7. The Oort cloud

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  8. Cloud pumping in a one-dimensional photochemical model

    NASA Technical Reports Server (NTRS)

    Costen, Robert C.; Tennille, Geoffrey M.; Levine, Joel S.

    1988-01-01

    Cloud pumping data based on tropical maritime updraft statistics are incorporated in a one-dimensional steady-state eddy diffusive photochemical model of the troposphere. It is suggested that regions with weaker convection, such as the midlatitudes, may also experience substantial effects from cloud pumping. The direct effects of cloud pumping on CO were found to be more significant than implied by sensitivity studies. The (CH3)2S profile computed with cloud pumping agrees well with previous data.

  9. CUMULUS CLOUD VENTING OF MIXED LAYER OZONE

    EPA Science Inventory

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols (and possibly other compounds) occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments conducted in July...

  10. Condensed Acids In Antartic Stratospheric Clouds

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Snetsinger, K. G.; Toon, O. B.; Ferry, G. V.; Starr, W. L.; Oberbeck, V. R.; Chan, K. R.; Goodman, J. K.; Livingston, J. M.; Verma, S.; Fong, W.

    1992-01-01

    Report dicusses nitrate, sulfate, and chloride contents of stratospheric aerosols during 1987 Airborne Antarctic Ozone Experiment. Emphasizes growth of HNO3*3H2O particles in polar stratospheric clouds. Important in testing theories concerning Antarctic "ozone hole".

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  12. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. VII. Classical Cepheids in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Poleski, R.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Szewczyk, O.; Ulaczyk, K.

    2010-03-01

    The seventh part of the OGLE-III Catalog of Variable Stars (OIII-CVS) consists of 4630 classical Cepheids in the Small Magellanic Cloud (SMC). The sample includes 2626 fundamental-mode (F), 1644 first-overtone (1O), 83 second-overtone (2O), 59 double-mode F/1O, 215 double-mode 1O/2O, and three triple-mode classical Cepheids. For each object basic parameters, multi-epoch VI photometry collected within 8 or 13 years of observations, and finding charts are provided in the OGLE Internet archive. We present objects of particular interest: exceptionally numerous sample of single-mode second-overtone pulsators, five double Cepheids, two Cepheids with eclipsing variations superimposed on the pulsation light curves. At least 139 first-overtone Cepheids exhibit low-amplitude secondary variations with periods in the range 0.60-0.65 of the primary ones. These stars populate three distinct sequences in the Petersen diagram. The origin of this secondary modulation is still unknown. Contrary to the Large Magellanic Cloud (LMC) we found only a few candidates for anomalous Cepheids in the SMC. This fact may be a clue for the explanation of the origin of the anomalous Cepheids. The period and luminosity distributions of Cepheids in both Magellanic Clouds suggest that there are two or three populations of classical Cepheids in each of the galaxies. The main difference between the LMC and SMC lays in different numbers of Cepheids in each group. We fit the period-luminosity (PL) relations of SMC Cepheids and compare them with the LMC PL laws.

  13. On water in volcanic clouds

    NASA Astrophysics Data System (ADS)

    Durant, Adam J.

    2007-12-01

    Volcanic clouds and tephra fallout present a hazard to aviation, human and animal health (direct inhalation or ingestion, contamination of water supplies), and infrastructure (building collapse, burial of roads and railways, agriculture, abrasive and chemical effects on machinery). Understanding sedimentation processes is a fundamental component in the prediction of volcanic cloud lifetime and fallout at the ground, essential in the mitigation of these hazards. The majority of classical volcanic ash transport and dispersion models (VATDM) are based solely on fluid dynamics. The non-agreement between VATDM and observed regional-scale tephra deposit characteristics is especially obvious at large distances from the source volcano. In meteorology, the processes of hydrometeor nucleation, growth and collection have been long-established as playing a central role in sedimentation and precipitation. Taking this as motivation, the hypothesis that hydrometeor formation drives sedimentation from volcanic clouds was tested. The research objectives of this dissertation are: (1) To determine the effectiveness of tephra particles in the catalysis of the liquid water to ice phase transformation, with application to ice hydrometeor formation in volcanic clouds. (2) To determine the sedimentological characteristics of distal (100s km) tephra fallout from recent volcanic clouds. (3) To assess particle fallout rates from recent volcanic clouds in the context of observed deposit characteristics. (4) To assess the implications of hydrometeor formation on the enhancement of volcanic sedimentation and the potential for cloud destabilization from volcanic hydrometeor sublimation. Dissertation Overview. The following chapters present the analysis, results and conclusions of heterogeneous ice nucleation experiments and sedimentological characterization of several recent tephra deposits. The dissertation is organized in three chapters, each prepared in journal article format. In Chapter 1

  14. Surface radiation budget in the Clouds and the Earth's Radiant Energy System (CERES) effort and in the Global Energy and Water Cycle Experiment (GEWEX)

    NASA Technical Reports Server (NTRS)

    Charlock, Thomas P.; Smith, G. L.; Rose, Fred G.

    1990-01-01

    The surface radiation budget (SRB) and the atmospheric radiative flux divergence (ARD) are vital components of the weather and climate system. The importance of radiation in a complex international scientific endeavor, the GEWEX of the World Climate Research Programme is explained. The radiative transfer techniques and satellite instrumentation that will be used to retrieve the SRB and ARD later in this decade with the CERES are discussed; CERES is a component of the Earth Observing System satellite program. Examples of consistent SRB and ARD retrievals made with Nimbus-7 and International Satellite Cloud Climatology Project data from July 1983 are presented.

  15. The composition of ternary N2/CH4/C2H6 cloud droplets under Titan conditions: Monte Carlo simulations and experiment

    NASA Astrophysics Data System (ADS)

    Luckhaus, David; Firanescu, George; Kathrin Lang, E.; Patey, Grenfell N.; Signorell, Ruth

    2013-08-01

    Molecular-level Monte Carlo simulations are performed to validate equation of state approaches for the description of the N2/CH4/C2H6 vapour-liquid equilibria under conditions relevant to Titan's lower atmosphere. The Monte Carlo simulations confirm the validity of the equation of state approaches, so that both provide a reliable description of the unknown composition of cloud droplets in this region of Titan's atmosphere. Furthermore, the models are compared with experimental data from laboratory studies of aerosol droplets that contain N2, CH4 and C2H6. Good agreement is also found here.

  16. Atmospheric Rivers Coming to a Cloud Near You

    ScienceCinema

    Leung, Ruby

    2014-06-12

    Learn about the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) field campaign in this short video. Ruby Leung, PNNL's lead scientist on this campaign's observational strategy to monitor precipitation.

  17. Atmospheric Rivers Coming to a Cloud Near You

    SciTech Connect

    Leung, Ruby

    2014-03-29

    Learn about the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) field campaign in this short video. Ruby Leung, PNNL's lead scientist on this campaign's observational strategy to monitor precipitation.

  18. The EOS CERES Global Cloud Mask

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  19. Cloud CCN feedback

    SciTech Connect

    Hudson, J.G.

    1992-12-31

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

  20. Self-consistency tests of large-scale dynamics parameterizations for single-column modeling

    SciTech Connect

    Edman, Jacob P.; Romps, David M.

    2015-03-18

    Large-scale dynamics parameterizations are tested numerically in cloud-resolving simulations, including a new version of the weak-pressure-gradient approximation (WPG) introduced by Edman and Romps (2014), the weak-temperature-gradient approximation (WTG), and a prior implementation of WPG. We perform a series of self-consistency tests with each large-scale dynamics parameterization, in which we compare the result of a cloud-resolving simulation coupled to WTG or WPG with an otherwise identical simulation with prescribed large-scale convergence. In self-consistency tests based on radiative-convective equilibrium (RCE; i.e., no large-scale convergence), we find that simulations either weakly coupled or strongly coupled to either WPG or WTG are self-consistent, but WPG-coupled simulations exhibit a nonmonotonic behavior as the strength of the coupling to WPG is varied. We also perform self-consistency tests based on observed forcings from two observational campaigns: the Tropical Warm Pool International Cloud Experiment (TWP-ICE) and the ARM Southern Great Plains (SGP) Summer 1995 IOP. In these tests, we show that the new version of WPG improves upon prior versions of WPG by eliminating a potentially troublesome gravity-wave resonance.

  1. Self-consistency tests of large-scale dynamics parameterizations for single-column modeling

    DOE PAGESBeta

    Edman, Jacob P.; Romps, David M.

    2015-03-18

    Large-scale dynamics parameterizations are tested numerically in cloud-resolving simulations, including a new version of the weak-pressure-gradient approximation (WPG) introduced by Edman and Romps (2014), the weak-temperature-gradient approximation (WTG), and a prior implementation of WPG. We perform a series of self-consistency tests with each large-scale dynamics parameterization, in which we compare the result of a cloud-resolving simulation coupled to WTG or WPG with an otherwise identical simulation with prescribed large-scale convergence. In self-consistency tests based on radiative-convective equilibrium (RCE; i.e., no large-scale convergence), we find that simulations either weakly coupled or strongly coupled to either WPG or WTG are self-consistent, butmore » WPG-coupled simulations exhibit a nonmonotonic behavior as the strength of the coupling to WPG is varied. We also perform self-consistency tests based on observed forcings from two observational campaigns: the Tropical Warm Pool International Cloud Experiment (TWP-ICE) and the ARM Southern Great Plains (SGP) Summer 1995 IOP. In these tests, we show that the new version of WPG improves upon prior versions of WPG by eliminating a potentially troublesome gravity-wave resonance.« less

  2. The impact of parametrized convection on cloud feedback

    PubMed Central

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

    2015-01-01

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

  3. The diurnal variability of marine stratocumulus clouds

    NASA Technical Reports Server (NTRS)

    Rogers, David P.; Olsen, Lola M.

    1990-01-01

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

  4. Absolute Measurement of Electron Cloud Density

    SciTech Connect

    Covo, M K; Molvik, A W; Cohen, R H; Friedman, A; Seidl, P A; Logan, G; Bieniosek, F; Baca, D; Vay, J; Orlando, E; Vujic, J L

    2007-06-21

    Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 {micro}s duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.

  5. Target response to debris cloud incidence

    SciTech Connect

    Kipp, M.E.

    1993-07-01

    The extent of penetration and/or perforation of a target layer by a debris cloud, whose particle mass distribution and velocities were calculated from a previous impact, was determined with two computational approaches. First, the size of single or paired particles required for target perforation was calculated and compared with the largest particle expected based on the fragment size distribution in the debris cloud. A second approach used a three-dimensional shock-wave code to calculate the explicit interaction of individual particles in the debris cloud with the target. The cloud was represented by randomly locating the particles within an envelope, maintaining the mass and size distribution of the particles. This interaction of the cloud of particles produced target surface craters and penetration comparable to recovered witness plates from impact experiments.

  6. Cloud Computing for radiologists.

    PubMed

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

    2012-07-01

    Cloud computing is a concept wherein a computer grid is created using the Internet with the sole purpose of utilizing shared resources such as computer software, hardware, on a pay-per-use model. Using Cloud computing, radiology users can efficiently manage multimodality imaging units by using the latest software and hardware without paying huge upfront costs. Cloud computing systems usually work on public, private, hybrid, or community models. Using the various components of a Cloud, such as applications, client, infrastructure, storage, services, and processing power, Cloud computing can help imaging units rapidly scale and descale operations and avoid huge spending on maintenance of costly applications and storage. Cloud computing allows flexibility in imaging. It sets free radiology from the confines of a hospital and creates a virtual mobile office. The downsides to Cloud computing involve security and privacy issues which need to be addressed to ensure the success of Cloud computing in the future. PMID:23599560

  7. Noctilucent Cloud Sightings

    NASA Video Gallery

    Polar Mesospheric Clouds form during each polar region's summer months in the coldest place in the atmosphere, 50 miles above Earth's surface. Noctilucent Clouds were first observed in 1885 by an a...

  8. Closed Small Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

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

  9. Measurements of cloud condensation nuclei spectra within maritime cumulus cloud droplets: Implications for mixing processes

    NASA Technical Reports Server (NTRS)

    Twohy, Cynthia H.; Hudson, James G.

    1995-01-01

    In a cloud formed during adiabatic expansion, the droplet size distribution will be systematically related to the critical supersaturation of the cloud condensation nuclei (CNN), but this relationship can be complicated in entraining clouds. Useful information about cloud processes, such as mixing, can be obtained from direct measurements of the CNN involved in droplet nucleation. This was accomplished by interfacing two instruments for a series of flights in maritime cumulus clouds. One instrument, the counterflow virtual impactor, collected cloud droplets, and the nonvolatile residual nuclei of the droplets was then passed to a CCN spectrometer, which measured the critical supersaturation (S(sub c)) spectrum of the droplet nuclei. The measured S(sub c) spectra of the droplet nuclei were compared with the S(sub c) spectra of ambient aerosol particles in order to identify which CCN were actually incorporated into droplets and to determine when mixing processes were active at different cloud levels. The droplet nuclei nearly always exhibited lower median S(sub c)'s than the ambient aerosol, as expected since droplets nucleate perferentially on particles with lower critical supersaturations. Critical supersaturation spectra from nuclei of droplets near cloud base were similar to those predicted for cloud regions formed adiabatically, but spectra of droplet nuclei from middle cloud levels showed some evidence that mixing had occurred. Near cloud top, the greatest variation in the spectra of the droplet nuclei was observed, and nuclei with high S(sub c)'s were sometimes present even within relatively large droplets. This suggests that the extent of mixing increases with height in cumulus clouds and that inhomogeneous mixing may be important near cloud top. These promising initial results suggest improvements to the experimental technique that will permit more quantitative results in future experiments.

  10. The albedo of fractal stratocumulus clouds

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  11. Computer animation of clouds

    SciTech Connect

    Max, N.

    1994-01-28

    Computer animation of outdoor scenes is enhanced by realistic clouds. I will discuss several different modeling and rendering schemes for clouds, and show how they evolved in my animation work. These include transparency-textured clouds on a 2-D plane, smooth shaded or textured 3-D clouds surfaces, and 3-D volume rendering. For the volume rendering, I will present various illumination schemes, including the density emitter, single scattering, and multiple scattering models.

  12. Cloud Scaling Properties and Cloud Parameterization

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  13. Cloud microphysics and surface properties in climate

    SciTech Connect

    Stamnes, K.

    1995-09-01

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

  14. Cloud Computing Explained

    ERIC Educational Resources Information Center

    Metz, Rosalyn

    2010-01-01

    While many talk about the cloud, few actually understand it. Three organizations' definitions come to the forefront when defining the cloud: Gartner, Forrester, and the National Institutes of Standards and Technology (NIST). Although both Gartner and Forrester provide definitions of cloud computing, the NIST definition is concise and uses…

  15. Preliminary investigation of radiatively driven convection in marine stratocumulus clouds

    SciTech Connect

    Norris, P.

    1995-09-01

    Marine stratocumulus play an important yet still poorly modeled role in the climate system. These clouds cool the planet, having a large albedo, but little infrared effect. A fundamental question is whether such clouds will exist at a given time and location. Stratocumulus is often formed at higher latitudes as stratus and advected equatorward until it breaks up. Possible mechanisms for cloud breakup include strong subsidence, cloud top entrainment instability (CTEI), drizzle, solar heating and resultant boundary layer decoupling, and surface forcing. The Atlantic Stratocumulus Transition Experiment (ASTEX) was conducted to investigate these potential cloud breakup mechanisms. 5 refs., 3 figs.

  16. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  17. A system for recording physical properties of clouds

    NASA Technical Reports Server (NTRS)

    Purgold, G. C.; Whitlock, C. H.

    1990-01-01

    Characterization of the physical properties of clouds is an important objective of the FIRE Project intensive field operations (IFO) planned for 1990 thru 1992. Physical properties observed from satellites will be directly compared to ground based observations during this period. The technical information is provided which is required to record local cloud parameters such as type of clouds, direction of travel, layering, and cloud fraction data. Such information should be very useful in analyzing other cloud and meteorological data. A system of the type described was deployed as part of the First Global Surface Radiation Budget Experiment in April 1989.

  18. Simple cloud chambers using gel ice packs

    NASA Astrophysics Data System (ADS)

    Kamata, Masahiro; Kubota, Miki

    2012-07-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry ice or liquid nitrogen. The gel can be frozen in normal domestic freezers, and can be used repeatedly by re-freezing. The tracks of alpha-ray particles can be observed continuously for about 20 min, and the operation is simple and easy.

  19. Corona Discharge in Clouds

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  20. Cloud microstructure studies

    NASA Technical Reports Server (NTRS)

    Blau, H. H., Jr.; Fowler, M. G.; Chang, D. T.; Ryan, R. T.

    1972-01-01

    Over two thousand individual cloud droplet size distributions were measured with an optical cloud particle spectrometer flown on the NASA Convair 990 aircraft. Representative droplet spectra and liquid water content, L (gm/cu m) were obtained for oceanic stratiform and cumuliform clouds. For non-precipitating clouds, values of L range from 0.1 gm/cu m to 0.5 gm/cu m; with precipitation, L is often greater than 1 gm/cu m. Measurements were also made in a newly formed contrail and in cirrus clouds.

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

    NASA Astrophysics Data System (ADS)

    Zhang, F.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  3. Methane Clouds on Titan

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.

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

  4. Clouds Over Crater Rim

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

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

  5. Ignition of Aluminum Particles and Clouds

    SciTech Connect

    Kuhl, A L; Boiko, V M

    2010-04-07

    Here we review experimental data and models of the ignition of aluminum (Al) particles and clouds in explosion fields. The review considers: (i) ignition temperatures measured for single Al particles in torch experiments; (ii) thermal explosion models of the ignition of single Al particles; and (iii) the unsteady ignition Al particles clouds in reflected shock environments. These are used to develop an empirical ignition model appropriate for numerical simulations of Al particle combustion in shock dispersed fuel explosions.

  6. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. VIII. Type II Cepheids in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.

    2010-06-01

    The eighth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains type II Cepheids in the Small Magellanic Cloud (SMC). The sample consists of 43 objects, including 17 BL Her, 17 W Vir and 9 RV Tau stars (first examples ever found in the SMC). Seven stars have been classified as peculiar W Vir stars - a recently identified subclass of type II Cepheids. These stars have distinctive light curves, are brighter and bluer than the ordinary W Vir variables. We confirm that a large fraction of the peculiar W Vir stars are members of binary systems. Three type II Cepheids exhibit eclipsing variations superimposed on the pulsation light curves, and three other objects show long-period ellipsoidal variability. All stars with the indication of binarity display secondary periods which may be interpreted as amplitude and/or phase modulations of the pulsation light curves with periods equal to the orbital periods or half the orbital periods. We do not have any model for these modulations, however this phenomenon rules out a possibility of the optical blends of a pulsating star and a binary system. For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.

  7. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IX. RR Lyr Stars in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, J.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.

    2010-09-01

    The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyr stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variable stars, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. We discuss some statistical features of the sample. Period distributions show distinct differences between SMC and LMC populations of RR Lyr variable stars, with the SMC stars having on average longer periods. The mean periods for RRab, RRc and RRe stars are 0.596, 0.366 and 0.293 days, respectively. The mean apparent magnitudes of RRab stars are equal to 19.70 mag in the V-band and 19.12 mag in the I-band. Spatial distribution of RRLyr stars shows that the halo of the SMC is roughly round in the sky, however the density map reveals two maxima near the center of the SMC. For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.

  8. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. II.Type II Cepheids and Anomalous Cepheids in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Szewczyk, O.; Ulaczyk, K.; Poleski, R.

    2008-12-01

    In the second part of the OGLE-III Catalog of Variable Stars (OIII-CVS) we present 197 type II Cepheids and 83 anomalous Cepheids in the Large Magellanic Cloud (LMC). The sample of type II Cepheids consists of 64 BL Her stars, 96 W Vir stars and 37 RV Tau stars. Anomalous Cepheids are divided into 62 fundamental-mode and 21 first-overtone pulsators. These are the largest samples of such types of variable stars detected anywhere outside the Galaxy. We present the period-luminosity and color-magnitude diagrams of stars in the sample. If the boundary period between BL Her and W Vir stars is adopted at 4 days, both groups differ significantly in (V-I) colors. We identify a group of 16 peculiar W Vir stars with different appearance of the light curves, brighter and bluer than ordinary stars of that type. Four of these peculiar W Vir stars show additional eclipsing modulation superimposed on the pulsation light curves. Four other stars of that type show long-period secondary variations which may be ellipsoidal modulations. It suggests that peculiar W Vir subgroup may be related to binarity. In total, we identified seven type II Cepheids simultaneously exhibiting eclipsing variations which is a very large fraction compared to classical Cepheids in the LMC. We discuss diagrams showing Fourier parameters of the light curve decomposition against periods. Three sharp features interpreted as an effect of resonances between radial modes are detectable in these diagrams for type II Cepheids.

  9. Analysis of Cirrus Cloud Microphysical Data

    NASA Technical Reports Server (NTRS)

    Poellot, Michael R.; Grainger, Cedric A.

    1999-01-01

    The First International Satellite Cloud Climatology Regional Experiment (FIRE) program has the goal of improving our capabilities to understand, model and detect the properties of climatically-important clouds. This is being undertaken through a three-pronged effort of modeling, long-term observations and short-term intensive field studies. Through examination of satellite and other data it is apparent that stratus and cirrus cloud types have the greatest impact on climate due to their radiative effects and ubiquitous nature. As a result, the FIRE program has developed two paths of investigation, each having its own subset of research objectives and measurement programs. The work conducted under this grant was directed toward furthering our understanding of cirrus cloud systems. While it is known that cirrus are climatically important, the magnitude and even sign of the impact is unclear. Cirrus clouds affect the transfer of radiation according to their physical depth and location in the atmosphere and their microphysical composition. However, significant uncertainties still exist in how cirrus clouds form and how they are maintained, what their physical properties are and how they can be parameterized in numerical models. Better remote sensing techniques for monitoring cirrus cloud systems and improved modeling of radiative transfer through ice particles are also needed. A critical element in resolving these issues is a better understanding of cirrus cloud microphysical properties and how they vary. The focus of the research to be conducted under this grant was th data collected in situ by the University of North Dakota Citation aircraft. The goals of this research were to add to the body of knowledge of cirrus cloud microphysics, particularly at the small end of the size spectrum; and analyze the spatial variation of cirrus clouds.

  10. A Benchmark for Cloud Tracking Wind Measurements

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  12. VHF Wind Profiling Radar Studies at Darwin, Australia

    NASA Astrophysics Data System (ADS)

    Dolman, B. K.; Reid, I. M.; May, P. T.; Vincent, R. A.

    2012-12-01

    A 54.1 MHz wind profiling radar was installed at Darwin, Australia in late 2005, to participate in the TWP-ICE campaign, and it has remained in this location. The primary purpose of the instrument was to measure the horizontal and vertical lower troposphere winds in the vertical column above the profiler. The profiler operates at 7.5 kW, and utilizes the Spaced Antenna Full Correlation Analysis (FCA) technique to measure winds, this achieving high temporal resolution. In addition to sampling the wind field, VHF profilers are capable of retrieving the rain drop size distribution (DSD), as radar returns are received from precipitation and clear-air with roughly equal magnitude. DSD retrievals then permit examination of the precipitation structure and spatial and temporal evolution in the vertical column above the profiler as rain bands pass over head. Understanding the evolution of the rain drop size distribution (DSD) in the descent from cloud to ground is important for quantitative precipitation estimation. The Darwin profiler has been used in multiple intercomparison studies. The FCA technique is well known to underestimate the wind magnitude by up to 10%, when compared to other measurement techniques, but agree well in direction. As the profiler is co-located with routine sonde launches, a large intercomparison data set exists, which can be used to investigate empirical corrections to the underestimation. Similarly, profiler vertical velocity estimates can be compared to Doppler Lidar measurements, and the relative strengths of both instruments examined. The profiler can also be used in rainfall studies. During TWP-ICE, when rainfall events passed over the profiler the DSD was retrieved. Each rain event was then separated into stratiform, convective and transitional regions. The integral rainfall parameters were then averaged through each region, and examined for evidence of a dominant microphysical process. For example, evaporation is detected through an

  13. Nutrient limitation restricts growth and reproductive output in a tropical montane cloud forest bromeliad: findings from a long-term forest fertilization experiment.

    PubMed

    Lasso, Eloisa; Ackerman, James D

    2013-01-01

    From studies in seasonal lowland tropical forests, bromeliad epiphytes appear to be limited mainly by water, and to a lesser extent by nutrient supply, especially phosphorous. Less is understood about the mineral nutrition of tropical montane cloud forest (TMCF) epiphytes, even though their highest diversity is in this habitat. Nutrient limitation is known to be a key factor restricting forest productivity in TMCF, and if epiphytes are nutritionally linked to their host trees, as has been suggested, we would expect that they are also nutrient limited. We studied the effect of a higher nutrient input on reproduction and growth of the tank bromeliad Werauhia sintenisii in experimental plots located in a TMCF in Puerto Rico, where all macro- and micronutrients had been added quarterly starting in 1989 and continuing throughout the duration of this study. We found that bromeliads growing in fertilized plots were receiving litterfall with higher concentrations of N, P, and Zn and had higher concentrations of P, Zn, Fe, Al, and Na in their vegetative body. The N:P ratios found (fertilized = 27.5 and non-fertilized = 33.8) suggest that W. sintenisii may also be phosphorous limited as are lowland epiphytes. Fertilized plants had slightly longer inflorescences, and more flowers per inflorescence, than non-fertilized plants, but their flowers produced nectar in similar concentrations and quantities. Fertilized plants produced more seeds per fruit and per plant. Frequency of flowering in two consecutive years was higher for fertilized plants than for controls, suggesting that fertilized plants overcome the cost of reproduction more readily than non-fertilized plants. These results provide evidence that TMCF epiphytic bromeliads are nutrient limited like their lowland counterparts. PMID:22767363

  14. A numerical cloud model for the support of laboratory experimentation

    NASA Technical Reports Server (NTRS)

    Hagen, D. E.

    1979-01-01

    A numerical cloud model is presented which can describe the evolution of a cloud starting from moist aerosol-laden air through the diffusional growth regime. The model is designed for the direct support of cloud chamber laboratory experimentation, i.e., experiment preparation, real-time control and data analysis. In the model the thermodynamics is uncoupled from the droplet growth processes. Analytic solutions for the cloud droplet growth equations are developed which can be applied in most laboratory situations. The model is applied to a variety of representative experiments.

  15. Implications of microphysics for cloud-radiation parameterizations: Lessons from TOGA COARE

    SciTech Connect

    Iacobellis, S.F.; Somerville, R.C.J.

    2000-01-15

    A single-column model (SCM) and observational data collected during TOGA COARE were used to investigate the sensitivity of model-produced cloud properties and radiative fluxes to the representation of cloud microphysics in the cloud-radiation parameterizations. Four 78-day SCM numerical experiments were conducted for the atmospheric column overlying the COARE Intensive Flux Array. Each SCM experiment used a different cloud-radiation parameterization with a different representation of cloud microphysics. All the SCM experiments successfully reproduced most of the observed temporal variability in precipitation, cloud fraction, shortwave and longwave cloud forcing, and downwelling surface shortwave flux. The magnitude and temporal variability of the downward surface longwave flux was overestimated by all the SCM experiments. This bias is probably due to clouds forming too low in the model atmosphere. Time-averaged model results were used to examine the sensitivity of model performance to the differences between the four cloud-radiation parameterization packages. The SCM versions that calculated cloud amount as a function of cloud liquid water, instead of using a relative humidity-based cloud scheme, produced smaller amounts of both low and deep convective clouds. Additionally, larger high (cirrus) cloud emissivities were obtained with interactive cloud liquid water schemes than with the relative humidity-based scheme. Surprisingly, calculating cloud optical properties as a function of cloud liquid water amount, instead of parameterizing them based on temperature, humidity, and pressure, resulted in relatively little change in radiative fluxes. However, model radiative fluxes were sensitive to the specification of the effective cloud droplet radius. Optically thicker low clouds and optically thinner high clouds were produced when an interactive effective cloud droplet radius scheme was used instead of specifying a constant value. Comparison of model results to both

  16. Annual cycle of radiation fluxes over the Arctic ocean: Sensitivity to cloud optical properties

    SciTech Connect

    Curry, J.A. ); Ebert, E.E. )

    1992-11-01

    The relationship between cloud optical properties and the radiative fluxes over the Arctic Ocean is explored by conducting a series of modeling experiments. The annual cycle of arctic cloud optical properties that are required to reproduce both the outgoing radiative fluxes at the top of the atmosphere as determined from satellite observations and the available determinations of surface radiative fluxes are derived. Existing data on cloud fraction and cloud microphysical properties are utilized. Four types of cloud are considered: low stratus clouds, midlevel clouds, citrus clouds, and wintertime ice crystal precipitation. Internally consistent annual cycles of surface temperature, surface albedo, cloud fraction and cloud optical properties, components of surface and top of atmosphere radiative fluxes, and cloud radiative forcing are presented. The modeled total cloud optical depth (weighted by cloud fraction) ranges from a low value in winter of 2 to a high summertime value of 8. Infrared emmissivities for liquid water clouds are shown to be substantially less than unity during the cold half of the year. Values of modeled surface cloud radiative forcing are positive except for two weeks in midsummer; over the course of the year clouds have a net warming effect on the surface in the Arctic. Total cloud radiative forcing at the top of the atmosphere is determined to be positive only briefly in early autumn. Surface longwave fluxes are shown to be very sensitive to the presence of lower-tropospheric ice crystal precipitation during the cold half of the year.

  17. Interpretation of FRESCO cloud retrievals in case of absorbing aerosol events

    NASA Astrophysics Data System (ADS)

    Wang, P.; Tuinder, O. N. E.; Tilstra, L. G.; de Graaf, M.; Stammes, P.

    2012-10-01

    Cloud and aerosol information is needed in trace gas retrievals from satellite measurements. The Fast REtrieval Scheme for Clouds from the Oxygen A band (FRESCO) cloud algorithm employs reflectance spectra of the O2 A band around 760 nm to derive cloud pressure and effective cloud fraction. In general, clouds contribute more to the O2 A band reflectance than aerosols. Therefore, the FRESCO algorithm does not correct for aerosol effects in the retrievals and attributes the retrieved cloud information entirely to the presence of clouds, and not to aerosols. For events with high aerosol loading, aerosols may have a dominant effect, especially for almost cloud free scenes. We have analysed FRESCO cloud data and Absorbing Aerosol Index (AAI) data from the Global Ozone Monitoring Experiment (GOME-2) instrument on the Metop-A satellite for events with typical absorbing aerosol types, such as volcanic ash, desert dust and smoke. We find that the FRESCO effective cloud fractions are correlated with the AAI data for these absorbing aerosol events and that the FRESCO cloud pressure contains information on aerosol layer pressure. For cloud free scenes, the derived FRESCO cloud pressure is close to the aerosol layer pressure, especially for optically thick aerosol layers. For cloudy scenes, if the strongly absorbing aerosols are located above the clouds, then the retrieved FRESCO cloud pressure may represent the height of the aerosol layer rather than the height of the clouds. Combining FRESCO and AAI data, an estimate for the aerosol layer pressure can be given.

  18. Statistical properties of a cloud ensemble - A numerical study

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Simpson, Joanne; Soong, Su-Tzai

    1987-01-01

    The statistical properties of cloud ensembles under a specified large-scale environment, such as mass flux by cloud drafts and vertical velocity as well as the condensation and evaporation associated with these cloud drafts, are examined using a three-dimensional numerical cloud ensemble model described by Soong and Ogura (1980) and Tao and Soong (1986). The cloud drafts are classified as active and inactive, and separate contributions to cloud statistics in areas of different cloud activity are then evaluated. The model results compare well with results obtained from aircraft measurements of a well-organized ITCZ rainband that occurred on August 12, 1974, during the Global Atmospheric Research Program's Atlantic Tropical Experiment.

  19. Interpretation of MODIS Cloud Images by CloudSat/CALIPSO Cloud Vertical Profiles

    NASA Astrophysics Data System (ADS)

    Wang, T.; Fetzer, E. J.; Wong, S.; Yue, Q.

    2015-12-01

    Clouds observed by passive remote-sensing imager (Aqua-MODIS) are collocated to cloud vertical profiles observed by active profiling sensors (CloudSat radar and CALIPSO lidar) at the pixel-scale. By comparing different layers of cloud types classified in the 2B-CLDCLASS-LIDAR product from CloudSat+CALIPSO to those cloud properties observed by MODIS, we evaluate the occurrence frequencies of cloud types and cloud-overlap in CloudSat+CALIPSO for each MODIS cloud regime defined by cloud optical depth (τ) and cloud-top pressure (P) histograms. We find that about 70% of MODIS clear sky agrees with the clear category in CloudSat+CALIPSO; whereas the remainder is either single layer (~25%) cirrus (Ci), low-level cumulus (Cu), stratocumulus (Sc), or multi-layer (<5%) clouds in CloudSat+CALIPSO. Under MODIS cloudy conditions, 60%, 28%, and 8% of the occurrences show single-, double-, and triple-layer clouds, respectively in CloudSat+CALIPSO. When MODIS identifies single-layer clouds, 50-60% of the MODIS low-level clouds are categorized as stratus (Sc) in CloudSat+CALIPSO. Over the tropics, ~70% of MODIS high and optically thin clouds (considered as cirrus in the histogram) is also identified as Ci in CloudSat+CALIPSO, and ~40% of MODIS high and optically thick clouds (considered as convective in the histogram) agrees with CloudSat+CALIPSO deep convections (DC). Over mid-latitudes these numbers drop to 45% and 10%, respectively. The best agreement occurs in tropical single-layer cloud regimes, where 90% of MODIS high-thin clouds are identified as Ci by CloudSat+CALIPSO and 60% of MODIS high-thick clouds are identified as DC. Worst agreement is found for multi-layer clouds, where cirrus on top of low- and mid-level clouds in MODIS are frequently categorized as high-thick clouds by passive imaging - among these only 5-12% are DC in CloudSat+CALIPSO. It is encouraging that both MODIS low-level clouds (regardless of optical thickness) and high-level thin clouds are consistently

  20. Ionospheric Geo-effectiveness of Magnetic Clouds

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Knipp, D. J.; Lynch, B.; Zurbuchen, T.; McHarg, M. G.; Chun, F. K.

    2002-12-01

    We present an analysis of the geo-effectiveness of magnetic clouds and the disturbed solar wind surrounding them. Estimates of the ionospheric Joule heating rates based on two ground magnetic indices and estimates of auroral zone particle heating from polar satellites will be combined to provide a summary of the total geomagnetic heating during magnetic cloud passage. Preliminary estimates suggest that intervals of magnetic cloud passage experience about 50 percent greater heating rates than intervals associated with the more general class of interplanetary coronal mass ejection. Heating rates for magnetic clouds are about four times greater than heating rates estimated for intervals of background slow solar wind flow. Preliminary work also indicates that magnetic clouds lying in the ecliptic plane (leading or trailing fields oriented N-S or S-N) have heating rates about 50 percent greater than clouds with leading or trailing fields perpendicular to the ecliptic plane. We will provide hourly heating profiles for more than 50 magnetic clouds passing the earth during the rise and peak of solar cycle 23.

  1. Cloud interactions and merging - Numerical simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Simpson, J.

    1984-01-01

    A total of 48 numerical experiments have been performed to study cloud interactions adn merging by means of a two-dimensional multi-cell model. Two soundings of deep convection during GATE and two different magnitudes of large-scale lifting have been used as the initial conditions and as the main forcing on the model. Over two hundred groups of cloud systems with a life history of over sixty minutes have been generated under the influence of different combinations of the stratification and large-scale lifting. The results demonstrate the increase in convective activity and in amount of precipitation with increased intensity of large-scale lifting. The results also show increased occurrence of cloud merger with increased intensity of large-scale lifting. The most unfavorable environmental conditions for cloud merging are (1) less unstable stratification of the atmosphere and (2) weaker large-scale lifting. A total of fourteen cloud systems qualify as mergers. Two selected cases will be described dynamically and thermodynamically in this paper. Although these cloud mergers have been simulated under the influence of different synoptic-scale conditions, the major physical mechanism related to the cloud merging process is the same as that proposed by Simpson. Cumulus downdrafts and associated cold outflows play a dominant role in the merging process in all cases studied.

  2. Glory of clouds in the near infrared.

    PubMed

    Spinhirne, J D; Nakajima, T

    1994-07-20

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

  3. What is a Cloud?

    NASA Astrophysics Data System (ADS)

    Long, C. N.; Wu, W.

    2013-12-01

    There are multiple factors that cause disagreements between differing methods using differing instruments to infer cloud amounts. But along with these issues is a fundamental concern that has permeated all comparisons and supersedes such questions as what are the uncertainty estimates of a given retrieval. To wit: what is a cloud? How can uncertainty of a cloud amount measurement be determined when there is no absolute 'truth' on what defines a cloud, as opposed to cloud-free? Recent research comparing a decade of surface- and satellite-based retrievals of cloud amount for the ARM Southern Great Plains site shows significant disagreements. While Total Sky Imager 100-degree FOV, Shortwave (SW) Radiative Flux Analysis, GOES satellite and PATMOS-x satellite amounts agree relatively well, ISCCP satellite and ARSCL time-series cloud amounts are significantly greater, 15% (ISCCP) and 8% (ARSCL) larger in average diurnal variations. In both cases, it appears that optically thin high ice is counted as 'cloud' in ARSCL and ISCCP that is not categorized as cloud by all the others. Additionally, cloud amounts from three methods (ISCCP, ARSCL, and GOES) show an overall increase of 8%-10% in the annually averaged cloud fractions from 1998 to 2009, while those from the other three (TSI, SWFA, PATMOS-x) show little trend for this period. So one wonders: are cloud amounts increasing or not over this period? The SW Flux Analysis used sky imager retrievals as 'truth' in development of the methodology (Long et al, 2006a), where sky imagery itself used human observations as the model (Long et al., 2006b). Min et al. (2008) then used SW Flux Analysis retrievals as 'truth' to develop an MFRSR-based spectral SW retrieval method. Dupont et al. (2008) show that the SW-based retrievals allow up to a visible optical depth of 0.15 (95% of occurrences) under the 'clear-sky' category which primarily consists of sub-visual cirrus, which by ancestry applies to spectral SW, sky imager and human

  4. Stratus Cloud Supersaturations

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  5. Energy Aware Clouds

    NASA Astrophysics Data System (ADS)

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

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

  6. Ammonia Clouds on Jupiter

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

    In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

  7. Clouds and Shortwave Fluxes at Nauru. Part I: Retrieved Cloud Properties

    SciTech Connect

    McFarlane, Sally A.; Evans, K. F.

    2004-03-01

    The datasets currently being collected at the Atmospheric Radiation Measurement (ARM)Program's sites on the islands of Nauru and Manus represent the longest time series of ground based cloud measurements available in the tropical western Pacific region. This paper presents statistics of retrieved microphysical properties of non-precipitating liquid and ice clouds and estimates of the shortwave cloud radiative effect from 12 months of data collected at the Nauru site between June 1999 and May 2000. Non-precipitating liquid clouds observed at Nauru were primarily shallow cumulus with bases less than 1 km. Of the retrieved liquid clouds, 90% had liquid water path less than 100 grams per square meter. The average retrieved effective radius was 9.9 microns, however limitations in the sensitivity of the two-channel microwave radiometer led to large uncertainties in retrieved effective radius and liquid water content for the shallow clouds typically seen at Nauru. The frequency of liquid c loud detection, height of liquid cloud base, and magnitude of the shortwave cloud radiative effect showed a clear diurnal cycle, which is most likely related to the island effect and the existence of the Nauru cloud plume. An average shortwave radiative cloud effect of -55.4 watts per square meter was estimated over the study period, which is significantly lower than studies during the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA-COARE). Differences in clear sky modeling do not seem large enough to account for this difference, indicating that there was probably less cloud over Nauru during the current study period than during TOGA-COARE, which is consistent with the phase of the El-Nino Southern Oscillation (ENSO) during the two periods.

  8. Formation of Bidisperse Particle Clouds

    NASA Astrophysics Data System (ADS)

    Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

    2014-11-01

    When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

  9. Inter-comparison of CALIPSO and CloudSat retrieved profiles of aerosol and cloud microphysical parameters with aircraft profiles over a tropical region

    NASA Astrophysics Data System (ADS)

    Padmakumari, B.; Harikishan, G.; Maheskumar, R. S.

    2016-05-01

    Satellites play a major role in understanding the spatial and vertical distribution of aerosols and cloud microphysical parameters over a large area. However, the inherent limitations in satellite retrievals can be improved through inter-comparisons with airborne platforms. Over the Indian sub-continent, the vertical profiles retrieved from space-borne lidar such as CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) on board the satellite CALIPSO and Cloud Profiling Radar (CPR) on board the satellite CloudSat were inter- compared with the aircraft observations conducted during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX). In the absence of high clouds, both aircraft and CALIOP showed similar features of aerosol layering and water-ice cloud signatures. As CALIOP could not penetrate the thick clouds, the aerosol information below the cloud is missed. While the aircraft could measure high concentrations below the cloud base and above the low clouds in the presence of high clouds. The aircraft derived liquid water content (LWC) and droplet effective radii (Re) showed steady increase from cloud base to cloud top with a variable cloud droplet number concentration (CDNC). While the CloudSat derived LWC, CDNC and Re showed increase from the cloud top to cloud base in contradiction to the aircraft measurements. The CloudSat profiles are underestimated as compared to the corresponding aircraft profiles. Validation of satellite retrieved vertical profiles with aircraft measurements is very much essential over the tropics to improve the retrieval algorithms and to constrain the uncertainties in the regional cloud parameterization schemes.

  10. Statistical Properties of a Cloud Ensemble: A Numerical Study.

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Simpson, Joanne; Soong, Su-Tzai

    1987-11-01

    Two- and three-dimensional configurations of a cloud ensemble model are used to study the statistical properties of cloud ensembles under an observed large-scale condition. The basic design of the model has been presented in papers by Soong, Ogura, and Tao. An observed large-scale lifting and small amplitude random perturbations in the form of temperature fluctuations are imposed continuously in the model. The model then allows many clouds of different sizes to develop simultaneously. A 6-hour time integration is made to allow a large number of convective clouds to develop. After the model integration, horizontal and time averages of various relevant variables are computed to elucidate the statistical properties of clouds. The model is applied to the case of a well-organized intertropical convergence zone (ITCZ) rainband that occurred on 12 August 1974, during the Global Atmospheric Research Program's Atlantic Tropical Experiment.The statistical properties of clouds, such as mass flux by cloud drafts and vertical velocity as well as condensation and evaporation associated with these cloud drafts are examined in this study. The cloud drafts are further subclassified as inactive and active. Separate contributions to cloud statistics in areas of different cloud activity are then evaluated. The model results compared well with those obtained from aircraft measurements. Some implications of model results to the cumulus parameterization problem are briefly discussed. A comparison between the two- and three-dimensional model simulations is also made.

  11. Atmospheric cloud physics laboratory project study

    NASA Technical Reports Server (NTRS)

    Schultz, W. E.; Stephen, L. A.; Usher, L. H.

    1976-01-01

    Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

  12. Evaluating Clouds in Long-Term Cloud-Resolving Model Simulations with Observational Data

    NASA Technical Reports Server (NTRS)

    Zeng, Xiping; Tao, Wei-Kuo; Zhang, Minghua; Peters-Lidard, Christa; Lang, Stephen; Simpson, Joanne; Kumar, Sujay; Xie, Shaocheng; Eastman, Joseph L.; Shie, Chung-Lin; Geiger, James V.

    2006-01-01

    Two 20-day, continental midlatitude cases are simulated with a three-dimensional (3D) cloud-resolving model (CRM) and compared to Atmospheric Radiation Measurement (ARM) data. This evaluation of long-term cloud-resolving model simulations focuses on the evaluation of clouds and surface fluxes. All numerical experiments, as compared to observations, simulate surface precipitation well but over-predict clouds, especially in the upper troposphere. The sensitivity of cloud properties to dimensionality and other factors is studied to isolate the origins of the over prediction of clouds. Due to the difference in buoyancy damping between 2D and 3D models, surface precipitation fluctuates rapidly with time, and spurious dehumidification occurs near the tropopause in the 2D CRM. Surface fluxes from a land data assimilation system are compared with ARM observations. They are used in place of the ARM surface fluxes to test the sensitivity of simulated clouds to surface fluxes. Summertime simulations show that surface fluxes from the assimilation system bring about a better simulation of diurnal cloud variation in the lower troposphere.

  13. Comparison between SAGE II and ISCCP high-level clouds. 1: Global and zonal mean cloud amounts

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Global high-level clouds identified in Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements for January and July in the period 1985 to 1990 are compared with near-nadir-looking observations from the International Satellite Cloud Climatology Project (ISCCP). Global and zonal mean high-level cloud amounts from the two data sets agree very well, if clouds with layer extinction coefficients of less than 0.008/km at 1.02 micrometers wavelength are removed from the SAGE II results and all detected clouds are interpreted to have an average horizontal size of about 75 km along the 200 km transimission path length of the SAGE II observations. The SAGE II results are much more sensitive to variations of assumed cloud size than to variations of detection threshold. The geographical distribution of cloud fractions shows good agreement, but systematic regional differences also indicate that the average cloud size varies somewhat among different climate regimes. The more sensitive SAGE II results show that about one third of all high-level clouds are missed by ISCCP but that these clouds have very low optical thicknesses (less than 0.1 at 0.6 micrometers wavelength). SAGE II sampling error in monthly zonal cloud fraction is shown to produce no bias, to be less than the intraseasonal natural variability, but to be comparable with the natural variability at longer time scales.

  14. Lost in Cloud

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  15. Correction of Rayleigh Scattering Effects in Cloud Optical Thickness Retrievals

    NASA Technical Reports Server (NTRS)

    Wang, Meng-Hua; King, Michael D.

    1997-01-01

    Stratocumulus Transition Experiment (ASTEX) conducted near the Azores in June 1992 and compare these results to corresponding retrievals obtained using 0.88 Am. These results provide an example of the Rayleigh scattering effects on thin clouds and further test the Rayleigh correction scheme. Using a nonabsorbing near-infrared wavelength lambda (0.88 Am) in retrieving cloud optical thickness is only applicable over oceans, however, since most land surfaces are highly reflective at 0.88 Am. Hence successful global retrievals of cloud optical thickness should remove Rayleigh scattering effects when using reflectance measurements at 0.66 Am.

  16. Microphysical Timescales in Clouds and their Application in Cloud-Resolving Modeling

    NASA Technical Reports Server (NTRS)

    Zeng, Xiping; Tao, Wei-Kuo; Simpson, Joanne

    2007-01-01

    Independent prognostic variables in cloud-resolving modeling are chosen on the basis of the analysis of microphysical timescales in clouds versus a time step for numerical integration. Two of them are the moist entropy and the total mixing ratio of airborne water with no contributions from precipitating particles. As a result, temperature can be diagnosed easily from those prognostic variables, and cloud microphysics be separated (or modularized) from moist thermodynamics. Numerical comparison experiments show that those prognostic variables can work well while a large time step (e.g., 10 s) is used for numerical integration.

  17. Flame propagation and extinction in particle clouds

    NASA Technical Reports Server (NTRS)

    Berlad, A. L.; Joshi, N. D.

    1986-01-01

    Two phase flame propagation and extinction theory required to support the corresponding experiments planned for the space shuttle is being developed. Also being planned are specialized collaborative, experimental and theoretical NASA UCSD studies needed to support the ongoing definition of needed experimental hardware, experimental procedures, data acquisition philosophy, and other ground based support activities required to assure the success of space shuttle based experiments concerned with combustion of clouds of particulates at reduced gravitational conditions. The further development of relations delineating premixed particle cloud and premixed gaseous systems as well as burner stabilized and freely propagating flame systems is considered.

  18. Response of Deep Tropical Cumulus Clouds to Mesoscale Processes.

    NASA Astrophysics Data System (ADS)

    Soong, S.-T.; Tao, W.-K.

    1980-09-01

    The two-dimensional cloud ensemble model developed by Soong and Ogura (1980) is used to simulate the response of deep clouds to mesoscale lifting using data obtained in the Global Atmospheric Research Program (GARP) Atlantic Tropical Experiment (GATE). The input to the model includes the mesoscale vertical velocity, horizontal advections of temperature and mixing ratio of water vapor, radiative cooling and sea surface temperature. The cloud ensemble feedback effects due to the condensation and evaporation of cloud liquid drops and vertical fluxes of heat and moisture are determined by the model.The simulated upward mass flux inside the model clouds is about three times the mass flux due to mesoscale lifting. The downward mass flux inside clouds is also large, leaving a small downward mass flux in the cloud-free area. The major portion of the heat flux is produced by the updraft inside clouds. On the other hand, the moisture fluxes due to both updraft and downdraft are important. In the cloud-free area, the heat and moisture fluxes are both small due to the small mass flux in that area.Experiments with different magnitudes of mesoscale lifting generate different sizes of clouds and different cloud heating and moistening profiles. However, in each simulation, the changes of temperature and mixing ratio due to mesoscale processes are almost balanced by the cloud heating and drying effects, leaving only small temporal changes in the horizontal mean temperature and mixing ratio.In a simulation with only low-level lifting, a warming is generated in the middle levels. This warming can be important in producing higher level vertical lifting, which in turn could produce even higher clouds.

  19. Cloud Resolving Modeling

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2007-01-01

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

  20. On Cloud Nine

    ERIC Educational Resources Information Center

    McCrea, Bridget; Weil, Marty

    2011-01-01

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

  1. Smoke Above Clouds

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.

    2009-01-01

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

  2. Cloud shadow speed sensor

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  3. Cloud speed sensor

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  4. Kernel structures for Clouds

    NASA Technical Reports Server (NTRS)

    Spafford, Eugene H.; Mckendry, Martin S.

    1986-01-01

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

  5. Learning in the Clouds?

    ERIC Educational Resources Information Center

    Butin, Dan W.

    2013-01-01

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

  6. Clouds over Open Ocean

    NASA Technical Reports Server (NTRS)

    1981-01-01

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

  7. Polarimetric Retrievals of Cloud Droplet Number Concentrations

    NASA Astrophysics Data System (ADS)

    Sinclair, K.; Cairns, B.; Hair, J. W.; Hu, Y.; Hostetler, C. A.

    2014-12-01

    Cloud droplet number concentration (CDNC) is one of the most significant microphysical properties of liquid clouds and is essential for the understanding of aerosol-cloud interaction. It impacts radiative forcing, cloud evolution, precipitation, global climate and, through observation, can be used to monitor the cloud albedo effect, or the first indirect effect. The IPCC's Fifth Assessment Report continues to consider aerosol-cloud interactions as one of the largest uncertainties in radiative forcing of climate. The SABOR experiment, which was a NASA-led ship and air campaign off the east coast of the United States during July and August of 2014, provided an opportunity for the Research Scanning Polarimeter (RSP) to develop and cross-validate a new approach of sensing CDNC with the High Spectral Resolution Lidar (HSRL). The RSP is an airborne prototype of the Aerosol Polarimetry Sensor (APS) that was on-board the Glory satellite. It is a scanning sensor that provides high-precision measurements of polarized and full-intensity radiances at multiple angles over a wide spectral range. The distinctive feature of the polarimetric technique is that it does not make any assumption of the liquid water profile within the cloud. The approach involves (1) estimating the droplet size distribution from polarized reflectance observations in the rainbow, (2) using polarized reflectance to estimate above cloud water vapor and total reflectance to find how much near infra-red light is being absorbed in clouds, (3) finding cloud physical thickness from the absorption and cloud top pressure retrievals assuming a saturated mixing ratio for water vapor and (4) determining the cloud droplet number concentration from the physical thickness and droplet size distribution retrievals. An overview of the polarimetric technique will be presented along with the results of applying the new approach to SABOR campaign data. An analysis of the algorithm's performance when compared with the HSRL

  8. Belle II public and private cloud management in VMDIRAC system.

    NASA Astrophysics Data System (ADS)

    Grzymkowski, Rafa; Hara, Takanori; Belle computing Group, II

    2015-12-01

    The role of cloud computing technology in the distributed computing for HEP experiments grows rapidly. Some experiments (Atlas, BES-III, LHCb) already exploit private and public cloud resources for the data processing. Future experiments such as Belle II or upgraded LHC experiments will largely rely on the availability of cloud resources and therefore their computing models have to be adjusted to the specific features of cloud environment, in particular to the on-demand computing paradigm. Belle II experiment at SuperKEKB will start physics run in 2017. Belle II computing requirements are challenging. The data size at the level of hundred PB is expected after several years of operation, around 2020. The baseline solution selected for distributed processing is the DIRAC system. DIRAC can handle variety of computing resources including Grids, Clouds and independent clusters. Cloud resources can be connected by VMDIRAC module through public interfaces. In particular the mechanism of dynamic activation of new virtual machines with reserved job slots for new tasks in case of an increasing demand for computing resources is introduced. This work is focused on VMDIRAC interaction with public (Amazon EC2) and private (CC1) cloud. The solution applied by Belle II experiment and the experience from Monte Carlo production campaigns will be presented. Updated computation costs for different use cases will be shown.

  9. Io's sodium cloud

    NASA Astrophysics Data System (ADS)

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

    1984-11-01

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

  10. SMILES ice cloud products

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  11. Cloud computing security.

    SciTech Connect

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

    2010-10-01

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

  12. Cloud model bat algorithm.

    PubMed

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

    2014-01-01

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

  13. Prebiotic chemistry in clouds

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    SciTech Connect

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

    2011-07-21

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

  15. The chemistry of phosphorus in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Thorne, L. R.; Anicich, V. G.; Prasad, S. S.; Huntress, W. T., Jr.

    1984-01-01

    Laboratory experiments show that the ion-molecule chemistry of phosphorus is significantly different from that of nitrogen in dense interstellar clouds. The PH3 molecule is not readily formed by gas-phase, ion-molecule reactions in these regions. Laboratory results used in a simple kinetic model indicate that the most abundant molecule containing phosphorus in dense clouds is PO.

  16. 5 THE RADIATIVE FORCING DUE TO CLOUDS AND WATER VAPOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter utilizes results from the spaceborne Earth Radiation Budget Experiment (ERBE), launched in 1984 aboard the NOAA-9 (National Oceanic and Atmospheric Agency) satellite, to summarize our understanding of the radiative forcing due to water vapor and clouds. The effect of clouds on the rad...

  17. Using Clouds for MapReduce Measurement Assignments

    ERIC Educational Resources Information Center

    Rabkin, Ariel; Reiss, Charles; Katz, Randy; Patterson, David

    2013-01-01

    We describe our experiences teaching MapReduce in a large undergraduate lecture course using public cloud services and the standard Hadoop API. Using the standard API, students directly experienced the quality of industrial big-data tools. Using the cloud, every student could carry out scalability benchmarking assignments on realistic hardware,…

  18. Ammonium Hydrosulfide: Coloring Jupiter's Clouds

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. Cumulus cloud model estimates of trace gas transports

    NASA Technical Reports Server (NTRS)

    Garstang, Michael; Scala, John; Simpson, Joanne; Tao, Wei-Kuo; Thompson, A.; Pickering, K. E.; Harris, R.

    1989-01-01

    Draft structures in convective clouds are examined with reference to the results of the NASA Amazon Boundary Layer Experiments (ABLE IIa and IIb) and calculations based on a multidimensional time dependent dynamic and microphysical numerical cloud model. It is shown that some aspects of the draft structures can be calculated from measurements of the cloud environment. Estimated residence times in the lower regions of the cloud based on surface observations (divergence and vertical velocities) are within the same order of magnitude (about 20 min) as model trajectory estimates.

  20. A study of surface temperatures, clouds and net radiation

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans

    1994-01-01

    The study is continuing and it is focused on examining seasonal relationships between climate parameters such as the surface temperatures, the net radiation and cloud types and amount on a global basis for the period February 1985 to January 1987. The study consists of an analysis of the combined Earth Radiation Budget Experiment (ERBE) and International Satellite Cloud Climatology Program (ISCCP) products. The main emphasis is on obtaining the information about the interactions and relationships of Earth Radiation Budget parameters, cloud and temperature information. The purpose is to gain additional qualitative and quantitative insight into the cloud climate relationship.

  1. Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals

    DOE Data Explorer

    Shupe, Matthew

    2013-05-22

    Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May 2008). These time periods will be expanded in a future submission.

  2. Direct Observations of Excess Solar Absorption by Clouds

    NASA Technical Reports Server (NTRS)

    Pilewskie, Peter; Valero, Francisco P. J.

    1995-01-01

    Aircraft measurements of solar flux in the cloudy tropical atmosphere reveal that solar absorption by clouds is anomalously large when compared to theoretical estimates. The ratio of cloud forcing at an altitude of 20 kilometers to that at the surface is 1.58 rather than 1.0 as predicted by models. These results were derived from a cloud radiation experiment in which identical instrumentation was deployed on coordinated stacked aircraft. These findings indicate a significant difference between measurements and theory and imply that the interaction between clouds and solar radiation is poorly understood.

  3. Cloud cover determination in polar regions from satellite imagery

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  4. Cloud Microphysics by Thermal Wave Methods

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Bowdle, D. A.; Reischel, M.

    1985-01-01

    This experiments series is the first application of a low-gravity experimental technique to the study of cloud microphysics. The low-gravity environment is provided by the parabolic maneuver of NASA's KC-135 aircraft. The primary objective is to compare experimental observations of cloud droplet growth and evaporation in a convection free environment with a numerical model of the process. Beyond that, the work also involves the development and testing of low-gravity research techniques. In particular, passive methods of thermal control have been devised and used effectively. The study to date has shown that the method is particularly suitable for looking at interactions between adjoining portions of the cloud drop field and interactions of the drop field with a solid interface. After final analysis of the data, it is expected the results will shed light on the development of cloud droplet size spectra in natural clouds as well as the performance of certain types of cloud physics instrumentation, particularly continuous flow diffusion chambers and loud condensation nuclei counters.

  5. The seasonal cycle of low stratiform clouds

    NASA Technical Reports Server (NTRS)

    Klein, Stephen A.; Hartmann, Dennis L.

    1993-01-01

    The seasonal cycle of low stratiform clouds is studied using data from surface-based cloud climatologies. The impact of low clouds on the radiation budget is illustrated by comparison of data from the Earth Radiation Budget Experiment with the cloud climatologies. Ten regions of active stratocumulus convection are identified. These regions fall into four categories: subtropical marine, midlatitude marine, Arctic stratus, and Chinese stratus. With the exception of the Chinese region, all the regions with high amounts of stratus clouds are over the oceans. In all regions except the Arctic, the season of maximum stratus corresponds to the season of greatest lower-troposphere static stability. Interannual variations in stratus cloud amount also are related to changes in static stability. A linear analysis indicates that a 6 percent increase in stratus fractional area coverage is associated with each 1 C increase in static stability. Over midlatitude oceans, sky-obscuring fog is a large component of the summertime stratus amount. The amount of fog appears to be related to warm advection across sharp gradients of SST.

  6. Parameterizing Size Distribution in Ice Clouds

    SciTech Connect

    DeSlover, Daniel; Mitchell, David L.

    2009-09-25

    cloud optical properties formulated in terms of PSD parameters in combination with remote measurements of thermal radiances to characterize the small mode. This is possible since the absorption efficiency (Qabs) of small mode crystals is larger at 12 µm wavelength relative to 11 µm wavelength due to the process of wave resonance or photon tunneling more active at 12 µm. This makes the 12/11 µm absorption optical depth ratio (or equivalently the 12/11 µm Qabs ratio) a means for detecting the relative concentration of small ice particles in cirrus. Using this principle, this project tested and developed PSD schemes that can help characterize cirrus clouds at each of the three ARM sites: SGP, NSA and TWP. This was the main effort of this project. These PSD schemes and ice sedimentation velocities predicted from them have been used to test the new cirrus microphysics parameterization in the GCM known as the Community Climate Systems Model (CCSM) as part of an ongoing collaboration with NCAR. Regarding the second problem, we developed and did preliminary testing on a passive thermal method for retrieving the total water path (TWP) of Arctic mixed phase clouds where TWPs are often in the range of 20 to 130 g m-2 (difficult for microwave radiometers to accurately measure). We also developed a new radar method for retrieving the cloud ice water content (IWC), which can be vertically integrated to yield the ice water path (IWP). These techniques were combined to determine the IWP and liquid water path (LWP) in Arctic clouds, and hence the fraction of ice and liquid water. We have tested this approach using a case study from the ARM field campaign called M-PACE (Mixed-Phase Arctic Cloud Experiment). This research led to a new satellite remote sensing method that appears promising for detecting low levels of liquid water in high clouds typically between -20 and -36 oC. We hope to develop this method in future research.

  7. The effect of clouds on the earth's solar and infrared radiation budgets

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Wu, M.-L. C.; Johnson, W. T.

    1980-01-01

    The effect of global cloudiness on the solar and infrared components of the earth's radiation balance is studied in general circulation model experiments. A wintertime simulation is conducted in which the cloud radiative transfer calculations use realistic cloud optical properties and are fully interactive with model-generated cloudiness. This simulation is compared to others in which the clouds are alternatively non-interactive with respect to the solar or thermal radiation calculations. Other cloud processes (formation, latent heat release, precipitation, vertical mixing) were accurately simulated in these experiments. It is concluded that on a global basis clouds increase the global radiation balance by 40 W/sq m by absorbing longwave radiation, but decrease it by 56 W/sq m by reflecting solar radiation to space. The net cloud effect is therefore a reduction of the radiation balance by 16 W/sq m, and is dominated by the cloud albedo effect. Changes in cloud frequency and distribution and in atmospheric and land temperatures are also reported for the control and for the non-interactive simulations. In general, removal of the clouds' infrared absorption cools the atmosphere and causes additional cloudiness to occur, while removal of the clouds' solar radiative properties warms the atmosphere and causes fewer clouds to form. It is suggested that layered clouds and convective clouds over water enter the climate system as positive feedback components, while convective clouds over land enter as negative components.

  8. On the Global Variation of Precipitating Layer Clouds.

    NASA Astrophysics Data System (ADS)

    Ryan, B. F.

    1996-01-01

    The aim of the Global Energy and Water Cycle Experiment Cloud System Study (GCSS) is to promote the description and understanding of key cloud system processes, with the aim of developing and improving the representation of cloud processes in general circulation models. The GCSS Science Panel identified a need to document important observational gaps in the structure of cloud systems inhibiting the development of cloud-resolving models as a tool for parameterizing cloud systems in general circulation models.The nature of precipitating layer clouds around the world is not well documented. To better quantify this, a synthesis of observations of these types of clouds made during field experiments conducted around the world has been developed. The synthesis draws on observations made in Australia, Canada, China, Israel, Japan, Russia, the Ukraine, the United States, and several European countries.The survey examines the global variation of the horizontal scales of cloud and precipitation, embedded phenomena such as rainbands, conveyor belt characteristics, ice crystal and water droplet concentrations, and raindrop and ice crystal size distributions.

  9. Investigation of cloud properties and atmospheric stability with MODIS

    NASA Technical Reports Server (NTRS)

    Menzel, Paul

    1993-01-01

    The work accomplished with the MAS (MODIS Airborne Simulator) during the TOGA-COARE (Tropical Ocean Global Atmosphere - Coupled Ocean Atmosphere Response Experiment) from January through June 1993 included cloud investigations with longwave CO2 channels (out to 13.9 microns) that reconfigured spectral channels. The comparison data was used with HIRS (high resolution Infrared Radiation Sounder) data from FIRE (First ISSCP Regional Experiment), CEPEX, and SCAR (Smoke Clouds, Aerosol and Radiation) data for the development of a two layer cloud CO2 slicing algorithm and the development of multi-spectral cloud detection algorithms (specifically tri-spectral) for cloud identification. Regarding the latter, a clustering analysis was added to improve cloud identification within the scatter diagram of tri-spectral (8, 11, and 12 microns) brightness temperatures. Via the regressions of the 8 - 11 and the 11 - 12 micron brightness temperature differences versus precipitable water, the problem of clear sky identification in the scatter diagram was further addressed. Comparison of the tri-spectral technique and visible channel reflectance ratioing indicate the tri-spectral infrared method distinguishes cloud phase more consistently in mixed cloud scenes rather than single phase cloud scenes where visible ratioing performs best.

  10. Droplet dispersion in premonsoon and monsoon clouds over Indo-Gangetic valley during CAIPEEX

    NASA Astrophysics Data System (ADS)

    Prabhakaran, T.; Patade, S.; Pandithuri, G.; Khain, A.; Axisa, D.; Pallath, P.; RS, M.; Kulkarni, J.; Goswami, B.

    2012-12-01

    The combined effect of humidity and aerosol on cloud droplet spectral width (σ) in continental monsoon clouds is a topic of significant relevance for precipitation and radiation budgets over monsoon regions. The droplet spectral width in polluted, dry premonsoon conditions and moist monsoon conditions observed near the Himalayan Foothills region during Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) is the focus of this study. σ is small in premonsoon clouds growing over very dry boundary layers, This is attributed to numerous aerosol particles and the absence/suppression of collision-coalescence during premonsoon. For polluted and dry premonsoon clouds, spectral width is constant with height. In contrast to premonsoon clouds, spectral width in monsoon clouds increases with height irrespective of whether it is a polluted or clean. The mean radius of polluted monsoon clouds is half that of clean monsoon clouds. In monsoon clouds, both mean radius and spectral width decreased with total cloud droplet number concentrations. The spectral widths of premonsoon clouds were however independent of total droplet number concentrations, but both spectral width and mean radius decreased with small droplet (diameter <20 μm) number concentrations in the diluted part of the cloud. Observational evidence is provided for the formation of large droplets in the adiabatic regions of monsoon clouds. The number concentration of small droplets is found to decrease in the diluted cloud volumes that may be characterized by various spectral widths or mean droplet radii attributed to entrainment effects.

  11. Community Cloud Computing

    NASA Astrophysics Data System (ADS)

    Marinos, Alexandros; Briscoe, Gerard

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

  12. Diagnosing AIRS Sampling with CloudSat Cloud Classes

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.; Lin, Ruei-Fong

    1993-01-01

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

  14. Cloud computing basics for librarians.

    PubMed

    Hoy, Matthew B

    2012-01-01

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

  15. Evaluating the Usage of Cloud-Based Collaboration Services through Teamwork

    ERIC Educational Resources Information Center

    Qin, Li; Hsu, Jeffrey; Stern, Mel

    2016-01-01

    With the proliferation of cloud computing for both organizational and educational use, cloud-based collaboration services are transforming how people work in teams. The authors investigated the determinants of the usage of cloud-based collaboration services including teamwork quality, computer self-efficacy, and prior experience, as well as its…

  16. Assessing Cloud-Phase Conditions.

    NASA Astrophysics Data System (ADS)

    Cober, Stewart G.; Isaac, George A.; Korolev, Alexei V.; Strapp, J. Walter

    2001-11-01

    In situ microphysics measurements made during the First and Third Canadian Freezing Drizzle Experiments (CFDE I and III, respectively) have been used to assess the relative responses to ice and liquid hydrometeors for several common instruments. These included the Rosemount icing detector, 2D-C monoscale and 2D-C grayscale probes, forward-scattering spectrometer probes (FSSP) on three measurement ranges, Nevzorov liquid water content (LWC) and total water content probes, and King LWC probes. The Nevzorov LWC and King LWC probes responded to between 5% and 30% of the ice water content, with an average response of approximately 20%. The average FSSP measurements of droplet spectra were dominated by ice particles for sizes greater than 35 m, independent of the measurement range used, when the ice-crystal concentrations exceeded approximately 1 L1. In contrast, the FSSP measurements of the droplet spectra less than 30 m appeared free of ice-crystal contamination, independent of the ice-crystal concentrations observed. Glaciated cloud conditions always had FSSP-measured median volume diameters greater than 30 m and particle concentrations less than 15 cm3, whereas similar measurements in entirely liquid-phase clouds were observed less than 4% of the time. Images of drops greater than or equal to 125 m in diameter, which were collected in warm clouds greater than 0°C, were used to calibrate geometric criteria, which were, in turn, used to segregate 2D images into circular and noncircular categories. It is shown that, on average, between 5% and 40% of ice crystals greater than or equal to 125 m in diameter will be classified as circular, depending on the particle size, with the percentage decreasing with increasing particle size. In liquid-phase clouds, between 85% and 95% of the 2D images will be correctly classified as circular for all particle sizes. At temperatures less than 4°C, a Rosemount icing-detector threshold of 2 mV s1, corresponding to a maximum LWC of 0

  17. Where the Cloud Meets the Commons

    ERIC Educational Resources Information Center

    Ipri, Tom

    2011-01-01

    Changes presented by cloud computing--shared computing services, applications, and storage available to end users via the Internet--have the potential to seriously alter how libraries provide services, not only remotely, but also within the physical library, specifically concerning challenges facing the typical desktop computing experience.…

  18. Entrainment, Drizzle, and Cloud Albedo

    NASA Technical Reports Server (NTRS)

    Ackerman, A. S.; Kirkpatrick, J. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

  19. Methanol in dark clouds

    NASA Astrophysics Data System (ADS)

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

    1988-04-01

    The authors report observations, for the first time, of the 20 - 10A+ and E, 2-1 - 1-1 E, and 10 - 00A+ lines of methanol (CH3OH) in three dark cold clouds, TMC 1, L 134N, and B 335. The CH3OH emission is extended in these clouds and shows a complex velocity structure. Clear indications of non LTE excitation are observed in TMC 1. Estimated column densities are a few×1013cm-2. Although less abundant than formaldehyde (H2CO), methanol is almost an order of magnitude more abundant than acetaldehyde (CH3CHO), in these clouds. Dimethyl ether was searched for in L 134N, to an upper limit of 4×1012cm-2 (3σ). Implications for dark cloud excitation and chemistry are discussed.

  20. Fingerprinting the Clouds

    NASA Astrophysics Data System (ADS)

    Orellana, M. V.; Caballero, J.; Lee, A. M.; Matrai, P. A.; Leck, C.; Madan, A.; Collins, H.

    2012-12-01

    Marine microgels play an important role in regulating ocean-basin-scale biogeochemical dynamics. We have found them in surface waters, in airborne aerosol, fog, and cloud water in the high Arctic (north of 80oN). Microgels dominated the available cloud condensation nuclei number population during the summer season. These microgels have unique physicochemical characteristics and originate from the ice algae and/or phytoplankton in the surface water. We have sequenced the genomic material found in the microgels from the sea surface and cloud waters with next-generation sequencing technology. The sequence analysis and annotation, show a high abundance of proteins of microbial and diatom origin, including a high number of proteins from different taxonomical origin associated with antifreeze functions. Our results have implications not only for cloud droplet activation but also for ice nucleation.

  1. My NASA Data Clouds

    NASA Video Gallery

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

  2. Noctilucent Clouds in Motion

    NASA Video Gallery

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

  3. GEOS-5 Modeled Clouds

    NASA Video Gallery

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

  4. Methanol in dark clouds

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  5. Closed Large Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

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

  6. Cloud Ozone Dust Imager (CODI)

    NASA Astrophysics Data System (ADS)

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

    1995-01-01

    The Cloud Ozone Dust Imager (CODI) is proposed to investigate the current climatic balance of the Mars atmosphere, with particular emphasis on the important but poorly understood roles which dust and water ice aerosols play in this balance. The large atmospheric heating (20-50 K) resulting from global dust storms around Mars perihelion is well recognized. However, groundbased observations of Mars atmospheric temperatures, water vapor, and clouds since the Viking missions have identified a much colder, cloudier atmosphere around Mars aphelion that may prove as important as global dust storms in determining the interannual and long-term behavior of the Mars climate. The key climate issues CODI is designed to investigate are: 1) the degree to which non-linear interactions between atmospheric dust heating, water vapor saturation, and cloud nucleation influence the seasonal and interannual variability of the Mars atmosphere, and 2) whether the strong orbital forcing of atmospheric dust loading, temperatures and water vapor saturation determines the long-term balance of Mars water, as reflected in the north-south hemispheric asymmetries of atmospheric water vapor and polar water ice abundances. The CODI experiment will measure the daily, seasonal and (potentially) interannual variability of atmospheric dust and cloud opacities, and the key physical properties of these aerosols which determine their role in the climate cycles of Mars. CODI is a small (1.2 kg), fixed pointing camera, in which four wide-angle (+/- 70 deg) lenses illuminate fixed filters and CCD arrays. Simultaneous sky/surface imaging of Mars is obtained at an angular resolution of 0.28 deg/pixel for wavelengths of 255, 336, 502, and 673 nm (similar to Hubble Space Telescope filters). These wavelengths serve to measure atmospheric ozone (255 and 336 nm), discriminate ice and dust aerosols (336 and 673 nm), and construct color images (336, 502, and 673 nm). The CODI images are detected on four 512 x 512

  7. Cloud Inhomogeneity from MODIS

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Cahalan, Robert F.

    2004-01-01

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

  8. Mesospheric cloud formations

    NASA Technical Reports Server (NTRS)

    Forbes, J. M.

    1980-01-01

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

  9. Cloud Drop Size Distribution in Different Regions over India during CAIPEEX-2009

    NASA Astrophysics Data System (ADS)

    Morwal, Savita B.; Maheshkumar R., S.; Kulkarni J., R.

    2010-05-01

    Tropical clouds have high albedos and they decrease the amount of solar energy absorbed by the earth system, reducing heating rates. During cloud formation the number concentration of the cloud droplets depends on the number of aerosols present in the air mass. Therefore, aerosols determine the cloud properties such as number concentration of cloud droplets and their size. Recent studies have shown that size distributions of cloud droplets change with the vertical development of the cloud. The fair weather continental cumulus clouds with no precipitation have relatively narrow drop size spectrum while the continental cumulus clouds which have reached more matured stage of cumulus congetus show much broader cloud drop spectrum (Hobbs et al., 1980). The maritime clouds have even broader drop size spectrum as compared to continental clouds (Battan and Reitan, 1957). Warner (1969a; 1969b) has studied in detail the drop size distributions over the Australian coast. Such studies on cloud droplet size distributions, effective radius and their effect on cloud microphysics and dynamics are sparse or non existent in the tropical monsoon clouds occurring over the Indian sub-continent. Recently a national level observational experiment called ‘Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)' has been conducted over the Indian region during May-September 2009. In this experiment an instrumented aircraft was used to collect in-situ observations of aerosols and cloud microphysical parameters viz. liquid water content, total water content, concentrations of aerosols, Cloud Condensation Nuclei (CCN) and cloud droplets of different sizes, temperature, humidity etc over different parts of Indian sub-continent. Utilizing the data collected through this experiment an attempt has been made to examine the characteristics of cloud droplets distributions in different regions over. The results of the investigation will be discussed. Battan, L.J. and Raitan, C

  10. Interstellar Cloud Collisions

    NASA Astrophysics Data System (ADS)

    Lattanzio, J. C.; Monaghan, J. J.; Pongracic, H.; Schwarz, M. P.

    1985-07-01

    We describe the results of a three-dimensional numerical simulation of isothermal interstellar clouds in the absence of magnetic fields. A wide variety of high and low Mach number, head-on and off-centre collisions of clouds with mass ratios 1, 2.5, 5.0 and 10.1 have been studied. The results show that a necessary, but not sufficient, condition for the gravitational instability of a substantial fraction of the matter is that the initial clouds should be either marginally stable or unstable according to the usual Jeans criterion. The collisions, in general, do not result in one or more clouds. Instead we find, in most cases, that the matter disperses in an irregular way. The calculations therefore suggest that if the initial state of the interstellar medium is one of cool dense clouds in a hotter more tenuous background, collisions will rapidly mix the medium rather than produce a steady-state spectrum of cool clouds.

  11. A cloud physics radiometer

    NASA Technical Reports Server (NTRS)

    Kyle, H. L.; Curran, R. J.; Barnes, W. L.; Escoe, D.

    1978-01-01

    The paper describes the design features and capabilities of a seven-channel cloud physics radiometer (CPR) for remote sensing of cloud properties. The CPR channel characteristics and functions are tabulated and diagrammed. Each of the first three channels utilizes a photo-multipler detector, with the high-voltage power supply integrated with the tube into a single unit. In operation a heater is used to keep the optics temperature at or above 273 K and this temperature is constantly monitored. The last four channel detectors and filters are all cooled to the temperature of liquid nitrogen. The inclined scanning mirror rotates at a rate of 3.48 rps. Registration pulses are triggered and recorded as the mirror enters and leaves the + or -45 deg earth observation region. The ice-cloud, water cloud, snow discriminator detector has worked quite well in general. Interesting radiometer data have been obtained and their analysis is under way. The combination of the CPR and the Cloud Lidar System will make possible sophisticated remote sensing cloud studies.

  12. Molecules in interstellar clouds

    NASA Astrophysics Data System (ADS)

    Irvine, W. M.; Hjalmarson, A.; Rydbeck, O. E. H.

    The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.

  13. EVIDENCE FOR CLOUD VENTING OF MIXED LAYER OZONE

    EPA Science Inventory

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosol pollutants occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. Flight experiments conducted in July 1981, utilized th...

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

    SciTech Connect

    Inoue, Tsuyoshi; Fukui, Yasuo

    2013-09-10

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

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

    SciTech Connect

    Borque, Paloma; Giangrande, Scott; Kollias, Pavlos

    2014-12-01

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

  16. Ice forming experiment

    NASA Technical Reports Server (NTRS)

    Vali, G.

    1982-01-01

    A low gravity experiment to assess the effect of the presence of supercooled cloud droplets on the diffusional growth rate of ice crystals is described. The theoretical work and the feasibility studies are summarized. The nucleation of ice crystals in supercooled clouds is also discussed.

  17. Comparison between observed and modelled radiative properties of stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Sun, Zhian; Pethick, David

    2002-10-01

    Measurements of radiative and microphysical characteristics of stratocumulus clouds in a coastal region of South Australia are reported. The measurements were taken on 14 April 1999 using two aircraft from Airborne Research Australia based at the Flinders University of South Australia during the Kangaroo Island Radiation and Cloud Experiments (KIRCE). The measurements include radiation, cloud liquid-water content, ambient temperature and humidity. A new method to process the measurements is described. Cloud albedo and absorption were determined using the observed solar irradiances at the cloud top and base and the results were compared with theoretical calculations. Five water-cloud optical parametrization schemes were tested against the observations. In addition, some observational data from the Joint Air-Sea Interaction (JASIN) experiment were used in the comparisons. It has been found that measured cloud properties from the KIRCE experiment are very similar to those of the JASIN experiment. The modelled results from most schemes are compatible and generally in good agreement with the measurements.

  18. Drizzle formation in stratocumulus clouds: effects of turbulent mixing

    NASA Astrophysics Data System (ADS)

    Magaritz-Ronen, L.; Pinsky, M.; Khain, A.

    2016-02-01

    The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian-Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic and characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. It was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.

  19. Drizzle formation in stratocumulus clouds: Effects of turbulent mixing

    DOE PAGESBeta

    Magaritz-Ronen, L.; Pinsky, M.; Khain, A.

    2016-02-17

    The mechanism of drizzle formation in shallow stratocumulus clouds and the effect of turbulent mixing on this process are investigated. A Lagrangian–Eularian model of the cloud-topped boundary layer is used to simulate the cloud measured during flight RF07 of the DYCOMS-II field experiment. The model contains ~ 2000 air parcels that are advected in a turbulence-like velocity field. In the model all microphysical processes are described for each Lagrangian air volume, and turbulent mixing between the parcels is also taken into account. It was found that the first large drops form in air volumes that are closest to adiabatic andmore » characterized by high humidity, extended residence near cloud top, and maximum values of liquid water content, allowing the formation of drops as a result of efficient collisions. The first large drops form near cloud top and initiate drizzle formation in the cloud. Drizzle is developed only when turbulent mixing of parcels is included in the model. Without mixing, the cloud structure is extremely inhomogeneous and the few large drops that do form in the cloud evaporate during their sedimentation. Lastly, it was found that turbulent mixing can delay the process of drizzle initiation but is essential for the further development of drizzle in the cloud.« less

  20. Annual Cycle of Cloud Forcing of Surface Radiation Budget

    NASA Technical Reports Server (NTRS)

    Wilber, Anne C.; Smith, G. Louis; Stackhouse, Paul W., Jr.; Gupta, Shashi K.

    2006-01-01

    The climate of the Earth is determined by its balance of radiation. The incoming and outgoing radiation fluxes are strongly modulated by clouds, which are not well understood. The Earth Radiation Budget Experiment (Barkstrom and Smith, 1986) provided data from which the effects of clouds on radiation at the top of the atmosphere (TOA) could be computed (Ramanathan, 1987). At TOA, clouds increase the reflected solar radiation, tending to cool the planet, and decrease the OLR, causing the planet to retain its heat (Ramanathan et al., 1989; Harrison et al., 1990). The effects of clouds on radiation fluxes are denoted cloud forcing. These shortwave and longwave forcings counter each other to various degrees, so that in the tropics the result is a near balance. Over mid and polar latitude oceans, cloud forcing at TOA results in large net loss of radiation. Here, there are large areas of stratus clouds and cloud systems associated with storms. These systems are sensitive to surface temperatures and vary strongly with the annual cycle. During winter, anticyclones form over the continents and move to the oceans during summer. This movement of major cloud systems causes large changes of surface radiation, which in turn drives the surface temperature and sensible and latent heat released to the atmosphere.

  1. Effects of observed horizontal inhomogeneities within cirrus clouds on solar radiative transfer

    NASA Astrophysics Data System (ADS)

    Buschmann, Nicole; McFarquhar, Greg M.; Heymsfield, Andrew J.

    2002-10-01

    In situ microphysical and combined radar and radiometer measurements of 11 cirrus clouds from Central Equatorial Pacific Experiment (CEPEX), European Cloud and Radiation Experiment (EUCREX), investigation of Clouds by Ground-Based and Airborne Radar and Lidar (CARL), and First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) are used to investigate effects of horizontal cloud inhomogeneities on solar radiative transfer. A three-dimensional ray-tracing model (GRIMALDI), based on the Monte Carlo method, is used to calculate upward and downward flux densities and absorption for the spectral range from 0.38 to 4.0 μm. Radiative flux densities are calculated using the inhomogeneous clouds derived from the observations and for horizontally and vertically averaged homogeneous clouds. Horizontally averaged values of radiative flux densities and absorption for heterogeneous clouds can differ by up to 30% from those calculated for the homogeneous clouds for convectively induced tropical cirrus clouds. The midlatitude cases examined tended to be more homogeneous, and hence differences between radiative properties for the homogeneous and heterogeneous clouds did not exceed 10%. For cirrus clouds with mean optical thicknesses smaller than 5 and with relative variances of optical thickness smaller than 0.2, errors caused by the homogeneous assumption are smaller than ±10%.

  2. Evaluating The Indirect Effect of Cirrus Clouds

    NASA Astrophysics Data System (ADS)

    Dobbie, S.; Jonas, P. R.

    What effect would an increase in nucleating aerosols have on the radiative and cloud properties? What error would be incurred by evaluating the indirect effect by taking an evolved cloud and fixing the integrated water content and vary the number of ice crystals? These questions will be addressed in this work. We will use the UK LES cloud resolving model to perform a sensitivity study for cirrus clouds to the indirect effect, and will evaluate approximate methods in the process. In this work, we will initialize the base (no increase of aerosol) cirrus clouds so that the double moment scheme is constrained to agree with observations through the ef- fective radius. Effective radius is calculated using the local concentration and the ice water content. We then perform a sensitivity experiment to investigate the dependence of the average IWC, effective size, and radiative properties (including heating rates) to variations in the nucleation rate. Conclusions will be draw as to the possible ef- fect of changes in aerosol amounts on cirrus. We will determine how sensitive the cloud and radiative properties are to various aerosol increases. We will also discuss the applicability of the Meyer et al. (1992) nucleation formulae for our simulations. It is important to stress that in this work we only change the nucleation rate for the newly forming cloud. By doing this, we are not fixing the total water content and redistributing the water amongst increased ice crystals. We increase the number of aerosols available to be nucleated and allow the model to evolve the size distributions. In this way, there is competition for the water vapour, the ice particles are evolved dynamically with different fall speeds, the conversion rates to other hydrometers (such as aggregates) are affected, and the heating rates are different due to the different size distributions that evolve. We will look at how the water content, the distribution of water, and the radiative properties are affected

  3. Cloud and Radiation Studies during SAFARI 2000

    NASA Technical Reports Server (NTRS)

    Platnick, Steven; King, M. D.; Hobbs, P. V.; Osborne, S.; Piketh, S.; Bruintjes, R.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Though the emphasis of the Southern Africa Regional Science Initiative 2000 (SAFARI-2000) dry season campaign was largely on emission sources and transport, the assemblage of aircraft (including the high altitude NASA ER-2 remote sensing platform and the University of Washington CV-580, UK MRF C130, and South African Weather Bureau JRA in situ aircrafts) provided a unique opportunity for cloud studies. Therefore, as part of the SAFARI initiative, investigations were undertaken to assess regional aerosol-cloud interactions and cloud remote sensing algorithms. In particular, the latter part of the experiment concentrated on marine boundary layer stratocumulus clouds off the southwest coast of Africa. Associated with cold water upwelling along the Benguela current, the Namibian stratocumulus regime has received limited attention but appears to be unique for several reasons. During the dry season, outflow of continental fires and industrial pollution over this area can be extreme. From below, upwelling provides a rich nutrient source for phytoplankton (a source of atmospheric sulphur through DMS production as well as from decay processes). The impact of these natural and anthropogenic sources on the microphysical and optical properties of the stratocumulus is unknown. Continental and Indian Ocean cloud systems of opportunity were also studied during the campaign. Aircraft flights were coordinated with NASA Terra Satellite overpasses for synergy with the Moderate Resolution Imaging Spectroradiometer (MODIS) and other Terra instruments. An operational MODIS algorithm for the retrieval of cloud optical and physical properties (including optical thickness, effective particle radius, and water path) has been developed. Pixel-level MODIS retrievals (11 km spatial resolution at nadir) and gridded statistics of clouds in th SAFARI region will be presented. In addition, the MODIS Airborne Simulator flown on the ER-2 provided high spatial resolution retrievals (50 m at nadir

  4. Metastable NAT in Ice-Clouds

    NASA Astrophysics Data System (ADS)

    Weiss, Fabian; Kubel, Frank; Gálvez, Óscar; Hoelzel, Markus; Parker, Stewart F.; Iannarelli, Riccardo; Rossi, Michel J.; Grothe, Hinrich

    2015-04-01

    Polar Stratospheric Clouds and Cirrus Clouds contain, besides pure water ice, a rather large fraction of various hydrates. These are very important for the formation of the cloud, which is a yet not well understood process. We recently solved the structure of a metastable NAT phase (alpha-NAT), we believe to not only be present, but playing a major role in the formation of clouds. On the basis of previous work on this phase by Grothe et al. [1], we enhanced the production of alpha-NAT to the point, where we could produce enough sample to do neutron diffraction. This enabled us to solve the structure. Our quantum mechanical calculations, using this newly found structure, show a large affinity towards water-ice. With this in mind, we interlaced our results with the experiments of R. Iannarelli [2] to derive a new 3-step NAT-formation mechanism in ice-clouds, which could explain some of the observed kinetics better than the mechanism postulated in Zondlo et al. [3]. 1. Grothe, H., Tizek, H., Waller, D. & Stokes, D. The crystallization kinetics and morphology of nitric acid trihydrate. Phys. Chem. Chem. Phys., 8, 2232-2239 (2006) 2. Iannarelli, R. Multidiagnostic Observations on HCl and HNO3 Hydrate Films in the Temperature Range 170-205K: A Kinetic Study. PhD Thesis 21791, ETH Zürich, (2013). 3. Zondlo, M.A., Hudson, P.K., Prenni A.J. & Tolbert, M.A. Chemistry and microphysics of polar stratospheric clouds and Cirrus clouds. Ann. Rev. Phys. Chem., 51, 473-499 (2000).

  5. A Comparison between Airborne and Mountaintop Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    David, R.; Lowenthal, D. H.; Hallar, A. G.; McCubbin, I.; Avallone, L. M.; Mace, G. G.; Wang, Z.

    2014-12-01

    Complex terrain has a large impact on cloud dynamics and microphysics. Several studies have examined the microphysical details of orographically-enhanced clouds from either an aircraft or from a mountain top location. However, further research is needed to characterize the relationships between mountain top and airborne microphysical properties. During the winter of 2011, an airborne study, the Colorado Airborne Mixed-Phase Cloud Study (CAMPS), and a ground-based field campaign, the Storm Peak Lab (SPL) Cloud Property Validation Experiment (StormVEx) were conducted in the Park Range of the Colorado Rockies. The CAMPS study utilized the University of Wyoming King Air (UWKA) to provide airborne cloud microphysical and meteorological data on 29 flights totaling 98 flight hours over the Park Range from December 15, 2010 to February 28, 2011. The UWKA was equipped with instruments that measured both cloud droplet and ice crystal size distributions, liquid water content, total water content (vapor, liquid, and ice), and 3-dimensional wind speed and direction. The Wyoming Cloud Radar and Lidar were also deployed during the campaign. These measurements are used to characterize cloud structure upwind and above the Park Range. StormVEx measured cloud droplet, ice crystal, and aerosol size distributions at SPL, located on the west summit of Mt. Werner at 3220m MSL. The observations from SPL are used to determine mountain top cloud microphysical properties at elevations lower than the UWKA was able to sample in-situ. Comparisons showed that cloud microphysics aloft and at the surface were consistent with respect to snow growth processes while small crystal concentrations were routinely higher at the surface, suggesting ice nucleation near cloud base. The effects of aerosol concentrations and upwind stability on mountain top and downwind microphysics are considered.

  6. Cloud effective particle size and water content profile retrievals using combined lidar and radar observations, 2, Comparison with IR radiometer and in situ measurements of ice clouds

    NASA Astrophysics Data System (ADS)

    Donovan, D. P.; van Lammeren, A. C. A. P.; Hogan, R. J.; Russchenberg, H. W. J.; Apituley, A.; Francis, P.; Testud, J.; Pelon, J.; Quante, M.; Goddard, J.

    2001-11-01

    A new combined iidar/radar inversion procedure has been developed for cloud effective radius and water content retrievals. The algorithm treats the lidar extinction, derived effective particle size, and multiple-scattering effects together in a consistent fashion. This procedure has been applied to data taken during the Netherlands Cloud and Radiation (CLARA) campaign and the Cloud Lidar and Radar Experiment (CLARE'98) multisensor cloud measurement campaign. The results of the algorithm compare well with simultaneous IR radiometer cloud measurements as well as with measurements made by using aircraft-mounted two-dimensional probe particle-sizing instruments.

  7. Cloud draft structure and trace gas transport

    NASA Technical Reports Server (NTRS)

    Scala, John R.; Tao, Wei-Kuo; Thompson, Anne M.; Simpson, Joanne; Garstang, Michael; Pickering, Kenneth E.; Browell, Edward V.; Sachse, Glen W.; Gregory, Gerald L.; Torres, Arnold L.

    1990-01-01

    During the second Amazon Boundary Layer Experiment (ABLE 2B), meteorological observations, chemical measurements, and model simulations are utilized in order to interpret convective cloud draft structure and to analyze its role in transport and vertical distribution of trace gases. One-dimensional photochemical model results suggest that the observed poststorm changes in ozone concentration can be attributed to convective transports rather than photochemical production and the results of a two-dimensional time-dependent cloud model simulation are presented for the May 6, 1987 squall system. The mesoscale convective system exhibited evidence of significant midlevel detrainment in addition to transports to anvil heights. Chemical measurements of O3 and CO obtained in the convective environment are used to predict photochemical production within the troposphere and to corroborate the cloud model results.

  8. Metastable Nitric Acid Trihydrate in Ice Clouds

    PubMed Central

    Weiss, Fabian; Kubel, Frank; Gálvez, Óscar; Hoelzel, Markus; Parker, Stewart F.; Baloh, Philipp; Iannarelli, Riccardo; Rossi, Michel J.

    2016-01-01

    Abstract The composition of high‐altitude ice clouds is still a matter of intense discussion. The constituents in question are ice and nitric acid hydrates, but the exact phase composition of clouds and its formation mechanisms are still unknown. In this work, conclusive evidence for a long‐predicted phase, alpha‐nitric acid trihydrate (alpha‐NAT), is presented. This phase was characterized by a combination of X‐ray and neutron diffraction experiments, allowing a convincing structure solution. Furthermore, vibrational spectra (infrared and inelastic neutron scattering) were recorded and compared with theoretical calculations. A strong interaction between water ice and alpha‐NAT was found, which explains the experimental spectra and the phase‐transition kinetics. On the basis of these results, we propose a new three‐step mechanism for NAT formation in high‐altitude ice clouds. PMID:26879259

  9. Metastable Nitric Acid Trihydrate in Ice Clouds.

    PubMed

    Weiss, Fabian; Kubel, Frank; Gálvez, Óscar; Hoelzel, Markus; Parker, Stewart F; Baloh, Philipp; Iannarelli, Riccardo; Rossi, Michel J; Grothe, Hinrich

    2016-03-01

    The composition of high-altitude ice clouds is still a matter of intense discussion. The constituents in question are ice and nitric acid hydrates, but the exact phase composition of clouds and its formation mechanisms are still unknown. In this work, conclusive evidence for a long-predicted phase, alpha-nitric acid trihydrate (alpha-NAT), is presented. This phase was characterized by a combination of X-ray and neutron diffraction experiments, allowing a convincing structure solution. Furthermore, vibrational spectra (infrared and inelastic neutron scattering) were recorded and compared with theoretical calculations. A strong interaction between water ice and alpha-NAT was found, which explains the experimental spectra and the phase-transition kinetics. On the basis of these results, we propose a new three-step mechanism for NAT formation in high-altitude ice clouds. PMID:26879259

  10. Stratocumulus cloud evolution

    SciTech Connect

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

    1994-12-31

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

  11. Remote-controlled experiments with cloud chemistry

    NASA Astrophysics Data System (ADS)

    Skilton, Ryan A.; Bourne, Richard A.; Amara, Zacharias; Horvath, Raphael; Jin, Jing; Scully, Michael J.; Streng, Emilia; Tang, Samantha L. Y.; Summers, Peter A.; Wang, Jiawei; Pérez, Eduardo; Asfaw, Nigist; Aydos, Guilherme L. P.; Dupont, Jairton; Comak, Gurbuz; George, Michael W.; Poliakoff, Martyn

    2015-01-01

    Developing cleaner chemical processes often involves sophisticated flow-chemistry equipment that is not available in many economically developing countries. For reactions where it is the data that are important rather than the physical product, the networking of chemists across the internet to allow remote experimentation offers a viable solution to this problem.

  12. Vertical transport and processing of aerosols in a mixed-phase convective cloud and the feedback on cloud development

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Carslaw, K. S.; Feingold, G.

    2005-01-01

    A modelling study of vertical transport and processing of sulphate aerosol by a mixed-phase convective cloud, and the feedback of the cloud-processed aerosols on the development of cloud microphysical properties and precipitation is presented. An axisymmetric dynamic cloud model with bin-resolved microphysics and aqueousphase chemistry is developed and is used to examine the relative importance of microphysical and chemical processes on the aerosol budget, the fate of the aerosol material inside hydrometeors, and the size distributions of cloud-processed sulphate aerosols. Numerical simulations are conducted for a moderately deep convective cloud observed during the Cooperative Convective Precipitation Experiments. The results show that aerosol particles that have been transported from the boundary layer, detrained, and then re-entrained at midcloud levels account for a large fraction of the aerosol inside hydrometeors (~40% by mass). Convective transport by the simulated cloud enhances upper-tropospheric aerosol number and mass concentrations by factors of 2-3 and 3-4, respectively. Sensitivity studies suggest that, for the simulated case, aqueous chemistry does not modify the evolution of the cloud significantly. Finally, ice-phase hydrometeor development is very sensitive to aerosol concentrations at midcloud levels. The latter result suggests that the occurrence of mid-tropospheric aerosol layers that have been advected through long-range transport could strongly affect cloud microphysical processes and precipitation formation.

  13. The diverse use of clouds by CMS

    DOE PAGESBeta

    Andronis, Anastasios; Bauer, Daniela; Chaze, Olivier; Colling, David; Dobson, Marc; Fayer, Simon; Girone, Maria; Grandi, Claudio; Huffman, Adam; Hufnagel, Dirk; et al

    2015-01-01

    The resources CMS is using are increasingly being offered as clouds. In Run 2 of the LHC the majority of CMS CERN resources, both in Meyrin and at the Wigner Computing Centre, will be presented as cloud resources on which CMS will have to build its own infrastructure. This infrastructure will need to run all of the CMS workflows including: Tier 0, production and user analysis. In addition, the CMS High Level Trigger will provide a compute resource comparable in scale to the total offered by the CMS Tier 1 sites, when it is not running as part of themore » trigger system. During these periods a cloud infrastructure will be overlaid on this resource, making it accessible for general CMS use. Finally, CMS is starting to utilise cloud resources being offered by individual institutes and is gaining experience to facilitate the use of opportunistically available cloud resources. Lastly, we present a snap shot of this infrastructure and its operation at the time of the CHEP2015 conference.« less

  14. The diverse use of clouds by CMS

    SciTech Connect

    Andronis, Anastasios; Bauer, Daniela; Chaze, Olivier; Colling, David; Dobson, Marc; Fayer, Simon; Girone, Maria; Grandi, Claudio; Huffman, Adam; Hufnagel, Dirk; Khan, Farrukh Aftab; Lahiff, Andrew; McCrae, Alison; Rand, Duncan; Sgaravatto, Massimo; Tiradani, Anthony; Zhang, Xiaomei

    2015-01-01

    The resources CMS is using are increasingly being offered as clouds. In Run 2 of the LHC the majority of CMS CERN resources, both in Meyrin and at the Wigner Computing Centre, will be presented as cloud resources on which CMS will have to build its own infrastructure. This infrastructure will need to run all of the CMS workflows including: Tier 0, production and user analysis. In addition, the CMS High Level Trigger will provide a compute resource comparable in scale to the total offered by the CMS Tier 1 sites, when it is not running as part of the trigger system. During these periods a cloud infrastructure will be overlaid on this resource, making it accessible for general CMS use. Finally, CMS is starting to utilise cloud resources being offered by individual institutes and is gaining experience to facilitate the use of opportunistically available cloud resources. Lastly, we present a snap shot of this infrastructure and its operation at the time of the CHEP2015 conference.

  15. Detecting Abnormal Machine Characteristics in Cloud Infrastructures

    NASA Technical Reports Server (NTRS)

    Bhaduri, Kanishka; Das, Kamalika; Matthews, Bryan L.

    2011-01-01

    In the cloud computing environment resources are accessed as services rather than as a product. Monitoring this system for performance is crucial because of typical pay-peruse packages bought by the users for their jobs. With the huge number of machines currently in the cloud system, it is often extremely difficult for system administrators to keep track of all machines using distributed monitoring programs such as Ganglia1 which lacks system health assessment and summarization capabilities. To overcome this problem, we propose a technique for automated anomaly detection using machine performance data in the cloud. Our algorithm is entirely distributed and runs locally on each computing machine on the cloud in order to rank the machines in order of their anomalous behavior for given jobs. There is no need to centralize any of the performance data for the analysis and at the end of the analysis, our algorithm generates error reports, thereby allowing the system administrators to take corrective actions. Experiments performed on real data sets collected for different jobs validate the fact that our algorithm has a low overhead for tracking anomalous machines in a cloud infrastructure.

  16. The Diverse use of Clouds by CMS

    NASA Astrophysics Data System (ADS)

    Andronis, Anastasios; Bauer, Daniela; Chaze, Olivier; Colling, David; Dobson, Marc; Fayer, Simon; Girone, Maria; Grandi, Claudio; Huffman, Adam; Hufnagel, Dirk; Aftab Khan, Farrukh; Lahiff, Andrew; McCrae, Alison; Rand, Duncan; Sgaravatto, Massimo; Tiradani, Anthony; Zhang, Xiaomei

    2015-12-01

    The resources CMS is using are increasingly being offered as clouds. In Run 2 of the LHC the majority of CMS CERN resources, both in Meyrin and at the Wigner Computing Centre, will be presented as cloud resources on which CMS will have to build its own infrastructure. This infrastructure will need to run all of the CMS workflows including: Tier 0, production and user analysis. In addition, the CMS High Level Trigger will provide a compute resource comparable in scale to the total offered by the CMS Tier 1 sites, when it is not running as part of the trigger system. During these periods a cloud infrastructure will be overlaid on this resource, making it accessible for general CMS use. Finally, CMS is starting to utilise cloud resources being offered by individual institutes and is gaining experience to facilitate the use of opportunistically available cloud resources. We present a snap shot of this infrastructure and its operation at the time of the CHEP2015 conference.

  17. The Diverse use of Clouds by CMS

    SciTech Connect

    Andronis, Anastasios; Bauer, Daniela; Chaze, Olivier; Colling, David; Dobson, Marc; Fayer, Simon; Girone, Maria; Grandi, Claudio; Huffman, Adam; Hufnagel, Dirk; Khan, Farrukh Aftab; Lahiff, Andrew; McCrae, Alison; Rand, Duncan; Sgaravatto, Massimo; Tiradani, Anthony; Zhang, Xiaomei

    2015-12-23

    The resources CMS is using are increasingly being offered as clouds. In Run 2 of the LHC the majority of CMS CERN resources, both in Meyrin and at the Wigner Computing Centre, will be presented as cloud resources on which CMS will have to build its own infrastructure. This infrastructure will need to run all of the CMS workflows including: Tier 0, production and user analysis. In addition, the CMS High Level Trigger will provide a compute resource comparable in scale to the total offered by the CMS Tier 1 sites, when it is not running as part of the trigger system. During these periods a cloud infrastructure will be overlaid on this resource, making it accessible for general CMS use. Finally, CMS is starting to utilise cloud resources being offered by individual institutes and is gaining experience to facilitate the use of opportunistically available cloud resources.We present a snap shot of this infrastructure and its operation at the time of the CHEP2015 conference.

  18. Modeled Impact of Cirrus Cloud Increases Along Aircraft Flight Paths

    NASA Technical Reports Server (NTRS)

    Rind, David; Lonergan, P.; Shah, K.

    1999-01-01

    The potential impact of contrails and alterations in the lifetime of background cirrus due to subsonic airplane water and aerosol emissions has been investigated in a set of experiments using the GISS GCM connected to a q-flux ocean. Cirrus clouds at a height of 12-15km, with an optical thickness of 0.33, were input to the model "x" percentage of clear-sky occasions along subsonic aircraft flight paths, where x is varied from .05% to 6%. Two types of experiments were performed: one with the percentage cirrus cloud increase independent of flight density, as long as a certain minimum density was exceeded; the other with the percentage related to the density of fuel expenditure. The overall climate impact was similar with the two approaches, due to the feedbacks of the climate system. Fifty years were run for eight such experiments, with the following conclusions based on the stable results from years 30-50 for each. The experiments show that adding cirrus to the upper troposphere results in a stabilization of the atmosphere, which leads to some decrease in cloud cover at levels below the insertion altitude. Considering then the total effect on upper level cloud cover (above 5 km altitude), the equilibrium global mean temperature response shows that altering high level clouds by 1% changes the global mean temperature by 0.43C. The response is highly linear (linear correlation coefficient of 0.996) for high cloud cover changes between 0. 1% and 5%. The effect is amplified in the Northern Hemisphere, more so with greater cloud cover change. The temperature effect maximizes around 10 km (at greater than 40C warming with a 4.8% increase in upper level clouds), again more so with greater warming. The high cloud cover change shows the flight path influence most clearly with the smallest warming magnitudes; with greater warming, the model feedbacks introduce a strong tropical response. Similarly, the surface temperature response is dominated by the feedbacks, and shows

  19. Interpretation of FRESCO cloud retrievals in case of absorbing aerosol events

    NASA Astrophysics Data System (ADS)

    Wang, P.; Tuinder, O. N. E.; Tilstra, L. G.; Stammes, P.

    2011-12-01

    Cloud and aerosol information is needed in trace gas retrievals from satellite measurements. The Fast REtrieval Scheme for Clouds from the Oxygen A band (FRESCO) cloud algorithm employs reflectance spectra of the O2 A band around 760 nm to derive cloud pressure and effective cloud fraction. In general, clouds contribute more to the O2 A band reflectance than aerosols. Therefore, the FRESCO algorithm does not correct for aerosol effects in the retrievals and attributes the retrieved cloud information entirely to the presence of clouds, and not to aerosols. For events with high aerosol loading, aerosols may have a dominant effect, especially for almost cloud-free scenes. We have analysed FRESCO cloud data and Absorbing Aerosol Index (AAI) data from the Global Ozone Monitoring Experiment (GOME-2) instrument on the Metop-A satellite for events with typical absorbing aerosol types, such as volcanic ash, desert dust and smoke. We find that the FRESCO effective cloud fractions are correlated with the AAI data