Preliminary results of radiometric measurements of clear air and cloud brightness (antenna) temperatures at 37GHz

Science.gov (United States)

Arakelyan, A. K.; Hambaryan, A. K.; Arakelyan, A. A.

2012-05-01

In this paper the results of polarization measurements of clear air and clouds brightness temperatures at 37GHz are presented. The results were obtained during the measurements carried out in Armenia from the measuring complex built under the framework of ISTC Projects A-872 and A-1524. The measurements were carried out at vertical and horizontal polarizations, under various angles of sensing by Ka-band combined scatterometric-radiometric system (ArtAr-37) developed and built by ECOSERV Remote Observation Centre Co.Ltd. under the framework of the above Projects. In the paper structural and operational features of the utilized system and the whole measuring complex will be considered and discussed as well.

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

International Nuclear Information System (INIS)

Pelkowski, Joaquin; Anduckia Avila, Juan Carlos

2000-01-01

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

Rayleigh beacon for measuring the surface profile of a radio telescope.

Science.gov (United States)

Padin, S

2014-12-01

Millimeter-wavelength Rayleigh scattering from water droplets in a cloud is proposed as a means of generating a bright beacon for measuring the surface profile of a radio telescope. A λ=3  mm transmitter, with an output power of a few watts, illuminating a stratiform cloud, can generate a beacon with the same flux as Mars in 10 GHz bandwidth, but the beacon has a narrow line width, so it is extremely bright. The key advantage of the beacon is that it can be used at any time, and positioned anywhere in the sky, as long as there are clouds.

The Cloud-Aerosol Transport System (CATS): A New Lidar for Aerosol and Cloud Profiling from the International Space Station

Science.gov (United States)

Welton, Ellsworth J.; McGill, Mathew J.; Yorks. John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

2012-01-01

Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064,532,355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability ofthe ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a

Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

Energy Technology Data Exchange (ETDEWEB)

Rosenfeld, Daniel [Hebrew Univ. of Jerusalem (Israel)

2015-12-23

Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of the world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.

Physical Models of Layered Polar Firn Brightness Temperatures from 0.5 to 2 GHz

Science.gov (United States)

Tan, Shurun; Aksoy, Mustafa; Brogioni, Marco; Macelloni, Giovanni; Durand, Michael; Jezek, Kenneth C.; Wang, Tian-Lin; Tsang, Leung; Johnson, Joel T.; Drinkwater, Mark R.;

Hemispheric aerosol vertical profiles: anthropogenic impacts on optical depth and cloud nuclei.

Science.gov (United States)

Clarke, Antony; Kapustin, Vladimir

2010-09-17

Understanding the effect of anthropogenic combustion upon aerosol optical depth (AOD), clouds, and their radiative forcing requires regionally representative aerosol profiles. In this work, we examine more than 1000 vertical profiles from 11 major airborne campaigns in the Pacific hemisphere and confirm that regional enhancements in aerosol light scattering, mass, and number are associated with carbon monoxide from combustion and can exceed values in unperturbed regions by more than one order of magnitude. Related regional increases in a proxy for cloud condensation nuclei (CCN) and AOD imply that direct and indirect aerosol radiative effects are coupled issues linked globally to aged combustion. These profiles constrain the influence of combustion on regional AOD and CCN suitable for challenging climate model performance and informing satellite retrievals.

The DC-8 Submillimeter-Wave Cloud Ice Radiometer

Science.gov (United States)

Walter, Steven J.; Batelaan, Paul; Siegel, Peter; Evans, K. Franklin; Evans, Aaron; Balachandra, Balu; Gannon, Jade; Guldalian, John; Raz, Guy; Shea, James

2000-01-01

An airborne radiometer is being developed to demonstrate the capability of radiometry at submillimeter-wavelengths to characterize cirrus clouds. At these wavelengths, cirrus clouds scatter upwelling radiation from water vapor in the lower troposphere. Radiometric measurements made at multiple widely spaced frequencies permit flux variations caused by changes in scattering due to crystal size to be distinguished from changes in cloud ice content. Measurements at dual polarizations can also be used to constrain the mean crystal shape. An airborne radiometer measuring the upwelling submillimeter-wave flux should then able to retrieve both bulk and microphysical cloud properties. The radiometer is being designed to make measurements at four frequencies (183 GHz, 325 GHz, 448 GHz, and 643 GHz) with dual-polarization capability at 643 GHz. The instrument is being developed for flight on NASA's DC-8 and will scan cross-track through an aircraft window. Measurements with this radiometer in combination with independent ground-based and airborne measurements will validate the submillimeter-wave radiometer retrieval techniques. The goal of this effort is to develop a technique to enable spaceborne characterization of cirrus, which will meet a key climate measurement need. The development of an airborne radiometer to validate cirrus retrieval techniques is a critical step toward development of spaced-based radiometers to investigate and monitor cirrus on a global scale. The radiometer development is a cooperative effort of the University of Colorado, Colorado State University, Swales Aerospace, and Jet Propulsion Laboratory and is funded by the NASA Instrument Incubator Program.

Simultaneous and synergistic profiling of cloud and drizzle properties using ground-based observations

Science.gov (United States)

Rusli, Stephanie P.; Donovan, David P.; Russchenberg, Herman W. J.

2017-12-01

Despite the importance of radar reflectivity (Z) measurements in the retrieval of liquid water cloud properties, it remains nontrivial to interpret Z due to the possible presence of drizzle droplets within the clouds. So far, there has been no published work that utilizes Z to identify the presence of drizzle above the cloud base in an optimized and a physically consistent manner. In this work, we develop a retrieval technique that exploits the synergy of different remote sensing systems to carry out this task and to subsequently profile the microphysical properties of the cloud and drizzle in a unified framework. This is accomplished by using ground-based measurements of Z, lidar attenuated backscatter below as well as above the cloud base, and microwave brightness temperatures. Fast physical forward models coupled to cloud and drizzle structure parameterization are used in an optimal-estimation-type framework in order to retrieve the best estimate for the cloud and drizzle property profiles. The cloud retrieval is first evaluated using synthetic signals generated from large-eddy simulation (LES) output to verify the forward models used in the retrieval procedure and the vertical parameterization of the liquid water content (LWC). From this exercise it is found that, on average, the cloud properties can be retrieved within 5 % of the mean truth. The full cloud-drizzle retrieval method is then applied to a selected ACCEPT (Analysis of the Composition of Clouds with Extended Polarization Techniques) campaign dataset collected in Cabauw, the Netherlands. An assessment of the retrieval products is performed using three independent methods from the literature; each was specifically developed to retrieve only the cloud properties, the drizzle properties below the cloud base, or the drizzle fraction within the cloud. One-to-one comparisons, taking into account the uncertainties or limitations of each retrieval, show that our results are consistent with what is derived

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds.

Science.gov (United States)

Miller, Daniel J; Zhang, Zhibo; Ackerman, Andrew S; Platnick, Steven; Baum, Bryan A

2016-04-27

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness ( τ ) and effective radius ( r e ) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5-10 g/m 2 . In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic r e profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques.

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds

Science.gov (United States)

Miller, Daniel J.; Zhang, Zhibo; Ackerman, Andrew S.; Platnick, Steven; Baum, Bryan A.

2018-01-01

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness (τ) and effective radius (re) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5–10 g/m2. In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic re profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques. PMID:29637042

Winter QPF Sensitivities to Snow Parameterizations and Comparisons to NASA CloudSat Observations

Science.gov (United States)

Molthan, Andrew; Haynes, John M.; Jedlovec, Gary J.; Lapenta, William M.

2009-01-01

Steady increases in computing power have allowed for numerical weather prediction models to be initialized and run at high spatial resolution, permitting a transition from larger scale parameterizations of the effects of clouds and precipitation to the simulation of specific microphysical processes and hydrometeor size distributions. Although still relatively coarse in comparison to true cloud resolving models, these high resolution forecasts (on the order of 4 km or less) have demonstrated value in the prediction of severe storm mode and evolution and are being explored for use in winter weather events . Several single-moment bulk water microphysics schemes are available within the latest release of the Weather Research and Forecast (WRF) model suite, including the NASA Goddard Cumulus Ensemble, which incorporate some assumptions in the size distribution of a small number of hydrometeor classes in order to predict their evolution, advection and precipitation within the forecast domain. Although many of these schemes produce similar forecasts of events on the synoptic scale, there are often significant details regarding precipitation and cloud cover, as well as the distribution of water mass among the constituent hydrometeor classes. Unfortunately, validating data for cloud resolving model simulations are sparse. Field campaigns require in-cloud measurements of hydrometeors from aircraft in coordination with extensive and coincident ground based measurements. Radar remote sensing is utilized to detect the spatial coverage and structure of precipitation. Here, two radar systems characterize the structure of winter precipitation for comparison to equivalent features within a forecast model: a 3 GHz, Weather Surveillance Radar-1988 Doppler (WSR-88D) based in Omaha, Nebraska, and the 94 GHz NASA CloudSat Cloud Profiling Radar, a spaceborne instrument and member of the afternoon or "A-Train" of polar orbiting satellites tasked with cataloguing global cloud

Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

Directory of Open Access Journals (Sweden)

S. A. Buehler

2012-07-01

Full Text Available Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8, which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

The role of cloud-scale resolution on radiative properties of oceanic cumulus clouds

International Nuclear Information System (INIS)

Kassianov, Evgueni; Ackerman, Thomas; Kollias, Pavlos

2005-01-01

Both individual and combined effects of the horizontal and vertical variability of cumulus clouds on solar radiative transfer are investigated using a two-dimensional (x- and z-directions) cloud radar dataset. This high-resolution dataset of typical fair-weather marine cumulus is derived from ground-based 94GHz cloud radar observations. The domain-averaged (along x-direction) radiative properties are computed by a Monte Carlo method. It is shown that (i) different cloud-scale resolutions can be used for accurate calculations of the mean absorption, upward and downward fluxes; (ii) the resolution effects can depend strongly on the solar zenith angle; and (iii) a few cloud statistics can be successfully applied for calculating the averaged radiative properties

Thermodynamic phase profiles of optically thin midlatitude cloud and their relation to temperature

Energy Technology Data Exchange (ETDEWEB)

Naud, C. M.; Del Genio, Anthony D.; Haeffelin, M.; Morille, Y.; Noel, V.; Dupont, Jean-Charles; Turner, David D.; Lo, Chaomei; Comstock, Jennifer M.

2010-06-03

Winter cloud phase and temperature profiles derived from ground-based lidar depolarization and radiosonde measurements are analyzed for two midlatitude locations: the United States Atmospheric Radiation Measurement Program Southern Great Plains (SGP) site and the Site Instrumental de Recherche par Télédétection Atmosphérique (SIRTA) in France. Because lidars are attenuated in optically thick clouds, the dataset only includes optically thin clouds (optical thickness < 3). At SGP, 57% of the clouds observed with the lidar in the temperature range 233-273 K are either completely liquid or completely glaciated, while at SIRTA only 42% of the observed clouds are single phase, based on a depolarization ratio threshold of 11% for differentiating liquid from ice. Most optically thin mixed phase clouds show an ice layer at cloud top, and clouds with liquid at cloud top are less frequent. The relationship between ice phase occurrence and temperature only slightly changes between cloud base and top. At both sites liquid is more prevalent at colder temperatures than has been found previously in aircraft flights through frontal clouds of greater optical thicknesses. Liquid in clouds persists to colder temperatures at SGP than SIRTA. This information on the average temperatures of mixed phase clouds at both locations complements earlier passive satellite remote sensing measurements that sample cloud phase near cloud top and for a wider range of cloud optical thicknesses.

Analysis of 35 GHz Cloud Radar polarimetric variables to identify stratiform and convective precipitation.

Science.gov (United States)

Fontaine, Emmanuel; Illingworth, Anthony, J.; Stein, Thorwald

2017-04-01

This study is performed using vertical profiles of radar measurements at 35GHz, for the period going from 29th of February to 1rst October 2016, at the Chilbolton observatory in United Kingdom. During this period, more than 40 days with precipitation events are investigated. The investigation uses the synergy of radar reflectivity factors, vertical velocity, Doppler spectrum width, and linear depolarization ratio (LDR) to differentiate between stratiform and convective rain events. The depth of the layer with Doppler spectrum width values greater than 0.5 m s-1 is shown to be a suitable proxy to distinguish between convective and stratiform events. Using LDR to detect the radar bright band, bright band characteristics such as depth of the layer and maximum LDR are shown to vary with the amount of turbulence aloft. Profiles of radar measurements are also compared to rain gauge measurements to study the contribution of convective and stratiform rainfall to total rain duration and amount. To conclude, this study points out differences between convective and stratiform rains and quantifies their contributions over a precipitation event, highlighting that convective and stratiform rainfall should be considered as a continuum rather than a dichotomy.

Cloud sensitivity studies for stratospheric and lower mesospheric ozone profile retrievals from measurements of limb-scattered solar radiation

Directory of Open Access Journals (Sweden)

T. Sonkaew

2009-11-01

Full Text Available Clouds in the atmosphere play an important role in reflection, absorption and transmission of solar radiation and thus affect trace gas retrievals. The main goal of this paper is to examine the sensitivity of stratospheric and lower mesospheric ozone retrievals from limb-scattered radiance measurements to clouds using the SCIATRAN radiative transfer model and retrieval package. The retrieval approach employed is optimal estimation, and the considered clouds are vertically and horizontally homogeneous. Assuming an aerosol-free atmosphere and Mie phase functions for cloud particles, we compute the relative error of ozone profile retrievals in a cloudy atmosphere if clouds are neglected in the retrieval. To access altitudes from the lower stratosphere up to the lower mesosphere, we combine the retrievals in the Chappuis and Hartley ozone absorption bands. We find significant cloud sensitivity of the limb ozone retrievals in the Chappuis bands at lower stratospheric altitudes. The relative error in the retrieved ozone concentrations gradually decreases with increasing altitude and becomes negligible above approximately 40 km. The parameters with the largest impact on the ozone retrievals are cloud optical thickness, ground albedo and solar zenith angle. Clouds with different geometrical thicknesses or different cloud altitudes have a similar impact on the ozone retrievals for a given cloud optical thickness value, if the clouds are outside the field of view of the instrument. The effective radius of water droplets has a small influence on the error, i.e., less than 0.5% at altitudes above the cloud top height. Furthermore, the impact of clouds on the ozone profile retrievals was found to have a rather small dependence on the solar azimuth angle (less than 1% for all possible azimuth angles. For the most frequent cloud types, the total error is below 6% above 15 km altitude, if clouds are completely neglected in the retrieval. Neglecting clouds in

Precipitating clouds observed by 1.3-GHz boundary layer radars in equatorial Indonesia

Directory of Open Access Journals (Sweden)

F. Renggono

2001-08-01

Full Text Available Temporal variations of precipitating clouds in equatorial Indonesia have been studied based on observations with 1357.5 MHz boundary layer radars at Serpong (6.4° S, 106.7° E near Jakarta and Bukittinggi (0.2° S, 100.3° E in West Sumatera. We have classified precipitating clouds into four types: stratiform, mixed stratiform-convective, deep convective, and shallow convective clouds, using the Williams et al. (1995 method. Diurnal variations of the occurrence of precipitating clouds at Serpong and Bukittinggi have showed the same characteristics, namely, that the precipitating clouds primarily occur in the afternoon and the peak of the stratiform cloud comes after the peak of the deep convective cloud. The time delay between the peaks of stratiform and deep convective clouds corresponds to the life cycle of the mesoscale convective system. The precipitating clouds which occur in the early morning at Serpong are dominated by stratiform cloud. Concerning seasonal variations of the precipitating clouds, we have found that the occurrence of the stratiform cloud is most frequent in the rainy season, while the occurrence of the deep convective cloud is predominant in the dry season.Key words. Meteorology and atmospheric dynamics (convective processes; precipitation; tropical meteorology

Rotational emission-line spectrum of Orion A between 247 and 263 GHZ

International Nuclear Information System (INIS)

Blake, G.A.; Sutton, E.C.; Masson, C.R.; Phillips, T.G.

1986-01-01

Results are presented from a molecular line survey of the core of the Orion molecular cloud between 247 and 263 GHz. The spectrum contains a total of 243 resolvable lines from 23 different chemical species. When combined with the earlier survey of Orion from 215 to 247 GHz by Sutton et al (1985), the complete data set includes over 780 emission features from 29 distinct molecules. Of the 23 molecules detected in this survey, only NO, CCH, and HCO + were identified not in the lower frequency data

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

Science.gov (United States)

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

2006-12-01

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

CLOUD TECHNOLOGIES OF MONITORING OF THE QUALITY OF TRAINING OF WORKERS OF RAILWAY PROFILE

Directory of Open Access Journals (Sweden)

Tetyana Bondarenko

2016-06-01

Full Text Available With the purpose of creating the system of monitoring of the quality of professional training of future workers of railway profile, the author puts forward a technology of using cloud services of the search system of Google. The article proves that the system provides a complex support of monitoring, from creating appropriate forms and storing of the results in cloud storage to the\\processing of results of the monitoring and management of the system of testing on the basis of using the service of Google-Calendar. In the article there has been considered the usage of the concept of BYOD for testing of students’ achievement. The article demonstrates the advantages of  the proposed approach to monitoring the quality of training of future workers of railway profile highlighting  the usage of the cloud services of the search system of Google as a means of  expanding the boundaries of research in space and time and making the procedure more flexible and systematic.

Vertical Cloud Climatology During TC4 Derived from High-Altitude Aircraft Merged Lidar and Radar Profiles

Science.gov (United States)

Hlavka, Dennis; Tian, Lin; Hart, William; Li, Lihua; McGill, Matthew; Heymsfield, Gerald

2009-01-01

Aircraft lidar works by shooting laser pulses toward the earth and recording the return time and intensity of any of the light returning to the aircraft after scattering off atmospheric particles and/or the Earth s surface. The scattered light signatures can be analyzed to tell the exact location of cloud and aerosol layers and, with the aid of a few optical assumptions, can be analyzed to retrieve estimates of optical properties such as atmospheric transparency. Radar works in a similar fashion except it sends pulses toward earth at a much larger wavelength than lidar. Radar records the return time and intensity of cloud or rain reflection returning to the aircraft. Lidar can measure scatter from optically thin cirrus and aerosol layers whose particles are too small for the radar to detect. Radar can provide reflection profiles through thick cloud layers of larger particles that lidar cannot penetrate. Only after merging the two instrument products can accurate measurements of the locations of all layers in the full atmospheric column be achieved. Accurate knowledge of the vertical distribution of clouds is important information for understanding the Earth/atmosphere radiative balance and for improving weather/climate forecast models. This paper describes one such merged data set developed from the Tropical Composition, Cloud and Climate Coupling (TC4) experiment based in Costa Rica in July-August 2007 using the nadir viewing Cloud Physics Lidar (CPL) and the Cloud Radar System (CRS) on board the NASA ER-2 aircraft. Statistics were developed concerning cloud probability through the atmospheric column and frequency of the number of cloud layers. These statistics were calculated for the full study area, four sub-regions, and over land compared to over ocean across all available flights. The results are valid for the TC4 experiment only, as preferred cloud patterns took priority during mission planning. The TC4 Study Area was a very cloudy region, with cloudy

CloudMonitor: Profiling Power Usage

OpenAIRE

Smith, James William; Khajeh-Hosseini, Ali; Ward, Jonathan Stuart; Sommerville, Ian

2012-01-01

In Cloud Computing platforms the addition of hardware monitoring devices to gather power usage data can be impractical or uneconomical due to the large number of machines to be metered. CloudMonitor, a monitoring tool that can generate power models for software-based power estimation, can provide insights to the energy costs of deployments without additional hardware. Accurate power usage data leads to the possibility of Cloud providers creating a separate tariff for power and therefore incen...

Achievable Rate Estimation of IEEE 802.11ad Visual Big-Data Uplink Access in Cloud-Enabled Surveillance Applications.

Science.gov (United States)

Kim, Joongheon; Kim, Jong-Kook

2016-01-01

This paper addresses the computation procedures for estimating the impact of interference in 60 GHz IEEE 802.11ad uplink access in order to construct visual big-data database from randomly deployed surveillance camera sensing devices. The acquired large-scale massive visual information from surveillance camera devices will be used for organizing big-data database, i.e., this estimation is essential for constructing centralized cloud-enabled surveillance database. This performance estimation study captures interference impacts on the target cloud access points from multiple interference components generated by the 60 GHz wireless transmissions from nearby surveillance camera devices to their associated cloud access points. With this uplink interference scenario, the interference impacts on the main wireless transmission from a target surveillance camera device to its associated target cloud access point with a number of settings are measured and estimated under the consideration of 60 GHz radiation characteristics and antenna radiation pattern models.

A prompt radio burst from supernova 1987A in the Large Magellanic Cloud

International Nuclear Information System (INIS)

Turtle, A.J.; Campbell-Wilson, D.; Bunton, J.D.; Jauncey, D.L.; Kesteven, M.J.; Manchester, R.N.; Norris, R.P.; Storey, M.C.; Reynolds, J.E.

1987-01-01

The paper concerns a prompt radio burst from supernova 1987A in the Large Magellanic Cloud. Radio emission from the supernova was detected at Australian observatories within two days of the increase in optical brightness. Observations of radio emission at four frequencies i.e. 0.843, 1.415, 2.29 and 8.41 GHz are presented for the region of the Large Magellanic Cloud supernova. At frequencies around 1 GHz the peak flux density was about 150mJy and occurred within four days of the supernova. (U.K.)

Comparison of Monthly Mean Cloud Fraction and Cloud Optical depth Determined from Surface Cloud Radar, TOVS, AVHRR, and MODIS over Barrow, Alaska

Science.gov (United States)

Uttal, Taneil; Frisch, Shelby; Wang, Xuan-Ji; Key, Jeff; Schweiger, Axel; Sun-Mack, Sunny; Minnis, Patrick

2005-01-01

A one year comparison is made of mean monthly values of cloud fraction and cloud optical depth over Barrow, Alaska (71 deg 19.378 min North, 156 deg 36.934 min West) between 35 GHz radar-based retrievals, the TOVS Pathfinder Path-P product, the AVHRR APP-X product, and a MODIS based cloud retrieval product from the CERES-Team. The data sets represent largely disparate spatial and temporal scales, however, in this paper, the focus is to provide a preliminary analysis of how the mean monthly values derived from these different data sets compare, and determine how they can best be used separately, and in combination to provide reliable estimates of long-term trends of changing cloud properties. The radar and satellite data sets described here incorporate Arctic specific modifications that account for cloud detection challenges specific to the Arctic environment. The year 2000 was chosen for this initial comparison because the cloud radar data was particularly continuous and reliable that year, and all of the satellite retrievals of interest were also available for the year 2000. Cloud fraction was chosen as a comparison variable as accurate detection of cloud is the primary product that is necessary for any other cloud property retrievals. Cloud optical depth was additionally selected as it is likely the single cloud property that is most closely correlated to cloud influences on surface radiation budgets.

Achievable Rate Estimation of IEEE 802.11ad Visual Big-Data Uplink Access in Cloud-Enabled Surveillance Applications.

Directory of Open Access Journals (Sweden)

Joongheon Kim

Full Text Available This paper addresses the computation procedures for estimating the impact of interference in 60 GHz IEEE 802.11ad uplink access in order to construct visual big-data database from randomly deployed surveillance camera sensing devices. The acquired large-scale massive visual information from surveillance camera devices will be used for organizing big-data database, i.e., this estimation is essential for constructing centralized cloud-enabled surveillance database. This performance estimation study captures interference impacts on the target cloud access points from multiple interference components generated by the 60 GHz wireless transmissions from nearby surveillance camera devices to their associated cloud access points. With this uplink interference scenario, the interference impacts on the main wireless transmission from a target surveillance camera device to its associated target cloud access point with a number of settings are measured and estimated under the consideration of 60 GHz radiation characteristics and antenna radiation pattern models.

Aircraft profile measurements of 18O/16O and D/H isotope ratios of cloud condensate and water vapor constrain precipitation efficiency and entrainment rates in tropical clouds

Science.gov (United States)

Noone, D. C.; Raudzens Bailey, A.; Toohey, D. W.; Twohy, C. H.; Heymsfield, A.; Rella, C.; Van Pelt, A. D.

2011-12-01

Convective clouds play a significant role in the moisture and heat balance of the tropics. The dynamics of organized and isolated convection are a function of the background thermodynamic profile and wind shear, buoyancy sources near the surface and the latent heating inside convective updrafts. The stable oxygen and hydrogen isotope ratios in water vapor and condensate can be used to identify dominant moisture exchanges and aspects of the cloud microphysics that are otherwise difficult to observe. Both the precipitation efficiency and the dilution of cloud updrafts by entrainment can be estimated since the isotopic composition outside the plume is distinct from inside. Measurements of the 18O/16O and D/H isotope ratios were made in July 2011 on 13 research flights of the NCAR C130 aircraft during the ICE-T (Ice in Clouds Experiment - Tropical) field campaign near St Croix. Measurements were made using an instrument based on the Picarro Wave-Length Scanning Cavity Ring Down platform that includes a number of optical, hardware and software modifications to allow measurements to be made at 5 Hz for deployment on aircraft. The measurement system was optimized to make precise measurements of the isotope ratio of liquid and ice cloud condensate by coupling the gas analyzer to the NCAR Counter flow Virtual Impactor inlet. The inlet system provides a particle enhancement while rejecting vapor. Sample air is vigorously heated before flowing into the gas phase analyzer. We present statistics that demonstrate the performance and calibration of the instrument. Measured profiles show that environmental air exhibits significant layering showing controls from boundary layer processes, large scale horizontal advection and regional subsidence. Condensate in clouds is consistent with generally low precipitation efficiency, although there is significant variability in the isotope ratios suggesting heterogeneity within plumes and the stochastic nature of detrainment processes

Near Real Time Vertical Profiles of Clouds and Aerosols from the Cloud-Aerosol Transport System (CATS) on the International Space Station

Science.gov (United States)

Yorks, J. E.; McGill, M. J.; Nowottnick, E. P.

2015-12-01

Plumes from hazardous events, such as ash from volcanic eruptions and smoke from wildfires, can have a profound impact on the climate system, human health and the economy. Global aerosol transport models are very useful for tracking hazardous plumes and predicting the transport of these plumes. However aerosol vertical distributions and optical properties are a major weakness of global aerosol transport models, yet a key component of tracking and forecasting smoke and ash. The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar designed to provide vertical profiles of clouds and aerosols while also demonstrating new in-space technologies for future Earth Science missions. CATS has been operating on the Japanese Experiment Module - Exposed Facility (JEM-EF) of the International Space Station (ISS) since early February 2015. The ISS orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three-day repeat cycle. The ISS orbit also provides CATS with excellent coverage over the primary aerosol transport tracks, mid-latitude storm tracks, and tropical convection. Data from CATS is used to derive properties of clouds and aerosols including: layer height, layer thickness, backscatter, optical depth, extinction, and depolarization-based discrimination of particle type. The measurements of atmospheric clouds and aerosols provided by the CATS payload have demonstrated several science benefits. CATS provides near-real-time observations of cloud and aerosol vertical distributions that can be used as inputs to global models. The infrastructure of the ISS allows CATS data to be captured, transmitted, and received at the CATS ground station within several minutes of data collection. The CATS backscatter and vertical feature mask are part of a customized near real time (NRT) product that the CATS processing team produces within 6 hours of collection. The continuous near real time CATS data

Market capture by 30/20 GHz satellite systems. Volume 1: Executive summary

Science.gov (United States)

Gamble, R. B.; Saporta, L.

1981-01-01

Demand for 30/20 GHz satellite systems over the next two decades is projected. Topics include a profile of the communications market, switched, dedicated, and packet transmission modes, deferred and real-time traffic, quality and reliability considerations, the capacity of competing transmission media, and scenarios for the growth and development of 30/20 GHz satellite communications.

Height profile of particle concentration in an aeolian saltating cloud: A wind tunnel investigation by PIV MSD

Science.gov (United States)

Dong, Zhibao; Wang, Hongtao; Zhang, Xiaohang; Ayrault, Michael

2003-10-01

Attempt is made to define the particle concentration in an aeolian saltating cloud and its variation with height using artificial spherical quartz sand in a wind tunnel. The height profiles of the relative particle concentration in aeolian saltating cloud at three wind velocities were detected by the state of the art PIV (Particle Image Velocimetry) MSD (Mie Scattering Diffusion) technique, and converted to actual concentration based on sand transport rate and the variation with height of velocity of the saltating cloud. The particle concentration was found to decay exponentially with height and to increase with wind velocity. It decayed more rapidly when the wind velocity decreased. The volume/volume concentration in the near-surface layer was at the order of 10-4. The results obtained by PIV MSD technique were in good agreement with those derived from the sand flux and velocity profiles, the former being about 15% greater than the later.

Polar cloud observatory at Ny-Ålesund in GRENE Arctic Climate Change Research Project

Science.gov (United States)

Yamanouchi, Takashi; Takano, Toshiaki; Shiobara, Masataka; Okamoto, Hajime; Koike, Makoto; Ukita, Jinro

2016-04-01

Cloud is one of the main processes in the climate system and especially a large feed back agent for Arctic warming amplification (Yoshimori et al., 2014). From this reason, observation of polar cloud has been emphasized and 95 GHz cloud profiling radar in high precision was established at Ny-Ålesund, Svalbard in 2013 as one of the basic infrastructure in the GRENE (Green Network of Excellence Program) Arctic Climate Change Research Project. The radar, "FALCON-A", is a FM-CW (frequency modulated continuous wave) Doppler radar, developed for Arctic use by Chiba University (PI: T. Takano) in 2012, following its prototype, "FALCON-1" which was developed in 2006 (Takano et al., 2010). The specifications of the radar are, central frequency: 94.84 GHz; antenna power: 1 W; observation height: up to 15 km; range resolution: 48 m; beam width: 0.2 degree (15 m at 5 km); Doppler width: 3.2 m/s; time interval: 10 sec, and capable of archiving high sensitivity and high spatial and time resolution. An FM-CW type radar realizes similar sensitivity with much smaller parabolic antennas separated 1.4 m from each other used for transmitting and receiving the wave. Polarized Micro-Pulse Lidar (PMPL, Sigma Space MPL-4B-IDS), which is capable to measure the backscatter and depolarization ratio, has also been deployed to Ny-Ålesund in March 2012, and now operated to perform collocated measurements with FALCON-A. Simultaneous measurement data from collocated PMPL and FALCON-A are available for synergetic analyses of cloud microphysics. Cloud mycrophysics, such as effective radius of ice particles and ice water content, are obtained from the analysis based on algorithm, which is modified for ground-based measurements from Okamoto's retrieval algorithm for satellite based cloud profiling radar and lidar (CloudSat and CALIPSO; Okamoto et al., 2010). Results of two years will be shown in the presentation. Calibration is a point to derive radar reflectivity (dBZ) from original intensity data

Tropical High Cloud Fraction Controlled by Cloud Lifetime Rather Than Clear-sky Convergence

Science.gov (United States)

Seeley, J.; Jeevanjee, N.; Romps, D. M.

2016-12-01

Observations and simulations show a peak in cloud fraction below the tropopause. This peak is usually attributed to a roughly co-located peak in radiatively-driven clear-sky convergence, which is presumed to force convective detrainment and thus promote large cloud fraction. Using simulations of radiative-convective equilibrium forced by various radiative cooling profiles, we refute this mechanism by showing that an upper-tropospheric peak in cloud fraction persists even in simulations with no peak in clear-sky convergence. Instead, cloud fraction profiles seem to be controlled by cloud lifetimes — i.e., how long it takes for clouds to dissipate after they have detrained. A simple model of cloud evaporation shows that the small saturation deficit in the upper troposphere greatly extends cloud lifetimes there, while the large saturation deficit in the lower troposphere causes condensate to evaporate quickly. Since cloud mass flux must go to zero at the tropopause, a peak in cloud fraction emerges at a "sweet spot" below the tropopause where cloud lifetimes are long and there is still sufficient mass flux to be detrained.

Molecular clouds and galactic spiral structure

International Nuclear Information System (INIS)

Dame, T.M.

1984-02-01

Galactic CO line emission at 115 GHz was surveyed in order to study the distribution of molecular clouds in the inner galaxy. Comparison of this survey with similar H1 data reveals a detailed correlation with the most intense 21 cm features. To each of the classical 21 cm H1 spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is devised for the galactic distribution of molecular clouds. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide

Investigation of Cloud Properties and Atmospheric Profiles with Modis

Science.gov (United States)

Menzel, Paul; Ackerman, Steve; Moeller, Chris; Gumley, Liam; Strabala, Kathy; Frey, Richard; Prins, Elaine; Laporte, Dan; Wolf, Walter

1997-01-01

A major milestone was accomplished with the delivery of all five University of Wisconsin MODIS Level 2 science production software packages to the Science Data Support Team (SDST) for integration. These deliveries were the culmination of months of design and testing, with most of the work focused on tasks peripheral to the actual science contained in the code. LTW hosted a MODIS infrared calibration workshop in September. Considerable progress has been made by MCST, with help from LTW, in refining the calibration algorithm, and in identifying and characterization outstanding problems. Work continues on characterizing the effects of non-blackbody earth surfaces on atmospheric profile retrievals and modeling radiative transfer through cirrus clouds.

Theoretical assessment of the potential to deduce microphysical characteristics of ice clouds from polarimetric radar measurements at 95 GHz; Theoretische Untersuchungen zur Ableitung mikrophysikalischer Parameter von Eiswolken aus polarimetrischen Radarmessungen bei 95 GHz

Energy Technology Data Exchange (ETDEWEB)

Lemke, H.M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

2000-07-01

The potential of polarimetric radar measurements at 95 GHz to derive microphysical cloud characteristics is assessed. Scattering by atmospheric ice crystals is calculated applying the discrete dipole approximation (DDA) for single crystals of various shape, size, and orientation. The results are combined to acquire radar signals for collections of particles representing the radar volume. Expressing the particle size with respect to the radius of a volume equivalent sphere, the co-plar reflectivity is only slightly affected by particle shape variations. Thus, keeping the limitations of such an approach in mind, the simplified representation of crystals as spheres is applicable. On the other hand, the signal is strongly influenced by the particle size and the total ice water content. Polarimetric radar parameters like linear depolarisation ratio and differential reflectivity are almost independent of size and ice water content. They are predominantly affected by the crystal shape and orientation and therefore have a potential to deduce information about ice crystal habits. Unfortunately, to date such measurements are subject to technical restrictions. (orig.)

Photon-dominated region modeling of the [C I], [C II], and CO Line Emission From A Boundary In The Taurus molecular cloud

Energy Technology Data Exchange (ETDEWEB)

Orr, Matthew E. [Physics and Astronomy Department, University of Southern California, Los Angeles, CA 90089 (United States); Pineda, Jorge L.; Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)

2014-11-01

We present [C I] and [C II] observations of a linear edge region in the Taurus molecular cloud, and model this region as a cylindrically symmetric photon-dominated region (PDR) exposed to a low-intensity UV radiation field. The sharp, long profile of the linear edge makes it an ideal case to test PDR models and determine cloud parameters. We compare observations of the [C I], {sup 3} P {sub 1} → {sup 3} P {sub 0} (492 GHz), [C I] {sup 3} P {sub 2} → {sup 3} P {sub 1} (809 GHz), and [C II] {sup 2} P {sub 3/2} → {sup 2} P {sub 1/2} (1900 GHz) transitions, as well as the lowest rotational transitions of {sup 12}CO and {sup 13}CO, with line intensities produced by the RATRAN radiative transfer code from the results of the Meudon PDR code. We constrain the density structure of the cloud by fitting a cylindrical density function to visual extinction data. We study the effects of variation of the FUV field, {sup 12}C/{sup 13}C isotopic abundance ratio, sulfur depletion, cosmic ray ionization rate, and inclination of the filament relative to the sky-plane on the chemical network of the PDR model and resulting line emission. We also consider the role of suprathermal chemistry and density inhomogeneities. We find good agreement between the model and observations, and that the integrated line intensities can be explained by a PDR model with an external FUV field of 0.05 G {sub 0}, a low ratio of {sup 12}C to {sup 13}C ∼43, a highly depleted sulfur abundance (by a factor of at least 50), a cosmic ray ionization rate (3-6) × 10{sup –17} s{sup –1}, and without significant effects from inclination, clumping or suprathermal chemistry.

Performance Analysis of OFDM 60GHz System and SC-FDE 60GHz System

Directory of Open Access Journals (Sweden)

Han Xueyan

2016-01-01

Full Text Available In this paper, the performance of 60GHz wireless communication system with SC and OFDM is studied, the models of OFDM 60GHz system and SC 60GHz frequency domain equalization (SC-FDE system are established, and the bit error rate (BER performance of OFDM 60GHz system and SC-FDE 60GHz system in 802.15.3c channels is compared. The simulation results show that SC-FDE 60GHz system has a slight advantage over OFDM system in line-of-sight (LOS channels, while OFDM 60GHz system has a slight advantage over SC-FDE system in non-line-of-sight (NLOS channels. For 60GHz system, OFDM 60GHz system has a slight advantage over SC-FDE system in overcoming multipath fading, but the performance of both is close whether in the LOS or NLOS case.

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

Science.gov (United States)

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

2017-04-01

structure of the atmosphere is obtained from long-term radiosonde launches. In addition, continuous vertical profiles of temperature and humidity are provided by the microwave radiometer HATPRO. A set of active remote sensing instruments performs cloud observations at Ny-Ålesund: a ceilometer and a Doppler lidar operating since 2011 and 2013, respectively, are now complemented with a novel 94 GHz FMCW cloud radar. As a first step, the CLOUDNET algorithms, including a target categorization and classification, are applied to the observations. In this study, we will present a first analysis of cloud properties at Ny-Ålesund including for example cloud occurrence, cloud geometry (cloud base, cloud top, and thickness) and cloud type (liquid, ice, mixed-phase). The different types of clouds are set into context to the environmental conditions such as temperature, amount of water vapour, and liquid water. We also expect that the cloud properties strongly depend on the wind direction. The first results of this analysis will be also shown.

Structured surface reflector design for oblique incidence beam splitter at 610 GHz

OpenAIRE

Defrance , Fabien; Casaletti , Massimiliano; Sarrazin , Julien; Wiedner , Martina; Gibson , Hugh; Gay , Gregory; Lefevre , Roland; Delorme , Yan

2016-01-01

International audience; An iterative alternate projection-based algorithm is developed to design structured surface reflectors to operate as beam splitters at GHz and THz frequencies. To validate the method, a surface profile is determined to achieve a reflector at 610 GHz that generates four equal-intensity beams towards desired directions of ±12.6° with respect to the specular reflection axis. A prototype is fabricated and the beam splitter behavior is experimentally demonstrated. Measureme...

Observations of the J = 2 → 1 CO line in molecular clouds near compact H+ regions

International Nuclear Information System (INIS)

Riley, P.W.; Little, L.T.; Brown, A.T.; Hills, R.E.; Padman, R.; Vizard, D.; Lesurf, J.C.G.; Cronin, N.J.

1982-01-01

Observations of the J = 2 → 1 transitions of 12 CO and 13 CO at 230 and 220 GHz in 13 molecular clouds near compact H + regions have been made at UKIRT using an uncooled Schottky diode mixer and a digital auto-correlation spectrometer. The sources were chosen on the basis of their ammonia emission. A comparison between 12 CO and 13 CO spectra reveals a variety of self-absorption effects, ranging from slight asymmetries in the 12 CO profiles relative to their 13 CO counterparts (W43S, S88), to a deep narrow self-absorption dip (S68). The asymmetry observed in six sources out of ten is most easily explained if the clouds are collapsing; there is no clear evidence for expansion. The 13 CO linewidths are systematically wider than those from the NH 3 cores, suggesting that the velocity dispersion in the sources increases with distance from the centre. (author)

Entanglement swapping of a GHZ state via a GHZ-like state

Energy Technology Data Exchange (ETDEWEB)

Tsai, Chia-Wei; Hwang, Tzonelih, E-mail: hwangtl@ismail.csie.ncku.edu.t [National Cheng Kung University, Department of Computer Science and Information Engineering, No. 1 Ta-Hsueh Road, Tainan City 701, Taiwan (China)

2011-10-15

This study uses the Greenberger-Horne-Zeilinger (GHZ)-like state |G>= 1/2 (|001>+|010>+|100>+|111>) to establish an entanglement swapping protocol on a pure GHZ state. A quantum circuit is proposed to assist in teleporting the entanglement of the pure GHZ state. Furthermore, on the basis of the generation of the GHZ-like state, an improved protocol to reduce the number of transmitted photons required in the process of entanglement swapping is proposed.

Gain enhancement of low profile on-chip dipole antenna via Artificial Magnetic Conductor at 94 GHz

KAUST Repository

Nafe, Mahmoud

2015-04-13

The bottleneck for realizing high efficiency System-on-Chip is integrating the antenna on the lossy silicon substrate. To shield the antenna from the silicon, a ground plane can be used. However, the ultra-thin oxide does not provide enough separation between the antenna and the ground plane. In this work, we demonstrate one of the highest reported gains to date for low profile 94 GHz on-chip dipole antenna while the ground plane is in the lowest metal in the oxide (M1). This is achieved by optimizing an Artificial Magnetic Conductor (AMC) structure midway the antenna and M1. The dipole antenna without the AMC has a gain of − 11 dBi while with the AMC structure a gain of + 4.8 dBi and hence achieving a gain enhancement of + 15.8 dB.

A physically based algorithm for non-blackbody correction of the cloud top temperature for the convective clouds

Science.gov (United States)

Wang, C.; Luo, Z. J.; Chen, X.; Zeng, X.; Tao, W.; Huang, X.

2012-12-01

Cloud top temperature is a key parameter to retrieval in the remote sensing of convective clouds. Passive remote sensing cannot directly measure the temperature at the cloud tops. Here we explore a synergistic way of estimating cloud top temperature by making use of the simultaneous passive and active remote sensing of clouds (in this case, CloudSat and MODIS). Weighting function of the MODIS 11μm band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat retrievals and temperature and humidity profiles based on ECMWF ERA-interim reanalysis into a radiation transfer model. Among 19,699 tropical deep convective clouds observed by the CloudSat in 2008, the averaged effective emission level (EEL, where the weighting function attains its maximum) is at optical depth 0.91 with a standard deviation of 0.33. Furthermore, the vertical gradient of CloudSat radar reflectivity, an indicator of the fuzziness of convective cloud top, is linearly proportional to, d_{CTH-EEL}, the distance between the EEL of 11μm channel and cloud top height (CTH) determined by the CloudSat when d_{CTH-EEL}<0.6km. Beyond 0.6km, the distance has little sensitivity to the vertical gradient of CloudSat radar reflectivity. Based on these findings, we derive a formula between the fuzziness in the cloud top region, which is measurable by CloudSat, and the MODIS 11μm brightness temperature assuming that the difference between effective emission temperature and the 11μm brightness temperature is proportional to the cloud top fuzziness. This formula is verified using the simulated deep convective cloud profiles by the Goddard Cumulus Ensemble model. We further discuss the application of this formula in estimating cloud top buoyancy as well as the error characteristics of the radiative calculation within such deep-convective clouds.

Cloud point enhancement profile of libraries of modified Poly(N-isopropylmethacrylamide)

International Nuclear Information System (INIS)

Tavares, Alexandre Guilherme Silva; Silveira, Kelly Cristine da; Lucas, Elizabete Fernandes

2016-01-01

Full text: Poly(N-isopropyl methacrylamide) (PNIPMAM) based polymers are commercially available. These polymers present low cloud point, which may result in precipitation problems when applying for petroleum exploration [1]. Production of oil and gas has high temperature points, which can induce loss of activity for kinetic hydrate inhibitors (KHI), causing blockages by hydrates in pipes, fittings or valves. Hydrophobic groups can be added to modify PNIPMAM based polymers for hydrate inhibition during petroleum production. The cloud point enhancement profile of series of modified polymers was studied in this work. We synthesized poly(N-isopropyl methacrylamide-co-acrylic acid), P(NIPMAM-co-AA), by standard polymerization using AIBN as initiator. Series of modified polymers using two different groups (terc-butil and cyclopentyl) were studied. The characterization was made by nuclear magnetic resonance (NMR) to confirm the chemical structure; titration was used to determine the acrylic acid content for all synthesized polymers; Gel Permeation Chromatography (GPC) was applied to determine molar mass and polydispersity. A carbodiimide mediated coupling reaction (CMC) [2] was used to post synthetically modify the base polymer P(NIPMAM-co-AA) with N-(3-dimethylaminopropyl)-N’- ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as activation agents. The cloud point experiment was carried out with deionized water and brine water where small vials with polymer solution were heated at 12 deg C/min rate. The temperature when the solution became turbid was monitored. The modified PNIPMAM based polymers presented a significant enhancement on cloud point temperature, up to 80 deg C, in comparison to unmodified polymer, P(NIPMAM-co- AA). References: [1] Mady, M. F.; Kelland, M.A. Energy and Fuels,28, 5714 (2014) [2] Silveira, K.C.; Sheng, Q.; Tian, W.; Lucas, E.F.; Wood, C.D. J. Appl. Poly. Sci.,132, 42797 (2015). (author)

Structured surface reflector design for oblique incidence beam splitter at 610 GHz.

Science.gov (United States)

Defrance, F; Casaletti, M; Sarrazin, J; Wiedner, M C; Gibson, H; Gay, G; Lefèvre, R; Delorme, Y

2016-09-05

An iterative alternate projection-based algorithm is developed to design structured surface reflectors to operate as beam splitters at GHz and THz frequencies. To validate the method, a surface profile is determined to achieve a reflector at 610 GHz that generates four equal-intensity beams towards desired directions of ±12.6° with respect to the specular reflection axis. A prototype is fabricated and the beam splitter behavior is experimentally demonstrated. Measurements confirm a good agreement (within 1%) with computer simulations using Feko, validating the method. The beam splitter at 610 GHz has a measured efficiency of 78% under oblique incidence illumination that ensures a similar intensity between the four reflected beams (variation of about 1%).

Recent operating experience with Varian 70 GHz and 140 GHz gyrotrons

International Nuclear Information System (INIS)

Felch, K.; Bier, R.; Fox, L.; Huey, H.; Ives, L.; Jory, H.; Lopez, N.; Shively, J.; Spang, S.

1985-01-01

The design features and initial test results of Varian 70 GHz and 140 GHz CW gyrotrons are presented. The first experimental 140 GHz tube has achieved an output power of 102 kW at 24% efficiency under pulsed conditions in the desired TE 031 0 cavity mode. Further tests aimed at achieving the design goal of 100 kW CW are currently underway. The 70 GHz tube has achieved an output power of 200 kW under pulsed conditions and possesses a wide dynamic range for output power variations. 6 refs., 8 figs

A stochastic cloud model for cloud and ozone retrievals from UV measurements

International Nuclear Information System (INIS)

Efremenko, Dmitry S.; Schüssler, Olena; Doicu, Adrian; Loyola, Diego

2016-01-01

The new generation of satellite instruments provides measurements in and around the Oxygen A-band on a global basis and with a relatively high spatial resolution. These data are commonly used for the determination of cloud properties. A stochastic model and radiative transfer model, previously developed by the authors, is used as the forward model component in retrievals of cloud parameters and ozone total and partial columns. The cloud retrieval algorithm combines local and global optimization routines, and yields a retrieval accuracy of about 1% and a fast computational time. Retrieved parameters are the cloud optical thickness and the cloud-top height. It was found that the use of the independent pixel approximation instead of the stochastic cloud model leads to large errors in the retrieved cloud parameters, as well as, in the retrieved ozone height resolved partial columns. The latter can be reduced by using the stochastic cloud model to compute the optimal value of the regularization parameter in the framework of Tikhonov regularization. - Highlights: • A stochastic radiative transfer model for retrieving clouds/ozone is designed. • Errors of independent pixel approximation (IPA) for O3 total column are small. • The error of IPA for ozone profile retrieval may become large. • The use of stochastic model reduces the error of ozone profile retrieval.

The dependence of entrainment and drizzle in marine stratiform clouds on biomass burning aerosols derived from stable isotope and thermodynamic profiles

Science.gov (United States)

Henze, D.; Noone, D.

2017-12-01

A third of the world's biomass burning aerosol (BBA) particles are generated in southern Africa, and these particles are swept into the midlevel troposphere over the southeast Atlantic Ocean. The presence of these aerosols over the marine environment of the south east Atlantic offers a unique natural laboratory for studying aerosol effects on climate, and specifically a modification to the hydrologic cycle and microphysical characteristics of clouds. Different rates of condensation with high aerosol numbers change the precipitation rates in drizzling stratiform clouds, while the mixing of aerosols into the cloud layer is synonymous with entrainment from above cloud top near the top of the subtropical inversion. To better understanding the magnitude of the aerosol influence on southeast Atlantic boundary layer clouds we analyze the cloud-top entrainment and drizzle as a function of aerosol loading to determine the impact of BBA. Entrainment was determined from mixing line analysis based on profile measurements of moist static energy, total water, and the two most common heavy isotopes of water - HDO and H218O. Data was collected on the P-3 Orion aircraft during the NASA 2017 ORACLES campaign. Using these measurements, a box model was constructed using the combined conservation laws associated with all four of these quantities to estimate the entrainment and rainout of cloud liquid. The population of profiles sampled by the aircraft over the course of the 30 day mission spans varying concentrations of BBA. Initial plots of the water isotope mixing lines show where and to what degree the BBA air mass has mixed into the boundary layer air mass from above. This is demonstrated by the fact that the mixing end-members are the same for the different areas sampled, but the rate at which the various mixing lines are traversed as a function of altitude varies. Further, the mixing lines as a function of height traverse back and forth between end members multiple times over one

CloudSat-Based Assessment of GPM Microwave Imager Snowfall Observation Capabilities

Directory of Open Access Journals (Sweden)

Giulia Panegrossi

2017-12-01

Full Text Available The sensitivity of Global Precipitation Measurement (GPM Microwave Imager (GMI high-frequency channels to snowfall at higher latitudes (around 60°N/S is investigated using coincident CloudSat observations. The 166 GHz channel is highlighted throughout the study due to its ice scattering sensitivity and polarization information. The analysis of three case studies evidences the important combined role of total precipitable water (TPW, supercooled cloud water, and background surface composition on the brightness temperature (TB behavior for different snow-producing clouds. A regression tree statistical analysis applied to the entire GMI-CloudSat snowfall dataset indicates which variables influence the 166 GHz polarization difference (166 ∆TB and its relation to snowfall. Critical thresholds of various parameters (sea ice concentration (SIC, TPW, ice water path (IWP are established for optimal snowfall detection capabilities. The 166 ∆TB can identify snowfall events over land and sea when critical thresholds are exceeded (TPW > 3.6 kg·m−2, IWP > 0.24 kg·m−2 over land, and SIC > 57%, TPW > 5.1 kg·m−2 over sea. The complex combined 166 ∆TB-TB relationship at higher latitudes and the impact of supercooled water vertical distribution are also investigated. The findings presented in this study can be exploited to improve passive microwave snowfall detection algorithms.

Differential Absorption Radar: An Emerging Technology for Remote Sounding of Water Vapor Within Clouds

Science.gov (United States)

Lebsock, M. D.; Millan Valle, L. F.; Cooper, K. B.; Siles, J.; Monje, R.

2017-12-01

We present the results of our efforts to build and demonstrate the first Differential Absorption Radar (DAR), which will provide unique capabilities to remotely sound for water vapor within cloudy and precipitating atmospheres. The approach leverages multiple radar channels located near the 183 GHz water vapor absorption feature to simultaneously derive microphysical and water vapor profiles. The DAR technique has the potential to neatly complement existing water vapor sounding techniques such as infrared and microwave sounding and GPS radio occultation. These precisions rival those of existing water vapor remote sensing instruments. The approach works best from above clouds because the water vapor burden and line width increases towards the Earth surface allowing increased sampling from the top-down compared with bottom-up. From an airborne or satellite platform channels can be selected that target either upper-tropospheric or lower-tropospheric clouds. Our theoretical studies suggest that the water vapor concentration can be retrieved to within 1-3 gm-3 and the column integrated water vapor can be retrieved to within 1 kgm-2. The high-frequency radar is only recently enabled by technological advances that have allowed us to demonstrate 0.5 W of continuous power near 183 GHz. We are currently developing an airborne DAR using a Frequency Modulated Continuous Wave (FMCW) architecture with a quasi-optical duplexer providing 80 dB of transmit/receive isolation. A prototype of this instrument recently made the first ever range resolved DAR measurements of humidity out to several hundred meters during a light rain event at JPL. The spectral dependence of the attenuation was in excellent agreement with the predicted attenuation based on nearby weather stations, proving for the first time the feasibility of the concept. A major impediment to implementing DAR is the international regulation of radio-frequency transmissions below 300 GHz. The major roadblocks and potential

Retrieval of Cloud Properties for Partially Cloud-Filled Pixels During CRYSTAL-FACE

Science.gov (United States)

Nguyen, L.; Minnis, P.; Smith, W. L.; Khaiyer, M. M.; Heck, P. W.; Sun-Mack, S.; Uttal, T.; Comstock, J.

2003-12-01

resolution. Results are compared with the radar reflectivity techniques employed by the NOAA ETL MMCR and the PARSL 94 GHz radars located at the CRYSTAL-FACE Eastern & Western Ground Sites, respectively. This technique is most likely to yield improvements for low and midlevel layer clouds that have little thermal variability in cloud height.

Mitigation of the electron-cloud effect in the PSR and SNS protonstorage rings by tailoring the bunch profile

CERN Document Server

Pivi, M T

2003-01-01

For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure.

MITIGATION OF THE ELECTRON-CLOUD EFFECT IN THE PSR AND SNS PROTONSTORAGE RINGS BY TAILORING THE BUNCH PROFILE

International Nuclear Information System (INIS)

Pivi, Mauro T F

2003-01-01

For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

Ferrite Film Loaded Frequency Selective Metamaterials for Sub-GHz Applications

Directory of Open Access Journals (Sweden)

Bo Gao

2016-12-01

Full Text Available Electromagnetic metamaterials are constructed with sub-wavelength structures that exhibit particular electromagnetic properties under a certain frequency range. Because the form-factor of the substructures has to be comparable to the wavelength of the operating frequency, few papers have discussed the metamaterials under GHz frequency. In this paper, we developed an innovative method to reduce the resonant frequency of metamaterals. By integrating the meta-structures with ferrite materials of higher permeability, the cell size of the meta-structure can be scaled down. This paper describes the methodology, design, and development of low-profile GHz ferrite loaded metamaterials. A ferrite film with a permeability of 20 could reduce the resonant frequency of metamaterials by up to 50%. A prototype has been fabricated and the measurement data align well with the simulation results. Because of the lowered operational frequency, the proposed ferrite loaded metamaterials offer more flexibility for various sub-GHz microwave applications, such as cloaks, absorbers, and frequency selective surfaces.

The Earthcare Cloud Profiling Radar, its PFM development status (Conference Presentation)

Science.gov (United States)

Nakatsuka, Hirotaka; Tomita, Eichi; Aida, Yoshihisa; Seki, Yoshihiro; Okada, Kazuyuki; Maruyama, Kenta; Ishii, Yasuyuki; Tomiyama, Nobuhiro; Ohno, Yuichi; Horie, Hiroaki; Sato, Kenji

2016-10-01

The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is joint mission between Europe and Japan for the launch year of 2018. Mission objective is to improve scientific understanding of cloud-aerosol-radiation interactions that is one of the biggest uncertain factors for numerical climate and weather predictions. The EarthCARE spacecraft equips four instruments such as an ultra violet lidar (ATLID), a cloud profiling radar (CPR), a broadband radiometer (BBR), and a multi-spectral imager (MSI) and perform complete synergy observation to observe aerosols, clouds and their interactions simultaneously from the orbit. Japan Aerospace Exploration Agency (JAXA) is responsible for development of the CPR in this EarthCARE mission and the CPR will be the first space-borne W-band Doppler radar. The CPR is defined with minimum radar sensitivity of -35dBz (6dB better than current space-borne cloud radar, i.e. CloudSat, NASA), radiometric accuracy of 2.7 dB, and Doppler velocity measurement accuracy of less than 1.3 m/s. These specifications require highly accurate pointing technique in orbit and high power source with large antenna dish. JAXA and National Institute of Information and Communications Technology (NICT) have been jointly developed this CPR to meet these strict requirements so far and then achieved the development such as new CFRP flex-core structure, long life extended interaction klystron, low loss quasi optical feed technique, and so on. Through these development successes, CPR development phase has been progressed to critical design phase. In addition, new ground calibration technique is also being progressed for launch of EarthCARE/CPR. The unique feature of EarthCARE CPR is vertical Doppler velocity measurement capability. Vertical Doppler velocity measurement is very attractive function from the science point of view, because vertical motions of cloud particles are related with cloud microphysics and dynamics. However, from engineering point of

Potential profiles obtained from applied dust cloud perturbations

International Nuclear Information System (INIS)

Thomas, Edward Jr.

2002-01-01

This paper details an experimental investigation of the local potential structure within a cloud of suspended microparticles - a 'dusty' or 'complex' plasma - using particle image velocimetry (PIV) techniques. Applied perturbations, synchronized to the PIV measurements, are used to force a cloud of suspended microparticles to become unconfined. From the free-streaming motion of the particles during the loss of confinement and subsequent reformation of the dust cloud, an analysis of the potential is performed. Furthermore, a new method of analyzing the potential structure from the motion of free-streaming microparticles in the plasma is presented

Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands

Directory of Open Access Journals (Sweden)

Ahmed M. Al-samman

2018-01-01

Full Text Available This paper presents millimeter wave (mmWave measurements in an indoor environment. The high demands for the future applications in the 5G system require more capacity. In the microwave band below 6 GHz, most of the available bands are occupied; hence, the microwave band above 6 GHz and mmWave band can be used for the 5G system to cover the bandwidth required for all 5G applications. In this paper, the propagation characteristics at three different bands above 6 GHz (19, 28, and 38 GHz are investigated in an indoor corridor environment for line of sight (LOS and non-LOS (NLOS scenarios. Five different path loss models are studied for this environment, namely, close-in (CI free space path loss, floating-intercept (FI, frequency attenuation (FA path loss, alpha-beta-gamma (ABG, and close-in free space reference distance with frequency weighting (CIF models. Important statistical properties, such as power delay profile (PDP, root mean square (RMS delay spread, and azimuth angle spread, are obtained and compared for different bands. The results for the path loss model found that the path loss exponent (PLE and line slope values for all models are less than the free space path loss exponent of 2. The RMS delay spread for all bands is low for the LOS scenario, and only the directed path is contributed in some spatial locations. For the NLOS scenario, the angle of arrival (AOA is extensively investigated, and the results indicated that the channel propagation for 5G using high directional antenna should be used in the beamforming technique to receive the signal and collect all multipath components from different angles in a particular mobile location.

Multi-wavelength study of two possible cloud-cloud collision regions: IRAS 02459+6029 and IRAS 22528+5936

International Nuclear Information System (INIS)

Li Nan; Wang Junjie

2012-01-01

Based on observations of 12 CO (J=2–1), we select targets from archived Infrared Astronomical Satellite (IRAS) data of IRAS 02459+6029 and IRAS 22528+5936 as samples of cloud-cloud collision, according to the criteria given by Vallee. Then we use the Midcourse Space Experiment (MSX) A band (8.28 μm) images and the NRAO VLA Sky Survey (NVSS) (1.4 GHz) continuum images to investigate the association between molecular clouds traced by the CO contour maps. The distribution of dust and ionized hydrogen shows an obvious association with the CO contour maps toward IRAS 02459+6029. However, in the possible collision region of IRAS 22528+5936, NVSS continuum radiation is not detected and the MSX sources are merely associated with the central star. The velocity fields of the two regions indicate the direction of the pressure and interaction. In addition, we have identified candidates of young stellar objects (YSOs) by using data from the Two Micron All Sky Survey (2MASS) in JHK bands expressed in a color-color diagram. The distribution of YSOs shows that the possible collision region is denser than other regions. All the evidence suggests that IRAS 02459+6029 could be an example of cloud-cloud collision, and that IRAS 22528+5936 could be two separate non-colliding clouds. (research papers)

A New Algorithm for Detecting Cloud Height using OMPS/LP Measurements

Science.gov (United States)

Chen, Zhong; DeLand, Matthew; Bhartia, Pawan K.

2016-01-01

The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) ozone product requires the determination of cloud height for each event to establish the lower boundary of the profile for the retrieval algorithm. We have created a revised cloud detection algorithm for LP measurements that uses the spectral dependence of the vertical gradient in radiance between two wavelengths in the visible and near-IR spectral regions. This approach provides better discrimination between clouds and aerosols than results obtained using a single wavelength. Observed LP cloud height values show good agreement with coincident Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements.

Simulation of a Feedback System for the Attenuation of e-Cloud Driven Instability

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Fox, J.; Rivetta, C.; de Maria, R.; Rumolo, G.

2009-01-01

Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient electron clouds. We have used the simulation package WARP-POSINST and the code Headtail to study the growth rate and frequency patterns in space-time of the electron cloud driven beam breakup instability in the CERN SPS accelerator with, or without, an idealized feedback model for damping the instability.

Thermodynamic and cloud parameter retrieval using infrared spectral data

Science.gov (United States)

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).

Comparison of convective clouds observed by spaceborne W-band radar and simulated by cloud-resolving atmospheric models

Science.gov (United States)

Dodson, Jason B.

Deep convective clouds (DCCs) play an important role in regulating global climate through vertical mass flux, vertical water transport, and radiation. For general circulation models (GCMs) to simulate the global climate realistically, they must simulate DCCs realistically. GCMs have traditionally used cumulus parameterizations (CPs). Much recent research has shown that multiple persistent unrealistic behaviors in GCMs are related to limitations of CPs. Two alternatives to CPs exist: the global cloud-resolving model (GCRM), and the multiscale modeling framework (MMF). Both can directly simulate the coarser features of DCCs because of their multi-kilometer horizontal resolutions, and can simulate large-scale meteorological processes more realistically than GCMs. However, the question of realistic behavior of simulated DCCs remains. How closely do simulated DCCs resemble observed DCCs? In this study I examine the behavior of DCCs in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) and Superparameterized Community Atmospheric Model (SP-CAM), the latter with both single-moment and double-moment microphysics. I place particular emphasis on the relationship between cloud vertical structure and convective environment. I also emphasize the transition between shallow clouds and mature DCCs. The spatial domains used are the tropical oceans and the contiguous United States (CONUS), the latter of which produces frequent vigorous convection during the summer. CloudSat is used to observe DCCs, and A-Train and reanalysis data are used to represent the large-scale environment in which the clouds form. The CloudSat cloud mask and radar reflectivity profiles for CONUS cumuliform clouds (defined as clouds with a base within the planetary boundary layer) during boreal summer are first averaged and compared. Both NICAM and SP-CAM greatly underestimate the vertical growth of cumuliform clouds. Then they are sorted by three large-scale environmental variables: total preciptable

ARM Cloud Radar Simulator Package for Global Climate Models Value-Added Product

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuying [North Carolina State Univ., Raleigh, NC (United States); Xie, Shaocheng [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-05-01

It has been challenging to directly compare U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility ground-based cloud radar measurements with climate model output because of limitations or features of the observing processes and the spatial gap between model and the single-point measurements. To facilitate the use of ARM radar data in numerical models, an ARM cloud radar simulator was developed to converts model data into pseudo-ARM cloud radar observations that mimic the instrument view of a narrow atmospheric column (as compared to a large global climate model [GCM] grid-cell), thus allowing meaningful comparison between model output and ARM cloud observations. The ARM cloud radar simulator value-added product (VAP) was developed based on the CloudSat simulator contained in the community satellite simulator package, the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) (Bodas-Salcedo et al., 2011), which has been widely used in climate model evaluation with satellite data (Klein et al., 2013, Zhang et al., 2010). The essential part of the CloudSat simulator is the QuickBeam radar simulator that is used to produce CloudSat-like radar reflectivity, but is capable of simulating reflectivity for other radars (Marchand et al., 2009; Haynes et al., 2007). Adapting QuickBeam to the ARM cloud radar simulator within COSP required two primary changes: one was to set the frequency to 35 GHz for the ARM Ka-band cloud radar, as opposed to 94 GHz used for the CloudSat W-band radar, and the second was to invert the view from the ground to space so as to attenuate the beam correctly. In addition, the ARM cloud radar simulator uses a finer vertical resolution (100 m compared to 500 m for CloudSat) to resolve the more detailed structure of clouds captured by the ARM radars. The ARM simulator has been developed following the COSP workflow (Figure 1) and using the capabilities available in COSP

Antenne Design for 24 GHz and 60 GHz Emerging Microwave Applications

NARCIS (Netherlands)

Jansen, F.; Dolmans, W.M.C.

2006-01-01

In this project integrated antennas on a LAMP3 substrate for automotive radar systems at 24 GHz and wireless networks at 60 GHz have been designed. The most severe requirements on the antennas were the large bandwidth, which can not be met with conventional patch antennas. A tapered slot antenna and

An Integrated Cloud-Aerosol-Radiation Product Using CERES, MODIS, CALIPSO and CloudSat Data

Science.gov (United States)

Sun-Mack, S.; Gibson, S.; Chen, Y.; Wielicki, B.; Minnis, P.

2006-12-01

The goal of this paper is to provide the first integrated data set of global vertical profiles of aerosols, clouds, and radiation using the combined NASA A-Train data from Aqua CERES and MODIS, CALIPSO, and CloudSat. All of these instruments are flying in formation as part of the Aqua Train, or A-Train. This paper will present the preliminary results of merging aerosol and cloud data from the CALIPSO active lidar, cloud data from CloudSat, integrated column aerosol and cloud data from the MODIS CERES analyses, and surface and top-of-atmosphere broadband radiation fluxes from CERES. These new data will provide unprecedented ability to test and improve global cloud and aerosol models, to investigate aerosol direct and indirect radiative forcing, and to validate the accuracy of global aerosol, cloud, and radiation data sets especially in polar regions and for multi-layered cloud conditions.

Compression of Antiproton Clouds for Antihydrogen Trapping

CERN Document Server

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

2008-01-01

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

Transitioning ISR architecture into the cloud

Science.gov (United States)

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.

PROPERTIES OF GALACTIC CIRRUS CLOUDS OBSERVED BY BOOMERANG

International Nuclear Information System (INIS)

Veneziani, M.; De Bernardis, P.; Masi, S.; Ade, P. A. R.; Mauskopf, P. D.; Bock, J. J.; Crill, B. P.; Lange, A. E.; Boscaleri, A.; De Gasperis, G.; De Troia, G.; Natoli, P.; De Oliveira-Costa, A.; Stefano, G. Di; Ganga, K. M.; Jones, W. C.; Kisner, T. S.; Montroy, T. E.; MacTavish, C. J.; Netterfield, C. B.

2010-01-01

The physical properties of galactic cirrus emission are not well characterized. BOOMERANG is a balloon-borne experiment designed to study the cosmic microwave background at high angular resolution in the millimeter range. The BOOMERANG 245 and 345 GHz channels are sensitive to interstellar signals, in a spectral range intermediate between FIR and microwave frequencies. We look for physical characteristics of cirrus structures in a region at high galactic latitudes (b ∼ -40 deg.) where BOOMERANG performed its deepest integration, combining the BOOMERANG data with other available data sets at different wavelengths. We have detected eight emission patches in the 345 GHz map, consistent with cirrus dust in the Infrared Astronomical Satellite maps. The analysis technique we have developed allows us to identify the location and the shape of cirrus clouds, and to extract the flux from observations with different instruments at different wavelengths and angular resolutions. We study the integrated flux emitted from these cirrus clouds using data from Infrared Astronomical Satellite (IRAS), DIRBE, BOOMERANG and Wilkinson Microwave Anisotropy Probe in the frequency range 23-3000 GHz (13 mm-100 μm wavelength). We fit the measured spectral energy distributions with a combination of a gray body and a power-law spectra considering two models for the thermal emission. The temperature of the thermal dust component varies in the 7-20 K range and its emissivity spectral index is in the 1-5 range. We identified a physical relation between temperature and spectral index as had been proposed in previous works. This technique can be proficiently used for the forthcoming Planck and Herschel missions data.

FIRST INTERFEROMETRIC IMAGES OF THE 36 GHz METHANOL MASERS IN THE DR21 COMPLEX

International Nuclear Information System (INIS)

Fish, Vincent L.; Muehlbrad, Talitha C.; Pratap, Preethi; Sjouwerman, Lorant O.; Strelnitski, Vladimir; Pihlstroem, Ylva M.; Bourke, Tyler L.

2011-01-01

Class I methanol masers are believed to be produced in the shock-excited environment around star-forming regions. Many authors have argued that the appearance of various subsets of class I masers may be indicative of specific evolutionary stages of star formation or excitation conditions. Until recently, however, no major interferometer was capable of imaging the important 36 GHz transition. We report on Expanded Very Large Array observations of the 36 GHz methanol masers and Submillimeter Array observations of the 229 GHz methanol masers in DR21(OH), DR21N, and DR21W. The distribution of 36 GHz masers in the outflow of DR21(OH) is similar to that of the other class I methanol transitions, with numerous multitransition spatial overlaps. At the site of the main continuum source in DR21(OH), class I masers at 36 and 229 GHz are found in virtual overlap with class II 6.7 GHz masers. To the south of the outflow, the 36 GHz masers are scattered over a large region but usually do not appear coincident with 44 GHz masers. In DR21W, we detect an 'S-curve' signature in Stokes V that implies a large value of the magnetic field strength if interpreted as due to Zeeman splitting, suggesting either that class I masers may exist at higher densities than previously believed or that the direct Zeeman interpretation of S-curve Stokes V profiles in class I masers may be incorrect. We find a diverse variety of different maser phenomena in these sources, suggestive of differing physical conditions among them.

Superconducting ECR ion source: From 24-28 GHz SECRAL to 45 GHz fourth generation ECR

Science.gov (United States)

Zhao, H. W.; Sun, L. T.; Guo, J. W.; Zhang, W. H.; Lu, W.; Wu, W.; Wu, B. M.; Sabbi, G.; Juchno, M.; Hafalia, A.; Ravaioli, E.; Xie, D. Z.

2018-05-01

The development of superconducting ECR source with higher magnetic fields and higher microwave frequency is the most straight forward path to achieve higher beam intensity and higher charge state performance. SECRAL, a superconducting third generation ECR ion source, is designed for 24-28 GHz microwave frequency operation with an innovative magnet configuration of sextupole coils located outside the three solenoids. SECRAL at 24 GHz has already produced a number of record beam intensities, such as 40Ar12+ 1.4 emA, 129Xe26+ 1.1 emA, 129Xe30+ 0.36 emA, and 209Bi31+ 0.68 emA. SECRAL-II, an upgraded version of SECRAL, was built successfully in less than 3 years and has recently been commissioned at full power of a 28 GHz gyrotron and three-frequency heating (28 + 45 + 18 GHz). New record beam intensities for highly charged ion production have been achieved, such as 620 eμA 40Ar16+, 15 eμA 40Ar18+, 146 eμA 86Kr28+, 0.5 eμA 86Kr33+, 53 eμA 129Xe38+, and 17 eμA 129Xe42+. Recent beam test results at SECRAL and SECRAL II have demonstrated that the production of more intense highly charged heavy ion beams needs higher microwave power and higher frequency, as the scaling law predicted. A 45 GHz superconducting ECR ion source FECR (a first fourth generation ECR ion source) is being built at IMP. FECR will be the world's first Nb3Sn superconducting-magnet-based ECR ion source with 6.5 T axial mirror field, 3.5 T sextupole field on the plasma chamber inner wall, and 20 kW at a 45 GHz microwave coupling system. This paper will focus on SECRAL performance studies at 24-28 GHz and technical design of 45 GHz FECR, which demonstrates a technical path for highly charged ion beam production from 24 to 28 GHz SECRAL to 45 GHz FECR.

Electron temperature profiles in axial field 2.45 GHz ECR ion source with a ceramic chamber

Science.gov (United States)

Abe, K.; Tamura, R.; Kasuya, T.; Wada, M.

2017-08-01

An array of electrostatic probes was arranged on the plasma electrode of a 2.45 GHz microwave driven axial magnetic filter field type negative hydrogen (H-) ion source to clarify the spatial plasma distribution near the electrode. The measured spatial distribution of electron temperature indicated the lower temperature near the extraction hole of the plasma electrode corresponding to the effectiveness of the axial magnetic filter field geometry. When the ratio of electron saturation current to the ion saturation current was plotted as a function of position, the obtained distribution showed a higher ratio near the hydrogen gas inlet through which ground state hydrogen molecules are injected into the source. Though the efficiency in producing H- ions is smaller for a 2.45 GHz source than a source operated at 14 GHz, it gives more volume to measure spatial distributions of various plasma parameters to understand fundamental processes that are influential on H- production in this type of ion sources.

Contactless Investigations of Yeast Cell Cultivation in the 7 GHz and 240 GHz Ranges

International Nuclear Information System (INIS)

Wessel, J; Schmalz, K; Meliani, C; Gastrock, G; Cahill, B P

2013-01-01

Using a microfluidic system based on PTFE tubes, experimental results of contactless and label-free characterization techniques of yeast cell cultivation are presented. The PTFE tube has an inner diameter of 0.5 mm resulting in a sample volume of 2 μ1 for 1 cm sample length. Two approaches (at frequencies around 7 GHz and 240 GHz) are presented and compared in terms of sensitivity and applicability. These frequency bands are particularly interesting to gain information on the permittivity of yeast cells in Glucose solution. Measurements from 240 GHz to 300 GHz were conducted with a continuous wave spectrometer from Toptica. At 7 GHz band, measurements have been performed using a rat-race based characterizing system realized on a printed circuit board. The conducted experiments demonstrate that by selecting the phase as characterization parameter, the presented contactless and label-free techniques are suitable for cell cultivation monitoring in a PTFE pipe based microfluidic system.

Integrated cloud-aerosol-radiation product using CERES, MODIS, CALIPSO, and CloudSat data

Science.gov (United States)

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

2007-10-01

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

Characterizing the Trade Space Between Capability and Complexity in Next Generation Cloud and Precipitation Observing Systems Using Markov Chain Monte Carlos Techniques

Science.gov (United States)

Xu, Z.; Mace, G. G.; Posselt, D. J.

2017-12-01

As we begin to contemplate the next generation atmospheric observing systems, it will be critically important that we are able to make informed decisions regarding the trade space between scientific capability and the need to keep complexity and cost within definable limits. To explore this trade space as it pertains to understanding key cloud and precipitation processes, we are developing a Markov Chain Monte Carlo (MCMC) algorithm suite that allows us to arbitrarily define the specifications of candidate observing systems and then explore how the uncertainties in key retrieved geophysical parameters respond to that observing system. MCMC algorithms produce a more complete posterior solution space, and allow for an objective examination of information contained in measurements. In our initial implementation, MCMC experiments are performed to retrieve vertical profiles of cloud and precipitation properties from a spectrum of active and passive measurements collected by aircraft during the ACE Radiation Definition Experiments (RADEX). Focusing on shallow cumulus clouds observed during the Integrated Precipitation and Hydrology EXperiment (IPHEX), observing systems in this study we consider W and Ka-band radar reflectivity, path-integrated attenuation at those frequencies, 31 and 94 GHz brightness temperatures as well as visible and near-infrared reflectance. By varying the sensitivity and uncertainty of these measurements, we quantify the capacity of various combinations of observations to characterize the physical properties of clouds and precipitation.

Low conversion loss 94 GHz and 188 GHz doublers in InP DHBT technology

DEFF Research Database (Denmark)

Zhurbenko, Vitaliy; Johansen, Tom Keinicke; Squartecchia, Michele

2017-01-01

An Indium Phosphide (InP) Double Heterojunction Bipolar Transistor (DHBT) process has been utilized to design two doublers to cover the 94 GHz and 188 GHz bands. The 94 GHz doubler employs 4-finger DHBTs and provides conversion loss of 2 dB. A maximum output power of nearly 3 dBm is measured whil...... operate over a broad bandwidth. The total circuit area of each chip is 1.41 mm2....

Cold Water Vapor in the Barnard 5 Molecular Cloud

Science.gov (United States)

Wirstrom, E. S.; Charnley, S. B.; Persson, C. M.; Buckle, J. V.; Cordiner, M. A.; Takakuwa, S.

2014-01-01

After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold ((is) approximately 10 K) water vapor has been detected-L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work-likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 110-101) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

COLD WATER VAPOR IN THE BARNARD 5 MOLECULAR CLOUD

Energy Technology Data Exchange (ETDEWEB)

Wirström, E. S.; Persson, C. M. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala (Sweden); Charnley, S. B.; Cordiner, M. A. [Astrochemistry Laboratory and The Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20770 (United States); Buckle, J. V. [Astrophysics Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Takakuwa, S., E-mail: eva.wirstrom@chalmers.se [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China)

2014-06-20

After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold (∼10 K) water vapor has been detected—L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work—likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H{sub 2}O (J = 1{sub 10}-1{sub 01}) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

Cloud fraction and cloud base measurements from scanning Doppler lidar during WFIP-2

Science.gov (United States)

Bonin, T.; Long, C.; Lantz, K. O.; Choukulkar, A.; Pichugina, Y. L.; McCarty, B.; Banta, R. M.; Brewer, A.; Marquis, M.

2017-12-01

The second Wind Forecast Improvement Project (WFIP-2) consisted of an 18-month field deployment of a variety of instrumentation with the principle objective of validating and improving NWP forecasts for wind energy applications in complex terrain. As a part of the set of instrumentation, several scanning Doppler lidars were installed across the study domain to primarily measure profiles of the mean wind and turbulence at high-resolution within the planetary boundary layer. In addition to these measurements, Doppler lidar observations can be used to directly quantify the cloud fraction and cloud base, since clouds appear as a high backscatter return. These supplementary measurements of clouds can then be used to validate cloud cover and other properties in NWP output. Herein, statistics of the cloud fraction and cloud base height from the duration of WFIP-2 are presented. Additionally, these cloud fraction estimates from Doppler lidar are compared with similar measurements from a Total Sky Imager and Radiative Flux Analysis (RadFlux) retrievals at the Wasco site. During mostly cloudy to overcast conditions, estimates of the cloud radiating temperature from the RadFlux methodology are also compared with Doppler lidar measured cloud base height.

WATER ABSORPTION IN GALACTIC TRANSLUCENT CLOUDS: CONDITIONS AND HISTORY OF THE GAS DERIVED FROM HERSCHEL /HIFI PRISMAS OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Flagey, N.; Goldsmith, P. F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Lis, D. C.; Monje, R.; Phillips, T. G. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Gerin, M.; De Luca, M.; Godard, B. [LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Superieure, UPMC and UCP (France); Neufeld, D. [Department of Physics and Astronomy, Johns Hopkins Univ. 3400 N. Charles St., Baltimore, MD 21218 (United States); Sonnentrucker, P. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Goicoechea, J. R., E-mail: nflagey@jpl.nasa.gov [Centro de Astrobiologia (CSIC-INTA), E-28850 Torrejon de Ardoz, Madrid (Spain)

2013-01-01

We present Herschel/HIFI observations of the three ground state transitions of H{sub 2}O (556, 1669, and 1113 GHz) and H{sub 2}{sup 18}O (547, 1655, and 1101 GHz)-as well as the first few excited transitions of H{sub 2}O (987, 752, and 1661 GHz)-toward six high-mass star-forming regions, obtained as part of the PRISMAS (PRobing InterStellar Molecules with Absorption line Studies) Guaranteed Time Key Program. Water vapor associated with the translucent clouds in Galactic arms is detected in absorption along every line of sight in all the ground state transitions. The continuum sources all exhibit broad water features in emission in the excited and ground state transitions. Strong absorption features associated with the source are also observed at all frequencies except 752 GHz. We model the background continuum and line emission to infer the optical depth of each translucent cloud along the lines of sight. We derive the column density of H{sub 2}O or H{sub 2}{sup 18}O for the lower energy level of each transition observed. The total column density of water in translucent clouds is usually about a few 10{sup 13} cm{sup -2}. We find that the abundance of water relative to hydrogen nuclei is 1 Multiplication-Sign 10{sup -8} in agreement with models for oxygen chemistry in which high cosmic ray ionization rates are assumed. Relative to molecular hydrogen, the abundance of water is remarkably constant through the Galactic plane with X(H{sub 2}O) =5 Multiplication-Sign 10{sup -8}, which makes water a good traced of H{sub 2} in translucent clouds. Observations of the excited transitions of H{sub 2}O enable us to constrain the abundance of water in excited levels to be at most 15%, implying that the excitation temperature, T {sub ex}, in the ground state transitions is below 10 K. Further analysis of the column densities derived from the two ortho ground state transitions indicates that T {sub ex} {approx_equal} 5 K and that the density n(H{sub 2}) in the translucent clouds

Overview of MPLNET Version 3 Cloud Detection

Science.gov (United States)

Lewis, Jasper R.; Campbell, James; Welton, Ellsworth J.; Stewart, Sebastian A.; Haftings, Phillip

2016-01-01

The National Aeronautics and Space Administration Micro Pulse Lidar Network, version 3, cloud detection algorithm is described and differences relative to the previous version are highlighted. Clouds are identified from normalized level 1 signal profiles using two complementary methods. The first method considers vertical signal derivatives for detecting low-level clouds. The second method, which detects high-level clouds like cirrus, is based on signal uncertainties necessitated by the relatively low signal-to-noise ratio exhibited in the upper troposphere by eye-safe network instruments, especially during daytime. Furthermore, a multitemporal averaging scheme is used to improve cloud detection under conditions of a weak signal-to-noise ratio. Diurnal and seasonal cycles of cloud occurrence frequency based on one year of measurements at the Goddard Space Flight Center (Greenbelt, Maryland) site are compared for the new and previous versions. The largest differences, and perceived improvement, in detection occurs for high clouds (above 5 km, above MSL), which increase in occurrence by over 5%. There is also an increase in the detection of multilayered cloud profiles from 9% to 19%. Macrophysical properties and estimates of cloud optical depth are presented for a transparent cirrus dataset. However, the limit to which the cirrus cloud optical depth could be reliably estimated occurs between 0.5 and 0.8. A comparison using collocated CALIPSO measurements at the Goddard Space Flight Center and Singapore Micro Pulse Lidar Network (MPLNET) sites indicates improvements in cloud occurrence frequencies and layer heights.

Insights from a Regime Decomposition Approach on CERES and CloudSat-inferred Cloud Radiative Effects

Science.gov (United States)

Oreopoulos, L.; Cho, N.; Lee, D.

2015-12-01

Our knowledge of the Cloud Radiative Effect (CRE) not only at the Top-of-the-Atmosphere (TOA), but also (with the help of some modeling) at the surface (SFC) and within the atmospheric column (ATM) has been steadily growing in recent years. Not only do we have global values for these CREs, but we can now also plot global maps of their geographical distribution. The next step in our effort to advance our knowledge of CRE is to systematically assess the contributions of prevailing cloud systems to the global values. The presentation addresses this issue directly. We identify the world's prevailing cloud systems, which we call "Cloud Regimes" (CRs) via clustering analysis of MODIS (Aqua-Terra) daily joint histograms of Cloud Top Pressure and Cloud Optical Thickness (TAU) at 1 degree scales. We then composite CERES diurnal values of CRE (TOA, SFC, ATM) separately for each CR by averaging these values for each CR occurrence, and thus find the contribution of each CR to the global value of CRE. But we can do more. We can actually decompose vertical profiles of inferred instantaneous CRE from CloudSat/CALIPSO (2B-FLXHR-LIDAR product) by averaging over Aqua CR occurrences (since A-Train formation flying allows collocation). Such an analysis greatly enhances our understanding of the radiative importance of prevailing cloud mixtures at different atmospheric levels. We can, for example, in addition to examining whether the CERES findings on which CRs contribute to radiative cooling and warming of the atmospheric column are consistent with CloudSat, also gain insight on why and where exactly this happens from the shape of the full instantaneous CRE vertical profiles.

Investigation of Cloud Properties and Atmospheric Profiles with MODIS

Science.gov (United States)

Menzel, Paul; Ackerman, Steve; Moeller, Chris; Gumley, Liam; Strabala, Kathy; Frey, Richard; Prins, Elaine; LaPorte, Dan; Wolf, Walter

1997-01-01

The WINter Cloud Experiment (WINCE) was directed and supported by personnel from the University of Wisconsin in January and February. Data sets of good quality were collected by the MODIS Airborne Simulator (MAS) and other instruments on the NASA ER2; they will be used to develop and validate cloud detection and cloud property retrievals over winter scenes (especially over snow). Software development focused on utilities needed for all of the UW product executables; preparations for Version 2 software deliveries were almost completed. A significant effort was made, in cooperation with SBRS and MCST, in characterizing and understanding MODIS PFM thermal infrared performance; crosstalk in the longwave infrared channels continues to get considerable attention.

Structure, shape, and evolution of radiatively accelerated QSO emission-line clouds

International Nuclear Information System (INIS)

Blumenthal, G.R.; Mathews, W.G.

1979-01-01

The possibility that the broad emission-line regions of QSOs and active galactic nuclei are formed by a multitude of small clouds which are radiatively accelerated is discussed. Although this model is by no means certain at present, it has four virtues: (1) Observed emission-line widths can be produced with observationally allowed electron densities, UV luminosities, and ionization levels. (2) The acceleration force is coherent in each cloud are found. (3) Reasonable line profiles can result for all emission lines. (4) Photoionization of hydrogen accounts for both heating and acceleration of the emission-line gas. A self-consistent model is developed for the structure, shape, and evolution of radiatively accelerated clouds. The shape varies with cloud mass, and two distinct types of clouds. Fully ionized clouds of very low mass approach a nearly spherical shape. However, all clouds having masses greater than some critical mass adopt a ''pancake'' shape. The condition for constant cloud mass in the cloud frame is shown to be equivalent to the equation of motion of a cloud in the rest frame of the QSO. The emission-line profiles can be sensitive to radial variations in the properties of the intercloud medium, and those properties that correspond to observed profiles are discussed. Finally, the covering factor of a system of pancake clouds is estimated along with the total number of clouds required--approximately 10 14 clouds in each QSO

Retrieval of subvisual cirrus cloud optical thickness from limb-scatter measurements

Directory of Open Access Journals (Sweden)

J. T. Wiensz

2013-01-01

Full Text Available We present a technique for estimating the optical thickness of subvisual cirrus clouds detected by OSIRIS (Optical Spectrograph and Infrared Imaging System, a limb-viewing satellite instrument that measures scattered radiances from the UV to the near-IR. The measurement set is composed of a ratio of limb radiance profiles at two wavelengths that indicates the presence of cloud-scattering regions. Cross-sections and phase functions from an in situ database are used to simulate scattering by cloud-particles. With appropriate configurations discussed in this paper, the SASKTRAN successive-orders of scatter radiative transfer model is able to simulate accurately the in-cloud radiances from OSIRIS. Configured in this way, the model is used with a multiplicative algebraic reconstruction technique (MART to retrieve the cloud extinction profile for an assumed effective cloud particle size. The sensitivity of these retrievals to key auxiliary model parameters is shown, and it is shown that the retrieved extinction profile, for an assumed effective cloud particle size, models well the measured in-cloud radiances from OSIRIS. The greatest sensitivity of the retrieved optical thickness is to the effective cloud particle size. Since OSIRIS has an 11-yr record of subvisual cirrus cloud detections, the work described in this manuscript provides a very useful method for providing a long-term global record of the properties of these clouds.

Study of glow discharge positive column with cloud of disperse particles

International Nuclear Information System (INIS)

Polyakov, D.N.; Shumova, V.V.; Vasilyak, L.M.; Fortov, V.E.

2011-01-01

The study aims to describe plasma parameters changes induced by clouds of disperse micron size particles. Dust clouds were formed in the positive column of glow discharge in air at pressure 0.1-0.6 torr and current 0.1-3 mA. The simultaneous registration of discharge voltage and dust cloud parameters was carried out. Experimental results were simulated using diffusion model. The dust cloud is shown to smooth the radial electron concentration profile, increase electric field strength and electron temperature and stabilize the discharge. The cloud is demonstrated to be a trap for positive ions without increase of discharge current. -- Highlights: → 25% increase of longitudinal electric field strength in discharge with dust cloud. → The smoothing effect of dust cloud on radial electron and ion concentration profiles. → Dust cloud as a trap for positive ions without increase of discharge current. → Increase of electron temperature in discharge with dust cloud. → Increase of discharge stability in presence of dust cloud.

154 GHz collective Thomson scattering in LHD

Science.gov (United States)

Tanaka, K.; Nishiura, M.; Kubo, S.; Shimozuma, T.; Saito, T.; Moseev, D.; Abramovic, I.

2018-01-01

Collective Thomson scattering (CTS) was developed by using a 154 GHz gyrotron, and the first data has been obtained. Already, 77 GHz CTS has worked successfully. However, in order to access higher density region, 154 GHz option enhances the usability that reduces the refraction effect, which deteriorates in the local measurements. The system in the down converted frequency was almost identical to the system for 77 GHz. Probing beam, a notch filter, a mixer, and a local oscillator in the receiver system for 77 GHz option were replaced to those for the 154 GHz option. 154 GHz gyrotron was originally prepared for the second harmonic electron cyclotron heating (ECRH) at 2.75 T. However, scattering signal was masked by the second harmonic electron cyclotron emission (ECE) at 2.75 T. Therefore, 154 GHz CTS was operated at 1.375 T with fourth harmonic ECE, and an acceptable signal to noise ratio was obtained. There is a signature of fast ion components with neutral beam (NB) injection. In addition, the CTS spectrum became broader in hydrogen discharge than in deuterium discharge, as the theoretical CTS spectrum expects. This observation indicates a possibility to identify ion species ratio by the 154 GHz CTS diagnostic.

Integrated 60GHz RF beamforming in CMOS

CERN Document Server

Yu, Yikun; van Roermund, Arthur H M

2011-01-01

""Integrated 60GHz RF Beamforming in CMOS"" describes new concepts and design techniques that can be used for 60GHz phased array systems. First, general trends and challenges in low-cost high data-rate 60GHz wireless system are studied, and the phased array technique is introduced to improve the system performance. Second, the system requirements of phase shifters are analyzed, and different phased array architectures are compared. Third, the design and implementation of 60GHz passive and active phase shifters in a CMOS technology are presented. Fourth, the integration of 60GHz phase shifters

Prediction of slant path rain attenuation statistics at various locations

Science.gov (United States)

Goldhirsh, J.

1977-01-01

The paper describes a method for predicting slant path attenuation statistics at arbitrary locations for variable frequencies and path elevation angles. The method involves the use of median reflectivity factor-height profiles measured with radar as well as the use of long-term point rain rate data and assumed or measured drop size distributions. The attenuation coefficient due to cloud liquid water in the presence of rain is also considered. Absolute probability fade distributions are compared for eight cases: Maryland (15 GHz), Texas (30 GHz), Slough, England (19 and 37 GHz), Fayetteville, North Carolina (13 and 18 GHz), and Cambridge, Massachusetts (13 and 18 GHz).

The influence of rain and clouds on a satellite dual frequency radar altimeter system operating at 13 and 35 GHz

Science.gov (United States)

Walsh, E. J.; Monaldo, F. M.; Goldhirsh, J.

1983-01-01

The effects of inhomogeneous spatial attenuation resulting from clouds and rain on the altimeter estimate of the range to mean sea level are modelled. It is demonstrated that typical cloud and rain attenuation variability at commonly expected spatial scales can significantly degrade altimeter range precision. Rain cell and cloud scale sizes and attenuations are considered as factors. The model simulation of altimeter signature distortion is described, and the distortion of individual radar pulse waveforms by different spatial scales of attenuation is considered. Examples of range errors found for models of a single cloud, a rain cell, and cloud streets are discussed.

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

Science.gov (United States)

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

2017-12-01

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

Formaldehyde in the Diffuse Interstellar Cloud MBM40

Science.gov (United States)

Joy, Mackenzie; Magnani, Loris A.

2018-06-01

MBM40, a high-latitude molecular cloud, has been extensively studied using different molecular tracers. It appears that MBM40 is composed of a relatively dense, helical filament embedded in a more diffuse substrate of low density molecular gas. In order to study the transition between the two regimes, this project presents the first high-resolution mapping of MBM40 using the 110-111 hyperfine transition of formaldehyde (H2CO) at 4.83 GHz. We used H2CO spectra obtained with the Arecibo telescope more than a decade ago to construct this map. The results can be compared to previous maps made from the CO(1-0) transition to gain further understanding of the structure of the cloud. The intensity of the H2CO emission was compared to the CO emission. Although a correlation exists between the H2CO and CO emissivity, there seems to be a saturation of H2CO line strength for stronger CO emissivity. This is probably a radiative transfer effect of the CO emission. We have also found that the velocity dispersion of H2CO in the lower ridge of the cloud is significantly lower than in the rest of the cloud. This may indicate that this portion of the cloud is a coherent structure (analogous to an eddy) in a turbulent flow.

The Herschel/HIFI spectral survey of OMC-2 FIR 4 (CHESS). An overview of the 480 to 1902 GHz range

Science.gov (United States)

Kama, M.; López-Sepulcre, A.; Dominik, C.; Ceccarelli, C.; Fuente, A.; Caux, E.; Higgins, R.; Tielens, A. G. G. M.; Alonso-Albi, T.

2013-08-01

Context. Broadband spectral surveys of protostars offer a rich view of the physical, chemical and dynamical structure and evolution of star-forming regions. The Herschel Space Observatory opened up the terahertz regime to such surveys, giving access to the fundamental transitions of many hydrides and to the high-energy transitions of many other species. Aims: A comparative analysis of the chemical inventories and physical processes and properties of protostars of various masses and evolutionary states is the goal of the Herschel CHEmical Surveys of Star forming regions (CHESS) key program. This paper focusses on the intermediate-mass protostar, OMC-2 FIR 4. Methods: We obtained a spectrum of OMC-2 FIR 4 in the 480 to 1902 GHz range with the HIFI spectrometer onboard Herschel and carried out the reduction, line identification, and a broad analysis of the line profile components, excitation, and cooling. Results: We detect 719 spectral lines from 40 species and isotopologs. The line flux is dominated by CO, H2O, and CH3OH. The line profiles are complex and vary with species and upper level energy, but clearly contain signatures from quiescent gas, a broad component likely due to an outflow, and a foreground cloud. Conclusions: We find abundant evidence for warm, dense gas, as well as for an outflow in the field of view. Line flux represents 2% of the 7 L⊙ luminosity detected with HIFI in the 480 to 1250 GHz range. Of the total line flux, 60% is from CO, 13% from H2O and 9% from CH3OH. A comparison with similar HIFI spectra of other sources is set to provide much new insight into star formation regions, a case in point being a difference of two orders of magnitude in the relative contribution of sulphur oxides to the line cooling of Orion KL and OMC-2 FIR 4. Appendix A is available in electronic form at http://www.aanda.org

Privacy-preserving security solution for cloud services

OpenAIRE

L. Malina; J. Hajny; P. Dzurenda; V. Zeman

2015-01-01

We propose a novel privacy-preserving security solution for cloud services. Our solution is based on an efficient non-bilinear group signature scheme providing the anonymous access to cloud services and shared storage servers. The novel solution offers anonymous authenticationfor registered users. Thus, users' personal attributes (age, valid registration, successful payment) can be proven without revealing users' identity, and users can use cloud services without any threat of profiling their...

A framework for cloud - Aerosol interaction study

NARCIS (Netherlands)

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

2012-01-01

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

Protostellar formation in rotating interstellar clouds. VI. Nonuniform initial conditions

International Nuclear Information System (INIS)

Boss, A.P.

1987-01-01

The collapse and fragmentation of rotating protostellar clouds is explored, starting from nonuniform density and nonuniform rotation initial conditions. Whether binary fragmentation occurs during the first dynamic collapse phase depends strongly on the initial density profile. Exponential clouds are only somewhat more resistant to fragmentation than uniform-density clouds, but power-law clouds do not undergo fragmentation for likely values of a relevant parameter. Because binary fragments start from profiles intermediate between uniform density and exponential clouds, minimum protostellar mass for population I stars should be increased to approximately 0.02 solar mass. The axisymmetric Terey et al. (1984) model should be stable with respect to nonaxisymmetric perturbations. Considering the observed binary frequency, collapse from power-law initial conditions appears to be less common than collapse from more uniform initial conditions. 34 references

Combined Lidar-Radar Remote Sensing: Initial Results from CRYSTAL-FACE and Implications for Future Spaceflight Missions

Science.gov (United States)

McGill, Matthew J.; Li, Li-Hua; Hart, William D.; Heymsfield, Gerald M.; Hlavka, Dennis L.; Vaughan, Mark A.; Winker, David M.

2003-01-01

In the near future NASA plans to fly satellites carrying a multi-wavelength backscatter lidar and a 94-GHz cloud profiling radar in formation to provide complete global profiling of cloud and aerosol properties. The CRYSTAL-FACE field campaign, conducted during July 2002, provided the first high-altitude colocated measurements from lidar and cloud profiling radar to simulate these spaceborne sensors. The lidar and radar provide complementary measurements with varying degrees of measurement overlap. This paper presents initial results of the combined airborne lidar-radar measurements during CRYSTAL-FACE. The overlap of instrument sensitivity is presented, within the context of particular CRYSTAL-FACE conditions. Results are presented to quantify the portion of atmospheric profiles sensed independently by each instrument and the portion sensed simultaneously by the two instruments.

Measurement Results of the Caltech Submillimeter Observatory 230 GHz and 460 GHz Balanced Receivers

Science.gov (United States)

Kooi, J. W.; Monje, R. R.; Force, B. L.; Rice, F.; Miller, D.; Phillips, T. G.

2010-03-01

The Caltech Submillimeter observatory (CSO) is located on top of Mauna Kea, Hawaii, at an altitude of 4.2km. The existing suite of heterodyne receivers covering the submillimeter band is rapidly aging, and in need of replacement. To this extend we have developed a family of balanced receivers covering the astrophysical important 180-720 GHz atmospheric windows. For the CSO, wide IF bandwidth receivers are implemented in a balanced receiver configuration with dual frequency observation capability. This arrangement was opted to be an optimal compromise between scientific merit and finite funding. In principle, the balanced receiver configuration has the advantage that common mode amplitude noise in the LO system is canceled, while at the same time utilizing all available LO power. Both of these features facilitate the use of commercially available synthesized LO system. In combination with a 4 GHz IF bandwidth, the described receiver layout allows for rapid high resolution spectral line surveys. Dual frequency observation is another important mode of operation offered by the new facility instrumentation. Two band observations are accomplished by separating the H and V polarizations of the incoming signal and routing them via folded optics to the appropriate polarization sensitive balanced mixer. Scientifically this observation mode facilitates pointing for the higher receiver band under mediocre weather conditions and a doubling of scientific throughput (2 x 4 GHz) under good weather conditions. Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (eSMA) as an additional baseline. The upgrade of the 345 GHz/650 GHz dual band balanced receivers is not far behind. All the needed hardware has been procured, and commissioning is expected the summer of 2010. The SIS junctions are capable of a 2-12 GHz bandwidth.

Sampling of solid particles in clouds

International Nuclear Information System (INIS)

Feuillebois, F.; Lasek, A.; Scibilia, M.F.

1986-01-01

This paper is concerned with the sampling of small solid particles from clouds by an airborne apparatus to be mounted on an airplane for meteorological investigations. In the airborne experiment the particles entering the test tube should be as representative as possible of the upstream conditions ahead of the plane, in the real cloud. Due to the inertia of the particles, the proportion of the different sizes of particles entering the test tube depends on the location of the tube mouth. We present a method of calculating the real concentration in particles of different sizes, using the results of measurements executed during the flight of an airplane in a cloud. Two geometries are considered: the nose of the airplane, represented schematically by a hemisphere, and a wing represented by a (2D) Joukowski profile which matches well a NACA 0015 profile on its leading edge

Characterization of Ze and LDR of nonspherical and inhomogeneous ice particles for 95-GHz cloud radar: Its implication to microphysical retrievals

Science.gov (United States)

Sato, Kaori; Okamoto, Hajime

2006-11-01

Effect of density, shape, and orientation on radar reflectivity factor (Ze) and linear depolarization ratio (LDR) at 95 GHz are investigated by using the discrete dipole approximation (DDA) for ice cloud studies. We consider hexagonal plate, hollow hexagonal column, and hollow bullet rosette in horizontal (2-D) or three-dimensional (3-D) random orientation. We first validate a widely used method to take into account the density and shape effects by the combinational use of Mie theory with the Maxwell-Garnett mixing rule (the MG-Mie method). It is found that the MG-Mie method underestimates Ze and its applicability is limited to sizes smaller than 40 μm. On the basis of the DDA, it is possible to separately treat density, aspect ratio, orientation, and shape. Effect of density turns out to be minor. Orientation and shape are the major controlling factors for Ze especially at effective radius reff > 100 μm and LDR except for very large sizes where the effect of orientation in LDR diminishes. Comparison between the DDA results and the analytical solution for 3-D Rayleigh spheroids show that LDR in the small size range is characterized by the target boundary and aspect ratio. In the large size range, LDR reveals features of a single target element; for example, LDR of bullet rosette is similar to that of a single branch of the particle. Combinational use of Ze and LDR is effective in microphysics retrieval for LDR LDR > -23 dB, additional information such as Doppler velocity is required.

Jupiter's Deep Cloud Structure Revealed Using Keck Observations of Spectrally Resolved Line Shapes

Science.gov (United States)

Bjoraker, G. L.; Wong, M.H.; de Pater, I.; Adamkovics, M.

2015-01-01

Technique: We present a method to determine the pressure at which significant cloud opacity is present between 2 and 6 bars on Jupiter. We use: a) the strength of a Fraunhofer absorption line in a zone to determine the ratio of reflected sunlight to thermal emission, and b) pressure- broadened line profiles of deuterated methane (CH3D) at 4.66 meters to determine the location of clouds. We use radiative transfer models to constrain the altitude region of both the solar and thermal components of Jupiter's 5-meter spectrum. Results: For nearly all latitudes on Jupiter the thermal component is large enough to constrain the deep cloud structure even when upper clouds are present. We find that Hot Spots, belts, and high latitudes have broader line profiles than do zones. Radiative transfer models show that Hot Spots in the North and South Equatorial Belts (NEB, SEB) typically do not have opaque clouds at pressures greater than 2 bars. The South Tropical Zone (STZ) at 32 degrees South has an opaque cloud top between 4 and 5 bars. From thermochemical models this must be a water cloud. We measured the variation of the equivalent width of CH3D with latitude for comparison with Jupiter's belt-zone structure. We also constrained the vertical profile of H2O in an SEB Hot Spot and in the STZ. The Hot Spot is very dry for a probability less than 4.5 bars and then follows the H2O profile observed by the Galileo Probe. The STZ has a saturated H2O profile above its cloud top between 4 and 5 bars.

On the mechanism of Venusian atmosphere cloud layer formation

International Nuclear Information System (INIS)

Zhulanov, Yu.V.; Mukhin, L.M.; Nenarokov, D.F.

1987-01-01

Results of investigations into the aerosol component of Venusian atmosphere using a photoelectric counter in the 63-47 km range of heights at the Vega-1 and Vega-2 interplanetary stations are presented. The experiment was carried out in June, 11, 15, 1985 on the night-time side of the planet. Both devices were switched in at the height of 63 km, and data on the quantity of detected particles >=0.5 μm in diameter were transmitted every 0.43 s (that corresponds to 8-20 m spatial resolution). Study of particle concentration profiles obtained at the interval of 4 days (one period of rotation of Venusian atmosphere) permits to make the following conclusions on the structure of Venusian atmosphere cloud layer on the night side: 1) the cloud layer includes two distinct cloud strata: the upper- 56-60 km height range and the lower- 49.5-46.5 km height range separated by the zone of low particle concentrations ( -3 ); 2) the mentioned structure of the cloud layer is rather stable; concentration profiles obtained at the interval of 4 days well agree with each other; 3) concentration profiles, particularly, in the lower cloud-stratum are subjected to heavy fluctuations, that indicates essential spatial field heterogeneity of particle concentrations

Identification of the OGLE Blazars behind the Large and Small Magellanic Clouds

Directory of Open Access Journals (Sweden)

Natalia Żywucka

2017-11-01

Full Text Available We report the selection of blazar candidates behind the Large and Small Magellanic Clouds. Both flat spectrum radio quasar and BL Lacreate objects were selected based on the long-term, multi-colour Optical Gravitational Lensing Experiment photometric data. We cross-correlated the Magellanic Quasar Survey catalogue of spectroscopically confirmed quasars and quasar candidates located behind the Magellanic Clouds with the radio data at six frequencies from 0.8 to 20 GHz. Among the 1654 objects visible in optical range, we identified a sample of 44 newly selected blazar candidates, including 27 flat spectrum radio quasars and 17 BL Lacs. We examined selected objects with respect to their radio, optical, and mid-infrared properties.

110GHz ECH on DIII-D

International Nuclear Information System (INIS)

Cary, W.P.; Allen, J.C.; Callis, R.W.; Doane, J.L.; Harris, T.E.; Moetler, C.P.; Neren, A.; Prater, P.; Rensen, D.

1992-01-01

This paper reports on a new high power electron cyclotron heating (ECH) system which has been introduced on DIII-D. This system is designed to operate at 110 GHz with a total output power of 2 MW. The system consists of four Varian VGT-8011 gyrotrons (output power of 500 kW), and their associated support equipment. All components have been designed for up to a 10 second pulse duration. The 110 GHz system is intended to further progress in rf current drive experiments on DIII-D when used in conjunction with the existing 60 GHz ECH (1. 6 MW) , and the 30-60 MHz ICH (2MW) systems. H-mode physics, plasma stabilization experiments and transport studies are also to be conducted at 110 GHz

IS THE DUST CLOUD AROUND LAMBDA ORIONIS A RING OR A SHELL, OR BOTH?

Energy Technology Data Exchange (ETDEWEB)

Lee, Dukhang; Seon, Kwang-Il; Jo, Young-Soo, E-mail: lee.dukhang@gmail.com [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

2015-06-20

The dust cloud around λ Orionis is observed to be circularly symmetric with a large angular extent (≈8°). However, whether the three-dimensional (3D) structure of the cloud is shell- or ring-like has not yet been fully resolved. We study the 3D structure using a new approach that combines a 3D Monte Carlo radiative transfer model for ultraviolet (UV) scattered light and an inverse Abel transform, which gives a detailed 3D radial density profile from a two-dimensional column density map of a spherically symmetric cloud. By comparing the radiative transfer models for a spherical shell cloud and that for a ring cloud, we find that only the shell model can reproduce the radial profile of the scattered UV light, observed using the S2/68 UV observation, suggesting a dust shell structure. However, the inverse Abel transform applied to the column density data from the Pan-STARRS1 dust reddening map results in negative values at a certain radius range of the density profile, indicating the existence of additional, non-spherical clouds near the nebular boundary. The additional cloud component is assumed to be of toroidal ring shape; we subtracted from the column density to obtain a positive, radial density profile using the inverse Abel transform. The resulting density structure, composed of a toroidal ring and a spherical shell, is also found to give a good fit to the UV scattered light profile. We therefore conclude that the cloud around λ Ori is composed of both ring and shell structures.

A 60 GHz Frequency Generator Based on a 20 GHz Oscillator and an Implicit Multiplier

NARCIS (Netherlands)

Zong, Z.; Babaie, M.; Staszewski, R.B.

2016-01-01

This paper proposes a mm-wave frequency generation technique that improves its phase noise (PN) performance and power efficiency. The main idea is that a fundamental 20 GHz signal and its sufficiently strong third harmonic at 60 GHz are generated simultaneously in a single oscillator. The desired 60

Modeling study of cloud droplet nucleation and in-cloud sulfate production during the Sanitation of the Atmosphere (SANA) 2 campaign

Science.gov (United States)

Liu, Xiaohong; Seidl, Winfried

1998-01-01

Based upon the measurements of vertical profiles of gaseous SO2, H2O2, O3, and meteorological parameters from aircraft and of the aerosol chemical composition and gaseous NH3, HNO3, and SO2 at the surface in southeastern Germany (Melpitz) during the Sanitation of the Atmosphere (SANA) 2 campaign, realistic modeling of cloud droplet nucleation and in-cloud sulfate production was performed with an explicit microphysical cloud model with size-resolved chemistry and cloud top entrainment. For the fair weather cumulus observed during the measurements, the calculated cloud droplet number concentrations could be as high as 2000 cm-3 (and precloud aerosol sulfate up to 9.1 μg m-3), indicating strong sulfur pollution at Melpitz during the campaign. The in-cloud sulfate production is within 1.5-5.0 μg m-3, depending on the initial gaseous NH3 concentration in the parcel. This result shows the necessity of gaseous NH3 vertical profile measurements. Entrainment can reduce the cloud droplet number concentration and cause the distribution of in-cloud produced sulfate to shift toward larger particle sizes. Under the cases we studied, we do not find a significant effect of cloud top gaseous H2O2 entrainment on the in-cloud sulfate production. For the adiabatic cases the departure of bulk water H2O2 from the Henry's law equilibrium is very small. When entrainment included, however, bulk water H2O2 concentrations could be clearly less than the equilibrium values, and the deficiencies are higher (>20%) for droplets larger than 10 μm radius. Our results suggest that entrainment could be one of the important factors to account for the measured H2O2 deficiency in cloud water.

Depolarization Ratio Profiles Calibration and Observations of Aerosol and Cloud in the Tibetan Plateau Based on Polarization Raman Lidar

Directory of Open Access Journals (Sweden)

Guangyao Dai

2018-03-01

Full Text Available A brief description of the Water vapor, Cloud and Aerosol Lidar (WACAL system is provided. To calibrate the volume linear depolarization ratio, the concept of “ Δ 90 ° -calibration” is applied in this study. This effective and accurate calibration method is adjusted according to the design of WACAL. Error calculations and analysis of the gain ratio, calibrated volume linear depolarization ratio and particle linear depolarization ratio are provided as well. In this method, the influences of the gain ratio, the rotation angle of the plane of polarization and the polarizing beam splitter are discussed in depth. Two groups of measurements with half wave plate (HWP at angles of (0 ° , 45 ° and (22.5 ° , −22.5 ° are operated to calibrate the volume linear depolarization ratio. Then, the particle linear depolarization ratios measured by WACAL and CALIOP (the Cloud-Aerosol Lidar with Orthogonal Polarization during the simultaneous observations were compared. Good agreements are found. The calibration method was applied in the third Tibetan Plateau Experiment of Atmospheric Sciences (TIPEX III in 2013 and 2014 in China. Vertical profiles of the particle depolarization ratio of clouds and aerosol in the Tibetan Plateau were measured with WACAL in Litang (30.03° N, 100.28° E, 3949 m above sea level (a.s.l. in 2013 and Naqu (31.48° N, 92.06° E, 4508 m a.s.l. in 2014. Then an analysis on the polarizing properties of the aerosol, clouds and cirrus over the Tibetan Plateau is provided. The particle depolarization ratio of cirrus clouds varies from 0.36 to 0.52, with a mean value of 0.44 ± 0.04. Cirrus clouds occurred between 5.2 and 12 km above ground level (a.g.l.. The cloud thickness ranges from 0.12 to 2.55 km with a mean thickness of 1.22 ± 0.70 km. It is found that the particle depolarization ratio of cirrus clouds become larger as the height increases. However, the increase rate of the particle depolarization ratio becomes smaller as

Elevation Change of Drangajokull, Iceland, from Cloud-Cleared ICESat Repeat Profiles and GPS Ground-Survey Data

Science.gov (United States)

Shuman, Christopher A.; Sigurdsson, Oddur; Williams, Richard, Jr.; Hall, Dorothy K.

2009-01-01

Located on the Vestfirdir Northwest Fjords), DrangaJokull is the northernmost ice map in Iceland. Currently, the ice cap exceeds 900 m in elevation and covered an area of approx.l46 sq km in August 2004. It was about 204 sq km in area during 1913-1914 and so has lost mass during the 20th century. Drangajokull's size and accessibility for GPS surveys as well as the availability of repeat satellite altimetry profiles since late 2003 make it a good subject for change-detection analysis. The ice cap was surveyed by four GPS-equipped snowmobiles on 19-20 April 2005 and has been profiled in two places by Ice, Cloud. and land Elevation Satellite (ICESat) 'repeat tracks,' fifteen times from late to early 2009. In addition, traditional mass-balance measurements have been taken seasonally at a number of locations across the ice cap and they show positive net mass balances in 2004/2005 through 2006/2007. Mean elevation differences between the temporally-closest ICESat profiles and the GPS-derived digital-elevation model (DEM)(ICESat - DEM) are about 1.1 m but have standard deviations of 3 to 4 m. Differencing all ICESat repeats from the DEM shows that the overall elevation difference trend since 2003 is negative with losses of as much as 1.5 m/a from same season to same season (and similar elevation) data subsets. However, the mass balance assessments by traditional stake re-measurement methods suggest that the elevation changes where ICESat tracks 0046 and 0307 cross Drangajokull are not representative of the whole ice cap. Specifically, the area has experienced positive mass balance years during the time frame when ICESat data indicates substantial losses. This analysis suggests that ICESat-derived elevations may be used for multi-year change detection relative to other data but suggests that large uncertainties remain. These uncertainties may be due to geolocation uncertainty on steep slopes and continuing cloud cover that limits temporal and spatial coverage across the

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

Science.gov (United States)

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

2008-12-01

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

Evaluation of Fog and Low Stratus Cloud Microphysical Properties Derived from In Situ Sensor, Cloud Radar and SYRSOC Algorithm

Directory of Open Access Journals (Sweden)

Jean-Charles Dupont

2018-05-01

Full Text Available The microphysical properties of low stratus and fog are analyzed here based on simultaneous measurement of an in situ sensor installed on board a tethered balloon and active remote-sensing instruments deployed at the Instrumented Site for Atmospheric Remote Sensing Research (SIRTA observatory (south of Paris, France. The study focuses on the analysis of 3 case studies where the tethered balloon is deployed for several hours in order to derive the relationship between liquid water content (LWC, effective radius (Re and cloud droplet number concentration (CDNC measured by a light optical aerosol counter (LOAC in situ granulometer and Bistatic Radar System for Atmospheric Studies (BASTA cloud radar reflectivity. The well-known relationship Z = α × (LWCβ has been optimized with α ϵ [0.02, 0.097] and β ϵ [1.91, 2.51]. Similar analysis is done to optimize the relationship Re = f(Z and CDNC = f(Z. Two methodologies have been applied to normalize the particle-size distribution measured by the LOAC granulometer with a visible extinction closure (R² ϵ [0.73, 0.93] and to validate the LWC profile with a liquid water closure using the Humidity and Temperature Profiler (HATPRO microwave radiometer (R² ϵ [0.83, 0.91]. In a second step, these relationships are used to derive spatial and temporal variability of the vertical profile of LWC, Re and CDNC starting from BASTA measurement. Finally, the synergistic remote sensing of clouds (SYRSOC algorithm has been tested on three tethered balloon flights. Generally, SYRSOC CDNC and Re profiles agreed well with LOAC in situ and BASTA profiles for the studied fog layers. A systematic overestimation of LWC by SYRSOC in the top half of the fog layer was found due to fog processes that are not accounted for in the cloud algorithm SYRSOC.

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

Science.gov (United States)

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

2017-08-01

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

The carbon inventory in a quiescent, filamentary molecular cloud in G328

International Nuclear Information System (INIS)

Burton, Michael G.; Ashley, Michael C. B.; Braiding, Catherine; Storey, John W. V.; Kulesa, Craig; Hollenbach, David J.; Wolfire, Mark; Glück, Christian; Rowell, Gavin

2014-01-01

We present spectral line images of [C I] 809 GHz, CO J = 1-0 115 GHz and H I 1.4 GHz line emission, and calculate the corresponding C, CO and H column densities, for a sinuous, quiescent giant molecular cloud about 5 kpc distant along the l = 328° sightline (hereafter G328) in our Galaxy. The [C I] data comes from the High Elevation Antarctic Terahertz telescope, a new facility on the summit of the Antarctic plateau where the precipitable water vapor falls to the lowest values found on the surface of the Earth. The CO and H I data sets come from the Mopra and Parkes/ATCA telescopes, respectively. We identify a filamentary molecular cloud, ∼75 × 5 pc long with mass ∼4 × 10 4 M ☉ and a narrow velocity emission range of just 4 km s –1 . The morphology and kinematics of this filament are similar in CO, [C I], and H I, though in the latter appears as self-absorption. We calculate line fluxes and column densities for the three emitting species, which are broadly consistent with a photodissociation region model for a GMC exposed to the average interstellar radiation field. The [C/CO] abundance ratio averaged through the filament is found to be approximately unity. The G328 filament is constrained to be cold (T Dust < 20 K) by the lack of far-IR emission, to show no clear signs of star formation, and to only be mildly turbulent from the narrow line width. We suggest that it may represent a GMC shortly after formation, or perhaps still in the process of formation.

The carbon inventory in a quiescent, filamentary molecular cloud in G328

Energy Technology Data Exchange (ETDEWEB)

Burton, Michael G.; Ashley, Michael C. B.; Braiding, Catherine; Storey, John W. V. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Kulesa, Craig [Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Hollenbach, David J. [Carl Sagan Center, SETI Institute, 189 Bernado Avenue, Mountain View, CA 94043-5203 (United States); Wolfire, Mark [Astronomy Department, University of Maryland, College Park, MD 20742 (United States); Glück, Christian [KOSMA, I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany); Rowell, Gavin, E-mail: m.burton@unsw.edu.au [School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005 (Australia)

2014-02-20

We present spectral line images of [C I] 809 GHz, CO J = 1-0 115 GHz and H I 1.4 GHz line emission, and calculate the corresponding C, CO and H column densities, for a sinuous, quiescent giant molecular cloud about 5 kpc distant along the l = 328° sightline (hereafter G328) in our Galaxy. The [C I] data comes from the High Elevation Antarctic Terahertz telescope, a new facility on the summit of the Antarctic plateau where the precipitable water vapor falls to the lowest values found on the surface of the Earth. The CO and H I data sets come from the Mopra and Parkes/ATCA telescopes, respectively. We identify a filamentary molecular cloud, ∼75 × 5 pc long with mass ∼4 × 10{sup 4} M {sub ☉} and a narrow velocity emission range of just 4 km s{sup –1}. The morphology and kinematics of this filament are similar in CO, [C I], and H I, though in the latter appears as self-absorption. We calculate line fluxes and column densities for the three emitting species, which are broadly consistent with a photodissociation region model for a GMC exposed to the average interstellar radiation field. The [C/CO] abundance ratio averaged through the filament is found to be approximately unity. The G328 filament is constrained to be cold (T {sub Dust} < 20 K) by the lack of far-IR emission, to show no clear signs of star formation, and to only be mildly turbulent from the narrow line width. We suggest that it may represent a GMC shortly after formation, or perhaps still in the process of formation.

Liquid water content variation with altitude in clouds over Europe

Science.gov (United States)

Andreea, Boscornea; Sabina, Stefan

2013-04-01

Cloud water content is one of the most fundamental measurements in cloud physics. Knowledge of the vertical variability of cloud microphysical characteristics is important for a variety of reasons. The profile of liquid water content (LWC) partially governs the radiative transfer for cloudy atmospheres, LWC profiles improves our understanding of processes acting to form and maintain cloud systems and may lead to improvements in the representation of clouds in numerical models. Presently, in situ airborne measurements provide the most accurate information about cloud microphysical characteristics. This information can be used for verification of both numerical models and cloud remote sensing techniques. The aim of this paper was to analyze the liquid water content (LWC) measurements in clouds, in time of the aircraft flights. The aircraft and its platform ATMOSLAB - Airborne Laboratory for Environmental Atmospheric Research is property of the National Institute for Aerospace Research "Elie Carafoli" (INCAS), Bucharest, Romania. The airborne laboratory equipped for special research missions is based on a Hawker Beechcraft - King Air C90 GTx aircraft and is equipped with a sensors system CAPS - Cloud, Aerosol and Precipitation Spectrometer (30 bins, 0.51-50 m). The processed and analyzed measurements are acquired during 4 flights from Romania (Bucharest, 44°25'57″N 26°06'14″E) to Germany (Berlin 52°30'2″N 13°23'56″E) above the same region of Europe. The flight path was starting from Bucharest to the western part of Romania above Hungary, Austria at a cruse altitude between 6000-8500 m, and after 5 hours reaching Berlin. In total we acquired data during approximately 20 flight hours and we presented the vertical and horizontal LWC variations for different cloud types. The LWC values are similar for each type of cloud to values from literature. The vertical LWC profiles in the atmosphere measured during takeoff and landing of the aircraft have shown their

Vertical distribution of the particle phase in tropical deep convective clouds as derived from cloud-side reflected solar radiation measurements

Directory of Open Access Journals (Sweden)

E. Jäkel

2017-07-01

Full Text Available Vertical profiles of cloud particle phase in tropical deep convective clouds (DCCs were investigated using airborne solar spectral radiation data collected by the German High Altitude and Long Range Research Aircraft (HALO during the ACRIDICON-CHUVA campaign, which was conducted over the Brazilian rainforest in September 2014. A phase discrimination retrieval based on imaging spectroradiometer measurements of DCC side spectral reflectivity was applied to clouds formed in different aerosol conditions. From the retrieval results the height of the mixed-phase layer of the DCCs was determined. The retrieved profiles were compared with in situ measurements and satellite observations. It was found that the depth and vertical position of the mixed-phase layer can vary up to 900 m for one single cloud scene. This variability is attributed to the different stages of cloud development in a scene. Clouds of mature or decaying stage are affected by falling ice particles resulting in lower levels of fully glaciated cloud layers compared to growing clouds. Comparing polluted and moderate aerosol conditions revealed a shift of the lower boundary of the mixed-phase layer from 5.6 ± 0.2 km (269 K; moderate to 6.2 ± 0.3 km (267 K; polluted, and of the upper boundary from 6.8 ± 0.2 km (263 K; moderate to 7.4 ± 0.4 km (259 K; polluted, as would be expected from theory.

Dynamic Extensions of Batch Systems with Cloud Resources

International Nuclear Information System (INIS)

Hauth, T; Quast, G; Büge, V; Scheurer, A; Kunze, M; Baun, C

2011-01-01

Compute clusters use Portable Batch Systems (PBS) to distribute workload among individual cluster machines. To extend standard batch systems to Cloud infrastructures, a new service monitors the number of queued jobs and keeps track of the price of available resources. This meta-scheduler dynamically adapts the number of Cloud worker nodes according to the requirement profile. Two different worker node topologies are presented and tested on the Amazon EC2 Cloud service.

Rectenna Technology Program: Ultra light 2.45 GHz rectenna 20 GHz rectenna

Science.gov (United States)

Brown, William C.

1987-01-01

The program had two general objectives. The first objective was to develop the two plane rectenna format for space application at 2.45 GHz. The resultant foreplane was a thin-film, etched-circuit format fabricated from a laminate composed of 2 mil Kapton F sandwiched between sheets of 1 oz copper. The thin-film foreplane contains half wave dipoles, filter circuits, rectifying Schottky diode, and dc bussing lead. It weighs 160 grams per square meter. Efficiency and dc power output density were measured at 85% and 1 kw/sq m, respectively. Special testing techniques to measure temperature of circuit and diode without perturbing microwave operation using the fluoroptic thermometer were developed. A second objective was to investigate rectenna technology for use at 20 GHz and higher frequencies. Several fabrication formats including the thin-film scaled from 2.45 GHz, ceramic substrate and silk-screening, and monolithic were investigated, with the conclusion that the monolithic approach was the best. A preliminary design of the monolithic rectenna structure and the integrated Schottky diode were made.

ALMA Images of the Orion Hot Core at 349 GHz

Energy Technology Data Exchange (ETDEWEB)

Wright, M. C. H.; Plambeck, R. L., E-mail: wright@astro.berkeley.edu [Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 (United States)

2017-07-10

We present ALMA images of the dust and molecular line emission in the Orion Hot Core at 349 GHz. At 0.″2 angular resolution the images reveal multiple clumps in an arc ∼1″ east of Orion Source I, the protostar at the center of the Kleinmann–Low Nebula, and another chain of peaks from IRc7 toward the southwest. The molecular line images show narrow filamentary structures at velocities >10 km s{sup −1} away from the heavily resolved ambient cloud velocity ∼5 km s{sup −1}. Many of these filaments trace the SiO outflow from Source I, and lie along the edges of the dust emission. Molecular line emission at excitation temperatures 300–2000 K, and velocities >10 km s{sup −1} from the ambient cloud, suggest that the Hot Core may be heated in shocks by the outflow from Source I or from the Becklin–Neugebauer (BN)/SrcI explosion. The spectral line observations also reveal a remarkable molecular ring, ∼2″ south of SrcI, with a diameter ∼600 au. The ring is seen in high-excitation transitions of HC{sub 3}N, HCN v 2 = 1, and SO{sub 2}. An impact of ejecta from the BN/SrcI explosion with a dense dust clump could result in the observed ring of shocked material.

Diurnal Variation of Tropical Ice Cloud Microphysics inferred from Global Precipitation Measurement Microwave Imager (GPM-GMI)'s Polarimetric Measurement

Science.gov (United States)

Gong, J.; Zeng, X.; Wu, D. L.; Li, X.

2017-12-01

Diurnal variation of tropical ice cloud has been well observed and examined in terms of the area of coverage, occurring frequency, and total mass, but rarely on ice microphysical parameters (habit, size, orientation, etc.) because of lack of direct measurements of ice microphysics on a high temporal and spatial resolutions. This accounts for a great portion of the uncertainty in evaluating ice cloud's role on global radiation and hydrological budgets. The design of Global Precipitation Measurement (GPM) mission's procession orbit gives us an unprecedented opportunity to study the diurnal variation of ice microphysics on the global scale for the first time. Dominated by cloud ice scattering, high-frequency microwave polarimetric difference (PD, namely the brightness temperature difference between vertically- and horizontally-polarized paired channel measurements) from the GPM Microwave Imager (GMI) has been proven by our previous study to be very valuable to infer cloud ice microphysical properties. Using one year of PD measurements at 166 GHz, we found that cloud PD exhibits a strong diurnal cycle in the tropics (25S-25N). The peak PD amplitude varies as much as 35% over land, compared to only 6% over ocean. The diurnal cycle of the peak PD value is strongly anti-correlated with local ice cloud occurring frequency and the total ice mass with a leading period of 3 hours for the maximum correlation. The observed PD diurnal cycle can be explained by the change of ice crystal axial ratio. Using a radiative transfer model, we can simulate the observed 166 GHz PD-brightness temperature curve as well as its diurnal variation using different axial ratio values, which can be caused by the diurnal variation of ice microphysical properties including particle size, percentage of horizontally-aligned non-spherical particles, and ice habit. The leading of the change of PD ahead of ice cloud mass and occurring frequency implies the important role microphysics play in the

The Use of a 28 GHz Gyrotron for EBW Startup Experiments on MAST

Science.gov (United States)

Caughman, J. B.; Bigelow, T. S.; Diem, S. J.; Peng, Y. K. M.; Rasmussen, D. A.; Shevchenko, V.; Hawes, J.; Lloyd, B.

2009-11-01

The use of electron Bernstein waves for non-inductive plasma current startup in MAST has recently been demonstrated [1]. The injection of 100 kW at 28 GHz generated plasma currents of up to 33 kA without the use of solenoid flux, and limited solenoid assist resulted in up to 55 kA of plasma current. A higher power 28 GHz gyrotron, with power levels of up to 300 kW for 0.5 seconds, is currently being commissioned. It is being used to investigate the scaling of startup current with microwave power and power profile as a function of time. Power modulation experiments are also being explored. Gyrotron performance and experimental results will be presented. [4pt] [1] V. Shevchenko, et al., Proceedings of the 15^th Joint Workshop on ECE and ECRH, Yosimite, USA, p. 68 (2009)

Synergistic multi-sensor and multi-frequency retrieval of cloud ice water path constrained by CloudSat collocations

International Nuclear Information System (INIS)

Islam, Tanvir; Srivastava, Prashant K.

2015-01-01

The cloud ice water path (IWP) is one of the major parameters that have a strong influence on earth's radiation budget. Onboard satellite sensors are recognized as valuable tools to measure the IWP in a global scale. Albeit, active sensors such as the Cloud Profiling Radar (CPR) onboard the CloudSat satellite has better capability to measure the ice water content profile, thus, its vertical integral, IWP, than any passive microwave (MW) or infrared (IR) sensors. In this study, we investigate the retrieval of IWP from MW and IR sensors, including AMSU-A, MHS, and HIRS instruments on-board the N19 satellite, such that the retrieval is consistent with the CloudSat IWP estimates. This is achieved through the collocations between the passive satellite measurements and CloudSat scenes. Potential benefit of synergistic multi-sensor multi-frequency retrieval is investigated. Two modeling approaches are explored for the IWP retrieval – generalized linear model (GLM) and neural network (NN). The investigation has been carried out over both ocean and land surface types. The MW/IR synergy is found to be retrieved more accurate IWP than the individual AMSU-A, MHS, or HIRS measurements. Both GLM and NN approaches have been able to exploit the synergistic retrievals. - Highlights: • MW/IR synergy is investigated for IWP retrieval. • The IWP retrieval is modeled using CloudSat collocations. • Two modeling approaches are explored – GLM and ANN. • MW/IR synergy performs better than the MW or IR only retrieval

Estimating seasonal variations in cloud droplet number concentration over the boreal forest from satellite observations

NARCIS (Netherlands)

Janssen, R.; Ganzeveld, L.N.; Kabat, P.; Kulmala, M.; Nieminen, T.; Roebeling, R.A.

2011-01-01

Seasonal variations in cloud droplet number concentration (NCD) in low-level stratiform clouds over the boreal forest are estimated from MODIS observations of cloud optical and microphysical properties, using a sub-adiabatic cloud model to interpret vertical profiles of cloud properties. An

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

Science.gov (United States)

2017-06-04

further, changes in lower atmospheric temperature, humidity, winds , and clouds are likely to result from changed sea ice concentrations and ocean...affect changes in cloud properties and cover, • develop novel instrumentation including low cost, expendable, air-deployed micro -aircraft to obtain...from June through October to obtain atmospheric profiles of temperature, humidity, and winds from the time of ice edge retreat in spring to advance

Molecular clouds and galactic spiral structure

International Nuclear Information System (INIS)

Dame, T.M.

1983-01-01

Galactic CO line emission at 115 GHz has been surveyed in the region 12 0 less than or equal to l less than or equal to 60 0 and -1 0 less than or equal to b less than or equal to 1 0 in order to study the distribution of molecular clouds in the inner galaxy; an inner strip 0 0 .5 wide has been sampled every beamwidth (0 0 .125), the rest every two beamwidths. Comparison of the survey with similar HI data reveals a detailed correlation with the most intense 21-cm features, implying that the CO and HI trace the same galactic features and have the same large-scale kinematics. To each of the classical 21-cm (HI) spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is developed in which all of the CO emission from the inner galaxy arises from spiral arms. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide. A variety of methods are employed to estimate distances and masses for the largest clouds detected by the inner-galaxy survey and a catalogue is compiled. The catalogued clouds, the largest of which have masses of several 10 6 M/sub sunmass/ and linear dimensions in excess of 100 pc, are found to be excellent spiral-arm tracers. One of the nearest of the clouds, that associated with the supernova remnant W44, is fully mapped in both CO and 13 CO and is discussed in detail

Evidence for a rotating helical filament in L1641, part of the Orion cloud complex

International Nuclear Information System (INIS)

Uchida, Y.

1991-01-01

Interstellar cloud structures, typically 10-30 pc long and 3-5 pc wide, are often seen extending outwards from dense clouds that show marked enhancement of star formation within them. We have used the Nagoya 4-m radiotelescope to study one such 'streamer', L1641, a part of the giant molecular-cloud complex in Orion, lying south of the Kleinmann-Low (KL) nebula. Using the 110-GHz line of 13 Co (J=1-0), we have obtained intensity and velocity data, and find within the streamer a dense filament with a helical structure, spinning in the same sense as the gas in the Orion KL region. We propose a model for this structure in which the streamer, through the action of the interstellar magnetic field, acts as an angular-momentum drain on the Orion KL region, allowing it to collapse. In this model, the ∼30-pc-long streamer is essential to the formation of the cloud, as well as the formation of stars within the dense cloud. (author)

45-GHz and 60-GHz 90 nm CMOS power amplifiers with a fully symmetrical 8-way transformer power combiner

Institute of Scientific and Technical Information of China (English)

Zhengdong JIANG; Kaizhe GUO; Peng HUANG; Yiming FAN; Chenxi ZHAO; Yongling BAN; Jun LIU; Kai KANG

2017-01-01

In this paper,45 GHz and 60 GHz power amplifiers (PAs) with high output power have been successfully designed by using 90 nm CMOS process.The 45 GHz (60 GHz) PA consists of two (four) differential stages.The sizes of transistors have been designed in an appropriate way so as to trade-off gain,efficiency and stability.Due to limited supply voltage and low breakdown voltage of CMOS MOSFET compared with the traditional Ⅲ-Ⅴ technologies,the technique of power combining has been applied to achieve a high output power.In particular,a novel 8-way distributed active transformer power combiner has been proposed for realizing such mm-wave PA.The proposed transformer combiner with a fully symmetrical layout can improve its input impedance balance at mm-wave frequency regime significantly.Taking its advantages of this novel transformer based power combiner,our realized 45 GHz (60 GHz) mm-wave PA has achieved the gain of 20.3 dB (16.8 dB),the maximum PAE of 14.5％ (13.4％) and the saturated output power of 21 dBm (21 dBm) with the 1.2 V supply voltage.

A Low-Profile WLAN Antenna with Inductor and Tuning Stub for Broadband Impedance Matching

Directory of Open Access Journals (Sweden)

Woo-Su Kim

2014-01-01

Full Text Available This paper presents a low-profile multiband antenna suitable for wireless local area networks (WLANs, using a chip inductor and tuning stub for broadband impedance matching. The proposed antenna is compact 12×10×1 mm3 and covers three bands: 2.4-GHz (2.400–2.484 GHz, 5.2-GHz (5.150–5.350 GHz, and 5.8-GHz (5.725–5.825 GHz. The measured 10-dB bandwidths are 12.0% (2.28–2.57 GHz in the lower band for 2.4-GHz WLANs and 39.1% (4.81–7.15 GHz in the upper band for 5 GHz-WLANs. The measured peak gain of the antenna is between 2.7 and 4.39 dBi and the radiation patterns are omnidirectional.

Planck intermediate results: XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds

International Nuclear Information System (INIS)

Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Arnaud, M.; Arzoumanian, D.

2016-01-01

Within ten nearby (d < 450 pc) Gould belt molecular clouds we evaluate in this paper statistically the relative orientation between the magnetic field projected on the plane of sky, inferred from the polarized thermal emission of Galactic dust observed by Planck at 353 GHz, and the gas column density structures, quantified by the gradient of the column density, N_H. The selected regions, covering several degrees in size, are analysed at an effective angular resolution of 10' FWHM, thus sampling physical scales from 0.4 to 40 pc in the nearest cloud. The column densities in the selected regions range from N_H≈ 10"2"1 to10"2"3 cm"-"2, and hence they correspond to the bulk of the molecular clouds. The relative orientation is evaluated pixel by pixel and analysed in bins of column density using the novel statistical tool called “histogram of relative orientations”. Throughout this study, we assume that the polarized emission observed by Planck at 353 GHz is representative of the projected morphology of the magnetic field in each region, i.e., we assume a constant dust grain alignment efficiency, independent of the local environment. Within most clouds we find that the relative orientation changes progressively with increasing N_H, from mostly parallel or having no preferred orientation to mostly perpendicular. In simulations of magnetohydrodynamic turbulence in molecular clouds this trend in relative orientation is a signature of Alfvénic or sub-Alfvénic turbulence, implying that the magnetic field is significant for the gas dynamics at the scales probed by Planck. Finally, we compare the deduced magnetic field strength with estimates we obtain from other methods and discuss the implications of the Planck observations for the general picture of molecular cloud formation and evolution.

60-GHz Millimeter-Wave Radio: Principle, Technology, and New Results

Directory of Open Access Journals (Sweden)

Nan Guo

2006-12-01

Full Text Available The worldwide opening of a massive amount of unlicensed spectra around 60 GHz has triggered great interest in developing affordable 60-GHz radios. This interest has been catalyzed by recent advance of 60-GHz front-end technologies. This paper briefly reports recent work in the 60-GHz radio. Aspects addressed in this paper include global regulatory and standardization, justification of using the 60-GHz bands, 60-GHz consumer electronics applications, radio system concept, 60-GHz propagation and antennas, and key issues in system design. Some new simulation results are also given. Potentials and problems are explained in detail.

Submm-Wave Radiometry for Cloud/Humidity/Precipitation Sciences

Science.gov (United States)

Wu, Dong L.

2011-01-01

Although active sensors can provide cloud profiles at good vertical resolution, clouds are often coupled with dynamics to form fast and organized structures. Lack of understanding of these organized systems leads to great challenge for numerical models. The deficiency is partly reflected, for example, in poorly modeled intraseasonal variations (e.g., MJD). Remote sensing clouds in the middle and upper troposphere has been challenging from space. Vis/IR sensors are sensitive to the topmost cloud layers whereas low-frequency MW techniques are sensitivity to liquid and precipitation at the bottom of cloud layers. The middle-level clouds, mostly in the ice phase, require a sensor that has moderate penetration and sensitivity to cloud scattering, in order to measure cloud water content. Sensors at submm wavelengths provide promising sensitivity and coverage with the spatial resolution needed to measure cloud water content floating in the upper air. In addition, submm-wave sensors are able to provide better measurements of upper-tropospheric humidity than traditional microwave instruments.

G-Cloud Monitor: A Cloud Monitoring System for Factory Automation for Sustainable Green Computing

Directory of Open Access Journals (Sweden)

Hwa-Young Jeong

2014-11-01

Full Text Available Green and cloud computing (G-cloud are new trends in all areas of computing. The G-cloud provides an efficient function, which enables users to access their programs, systems and platforms at anytime and anyplace. Green computing can also yield greener technology by reducing power consumption for sustainable environments. Furthermore, in order to apply user needs to the system development, the user characteristics are regarded as some of the most important factors to be considered in product industries. In this paper, we propose a cloud monitoring system to observe and manage the manufacturing system/factory automation for sustainable green computing. For monitoring systems, we utilized the resources in the G-cloud environments, and hence, it can reduce the amount of system resources and devices, such as system power and processes. In addition, we propose adding a user profile to the monitoring system in order to provide a user-friendly function. That is, this function allows system configurations to be automatically matched to the individual’s requirements, thus increasing efficiency.

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

Directory of Open Access Journals (Sweden)

K. J. Sanchez

2017-08-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-02-01

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

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

International Nuclear Information System (INIS)

Ohno, Kazumasa; Okuzumi, Satoshi

2017-01-01

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

Planck intermediate results XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds

DEFF Research Database (Denmark)

Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.

2016-01-01

emission observed by Planck at 353 GHz is representative of the projected morphology of the magnetic field in each region, i.e., we assume a constant dust grain alignment efficiency, independent of the local environment. Within most clouds we find that the relative orientation changes progressively...... for the gas dynamics at the scales probed by Planck. We compare the deduced magnetic field strength with estimates we obtain from other methods and discuss the implications of the Planck observations for the general picture of molecular cloud formation and evolution....

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas: Atmospheric Observations and Modeling as Part of the Seasonal Ice Zone Reconnaissance Surveys

Science.gov (United States)

2017-06-04

conditions in the SIZ affeCt changes in cloud properties and cover, • develop novel instrumentation including low cost , expendable, air-deployed micro...hour per response, induding the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and...From- To) 04 - 06 - 2017 Final Technical 0/1/01/2012 - 12/31/2016 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Atmospheric Profiles , Clouds and the

The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

International Nuclear Information System (INIS)

Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J

2008-01-01

All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization

The Explicit-Cloud Parameterized-Pollutant hybrid approach for aerosol-cloud interactions in multiscale modeling framework models: tracer transport results

Energy Technology Data Exchange (ETDEWEB)

Jr, William I Gustafson; Berg, Larry K; Easter, Richard C; Ghan, Steven J [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, PO Box 999, MSIN K9-30, Richland, WA (United States)], E-mail: William.Gustafson@pnl.gov

2008-04-15

All estimates of aerosol indirect effects on the global energy balance have either completely neglected the influence of aerosol on convective clouds or treated the influence in a highly parameterized manner. Embedding cloud-resolving models (CRMs) within each grid cell of a global model provides a multiscale modeling framework for treating both the influence of aerosols on convective as well as stratiform clouds and the influence of clouds on the aerosol, but treating the interactions explicitly by simulating all aerosol processes in the CRM is computationally prohibitive. An alternate approach is to use horizontal statistics (e.g., cloud mass flux, cloud fraction, and precipitation) from the CRM simulation to drive a single-column parameterization of cloud effects on the aerosol and then use the aerosol profile to simulate aerosol effects on clouds within the CRM. Here, we present results from the first component of the Explicit-Cloud Parameterized-Pollutant parameterization to be developed, which handles vertical transport of tracers by clouds. A CRM with explicit tracer transport serves as a benchmark. We show that this parameterization, driven by the CRM's cloud mass fluxes, reproduces the CRM tracer transport significantly better than a single-column model that uses a conventional convective cloud parameterization.

Low cloud precipitation climatology in the southeastern Pacific marine stratocumulus region using CloudSat

International Nuclear Information System (INIS)

Rapp, Anita D; Lebsock, Matthew; L’Ecuyer, Tristan

2013-01-01

A climatology of low cloud surface precipitation occurrence and intensity from the new CloudSat 2C-RAIN-PROFILE algorithm is presented from June 2006 through December 2010 for the southeastern Pacific region of marine stratocumulus. Results show that over 70% of low cloud precipitation falls as drizzle. Application of an empirical evaporation model suggests that 50–80% of the precipitation evaporates before it reaches the surface. Segregation of the CloudSat ascending and descending overpasses shows that the majority of precipitation occurs at night. Examination of the seasonal cycle shows that the precipitation is most frequent during the austral winter and spring; however there is considerable regional variability. Conditional rain rates increase from east to west with a maximum occurring in the region influenced by the South Pacific Convergence Zone. Area average rain rates are highest in the region where precipitation rates are moderate, but most frequent. The area average surface rain rate for low cloud precipitation for this region is ∼0.22 mm d −1 , in good agreement with in situ estimates, and is greatly improved over earlier CloudSat precipitation products. These results provide a much-needed quantification of surface precipitation in a region that is currently underestimated in existing satellite-based precipitation climatologies. (letter)

Ice in the Taurus molecular cloud: modelling of the 3-μm profile

International Nuclear Information System (INIS)

Bult, C.E.P.M. van de; Greenberg, J.M.; Whittet, D.C.B.

1985-01-01

Detailed calculations of the absorption by interstellar core-mantle particles with mantles of different compositions are compared with observations of the 3μm ice band in the Taurus molecular cloud. The strength and shape of the 3-μm band is shown to be a remarkably good diagnostic of the physical state and evolution of the dust in molecular clouds. The strength of the band is consistent with large fractional H 2 O mantle concentrations, in the range 60-70 per cent, as predicted by theoretical studies of cloud chemistry and as expected from the high oxygen abundance in pre-molecular clouds. (author)

ATLAS 10 GHz electron cyclotron resonance ion source upgrade project

CERN Document Server

Moehs, D P; Pardo, R C; Xie, D

2000-01-01

A major upgrade of the first ATLAS 10 GHz electron cyclotron resonance (ECR) ion source, which began operations in 1987, is in the planning and procurement phase. The new design will convert the old two-stage source into a single-stage source with an electron donor disk and high gradient magnetic field that preserves radial access for solid material feeds and pumping of the plasma chamber. The new magnetic-field profile allows for the possibility of a second ECR zone at a frequency of 14 GHz. An open hexapole configuration, using a high-energy-product Nd-Fe-B magnet material, having an inner diameter of 8.8 cm and pole gaps of 2.4 cm, has been adopted. Models indicate that the field strengths at the chamber wall, 4 cm in radius, will be 9.3 kG along the magnet poles and 5.6 kG along the pole gaps. The individual magnet bars will be housed in austenitic stainless steel, allowing the magnet housing within the aluminum plasma chamber to be used as a water channel for direct cooling of the magnets. Eight solenoid...

Physically-Retrieving Cloud and Thermodynamic Parameters from Ultraspectral IR Measurements

Science.gov (United States)

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

2007-01-01

A physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. 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 relatively high accuracy (i.e., error < 1 km). NPOESS Airborne Sounder Testbed Interferometer (NAST-I) retrievals from the Atlantic-THORPEX Regional Campaign are compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar (CPL). This work was motivated by the need to obtain solutions for atmospheric soundings from infrared radiances observed for every individual field of view, regardless of cloud cover, from future ultraspectral geostationary satellite sounding instruments, such as the Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and the Hyperspectral Environmental Suite (HES). However, this retrieval approach can also be applied to the ultraspectral sounding instruments to fly on Polar satellites, such as the Infrared Atmospheric Sounding Interferometer (IASI) on the European MetOp satellite, the Cross-track Infrared Sounder (CrIS) on the NPOESS Preparatory Project and the following NPOESS series of satellites.

Spatiotemporal High-Resolution Cloud Mapping with a Ground-Based IR Scanner

Directory of Open Access Journals (Sweden)

Benjamin Brede

2017-01-01

Full Text Available The high spatiotemporal variability of clouds requires automated monitoring systems. This study presents a retrieval algorithm that evaluates observations of a hemispherically scanning thermal infrared radiometer, the NubiScope, to produce georeferenced, spatially explicit cloud maps. The algorithm uses atmospheric temperature and moisture profiles and an atmospheric radiative transfer code to differentiate between cloudy and cloudless measurements. In case of a cloud, it estimates its position by using the temperature profile and viewing geometry. The proposed algorithm was tested with 25 cloud maps generated by the Fmask algorithm from Landsat 7 images. The overall cloud detection rate was ranging from 0.607 for zenith angles of 0 to 10° to 0.298 for 50–60° on a pixel basis. The overall detection of cloudless pixels was 0.987 for zenith angles of 30–40° and much more stable over the whole range of zenith angles compared to cloud detection. This proves the algorithm’s capability in detecting clouds, but even better cloudless areas. Cloud-base height was best estimated up to a height of 4000 m compared to ceilometer base heights but showed large deviation above that level. This study shows the potential of the NubiScope system to produce high spatial and temporal resolution cloud maps. Future development is needed for a more accurate determination of cloud height with thermal infrared measurements.

Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA

Science.gov (United States)

Ka, Soohyun; de Wachter, Evelyn; Kaempfer, Niklaus; Oh, Jung Jin

2010-10-01

Water vapor is the strongest natural greenhouse gas in the atmosphere. It is most abundant in the troposphere at low altitudes, due to evaporation at the ocean surface, with maximum values of around 6 g/kg. The amount of water vapor reaches a minimum at tropopause level and increases again in the middle atmosphere through oxidation of methane and vertical transport. Water vapor has both positive and negative effects on global warming, and we need to study how it works on climate change by monitoring water vapor concentration in the middle atmosphere. In this paper, we focus on the 22 GHz ground-based radiometer called SWARA (Seoul Water vapor Radiometer) which has been operated at Sookmyung women's university in Seoul, Korea since Oct. 2006. It is a joint project of the University of Bern, Switzerland, and the Sookmyung Women's University of Seoul, South Korea. The SWARA receives 22.235 GHz emitted from water vapor spontaneously and converts down to 1.5 GHz with +/- 0.5 GHz band width in 61 kHz resolution. To represent 22.235 GHz water vapor spectrum precisely, we need some calibration methods because the signal shows very weak intensity in ~0.1 K on the ground. For SWARA, we have used the balancing and the tipping curve methods for a calibration. To retrieve the water vapor profile, we have applied ARTS and Qpack software. In this paper, we will present the calibration methods and water vapor variation over Seoul for the last 4 years.

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

Science.gov (United States)

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

2011-10-01

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

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Comparing airborne and satellite retrievals of cloud optical thickness and particle effective radius using a spectral radiance ratio technique: two case studies for cirrus and deep convective clouds

Science.gov (United States)

Krisna, Trismono C.; Wendisch, Manfred; Ehrlich, André; Jäkel, Evelyn; Werner, Frank; Weigel, Ralf; Borrmann, Stephan; Mahnke, Christoph; Pöschl, Ulrich; Andreae, Meinrat O.; Voigt, Christiane; Machado, Luiz A. T.

2018-04-01

Solar radiation reflected by cirrus and deep convective clouds (DCCs) was measured by the Spectral Modular Airborne Radiation Measurement System (SMART) installed on the German High Altitude and Long Range Research Aircraft (HALO) during the Mid-Latitude Cirrus (ML-CIRRUS) and the Aerosol, Cloud, Precipitation, and Radiation Interaction and Dynamic of Convective Clouds System - Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modelling and to the Global Precipitation Measurement (ACRIDICON-CHUVA) campaigns. On particular flights, HALO performed measurements closely collocated with overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. A cirrus cloud located above liquid water clouds and a DCC topped by an anvil cirrus are analyzed in this paper. Based on the nadir spectral upward radiance measured above the two clouds, the optical thickness τ and particle effective radius reff of the cirrus and DCC are retrieved using a radiance ratio technique, which considers the cloud thermodynamic phase, the vertical profile of cloud microphysical properties, the presence of multilayer clouds, and the heterogeneity of the surface albedo. For the cirrus case, the comparison of τ and reff retrieved on the basis of SMART and MODIS measurements yields a normalized mean absolute deviation of up to 1.2 % for τ and 2.1 % for reff. For the DCC case, deviations of up to 3.6 % for τ and 6.2 % for reff are obtained. The larger deviations in the DCC case are mainly attributed to the fast cloud evolution and three-dimensional (3-D) radiative effects. Measurements of spectral upward radiance at near-infrared wavelengths are employed to investigate the vertical profile of reff in the cirrus. The retrieved values of reff are compared with corresponding in situ measurements using a vertical weighting method. Compared to the MODIS observations, measurements of SMART provide more information on the

Satellite-derived vertical profiles of temperature and dew point for mesoscale weather forecast

Science.gov (United States)

Masselink, Thomas; Schluessel, P.

1995-12-01

Weather forecast-models need spatially high resolutioned vertical profiles of temperature and dewpoint for their initialisation. These profiles can be supplied by a combination of data from the Tiros-N Operational Vertical Sounder (TOVS) and the imaging Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA polar orbiting sate!- lites. In cloudy cases the profiles derived from TOVS data only are of insufficient accuracy. The stanthrd deviations from radiosonde ascents or numerical weather analyses likely exceed 2 K in temperature and 5Kin dewpoint profiles. It will be shown that additional cloud information as retrieved from AVHIRR allows a significant improvement in theaccuracy of vertical profiles. The International TOVS Processing Package (ITPP) is coupled to an algorithm package called AVHRR Processing scheme Over cLouds, Land and Ocean (APOLLO) where parameters like cloud fraction and cloud-top temperature are determined with higher accuracy than obtained from TOVS retrieval alone. Furthermore, a split-window technique is applied to the cloud-free AVHRR imagery in order to derive more accurate surface temperatures than can be obtained from the pure TOVS retrieval. First results of the impact of AVHRR cloud detection on the quality of the profiles are presented. The temperature and humidity profiles of different retrieval approaches are validated against analyses of the European Centre for Medium-Range Weatherforecasts.

Design of 2.5 GHz broad bandwidth microwave bandpass filter at operating frequency of 10 GHz using HFSS

Science.gov (United States)

Jasim, S. E.; Jusoh, M. A.; Mahmud, S. N. S.; Zamani, A. H.

2018-04-01

Development of low losses, small size and broad bandwidth microwave bandpass filter operating at higher frequencies is an active area of research. This paper presents a new route used to design and simulate microwave bandpass filter using finite element modelling and realized broad bandwidth, low losses, small dimension microwave bandpass filter operating at 10 GHz frequency using return loss method. The filter circuit has been carried out using Computer Aid Design (CAD), Ansoft HFSS software and designed with four parallel couple line model and small dimension (10 × 10 mm2) using LaAlO3 substrate. The response of the microwave filter circuit showed high return loss -50 dB at operating frequency at 10.4 GHz and broad bandwidth of 2.5 GHz from 9.5 to 12 GHz. The results indicate the filter design and simulation using HFSS is reliable and have the opportunity to transfer from lab potential experiments to the industry.

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

Directory of Open Access Journals (Sweden)

Yujun Qiu

2017-01-01

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

Flower elliptical constellation of millimeter-wave radiometers for precipitating cloud monitoring at geostationary scale

Science.gov (United States)

Marzano, F. S.; Cimini, D.; Montopoli, M.; Rossi, T.; Mortari, D.; di Michele, S.; Bauer, P.

2009-04-01

Millimeter-wave observation of the atmospheric parameters is becoming an appealing goal within satellite radiometry applications. The major technological advantage of millimeter-wave (MMW) radiometers is the reduced size of the overall system, for given performances, with respect to microwave sensor. On the other hand, millimeter-wave sounding can exploit window frequencies and various gaseous absorption bands at 50/60 GHz, 118 GHz and 183 GHz. These bands can be used to estimate tropospheric temperature profiles, integrated water vapor and cloud liquid content and, using a differentia spectral mode, light rainfall and snowfall. Millimeter-wave radiometers, for given observation conditions, can also exhibit relatively small field-of-views (FOVs), of the order of some kilometers for low-Earth-orbit (LEO) satellites. However, the temporal resolution of LEO millimeter-wave system observations remains a major drawback with respect to the geostationary-Earth-orbit (GEO) satellites. An overpass every about 12 hours for a single LEO platform (conditioned to a sufficiently large swath of the scanning MMW radiometer) is usually too much when compared with the typical temporal scale variation of atmospheric fields. This feature cannot be improved by resorting to GEO platforms due to their high orbit altitude and consequent degradation of the MMW-sensor FOVs. A way to tackle this impasse is to draw our attention at the regional scale and to focus non-circular orbits over the area of interest, exploiting the concept of micro-satellite flower constellations. The Flower Constellations (FCs) is a general class of elliptical orbits which can be optimized, through genetic algorithms, in order to maximize the revisiting time and the orbital height, ensuring also a repeating ground-track. The constellation concept nicely matches the choice of mini-satellites as a baseline choice, due to their small size, weight (less than 500 kilograms) and relatively low cost (essential when

Observations of electron heating during 28 GHz microwave power application in proto-MPEX

Science.gov (United States)

Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Diem, S. J.; Green, D. L.; Kafle, N.; Rapp, J.; Proto-MPEX Team

2018-02-01

The Prototype Material Plasma Exposure Experiment at the Oak Ridge National Laboratory utilizes a variety of power systems to generate and deliver a high heat flux plasma onto the surface of material targets. In the experiments described here, a deuterium plasma is produced via a ˜100 kW, 13.56 MHz RF helicon source, to which ˜20 kW of 28 GHz microwave power is applied. The electron density and temperature profiles are measured using a Thomson scattering (TS) diagnostic, and indicate that the electron density is centrally peaked. In the core of the plasma column, the electron density is higher than the cut-off density (˜0.9 × 1019 m-3) for the launched mixture of X- and O-mode electron cyclotron heating waves to propagate. TS measurements indicate electron temperature increases from ˜5 eV to ˜20 eV during 28 GHz power application when the neutral deuterium pressure is reduced below 0.13 Pa (˜1 mTorr.).

Subtropical Low Cloud Responses to Central and Eastern Pacific El Nino Events

Science.gov (United States)

Rapp, A. D.; Bennartz, R.; Jiang, J. H.; Kato, S.; Olson, W. S.; Pinker, R. T.; Su, H.; Taylor, P. C.

2014-12-01

The eastern Pacific El Niño event in 2006-2007 and the central Pacific El Niño event during 2009-2010 exhibit opposite responses in the top of atmosphere (TOA) cloud radiative effects. These responses are driven by differences in large-scale circulation that result in significant low cloud anomalies in the subtropical southeastern Pacific. Both the vertical profile of cloud fraction and cloud water content are reduced during the eastern Pacific El Niño; however, the shift in the distribution of cloud characteristics and the physical processes underlying these changes need further analysis. The NASA Energy and Water Cycle Study (NEWS) Clouds and Radiation Working Group will use a synthesis of NEWS data products, A-Train satellite measurements, reanalysis, and modeling approaches to further explore the differences in the low cloud response to changes in the large-scale forcing, as well as try to understand the physical mechanism driving the observed changes in the low clouds for the 2006/07 and 2009/10 distinct El Niño events. The distributions of cloud macrophysical, microphysical, and radiative properties over the southeast Pacific will first be compared for these two events using a combination of MODIS, CloudSat/CALIPSO, and CERES data. Satellite and reanalysis estimates of changes in the vertical temperature and moisture profiles, lower tropospheric stability, winds, and surface heat fluxes are then used to identify the drivers for observed differences in the clouds and TOA radiative effects.

Mitigation of the electron-cloud effect in the PSR and SNS proton storage rings by tailoring the bunch profile

International Nuclear Information System (INIS)

Pivi, M.; Furman, M.A.

2003-01-01

For the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electroncloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

105 GHz Notch Filter Design for Collective Thomson Scattering

DEFF Research Database (Denmark)

Furtula, Vedran; Michelsen, Poul; Leipold, Frank

2011-01-01

A millimeter-wave notch filter with 105-GHz center frequency, >20-GHz passband coverage, and 1-GHz rejection bandwidth has been constructed. The design is based on a fundamental rectangular waveguide with cylindrical cavities coupled by narrow iris gaps, i.e., small elongated holes of negligible...

Entrainment in Laboratory Simulations of Cumulus Cloud Flows

Science.gov (United States)

Narasimha, R.; Diwan, S.; Subrahmanyam, D.; Sreenivas, K. R.; Bhat, G. S.

2010-12-01

A variety of cumulus cloud flows, including congestus (both shallow bubble and tall tower types), mediocris and fractus have been generated in a water tank by simulating the release of latent heat in real clouds. The simulation is achieved through ohmic heating, injected volumetrically into the flow by applying suitable voltages between diametral cross-sections of starting jets and plumes of electrically conducting fluid (acidified water). Dynamical similarity between atmospheric and laboratory cloud flows is achieved by duplicating values of an appropriate non-dimensional heat release number. Velocity measurements, made by laser instrumentation, show that the Taylor entrainment coefficient generally increases just above the level of commencement of heat injection (corresponding to condensation level in the real cloud). Subsequently the coefficient reaches a maximum before declining to the very low values that characterize tall cumulus towers. The experiments also simulate the protected core of real clouds. Cumulus Congestus : Atmospheric cloud (left), simulated laboratory cloud (right). Panels below show respectively total heat injected and vertical profile of heating in the laboratory cloud.

Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

Science.gov (United States)

Drlica-Wagner, Alex; Gomez-Vargas, German A.; Hewitt, John W.; Linden, Tim; Tibaldo, Luigi

2014-01-01

Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (approximately 3 x 10 (sup -26) cubic centimeters per second) for dark matter masses less than or approximately 30 gigaelectronvolts annihilating via the B/B- bar oscillation or tau/antitau channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

Searching for dark matter annihilation in the Smith high-velocity cloud

International Nuclear Information System (INIS)

Drlica-Wagner, Alex; Gómez-Vargas, Germán A.; Hewitt, John W.; Linden, Tim; Tibaldo, Luigi

2014-01-01

Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (∼ 3 × 10 –26 cm 3 s –1 ) for dark matter masses ≲ 30 GeV annihilating via the b b-bar or τ + τ – channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

Searching for dark matter annihilation in the Smith high-velocity cloud

Energy Technology Data Exchange (ETDEWEB)

Drlica-Wagner, Alex [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Gómez-Vargas, Germán A. [Departamento de Fisíca, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Santiago (Chile); Hewitt, John W. [CRESST, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States); Linden, Tim [The Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Tibaldo, Luigi [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)

2014-07-20

Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (∼ 3 × 10{sup –26} cm{sup 3} s{sup –1}) for dark matter masses ≲ 30 GeV annihilating via the b b-bar or τ{sup +}τ{sup –} channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

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

Energy Technology Data Exchange (ETDEWEB)

Frisch, A.S. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C.W.; Snider, J.B. [NOAA Environmental Technology Lab., Boulder, CO (United States); Lenshow, D.H.; Mayer, S.D. [National Center for Atmospheric Research, Boulder, CO (United States)

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.

Fingerprints of a riming event on cloud radar Doppler spectra: observations and modeling

Directory of Open Access Journals (Sweden)

H. Kalesse

2016-03-01

Full Text Available Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW layer. The focus is on the "golden sample" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols – Effects on Clouds and Climate (BAECC field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations.

60 Gbit/s 400 GHz Wireless Transmission

DEFF Research Database (Denmark)

Yu, Xianbin; Asif, Rameez; Piels, Molly

2015-01-01

We experimentally demonstrate a 400 GHz carrier wireless transmission system with real-time capable detection and demonstrate transmission of a 60 Gbit/s signal derived from optical Nyquist channels in a 12.5 GHz ultra-dense wavelength division multiplexing (UD-WDM) grid and carrying QPSK...

High sensitivity broadband 360GHz passive receiver for TeraSCREEN

Science.gov (United States)

Wang, Hui; Oldfield, Matthew; Maestrojuán, Itziar; Platt, Duncan; Brewster, Nick; Viegas, Colin; Alderman, Byron; Ellison, Brian N.

2016-05-01

TeraSCREEN is an EU FP7 Security project aimed at developing a combined active, with frequency channel centered at 360 GHz, and passive, with frequency channels centered at 94, 220 and 360 GHz, imaging system for border controls in airport and commercial ferry ports. The system will include automatic threat detection and classification and has been designed with a strong focus on the ethical, legal and practical aspects of operating in these environments and with the potential threats in mind. Furthermore, both the passive and active systems are based on array receivers with the active system consisting of a 16 element MIMO FMCW radar centered at 360 GHz with a bandwidth of 30 GHz utilizing a custom made direct digital synthesizer. The 16 element passive receiver system at 360 GHz uses commercial Gunn diode oscillators at 90 GHz followed by custom made 90 to 180 GHz frequency doublers supplying the local oscillator for 360 GHz sub-harmonic mixers. This paper describes the development of the passive antenna module, local oscillator chain, frequency mixers and detectors used in the passive receiver array of this system. The complete passive receiver chain is characterized in this paper.

KINEMATIC STRUCTURE OF MOLECULAR GAS AROUND HIGH-MASS YSO, PAPILLON NEBULA, IN N159 EAST IN THE LARGE MAGELLANIC CLOUD: A NEW PERSPECTIVE WITH ALMA

International Nuclear Information System (INIS)

Saigo, Kazuya; Harada, Ryohei; Kawamura, Akiko; Onishi, Toshikazu; Tokuda, Kazuki; Morioka, Yuuki; Nayak, Omnarayani; Meixner, Margaret; Sewiło, Marta; Indebetouw, Remy; Torii, Kazufumi; Ohama, Akio; Hattori, Yusuke; Yamamoto, Hiroaki; Tachihara, Kengo; Minamidani, Tetsuhiro; Inoue, Tsuyoshi; Madden, Suzanne; Lebouteiller, Vianney; Galametz, Maud

2017-01-01

We present the ALMA Band 3 and Band 6 results of 12 CO(2-1), 13 CO(2-1), H30 α recombination line, free–free emission around 98 GHz, and the dust thermal emission around 230 GHz toward the N159 East Giant Molecular Cloud (N159E) in the Large Magellanic Cloud (LMC). LMC is the nearest active high-mass star-forming face-on galaxy at a distance of 50 kpc and is the best target for studing high-mass star formation. ALMA observations show that N159E is the complex of filamentary clouds with the width and length of ∼1 pc and several parsecs. The total molecular mass is 0.92 × 10 5 M ⊙ from the 13 CO(2-1) intensity. N159E harbors the well-known Papillon Nebula, a compact high-excitation H ii region. We found that a YSO associated with the Papillon Nebula has the mass of 35 M ⊙ and is located at the intersection of three filamentary clouds. It indicates that the formation of the high-mass YSO was induced by the collision of filamentary clouds. Fukui et al. reported a similar kinematic structure toward two YSOs in the N159 West region, which are the other YSOs that have the mass of ≳35 M ⊙ . This suggests that the collision of filamentary clouds is a primary mechanism of high-mass star formation. We found a small molecular hole around the YSO in Papillon Nebula with a sub-parsec scale. It is filled by free–free and H30 α emission. The temperature of the molecular gas around the hole reaches ∼80 K. It indicates that this YSO has just started the distruction of parental molecular cloud.

KINEMATIC STRUCTURE OF MOLECULAR GAS AROUND HIGH-MASS YSO, PAPILLON NEBULA, IN N159 EAST IN THE LARGE MAGELLANIC CLOUD: A NEW PERSPECTIVE WITH ALMA

Energy Technology Data Exchange (ETDEWEB)

Saigo, Kazuya; Harada, Ryohei; Kawamura, Akiko [Chile Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Science, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Onishi, Toshikazu; Tokuda, Kazuki; Morioka, Yuuki [Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Nayak, Omnarayani; Meixner, Margaret [The Johns Hopkins University, Department of Physics and Astronomy, 366 Bloomberg Center, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Sewiło, Marta [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Indebetouw, Remy [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Torii, Kazufumi; Ohama, Akio; Hattori, Yusuke; Yamamoto, Hiroaki; Tachihara, Kengo [Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Minamidani, Tetsuhiro [Nobeyama Radio Observatory, 462-2 Nobeyama Minamimaki-mura, Minamisaku-gun, Nagano 384-1305 (Japan); Inoue, Tsuyoshi [Division of Theoretical Astronomy, National Astronomical Observatory (Japan); Madden, Suzanne; Lebouteiller, Vianney [Laboratoire AIM, CEA, Universite Paris VII, IRFU/Service d’Astrophysique, Bat. 709, F-91191 Gif-sur-Yvette (France); Galametz, Maud [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); and others

2017-01-20

We present the ALMA Band 3 and Band 6 results of {sup 12}CO(2-1), {sup 13}CO(2-1), H30 α recombination line, free–free emission around 98 GHz, and the dust thermal emission around 230 GHz toward the N159 East Giant Molecular Cloud (N159E) in the Large Magellanic Cloud (LMC). LMC is the nearest active high-mass star-forming face-on galaxy at a distance of 50 kpc and is the best target for studing high-mass star formation. ALMA observations show that N159E is the complex of filamentary clouds with the width and length of ∼1 pc and several parsecs. The total molecular mass is 0.92 × 10{sup 5} M {sub ⊙} from the {sup 13}CO(2-1) intensity. N159E harbors the well-known Papillon Nebula, a compact high-excitation H ii region. We found that a YSO associated with the Papillon Nebula has the mass of 35 M {sub ⊙} and is located at the intersection of three filamentary clouds. It indicates that the formation of the high-mass YSO was induced by the collision of filamentary clouds. Fukui et al. reported a similar kinematic structure toward two YSOs in the N159 West region, which are the other YSOs that have the mass of ≳35 M {sub ⊙}. This suggests that the collision of filamentary clouds is a primary mechanism of high-mass star formation. We found a small molecular hole around the YSO in Papillon Nebula with a sub-parsec scale. It is filled by free–free and H30 α emission. The temperature of the molecular gas around the hole reaches ∼80 K. It indicates that this YSO has just started the distruction of parental molecular cloud.

The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar

Energy Technology Data Exchange (ETDEWEB)

P Kollias; MA Miller; KB Widener; RT Marchand; TP Ackerman

2005-12-30

The United States (U.S.) Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) operates millimeter wavelength cloud radars (MMCRs) in several climatological regimes. The MMCRs, are the primary observing tool for quantifying the properties of nearly all radiatively important clouds over the ACRF sites. The first MMCR was installed at the ACRF Southern Great Plains (SGP) site nine years ago and its original design can be traced to the early 90s. Since then, several MMCRs have been deployed at the ACRF sites, while no significant hardware upgrades have been performed. Recently, a two-stage upgrade (first C-40 Digital Signal Processors [DSP]-based, and later the PC-Integrated Radar AcQuisition System [PIRAQ-III] digital receiver) of the MMCR signal-processing units was completed. Our future MMCR related goals are: 1) to have a cloud radar system that continues to have high reliability and uptime and 2) to suggest potential improvements that will address increased sensitivity needs, superior sampling and low cost maintenance of the MMCRs. The Traveling Wave Tube (TWT) technology, the frequency (35-GHz), the radio frequency (RF) layout, antenna, the calibration and radar control procedure and the environmental enclosure of the MMCR remain assets for our ability to detect the profile of hydrometeors at all heights in the troposphere at the ACRF sites.

ASTEROID SIZING BY RADIOGALAXY OCCULTATION AT 5 GHZ

Energy Technology Data Exchange (ETDEWEB)

Lehtinen, K.; Muinonen, K.; Poutanen, M. [Finnish Geospatial Research Institute FGI, Geodeetinrinne 2, FI-02430 Masala (Finland); Bach, U. [Max-Planck-Institut für Radioastronomie, Radioobservatorium Effelsberg, Max-Planck-Str. 28, D-53902 Bad Münstereifel-Effelsberg (Germany); Petrov, L., E-mail: kimmo.lehtinen@nls.fi [Astrogeo Center, Falls Church, VA 22043 (United States)

2016-05-10

Stellar occultations by asteroids observed at visual wavelengths have been an important tool for studying the size and shape of asteroids and for revising the orbital parameters of asteroids. At radio frequencies, a shadow of an asteroid on the Earth is dominated by diffraction effects. Here, we show, for the first time, that a single observation of an occultation of a compact radio source at a frequency of 5 GHz can be used to derive the effective size of the occulting object and to derive the distance between the observer and the center of the occultation path on the Earth. The derived diameter of the occulting object, asteroid (115) Thyra, is 75 ± 6 km. The observed occultation profile shows features that cannot be explained by diffraction of a single asteroid.

41 GHz and 10.6 GHz low threshold and low noise InAs/InP quantum dash two-section mode-locked lasers in L band

DEFF Research Database (Denmark)

Dontabactouny, M.; Piron, R.; Klaime, K.

2012-01-01

This paper reports recent results on InAs/InP quantum dash-based, two-section, passively mode-locked lasers pulsing at 41 GHz and 10.6 GHz and emitting at 1.59 mu m at 20 degrees C. The 41-GHz device (1 mm long) starts lasing at 25 mA under uniform injection and the 10.6 GHz (4 mm long) at 71 m...

Arbitrary waveform modulated pulse EPR at 200 GHz

Science.gov (United States)

Kaminker, Ilia; Barnes, Ryan; Han, Songi

2017-06-01

We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.

The ARM Cloud Radar Simulator for Global Climate Models: Bridging Field Data and Climate Models

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuying [Lawrence Livermore National Laboratory, Livermore, California; Xie, Shaocheng [Lawrence Livermore National Laboratory, Livermore, California; Klein, Stephen A. [Lawrence Livermore National Laboratory, Livermore, California; Marchand, Roger [University of Washington, Seattle, Washington; Kollias, Pavlos [Stony Brook University, Stony Brook, New York; Clothiaux, Eugene E. [The Pennsylvania State University, University Park, Pennsylvania; Lin, Wuyin [Brookhaven National Laboratory, Upton, New York; Johnson, Karen [Brookhaven National Laboratory, Upton, New York; Swales, Dustin [CIRES and NOAA/Earth System Research Laboratory, Boulder, Colorado; Bodas-Salcedo, Alejandro [Met Office Hadley Centre, Exeter, United Kingdom; Tang, Shuaiqi [Lawrence Livermore National Laboratory, Livermore, California; Haynes, John M. [Cooperative Institute for Research in the Atmosphere/Colorado State University, Fort Collins, Colorado; Collis, Scott [Argonne National Laboratory, Argonne, Illinois; Jensen, Michael [Brookhaven National Laboratory, Upton, New York; Bharadwaj, Nitin [Pacific Northwest National Laboratory, Richland, Washington; Hardin, Joseph [Pacific Northwest National Laboratory, Richland, Washington; Isom, Bradley [Pacific Northwest National Laboratory, Richland, Washington

2018-01-01

Clouds play an important role in Earth’s radiation budget and hydrological cycle. However, current global climate models (GCMs) have had difficulties in accurately simulating clouds and precipitation. To improve the representation of clouds in climate models, it is crucial to identify where simulated clouds differ from real world observations of them. This can be difficult, since significant differences exist between how a climate model represents clouds and what instruments observe, both in terms of spatial scale and the properties of the hydrometeors which are either modeled or observed. To address these issues and minimize impacts of instrument limitations, the concept of instrument “simulators”, which convert model variables into pseudo-instrument observations, has evolved with the goal to improve and to facilitate the comparison of modeled clouds with observations. Many simulators have (and continue to be developed) for a variety of instruments and purposes. A community satellite simulator package, the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP; Bodas-Salcedo et al. 2011), contains several independent satellite simulators and is being widely used in the global climate modeling community to exploit satellite observations for model cloud evaluation (e.g., Klein et al. 2013; Zhang et al. 2010). This article introduces a ground-based cloud radar simulator developed by the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program for comparing climate model clouds with ARM observations from its vertically pointing 35-GHz radars. As compared to CloudSat radar observations, ARM radar measurements occur with higher temporal resolution and finer vertical resolution. This enables users to investigate more fully the detailed vertical structures within clouds, resolve thin clouds, and quantify the diurnal variability of clouds. Particularly, ARM radars are sensitive to low-level clouds, which are

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

Science.gov (United States)

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

2017-11-01

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

Improving Mixed-phase Cloud Parameterization in Climate Model with the ACRF Measurements

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhien [Univ. of Wyoming, Laramie, WY (United States)

2016-12-13

Mixed-phase cloud microphysical and dynamical processes are still poorly understood, and their representation in GCMs is a major source of uncertainties in overall cloud feedback in GCMs. Thus improving mixed-phase cloud parameterizations in climate models is critical to reducing the climate forecast uncertainties. This study aims at providing improved knowledge of mixed-phase cloud properties from the long-term ACRF observations and improving mixed-phase clouds simulations in the NCAR Community Atmosphere Model version 5 (CAM5). The key accomplishments are: 1) An improved retrieval algorithm was developed to provide liquid droplet concentration for drizzling or mixed-phase stratiform clouds. 2) A new ice concentration retrieval algorithm for stratiform mixed-phase clouds was developed. 3) A strong seasonal aerosol impact on ice generation in Arctic mixed-phase clouds was identified, which is mainly attributed to the high dust occurrence during the spring season. 4) A suite of multi-senor algorithms was applied to long-term ARM observations at the Barrow site to provide a complete dataset (LWC and effective radius profile for liquid phase, and IWC, Dge profiles and ice concentration for ice phase) to characterize Arctic stratiform mixed-phase clouds. This multi-year stratiform mixed-phase cloud dataset provides necessary information to study related processes, evaluate model stratiform mixed-phase cloud simulations, and improve model stratiform mixed-phase cloud parameterization. 5). A new in situ data analysis method was developed to quantify liquid mass partition in convective mixed-phase clouds. For the first time, we reliably compared liquid mass partitions in stratiform and convective mixed-phase clouds. Due to the different dynamics in stratiform and convective mixed-phase clouds, the temperature dependencies of liquid mass partitions are significantly different due to much higher ice concentrations in convective mixed phase clouds. 6) Systematic evaluations

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

Science.gov (United States)

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

Earth cloud, aerosol, and radiation explorer optical payload development status

Science.gov (United States)

Hélière, A.; Wallace, K.; Pereira do Carmo, J.; Lefebvre, A.

2017-09-01

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop as part of ESA's Living Planet Programme, the third Earth Explorer Core Mission, EarthCARE, with the ojective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth's atmosphere. EarthCARE payload consists of two active and two passive instruments: an ATmospheric LIDar (ATLID), a Cloud Profiling Radar (CPR), a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer (BBR). The four instruments data are processed individually and in a synergetic manner to produce a large range of products, which include vertical profiles of aerosols, liquid water and ice, observations of cloud distribution and vertical motion within clouds, and will allow the retrieval of profiles of atmospheric radiative heating and cooling. MSI is a compact instrument with a 150 km swath providing 500 m pixel data in seven channels, whose retrieved data will give context to the active instrument measurements, as well as providing cloud and aerosol information. BBR measures reflected solar and emitted thermal radiation from the scene. Operating in the UV range at 355 nm, ATLID provides atmospheric echoes from ground to an altitude of 40 km. Thanks to a high spectral resolution filtering, the lidar is able to separate the relative contribution of aerosol and molecular scattering, which gives access to aerosol optical depth. Co-polarised and cross-polarised components of the Mie scattering contribution are measured on dedicated channels. This paper will provide a description of the optical payload implementation, the design and characterisation of the instruments.

GHz-rate optical parametric amplifier in hydrogenated amorphous silicon

International Nuclear Information System (INIS)

Wang, Ke-Yao; Foster, Amy C

2015-01-01

We demonstrate optical parametric amplification operating at GHz-rates at telecommunications wavelengths using a hydrogenated amorphous silicon waveguide through the nonlinear optical process of four-wave mixing. We investigate how the parametric amplification scales with repetition rate. The ability to achieve amplification at GHz-repetition rates shows hydrogenated amorphous silicon’s potential for telecommunication applications and a GHz-rate optical parametric oscillator. (paper)

Visualizing nD Point Clouds as Topological Landscape Profiles to Guide Local Data Analysis

Energy Technology Data Exchange (ETDEWEB)

Oesterling, Patrick [Univ. of Leipzig (Germany). Computer Science Dept.; Heine, Christian [Univ. of Leipzig (Germany). Computer Science Dept.; Federal Inst. of Technology (ETH), Zurich (Switzerland). Dept. of Computer Science; Weber, Gunther H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division; Scheuermann, Gerik [Univ. of Leipzig (Germany). Computer Science Dept.

2012-05-04

Analyzing high-dimensional point clouds is a classical challenge in visual analytics. Traditional techniques, such as projections or axis-based techniques, suffer from projection artifacts, occlusion, and visual complexity.We propose to split data analysis into two parts to address these shortcomings. First, a structural overview phase abstracts data by its density distribution. This phase performs topological analysis to support accurate and non-overlapping presentation of the high-dimensional cluster structure as a topological landscape profile. Utilizing a landscape metaphor, it presents clusters and their nesting as hills whose height, width, and shape reflect cluster coherence, size, and stability, respectively. A second local analysis phase utilizes this global structural knowledge to select individual clusters or point sets for further, localized data analysis. Focusing on structural entities significantly reduces visual clutter in established geometric visualizations and permits a clearer, more thorough data analysis. In conclusion, this analysis complements the global topological perspective and enables the user to study subspaces or geometric properties, such as shape.

Ocean Profile Measurements During the Seasonal Ice Zone Reconnaissance Surveys Ocean Profiles

Science.gov (United States)

2017-01-01

converted to engineering units by the TSK Converter and recorded on the laptop computer . A backup recording of the raw received signal is made with...S, V, internal waves/mixing Clouds and the Evolution of the SIZ in Beaufort and Chukchi Seas Schweiger Lindsay, Zhang, Maslanik, Lawrence...Atmospheric profiles (dropsondes, micro-aircraft), cloud top/base heights UpTempO buoys for understanding and prediction…. Steele UpTempO buoy

A 31 GHz Survey of Low-Frequency Selected Radio Sources

Science.gov (United States)

Mason, B. S.; Weintraub, L.; Sievers, J.; Bond, J. R.; Myers, S. T.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.

2009-10-01

The 100 m Robert C. Byrd Green Bank Telescope and the 40 m Owens Valley Radio Observatory telescope have been used to conduct a 31 GHz survey of 3165 known extragalactic radio sources over 143 deg2 of the sky. Target sources were selected from the NRAO VLA Sky Survey in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4 GHz flux densities of 3-10 mJy. The resulting 31 GHz catalogs are presented in full online. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4-31 GHz spectral indices of these sources, we find a mean 31-1.4 GHz flux ratio of 0.110 ± 0.003 corresponding to a spectral index of α = -0.71 ± 0.01 (S ν vprop να) 9.0% ± 0.8% of sources have α > - 0.5 and 1.2% ± 0.2% have α > 0. By combining this spectral-index distribution with 1.4 GHz source counts, we predict 31 GHz source counts in the range 1 mJy S 31) = (16.7 ± 1.7) deg-2(S 31/1 mJy)-0.80±0.07. We also assess the contribution of mJy-level (S 1.4 GHz < 3.4 mJy) radio sources to the 31 GHz cosmic microwave background power spectrum, finding a mean power of ell(ell + 1)C src ell/(2π) = 44 ± 14 μK2 and a 95% upper limit of 80 μK2 at ell = 2500. Including an estimated contribution of 12 μK2 from the population of sources responsible for the turn-up in counts below S 1.4 GHz = 1 mJy, this amounts to 21% ± 7% of what is needed to explain the CBI high-ell excess signal, 275 ± 63 μK2. These results are consistent with other measurements of the 31 GHz point-source foreground.

Studies of dynamics of electron clouds in STAR silicon drift detectors

CERN Document Server

Bellwied, R; Brandon, N; Caines, H; Chen, W; Dimassimo, D; Dyke, H; Hall, J R; Hardtke, D; Hoffmann, G W; Humanic, T J; Kotova, A I; Kotov, I V; Kraner, H W; Li, Z; Lynn, D; Middelkamp, P; Ott, G; Pandey, S U; Pruneau, C A; Rykov, V L; Schambach, J; Sedlmeir, J; Sugarbaker, E R; Takahashi, J; Wilson, W K

2000-01-01

The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measured. Two methods were used to measure the cloud size. The method of cumulative functions was used to extract the electron cloud profiles. Another method obtains the cloud width from measurements of the charge collected on a single anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Experimental results agreed with theoretical expectations.

A New 95 GHz Methanol Maser Catalog. I. Data

Energy Technology Data Exchange (ETDEWEB)

Yang, Wenjin; Xu, Ye; Lu, Dengrong; Ju, Binggang; Li, Yingjie [Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China); Chen, Xi [Center for Astrophysics, GuangZhou University, Guangzhou 510006 (China); Ellingsen, Simon P., E-mail: wjyang@pmo.ac.cn, E-mail: xuye@pmo.ac.cn, E-mail: chenxi@shao.ac.cn [School of Physical Sciences, University of Tasmania, Hobart, Tasmania (Australia)

2017-08-01

The Purple Mountain Observatory 13.7 m radio telescope has been used to search for 95 GHz (8{sub 0}–7{sub 1}A{sup +}) class I methanol masers toward 1020 Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We have compared the line width of the methanol and HCO{sup +} thermal emission in all of the methanol detections, and on that basis, we find that 205 of the 213 detections are very likely to be masers. This corresponds to an overall detection rate of 95 GHz methanol masers toward our BGPS sample of 20%. Of the 205 detected masers, 144 (70%) are new discoveries. Combining our results with those of previous 95 GHz methanol maser searches, a total of 481 95 GHz methanol masers are now known. We have compiled a catalog listing the locations and properties of all known 95 GHz methanol masers.

77 FR 45558 - 4.9 GHz Band

Science.gov (United States)

2012-08-01

..., our rules currently require 4.9 GHz licensees to ``cooperate in the selection and use of channels in... directional and thus can be represented as narrow paths on a coordination map; in contrast, they note, the low-power, less- directional, geographically-dispersed links in a 4.9 GHz network must be represented as a...

Accomplish the Application Area in Cloud Computing

OpenAIRE

Bansal, Nidhi; Awasthi, Amit

2012-01-01

In the cloud computing application area of accomplish, we find the fact that cloud computing covers a lot of areas are its main asset. At a top level, it is an approach to IT where many users, some even from different companies get access to shared IT resources such as servers, routers and various file extensions, instead of each having their own dedicated servers. This offers many advantages like lower costs and higher efficiency. Unfortunately there have been some high profile incidents whe...

STAR FORMATION IN THE MOLECULAR CLOUD ASSOCIATED WITH THE MONKEY HEAD NEBULA: SEQUENTIAL OR SPONTANEOUS?

Energy Technology Data Exchange (ETDEWEB)

Chibueze, James O.; Imura, Kenji; Omodaka, Toshihiro; Handa, Toshihiro; Kamezaki, Tatsuya; Yamaguchi, Yoshiyuki [Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Nagayama, Takumi; Sunada, Kazuyoshi [Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Fujisawa, Kenta [Department of Physics and Informatics, Faculty of Science, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512 (Japan); Nakano, Makoto [Faculty of Education and Welfare Science, Oita University, Oita 870-1192 (Japan); Sekido, Mamoru, E-mail: james@milkyway.sci.kagoshima-u.ac.jp [Kashima Space Research Center, National Institute of Information and Communications Technology, 893-1 Hirai, Kashima, Ibaraki 314-8501 (Japan)

2013-01-01

We mapped the (1,1), (2,2), and (3,3) lines of NH{sub 3} toward the molecular cloud associated with the Monkey Head Nebula (MHN) with a 1.'6 angular resolution using a Kashima 34 m telescope operated by the National Institute of Information and Communications Technology (NICT). The kinetic temperature of the molecular gas is 15-30 K in the eastern part and 30-50 K in the western part. The warmer gas is confined to a small region close to the compact H II region S252A. The cooler gas is extended over the cloud even near the extended H II region, the MHN. We made radio continuum observations at 8.4 GHz using the Yamaguchi 32 m radio telescope. The resultant map shows no significant extension from the H{alpha} image. This means that the molecular cloud is less affected by the MHN, suggesting that the molecular cloud did not form by the expanding shock of the MHN. Although the spatial distribution of the Wide-field Infrared Survey Explorer and Two Micron All Sky Survey point sources suggests that triggered low- and intermediate-mass star formation took place locally around S252A, but the exciting star associated with it should be formed spontaneously in the molecular cloud.

INDICATORS FOR CLUSTER SURVIVABILITY IN A DISPERSING CLOUD

International Nuclear Information System (INIS)

Chen, H.-C.; Ko, C.-M.

2009-01-01

We use N-body simulations to survey the response of embedded star clusters to the dispersal of their parent molecular cloud. The final stages of the clusters can be divided into three classes: the cluster (1) is destroyed, (2) has a loose structure, and (3) has a compact core. We are interested in three of the governing parameters of the parent cloud: (1) the mass, (2) the size, and (3) the dispersing rate. It is known that the final stage of the cluster is well correlated with the star formation efficiency (SFE) for systems with the same cluster and cloud profile. We deem that the SFE alone is not enough to address systems with clouds of different sizes. Our result shows that the initial cluster-cloud mass ratio at a certain Lagrangian radius and the initial kinetic energy are better indicators for the survivability of embedded clusters.

A 1.8 GHz Voltage-Controlled Oscillator using CMOS Technology

Science.gov (United States)

Maisurah, M. H. Siti; Emran, F. Nazif; Norman Fadhil, Idham M.; Rahim, A. I. Abdul; Razman, Y. Mohamed

2011-05-01

A Voltage-Controlled Oscillator (VCO) for 1.8 GHz application has been designed using a combination of both 0.13 μm and 0.35 μm CMOS technology. The VCO has a large tuning range, which is from 1.39 GHz to 1.91 GHz, using a control voltage from 0 to 3V. The VCO exhibits a low phase-noise at 1.8 GHz which is around -119.8dBc/Hz at a frequency offset of 1 MHz.

Remote measurement of atmospheric temperature profiles in clouds with rotational Raman lidar; Fernmessung atmosphaerischer Temperaturprofile in Wolken mit Rotations-Raman-Lidar

Energy Technology Data Exchange (ETDEWEB)

Behrendt, A. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Physikalische und Chemische Analytik

2000-07-01

The development of a lidar receiver for remote measurements of atmospheric temperature profiles with the rotational Raman method is described. By a new receiver concept, this instrument allowed for the first time remote temperature measurements without any perturbation by the presence of clouds up to a backscatter ratio of 45. In addition, high efficiency of the spectral separation of atmospheric backscatter signals leads to improved measurement resolution: the minimum integration time needed for a statistical uncertainty < {+-}1 K at, e.g., 10 km height and 960 m height resolution is only 5 minutes. The measurement range extends to over 45 km altitude. Results of field campaigns obtained with the instrument are presented and discussed. In winter 1997/98, the instrument was transferred with the GKSS Raman lidar to Esrange (67.9 N, 21.1 E) in northern Sweden, where pioneering remote measurements of local temperatures in orographically induced polar stratospheric clouds could be carried out. (orig.)

A low noise 665 GHz SIS quasi-particle waveguide receiver

Science.gov (United States)

Kooi, J. W.; Walker, C. K.; Leduc, H. G.; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

1993-01-01

Recent results on a 565-690 GHz SIS heterodyne receiver employing a 0.36 micron(sup 2) Nb/AlOx/Nb SIS tunnel junction with high quality circular non-contacting back short and E-plane tuners in a full height wave guide mount are reported. No resonant tuning structures were incorporated in the junction design at this time, even though such structures are expected to help the performance of the receiver. The receiver operates to at least the gap frequency of Niobium, approximately 680 GHz. Typical receiver noise temperatures from 565-690 GHz range from 160K to 230K with a best value of 185K DSB at 648 GHz. With the mixer cooled from 4.3K to 2K the measured receiver noise temperatures decreased by approximately 15 percent, giving roughly 180K DSB from 660 to 680 GHz. The receiver has a full 1 GHz IF pass band and was successfully installed at the Caltech Submillimeter Observatory in Hawaii.

Magnetic films for GHz applications (abstract)

International Nuclear Information System (INIS)

Korenivski, V.; van Dover, R.B.

1997-01-01

Tremendous growth of the communications industry and the increasingly high demand for low-cost light-weight/small-size products drive technology to designs with a high degree of integration. In particular, planar inductors used in integrated circuits with significantly improved inductance per unit area characteristics are needed for further miniaturization of cellular phones operating at 0.95 and 1.9 GHz. Little has been done, however, to use magnetic films to improve the performance and/or reduce size of planar magnetic flux devices. The successful thin-film material would have a high ferromagnetic resonance (FMR) frequency (well above the operating frequency of the device), large permaeability, and low magnetic loss, and very importantly be technologically attractive, i.e., be process compatible with IC technology and have as few preparation steps as possible. Here, we report on fabrication of metallic ferromagnetic films of CoNbZr, CoNbZr/AlN mulitilayered laminates, and exchange-biased structures suitable for GHz applications. Lamination of CoNbZr with thin insulating layers of AlN is shown to significantly improve the microstructure and dc magnetic properties of the films having thicknesses >0.2 μm, as well as to be effective in suppressing eddy current losses at frequencies up to 1 endash 2 GHz. We use exchange biasing to increase the FMR frequency of soft CoNbZr. In-plane unidirectional anisotropy fields of ∼50 Oe are achieved, which result in FMR frequencies >2 GHz. Permeability values of ∼200 with quality factors of ∼10 at 1 GHz are demonstrated. The films are deposited at room temperature and require no postdeposition processing. Application of these films in planar inductors is discussed.copyright 1997 American Institute of Physics

Analysis of cirrus cloud spectral signatures in the far infrared

International Nuclear Information System (INIS)

Maestri, T.; Rizzi, R.; Tosi, E.; Veglio, P.; Palchetti, L.; Bianchini, G.; Di Girolamo, P.; Masiello, G.; Serio, C.; Summa, D.

2014-01-01

This paper analyses high spectral resolution downwelling radiance measurements in the far infrared in the presence of cirrus clouds taken by the REFIR-PAD interferometer, deployed at 3500 m above the sea level at the Testa Grigia station (Italy), during the Earth COoling by WAter vapouR emission (ECOWAR) campaign. Atmospheric state and cloud geometry are characterised by the co-located millimeter-wave spectrometer GBMS and by radiosonde profile data, an interferometer (I-BEST) and a Raman lidar system deployed at a nearby location (Cervinia). Cloud optical depth and effective diameter are retrieved from REFIR-PAD data using a limited number of channels in the 820–960 cm −1 interval. The retrieved cloud parameters are the input data for simulations covering the 250–1100 cm −1 band in order to test our ability to reproduce the REFIR-PAD spectra in the presence of ice clouds. Inverse and forward simulations are based on the same radiative transfer code. A priori information concerning cloud ice vertical distribution is used to better constrain the simulation scheme and an analysis of the degree of approximation of the phase function within the radiative transfer codes is performed to define the accuracy of computations. Simulation-data residuals over the REFIR-PAD spectral interval show an excellent agreement in the window region, but values are larger than total measurement uncertainties in the far infrared. Possible causes are investigated. It is shown that the uncertainties related to the water vapour and temperature profiles are of the same order as the sensitivity to the a priori assumption on particle habits for an up-looking configuration. In case of a down-looking configuration, errors due to possible incorrect description of the water vapour profile would be drastically reduced. - Highlights: • We analyze down-welling spectral radiances in the far infrared (FIR) spectrum. • Discuss the scattering in the fir and the ice crystals phase function

Optical spectra of radio planetary nebulae in the large Magellanic Cloud

Directory of Open Access Journals (Sweden)

Payne J.L.

2008-01-01

Full Text Available We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe in the Large Magellanic Cloud (LMC. Originally found in Australia Telescope Compact Array (ATCA LMC surveys at 1.4, 4.8 and 8.64 GHz and confirmed by new high resolution ATCA images at 6 and 3 cm (4' /2' , these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC. Their spectra were obtained using the Radcliff 1.9-meter telescope in Sutherland (South Africa. All of the optical PNe and radio candidates are within 2' and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8 Mfi, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB phase or prior. We also identify a sub-population (33% of radio PNe candidates with prominent ionized iron emission lines.

Comparison of cloud top heights derived from FY-2 meteorological satellites with heights derived from ground-based millimeter wavelength cloud radar

Science.gov (United States)

Wang, Zhe; Wang, Zhenhui; Cao, Xiaozhong; Tao, Fa

2018-01-01

Clouds are currently observed by both ground-based and satellite remote sensing techniques. Each technique has its own strengths and weaknesses depending on the observation method, instrument performance and the methods used for retrieval. It is important to study synergistic cloud measurements to improve the reliability of the observations and to verify the different techniques. The FY-2 geostationary orbiting meteorological satellites continuously observe the sky over China. Their cloud top temperature product can be processed to retrieve the cloud top height (CTH). The ground-based millimeter wavelength cloud radar can acquire information about the vertical structure of clouds-such as the cloud base height (CBH), CTH and the cloud thickness-and can continuously monitor changes in the vertical profiles of clouds. The CTHs were retrieved using both cloud top temperature data from the FY-2 satellites and the cloud radar reflectivity data for the same time period (June 2015 to May 2016) and the resulting datasets were compared in order to evaluate the accuracy of CTH retrievals using FY-2 satellites. The results show that the concordance rate of cloud detection between the two datasets was 78.1%. Higher consistencies were obtained for thicker clouds with larger echo intensity and for more continuous clouds. The average difference in the CTH between the two techniques was 1.46 km. The difference in CTH between low- and mid-level clouds was less than that for high-level clouds. An attenuation threshold of the cloud radar for rainfall was 0.2 mm/min; a rainfall intensity below this threshold had no effect on the CTH. The satellite CTH can be used to compensate for the attenuation error in the cloud radar data.

CloudSat 2C-ICE product update with a new Ze parameterization in lidar-only region.

Science.gov (United States)

Deng, Min; Mace, Gerald G; Wang, Zhien; Berry, Elizabeth

2015-12-16

The CloudSat 2C-ICE data product is derived from a synergetic ice cloud retrieval algorithm that takes as input a combination of CloudSat radar reflectivity ( Z e ) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation lidar attenuated backscatter profiles. The algorithm uses a variational method for retrieving profiles of visible extinction coefficient, ice water content, and ice particle effective radius in ice or mixed-phase clouds. Because of the nature of the measurements and to maintain consistency in the algorithm numerics, we choose to parameterize (with appropriately large specification of uncertainty) Z e and lidar attenuated backscatter in the regions of a cirrus layer where only the lidar provides data and where only the radar provides data, respectively. To improve the Z e parameterization in the lidar-only region, the relations among Z e , extinction, and temperature have been more thoroughly investigated using Atmospheric Radiation Measurement long-term millimeter cloud radar and Raman lidar measurements. This Z e parameterization provides a first-order estimation of Z e as a function extinction and temperature in the lidar-only regions of cirrus layers. The effects of this new parameterization have been evaluated for consistency using radiation closure methods where the radiative fluxes derived from retrieved cirrus profiles compare favorably with Clouds and the Earth's Radiant Energy System measurements. Results will be made publicly available for the entire CloudSat record (since 2006) in the most recent product release known as R05.

Global vertical mass transport by clouds - A two-dimensional model study

International Nuclear Information System (INIS)

Olofsson, Mats

1988-05-01

A two-dimensional global dispersion model, where vertical transport in the troposphere carried out by convective as well as by frontal cloud systems is explicitly treated, is developed from an existing diffusion model. A parameterization scheme for the cloud transport, based on global cloud statistics, is presented. The model has been tested by using Kr-85, Rn-222 and SO 2 as tracers. Comparisons have been made with observed distributions of these tracers, but also with model results without the cloud transport, using eddy diffusion as the primary means of vertical transport. The model results indicate that for trace species with a turnover time of days to weeks, the introduction of cloud-transport gives much more realistic simulations of their vertical distribution. Layers of increased mixing ratio with height, which can be found in real atmosphere, are reproduced in our cloud-transport model profiles, but can never be simulated with a pure eddy diffusion model. The horizontal transport in the model, by advection and eddy diffusion, gives a realistic distribution between the hemispheres of the more long-lived tracers (Kr-85). A combination of vertical transport by convective and frontal cloud systems is shown to improve the model simulations, compared to limiting it to convective transport only. The importance of including cumulus clouds in the convective transport scheme, in addition to the efficient transport by cumulonimbus clouds, is discussed. The model results are shown to be more sensitive to the vertical detrainment distribution profile than to the absolute magnitude of the vertical mass transport. The scavenging processes for SO 2 are parameterized without the introduction of detailed chemistry. An enhanced removal, due to the increased contact with droplets in the in-cloud lifting process, is introduced in the model. (author)

Space-borne clear air lidar measurements in the presence of broken cloud

Directory of Open Access Journals (Sweden)

I. Astin

Full Text Available A number of proposed lidar systems, such as ESA’s AEOLUS (formerly ADM and DIAL missions (e.g. WALES are to make use of lidar returns in clear air. However, on average, two-thirds of the globe is covered in cloud. Hence, there is a strong likelihood that data from these instruments may be contaminated by cloud. Similarly, optically thick cloud may not be penetrated by a lidar pulse, resulting in unobservable regions that are overshadowed by the cloud. To address this, it is suggested, for example, in AEOLUS, that a number of consecutive short sections of lidar data (between 1 and 3.5 km in length be tested for cloud contamination or for overshadowing and only those that are unaffected by cloud be used to derive atmospheric profiles. The prob-ability of obtaining profiles to near ground level using this technique is investigated both analytically and using UV air-borne lidar data recorded during the CLARE’98 campaign. These data were measured in the presence of broken cloud on a number of flights over southern England over a four-day period and were chosen because the lidar used has the same wavelength, footprint and could match the along-track spacing of the proposed AEOLUS lidar.

Key words. Atmospheric composition and structure (aerosols and particles Meteorology and atmospheric dynamics (instruments and techniques; general circulation

3D Cloud Field Prediction using A-Train Data and Machine Learning Techniques

Science.gov (United States)

Johnson, C. L.

2017-12-01

Validation of cloud process parameterizations used in global climate models (GCMs) would greatly benefit from observed 3D cloud fields at the size comparable to that of a GCM grid cell. For the highest resolution simulations, surface grid cells are on the order of 100 km by 100 km. CloudSat/CALIPSO data provides 1 km width of detailed vertical cloud fraction profile (CFP) and liquid and ice water content (LWC/IWC). This work utilizes four machine learning algorithms to create nonlinear regressions of CFP, LWC, and IWC data using radiances, surface type and location of measurement as predictors and applies the regression equations to off-track locations generating 3D cloud fields for 100 km by 100 km domains. The CERES-CloudSat-CALIPSO-MODIS (C3M) merged data set for February 2007 is used. Support Vector Machines, Artificial Neural Networks, Gaussian Processes and Decision Trees are trained on 1000 km of continuous C3M data. Accuracy is computed using existing vertical profiles that are excluded from the training data and occur within 100 km of the training data. Accuracy of the four algorithms is compared. Average accuracy for one day of predicted data is 86% for the most successful algorithm. The methodology for training the algorithms, determining valid prediction regions and applying the equations off-track is discussed. Predicted 3D cloud fields are provided as inputs to the Ed4 NASA LaRC Fu-Liou radiative transfer code and resulting TOA radiances compared to observed CERES/MODIS radiances. Differences in computed radiances using predicted profiles and observed radiances are compared.

Cloud Infrastructure & Applications - CloudIA

Science.gov (United States)

Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

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

A Variational Method to Retrieve the Extinction Profile in Liquid Clouds Using Multiple Field-of-View Lidar

Science.gov (United States)

Pounder, Nicola L.; Hogan, Robin J.; Varnai, Tamas; Battaglia, Alessandro; Cahalan, Robert F.

2011-01-01

While liquid clouds playa very important role in the global radiation budget, it's been very difficult to remotely determine their internal cloud structure. Ordinary lidar instruments (similar to radars but using visible light pulses) receive strong signals from such clouds, but the information is limited to a thin layer near the cloud boundary. Multiple field-of-view (FOV) lidars offer some new hope as they are able to isolate photons that were scattered many times by cloud droplets and penetrated deep into a cloud before returning to the instrument. Their data contains new information on cloud structure, although the lack of fast simulation methods made it challenging to interpret the observations. This paper describes a fast new technique that can simulate multiple-FOV lidar signals and can even estimate the way the signals would change in response to changes in cloud properties-an ability that allows quick refinements in our initial guesses of cloud structure. Results for a hypothetical airborne three-FOV lidar suggest that this approach can help determine cloud structure for a deeper layer in clouds, and can reliably determine the optical thickness of even fairly thick liquid clouds. The algorithm is also applied to stratocumulus observations by the 8-FOV airborne "THOR" lidar. These tests demonstrate that the new method can determine the depth to which a lidar provides useful information on vertical cloud structure. This work opens the way to exploit data from spaceborne lidar and radar more rigorously than has been possible up to now.

InP MMIC Chip Set for Power Sources Covering 80-170 GHz

Science.gov (United States)

Ngo, Catherine

2001-01-01

We will present a Monolithic Millimeter-wave Integrated Circuit (MMIC) chip set which provides high output-power sources for driving diode frequency multipliers into the terahertz range. The chip set was fabricated at HRL Laboratories using a 0.1-micrometer gate-length InAlAs/InGaAs/InP high electron mobility transistor (HEMT) process, and features transistors with an f(sub max) above 600 GHz. The HRL InP HEMT process has already demonstrated amplifiers in the 60-200 GHz range. In this paper, these high frequency HEMTs form the basis for power sources up to 170 GHz. A number of state-of-the-art InP HEMT MMICs will be presented. These include voltage-controlled and fixed-tuned oscillators, power amplifiers, and an active doubler. We will first discuss an 80 GHz voltage-controlled oscillator with 5 GHz of tunability and at least 17 mW of output power, as well as a 120 GHz oscillator providing 7 mW of output power. In addition, we will present results of a power amplifier which covers the full WRIO waveguide band (75-110 GHz), and provides 40-50 mW of output power. Furthermore, we will present an active doubler at 164 GHz providing 8% bandwidth, 3 mW of output power, and an unprecedented 2 dB of conversion loss for an InP HEMT MMIC at this frequency. Finally, we will demonstrate a power amplifier to cover 140-170 GHz with 15-25 mW of output power and 8 dB gain. These components can form a power source in the 155-165 GHz range by cascading the 80 GHz oscillator, W-band power amplifier, 164 GHz active doubler and final 140-170 GHz power amplifier for a stable, compact local oscillator subsystem, which could be used for atmospheric science or astrophysics radiometers.

Measurement of the Arctic UTLS composition in presence of clouds using millimetre-wave heterodyne spectroscopy

Directory of Open Access Journals (Sweden)

E. Castelli

2013-10-01

Full Text Available MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding is a limb viewing instrument working in the millimetre and sub-millimetre spectral regions (from 294 to 349 GHz. The scientific rationale of MARSCHALS is the study of the Upper Troposphere and Lower Stratosphere region. In March 2010 MARSCHALS was deployed on-board the M-55 Geophysica stratospheric aircraft during the PREMIER(PRocess Exploration through Measurements of Infrared and millimetre-wave Emitted Radiation-Ex field campaign. From the campaign base at Kiruna, Sweden, a research flight to investigate the Arctic atmosphere was conducted. For the first time the instrument fully exploited the three spectral bands. In this paper, we present results of the analysis of MARSCHALS measurements acquired during the PREMIER-Ex flight as processed by the Millimetre-wave Atmospheric Retrieval Code. For the second time after the SCOUT-O3 flight in 2005, MARSCHALS measured vertical distributions of temperature, water vapour, ozone and nitric acid over an altitude range of 4 to 24 km. In addition, vertical profiles of carbon monoxide and nitrous oxide were obtained for the first time. The measurements were performed in clear sky conditions and in presence of low and high altitude clouds (that were able to obscure measurements in the middle infrared spectroscopic region and some information about thick clouds were extracted from the data. The capabilities to derive information on upper tropospheric and lower stratospheric vertical profiles of temperature and minor constituents from millimetre-wave limb sounding observations in the northern polar region are presented and discussed for each of the individual targets. The results of MARSCHALS data analysis contributed to demonstrate the scientific relevance and technical feasibility of millimetre-wave limb-sounding of the UTLS proposed for the ESA Earth Explorer 7 candidate Core Mission PREMIER

A study of 60 GHz intersatellite link applications

Science.gov (United States)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

A study of 60 GHz intersatellite link applications

Science.gov (United States)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

1983-01-01

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

The 30/20 GHz communications system functional requirements

Science.gov (United States)

Siperko, C. M.; Frankfort, M.; Markham, R.; Wall, M.

1981-01-01

The characteristics of 30/20 GHz usage in satellite systems to be used in support of projected communication requirements of the 1990's are defined. A requirements analysis which develops projected market demand for satellite services by general and specialized carriers and an analysis of the impact of propagation and system constraints on 30/20 GHz operation are included. A set of technical performance characteristics for the 30/20 GHz systems which can serve the resulting market demand and the experimental program necessary to verify technical and operational aspects of the proposed systems is also discussed.

Simulation of Cloud-aerosol Lidar with Orthogonal Polarization (CALIOP Attenuated Backscatter Profiles Using the Global Model of Aerosol Processes (GLOMAP

Directory of Open Access Journals (Sweden)

Young Stuart

2016-01-01

Full Text Available To permit the calculation of the radiative effects of atmospheric aerosols, we have linked our aerosol-chemical transport model (CTMGLOMAP to a new radiation module (UKCARADAER. In order to help assess and improve the accuracy of the radiation code, in particular the height dependence of the predicted scattering, we have developed a module that simulates attenuated backscatter (ABS profiles that would be measured by the satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP if it were to sample an atmosphere with the same aerosol loading as predicted by the CTM. Initial results of our comparisons of the predicted ABS profiles with actual CALIOP data are encouraging but some differences are noted, particularly in marine boundary layers where the scattering is currently under-predicted and in dust layers where it is often over-predicted. The sources of these differences are being investigated.

Microphysical and Radiative Characteristics of Convective Clouds during COHMEX.

Science.gov (United States)

Fulton, Richard; Heymsfield, Gerald M.

1991-01-01

The use of passive remote microwave radiance measurements above cloud tops for rainrate estimation is complicated by the complex nature of cloud microphysics. The knowledge of the microphysical structure of clouds, specifically the hydrometeor types, shapes, sizes, and their vertical distribution, is important because radiative emission and scattering effects are dependent upon the hydrometeor distribution. This paper has two purposes: first, to document the structure and evolution of two strong thunderstorms in Alabama using radar multiparameter data; and second, to relate the inferred microphysics to the resulting upwelling microwave radiance observed concurrently by high altitude aircraft. These measurements were collected during the COHMEX field program in the summer of 1986. The radar analysis includes a description of the parameters reflectivity Z, differential reflectivity ZDR, linear depolarization ratio LDR, and hail signal HS for two thunderstorm cases on 11 July 1986. The simultaneous aircraft data includes passive microwave brightness temperature (TB) measurements at four frequencies ranging from 18 to 183 GHz as well as visible and infrared data.The remote radar observations reveal the existence of large ice particles within the storms which is likely to have caused the observed low microwave brightness temperatures. By relating the evolution of the radar measureables to the microwave TB's it has been found that knowledge of the storm microphysics and its evolution is important to adequately understand the microwave TB's.

Millimeter-Wave Radar Field Measurements and Inversion of Cloud Parameters for the 1999 Mt. Washington Icing Sensors Project

Science.gov (United States)

Pazmany, Andrew L.; Reehorst, Andrew (Technical Monitor)

2001-01-01

The Mount Washington Icing Sensors Project (MWISP) was a multi-investigator experiment with participants from Quadrant Engineering, NOAA Environmental Technology Laboratory (NOAA/ETL), the Microwave Remote Sensing Laboratory (MIRSL) of the University of Massachusetts (UMass), and others. Radar systems from UMass and NOAA/ETL were used to measure X-, Ka-, and W-band backscatter data from the base of Mt. Washington, while simultaneous in-situ particle measurements were made from aircraft and from the observatory at the summit. This report presents range and time profiles of liquid water content and particle size parameters derived from range profiles of radar reflectivity as measured at X-, Ka-, and W-band (9.3, 33.1, and 94.9 GHz) using an artificial neural network inversion algorithm. In this report, we provide a brief description of the experiment configuration, radar systems, and a review of the artificial neural network used to extract cloud parameters from the radar data. Time histories of liquid water content (LWC), mean volume diameter (MVD) and mean Z diameter (MZD) are plotted at 300 m range intervals for slant ranges between 1.1 and 4 km. Appendix A provides details on the extraction of radar reflectivity from measured radar power, and Appendix B provides summary logs of the weather conditions for each day in which we processed data.

An Examination of the Nature of Global MODIS Cloud Regimes

Science.gov (United States)

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

2014-01-01

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

Atmospheric Profiles, Clouds and the Evolution of Sea Ice Cover in the Beaufort and Chukchi Seas

Science.gov (United States)

2014-09-30

developed by incorporating the proposed IR sensors and ground-sky temperature difference algorithm into a tethered balloon borne payload (Figure 3...into the cloud base. RESULTS FROM FY 2014 • A second flight of the tethered balloon -borne IR cloud margin sensor was conducted in Colorado on...Figure 3: Tethered balloon -borne IR sensing payload IR Cloud Margin Sensor Figure 4: First successful flight validation of the IR cloud

Determining Cloud Thermodynamic Phase from Micropulse Lidar Network Data

Science.gov (United States)

Lewis, Jasper R.; Campbell, James; Lolli, Simone; Tan, Ivy; Welton, Ellsworth J.

2017-01-01

Determining cloud thermodynamic phase is a critical factor in studies of Earth's radiation budget. Here we use observations from the NASA Micro Pulse Lidar Network (MPLNET) and thermodynamic profiles from the Goddard Earth Observing System, version 5 (GEOS-5) to distinguish liquid water, mixed-phase, and ice water clouds. The MPLNET provides sparse global, autonomous, and continuous measurements of clouds and aerosols which have been used in a number of scientific investigations to date. The use of a standardized instrument and a common suite of data processing algorithms with thorough uncertainty characterization allows for straightforward comparisons between sites. Lidars with polarization capabilities have recently been incorporated into the MPLNET project which allows, for the first time, the ability to infer a cloud thermodynamic phase. This presentation will look specifically at the occurrence of ice and mixed phase clouds in the temperature region of -10 C to -40 C for different climatological regions and seasons. We compare MPLNET occurrences of mixed-phase clouds to an historical climatology based on observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft.

Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

Directory of Open Access Journals (Sweden)

T. Chubb

2016-01-01

Full Text Available Cloud physics data collected during the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER Pole-to-Pole Observations (HIPPO campaigns provide a snapshot of unusual wintertime microphysical conditions in the boundary layer over the Southern Ocean. On 29 June 2011, the HIAPER sampled the boundary layer in a region of pre-frontal warm air advection between 58 and 48° S to the south of Tasmania. Cloud droplet number concentrations were consistent with climatological values in the northernmost profiles but were exceptionally high for wintertime in the Southern Ocean at 100–200 cm−3 in the southernmost profiles. Sub-micron (0.06  < D <  1 µm aerosol concentrations for the southern profiles were up to 400 cm−3. Analysis of back trajectories and atmospheric chemistry observations revealed that while conditions in the troposphere were more typical of a clean remote ocean airmass, there was some evidence of continental or anthropogenic influence. However, the hypothesis of long-range transport of continental aerosol fails to explain the magnitude of the aerosol and cloud droplet concentration in the boundary layer. Instead, the gale force surface winds in this case (wind speed at 167 m above sea level was  > 25 m s−1 were most likely responsible for production of sea spray aerosol which influenced the microphysical properties of the boundary layer clouds. The smaller size and higher number concentration of cloud droplets is inferred to increase the albedo of these clouds, and these conditions occur regularly, and are expected to increase in frequency, over windy parts of the Southern Ocean.

Traveling-Wave Maser for 32 GHz

Science.gov (United States)

Shell, James; Clauss, Robert

2009-01-01

The figure depicts a traveling-wave ruby maser that has been designed (though not yet implemented in hardware) to serve as a low-noise amplifier for reception of weak radio signals in the frequency band of 31.8 to 32.3 GHz. The design offers significant improvements over previous designs of 32-GHz traveling-wave masers. In addition, relative to prior designs of 32-GHz amplifiers based on high-electron-mobility transistors, this design affords higher immunity to radio-frequency interference and lower equivalent input noise temperature. In addition to the basic frequency-band and low-noise requirements, the initial design problem included a requirement for capability of operation in a closed-cycle helium refrigerator at a temperature .4 K and a requirement that the design be mechanically simplified, relative to prior designs, in order to minimize the cost of fabrication and assembly. Previous attempts to build 32- GHz traveling-wave masers involved the use of metallic slow-wave structures comprising coupled transverse electromagnetic (TEM)-mode resonators that were subject to very tight tolerances and, hence, were expensive to fabricate and assemble. Impedance matching for coupling signals into and out of these earlier masers was very difficult. A key feature of the design is a slow-wave structure, the metallic portions of which would be mechanically relatively simple in that, unlike in prior slow-wave structures, there would be no internal metal steps, irises, or posts. The metallic portions of the slow-wave structure would consist only of two rectangular metal waveguide arms. The arms would contain sections filled with the active material (ruby) alternating with evanescent-wave sections. This structure would be transparent in both the signal-frequency band (the aforementioned range of 31.8 to 32.3 GHz) and the pump-frequency band (65.75 to 66.75 GHz), and would impose large slowing factors in both frequency bands. Resonant ferrite isolators would be placed in the

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

Science.gov (United States)

Ohno, Kazumasa; Okuzumi, Satoshi

2018-05-01

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

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite service. 25.143 Section 25.143 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision

OpenAIRE

Inoue, Tsuyoshi; Fukui, Yasuo

2013-01-01

Recent observations of molecular clouds around rich massive star clusters including NGC3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by the cloud-cloud collision. We find that the massive mol...

Single-footprint retrievals for AIRS using a fast TwoSlab cloud-representation model and the SARTA all-sky infrared radiative transfer algorithm

Science.gov (United States)

DeSouza-Machado, Sergio; Larrabee Strow, L.; Tangborn, Andrew; Huang, Xianglei; Chen, Xiuhong; Liu, Xu; Wu, Wan; Yang, Qiguang

2018-01-01

One-dimensional variational retrievals of temperature and moisture fields from hyperspectral infrared (IR) satellite sounders use cloud-cleared radiances (CCRs) as their observation. These derived observations allow the use of clear-sky-only radiative transfer in the inversion for geophysical variables but at reduced spatial resolution compared to the native sounder observations. Cloud clearing can introduce various errors, although scenes with large errors can be identified and ignored. Information content studies show that, when using multilayer cloud liquid and ice profiles in infrared hyperspectral radiative transfer codes, there are typically only 2-4 degrees of freedom (DOFs) of cloud signal. This implies a simplified cloud representation is sufficient for some applications which need accurate radiative transfer. Here we describe a single-footprint retrieval approach for clear and cloudy conditions, which uses the thermodynamic and cloud fields from numerical weather prediction (NWP) models as a first guess, together with a simple cloud-representation model coupled to a fast scattering radiative transfer algorithm (RTA). The NWP model thermodynamic and cloud profiles are first co-located to the observations, after which the N-level cloud profiles are converted to two slab clouds (TwoSlab; typically one for ice and one for water clouds). From these, one run of our fast cloud-representation model allows an improvement of the a priori cloud state by comparing the observed and model-simulated radiances in the thermal window channels. The retrieval yield is over 90 %, while the degrees of freedom correlate with the observed window channel brightness temperature (BT) which itself depends on the cloud optical depth. The cloud-representation and scattering package is benchmarked against radiances computed using a maximum random overlap (RMO) cloud scheme. All-sky infrared radiances measured by NASA's Atmospheric Infrared Sounder (AIRS) and NWP thermodynamic and cloud

Single-footprint retrievals for AIRS using a fast TwoSlab cloud-representation model and the SARTA all-sky infrared radiative transfer algorithm

Directory of Open Access Journals (Sweden)

S. DeSouza-Machado

2018-01-01

Full Text Available One-dimensional variational retrievals of temperature and moisture fields from hyperspectral infrared (IR satellite sounders use cloud-cleared radiances (CCRs as their observation. These derived observations allow the use of clear-sky-only radiative transfer in the inversion for geophysical variables but at reduced spatial resolution compared to the native sounder observations. Cloud clearing can introduce various errors, although scenes with large errors can be identified and ignored. Information content studies show that, when using multilayer cloud liquid and ice profiles in infrared hyperspectral radiative transfer codes, there are typically only 2–4 degrees of freedom (DOFs of cloud signal. This implies a simplified cloud representation is sufficient for some applications which need accurate radiative transfer. Here we describe a single-footprint retrieval approach for clear and cloudy conditions, which uses the thermodynamic and cloud fields from numerical weather prediction (NWP models as a first guess, together with a simple cloud-representation model coupled to a fast scattering radiative transfer algorithm (RTA. The NWP model thermodynamic and cloud profiles are first co-located to the observations, after which the N-level cloud profiles are converted to two slab clouds (TwoSlab; typically one for ice and one for water clouds. From these, one run of our fast cloud-representation model allows an improvement of the a priori cloud state by comparing the observed and model-simulated radiances in the thermal window channels. The retrieval yield is over 90 %, while the degrees of freedom correlate with the observed window channel brightness temperature (BT which itself depends on the cloud optical depth. The cloud-representation and scattering package is benchmarked against radiances computed using a maximum random overlap (RMO cloud scheme. All-sky infrared radiances measured by NASA's Atmospheric Infrared Sounder (AIRS and NWP

Identification of Dust and Ice Cloud Formation from A-Train Datasets

Science.gov (United States)

Russell, D. S.; Liou, K. N.

2014-12-01

Dust aerosols are effective ice nuclei for clouds and instances of nucleation have been well studied in laboratory experiments. We used CALIOP/CALIPSO, MODIS/Aqua, and CloudSat on the A-Train to find collocated instances of clouds characterized as water by MODIS, but contain ice water as indicated by CloudSat. The vertical profiles of CALIPSO detect the presence of dust and polluted dust near clouds. This study concentrates on high dust aerosol areas including the regions surrounding the Sahara Desert as well as South Asia including the Tibetan Plateau. These cases display the effects of dust acting as ice nuclei in the time frame between MODIS overpass and CloudSat overpass (~45 seconds). Utilizing available datasets, we then carried out radiative transfer calculations to understand spectral radiative forcing differences between water and ice clouds, particularly over snow surfaces at the Tibetan Plateau.

1.3 GHz superconducting RF cavity program at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Ginsburg, C.M.; Arkan, T.; Barbanotti, S.; Carter, H.; Champion, M.; Cooley, L.; Cooper, C.; Foley, M.; Ge, M.; Grimm, C.; Harms, E.; /Fermilab

2011-03-01

At Fermilab, 9-cell 1.3 GHz superconducting RF (SRF) cavities are prepared, qualified, and assembled into cryomodules (CMs) for Project X, an International Linear Collider (ILC), or other future projects. The 1.3 GHz SRF cavity program includes targeted R&D on 1-cell 1.3 GHz cavities for cavity performance improvement. Production cavity qualification includes cavity inspection, surface processing, clean assembly, and one or more cryogenic low-power CW qualification tests which typically include performance diagnostics. Qualified cavities are welded into helium vessels and are cryogenically tested with pulsed high-power. Well performing cavities are assembled into cryomodules for pulsed high-power testing in a cryomodule test facility, and possible installation into a beamline. The overall goals of the 1.3 GHz SRF cavity program, supporting facilities, and accomplishments are described.

Impact of Arctic sea-ice retreat on the recent change in cloud-base height during autumn

Science.gov (United States)

Sato, K.; Inoue, J.; Kodama, Y.; Overland, J. E.

2012-12-01

Cloud-base observations over the ice-free Chukchi and Beaufort Seas in autumn were conducted using a shipboard ceilometer and radiosondes during the 1999-2010 cruises of the Japanese R/V Mirai. To understand the recent change in cloud base height over the Arctic Ocean, these cloud-base height data were compared with the observation data under ice-covered situation during SHEBA (the Surface Heat Budget of the Arctic Ocean project in 1998). Our ice-free results showed a 30 % decrease (increase) in the frequency of low clouds with a ceiling below (above) 500 m. Temperature profiles revealed that the boundary layer was well developed over the ice-free ocean in the 2000s, whereas a stable layer dominated during the ice-covered period in 1998. The change in surface boundary conditions likely resulted in the difference in cloud-base height, although it had little impact on air temperatures in the mid- and upper troposphere. Data from the 2010 R/V Mirai cruise were investigated in detail in terms of air-sea temperature difference. This suggests that stratus cloud over the sea ice has been replaced as stratocumulus clouds with low cloud fraction due to the decrease in static stability induced by the sea-ice retreat. The relationship between cloud-base height and air-sea temperature difference (SST-Ts) was analyzed in detail using special section data during 2010 cruise data. Stratus clouds near the sea surface were predominant under a warm advection situation, whereas stratocumulus clouds with a cloud-free layer were significant under a cold advection situation. The threshold temperature difference between sea surface and air temperatures for distinguishing the dominant cloud types was 3 K. Anomalous upward turbulent heat fluxes associated with the sea-ice retreat have likely contributed to warming of the lower troposphere. Frequency distribution of the cloud-base height (km) detected by a ceilometer/lidar (black bars) and radiosondes (gray bars), and profiles of potential

Extending 3D near-cloud corrections from shorter to longer wavelengths

International Nuclear Information System (INIS)

Marshak, Alexander; Evans, K. Frank; Várnai, Tamás; Wen, Guoyong

2014-01-01

Satellite observations have shown a positive correlation between cloud amount and aerosol optical thickness (AOT) that can be explained by the humidification of aerosols near clouds, and/or by cloud contamination by sub-pixel size clouds and the cloud adjacency effect. The last effect may substantially increase reflected radiation in cloud-free columns, leading to overestimates in the retrieved AOT. For clear-sky areas near boundary layer clouds the main contribution to the enhancement of clear sky reflectance at shorter wavelengths comes from the radiation scattered into clear areas by clouds and then scattered to the sensor by air molecules. Because of the wavelength dependence of air molecule scattering, this process leads to a larger reflectance increase at shorter wavelengths, and can be corrected using a simple two-layer model [18]. However, correcting only for molecular scattering skews spectral properties of the retrieved AOT. Kassianov and Ovtchinnikov [9] proposed a technique that uses spectral reflectance ratios to retrieve AOT in the vicinity of clouds; they assumed that the cloud adjacency effect influences the spectral ratio between reflectances at two wavelengths less than it influences the reflectances themselves. This paper combines the two approaches: It assumes that the 3D correction for the shortest wavelength is known with some uncertainties, and then it estimates the 3D correction for longer wavelengths using a modified ratio method. The new approach is tested with 3D radiances simulated for 26 cumulus fields from Large-Eddy Simulations, supplemented with 40 aerosol profiles. The results showed that (i) for a variety of cumulus cloud scenes and aerosol profiles over ocean the 3D correction due to cloud adjacency effect can be extended from shorter to longer wavelengths and (ii) the 3D corrections for longer wavelengths are not very sensitive to unbiased random uncertainties in the 3D corrections at shorter wavelengths. - Highlights: �

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

OpenAIRE

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

2011-01-01

This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

Revealing Layers of Pristine Oriented Crystals Embedded Within Deep Ice Clouds Using Differential Reflectivity and the Copolar Correlation Coefficient

Science.gov (United States)

Keat, W. J.; Westbrook, C. D.

2017-11-01

Pristine ice crystals typically have high aspect ratios (≫ 1), have a high density and tend to fall preferentially with their major axis aligned horizontally. Consequently, they can, in certain circumstances, be readily identified by measurements of differential reflectivity (ZDR), which is related to their average aspect ratio. However, because ZDR is reflectivity weighted, its interpretation becomes ambiguous in the presence of even a few, larger aggregates or irregular polycrystals. An example of this is in mixed-phase regions that are embedded within deeper ice cloud. Currently, our understanding of the microphysical processes within these regions is hindered by a lack of good observations. In this paper, a novel technique is presented that removes this ambiguity using measurements from the 3 GHz Chilbolton Advanced Meteorological Radar in Southern England. By combining measurements of ZDR and the copolar correlation coefficient (ρhv), we show that it is possible to retrieve both the relative contribution to the radar signal and "intrinsic" ZDR (ZDRIP) of the pristine oriented crystals, even in circumstances where their signal is being masked by the presence of aggregates. Results from two case studies indicate that enhancements in ZDR embedded within deep ice clouds are typically produced by pristine oriented crystals with ZDRIP values between 3 and 7 dB (equivalent to 5-9 dB at horizontal incidence) but with varying contributions to the radar reflectivity. Vertically pointing 35 GHz cloud radar Doppler spectra and in situ particle images from the Facility for Airborne Atmospheric Measurements BAe-146 aircraft support the conceptual model used and are consistent with the retrieval interpretation.

Packaging of microwave integrated circuits operating beyond 100 GHz

Science.gov (United States)

Samoska, L.; Daniel, E.; Sokolov, V.; Sommerfeldt, S.; Bublitz, J.; Olson, K.; Gilbert, B.; Chow, D.

2002-01-01

Several methods of packaging high speed (75-330 GHz) InP HEMT MMIC devices are discussed. Coplanar wirebonding is presented with measured insertion loss of less than 0.5dB and return loss better than -17 dB from DC to 110 GHz. A motherboard/daughterboard packaging scheme is presented which supports minimum loss chains of MMICs using this coplanar wirebonding method. Split waveguide block packaging approaches are presented in G-band (140-220 GHz) with two types of MMIC-waveguide transitions: E-plane probe andantipodal finline.

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

Science.gov (United States)

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

2009-12-01

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

47 CFR 25.139 - NGSO FSS coordination and information sharing between MVDDS licensees in the 12.2 GHz to 12.7 GHz...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false NGSO FSS coordination and information sharing between MVDDS licensees in the 12.2 GHz to 12.7 GHz band. 25.139 Section 25.139 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

Production of lightning NOx and its vertical distribution calculated from three-dimensional cloud-scale chemical transport model simulations

KAUST Repository

Ott, Lesley E.

2010-02-18

A three-dimensional (3-D) cloud-scale chemical transport model that includes a parameterized source of lightning NOx on the basis of observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (PIC) and cloud-to-ground (PCG) flash is estimated by assuming various values of PIC and PCG for each storm and determining which production scenario yields NOx mixing ratios that compare most favorably with in-cloud aircraft observations. We obtain a mean PCG value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, PIC may be nearly equal to PCG, which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud-to-ground flashes. This study also presents vertical profiles of the mass of lightning NOx after convection based on 3-D cloud-scale model simulations. The results suggest that following convection, a large percentage of lightning NOx remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2-D cloud-scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a “C-shaped” profile). The new model results (a backward C-shaped profile) suggest that chemical transport models that assume a C-shaped vertical profile of lightning NOx mass may place too much mass near the surface and too little in the middle troposphere.

Meteorological observations in support of a hill cap cloud experiment

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Morten

1998-06-01

Humid air flows form a hill cap cloud over the Agana mountain ridge in the north-east of Tenerife. The HILLCLOUD project utilised this cloud formation to investigate the chemical and physical properties of cloud aerosols by land based observations. The project was part of the second Aerosol characterisation Experiment (ACE-2) of the International Global Atmospheric chemistry project (IGAC). The present report describes meteorological observations in support of the hill cap cloud experiment. Time-series of wind speed, wind direction, temperature and humidity were collected at ground-based meteorological stations during a period starting one year in advance of the main campaign. A series of radiosonde detecting the upstream stability and wind profile were launched during the main campaign. (au) 5 tabs., 32 ills., 6 refs.

Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges

Science.gov (United States)

Marshall, R. A.; Inan, U. S.; Glukhov, V. S.

2010-04-01

A 3-D finite difference time domain model is used to simulate the lightning electromagnetic pulse (EMP) and its interaction with the lower ionosphere. Results agree with the frequently observed, doughnut-shaped optical signature of elves but show that the structure exhibits asymmetry due to the presence of Earth's ambient magnetic field. Furthermore, in-cloud (horizontal) lightning channels produce observable optical emissions without the doughnut shape and, in fact, produce a much stronger optical output for the same channel current. Electron density perturbations associated with elves are also calculated, with contributions from attachment and ionization. Results presented as a function of parameters such as magnetic field direction, dipole current orientation, altitude and amplitude, and ambient ionospheric density profile demonstrate the highly nonlinear nature of the EMP-ionosphere interaction. Ionospheric effects of a sequence of in-cloud discharges are calculated, simulating a burst of in-cloud lightning activity and resulting in large density changes in the overlying ionosphere.

An improvement of the retrieval of temperature and relative humidity profiles from a combination of active and passive remote sensing

Science.gov (United States)

Che, Yunfei; Ma, Shuqing; Xing, Fenghua; Li, Siteng; Dai, Yaru

2018-03-01

This paper focuses on an improvement of the retrieval of atmospheric temperature and relative humidity profiles through combining active and passive remote sensing. Ground-based microwave radiometer and millimeter-wavelength cloud radar were used to acquire the observations. Cloud base height and cloud thickness determinations from cloud radar were added into the atmospheric profile retrieval process, and a back-propagation neural network method was used as the retrieval tool. Because a substantial amount of data are required to train a neural network, and as microwave radiometer data are insufficient for this purpose, 8 years of radiosonde data from Beijing were used as the database. The monochromatic radiative transfer model was used to calculate the brightness temperatures in the same channels as the microwave radiometer. Parts of the cloud base heights and cloud thicknesses in the training data set were also estimated using the radiosonde data. The accuracy of the results was analyzed through a comparison with L-band sounding radar data and quantified using the mean bias, root-mean-square error (RMSE), and correlation coefficient. The statistical results showed that an inversion with cloud information was the optimal method. Compared with the inversion profiles without cloud information, the RMSE values after adding cloud information reduced to varying degrees for the vast majority of height layers. These reductions were particularly clear in layers with clouds. The maximum reduction in the RMSE for the temperature profile was 2.2 K, while that for the humidity profile was 16%.

CIMS: A Context-Based Intelligent Multimedia System for Ubiquitous Cloud Computing

Directory of Open Access Journals (Sweden)

Abhilash Sreeramaneni

2015-06-01

Full Text Available Mobile users spend a tremendous amount of time surfing multimedia contents over the Internet to pursue their interests. A resource-constrained smart device demands more intensive computing tasks and lessens the battery life. To address the resource limitations (i.e., memory, lower maintenance cost, easier access, computing tasks in mobile devices, mobile cloud computing is needed. Several approaches have been proposed to confront the challenges of mobile cloud computing, but difficulties still remain. However, in the coming years, context collecting, processing, and interchanging the results on a heavy network will cause vast computations and reduce the battery life in mobiles. In this paper, we propose a “context-based intelligent multimedia system” (CIMS for ubiquitous cloud computing. The main goal of this research is to lessen the computing percentage, storage complexities, and battery life for mobile users by using pervasive cloud computing. Moreover, to reduce the computing and storage concerns in mobiles, the cloud server collects several groups of user profiles with similarities by executing K-means clustering on users’ data (context and multimedia contents. The distribution process conveys real-time notifications to smartphone users, according to what is stated in his/her profile. We considered a mobile cloud offloading system, which decides the offloading actions to/from cloud servers. Context-aware decision-making (CAD customizes the mobile device performance with different specifications such as short response time and lesser energy consumption. The analysis says that our CIMS takes advantage of cost-effective features to produce high-quality information for mobile (or smart device users in real time. Moreover, our CIMS lessens the computation and storage complexities for mobile users, as well as cloud servers. Simulation analysis suggests that our approach is more efficient than existing domains.

Spatial and Temporal Characterization of Indoor Millimeter Wave Propagation at 24 GHz

Directory of Open Access Journals (Sweden)

Seok-hwan Min

2016-01-01

Full Text Available Indoor millimeter wave propagation at the frequency of 24 GHz is studied by experimental methods. Measurements are performed to obtain temporal and spatial channel model using a channel sounder and rotating antennas in a corridor. The measured impulse responses are processed to obtain compact channel model following Saleh-Valenzuela’s model. The responses are compared with those of 5.3 GHz for the same test sites. Angular spread of 24 GHz is found to be smaller than that of 5.3 GHz, while echoes of 24 GHz are found to be longer than those of 5.3 GHz.

3d object segmentation of point clouds using profiling techniques

African Journals Online (AJOL)

Administrator

optimization attempts to physically store the point cloud so that storage, retrieval and visualisation ..... Ideally three stacks should be sufficient, but in practice four or five are used. .... The authors would like to acknowledge that this paper is based on a paper presented at ... Theory, Processing and Application, 5 pages.

Comparison of Stationarity Regions for Wireless Channels From 2 GHz to 30 GHz

DEFF Research Database (Denmark)

Yi, Tan; Wang, Chengxiang; Nielsen, Jesper Ødum

2017-01-01

Millimeter wave (mmWave) communication works in the frequencies above 6 gigahertz (GHz), with the system bandwidth up to 500 megahertz (MHz) or wider. In this case, the channel situations are dramatically different from the existing wireless channels in Third Generation/Fourth Generation (3G/4G...

The EUMETSAT OSI SAF near 50 GHz sea ice emissivity model

Directory of Open Access Journals (Sweden)

Rasums T. Tonboe

2013-02-01

Full Text Available A sea ice thermal microwave emission model for 50 GHz was developed under EUMETSAT's Ocean and Sea Ice Satellite Application Facility (OSI SAF programme. The model is based on correlations between the surface brightness temperature at 18, 36 and 50 GHz. The model coefficients are estimated using simulated data from a combined thermodynamic and emission model. The intention with the model is to provide a first guess sea ice surface emissivity estimate for atmospheric temperature sounding applications in the troposphere in numerical weather prediction (NWP models assimilating Advanced Microwave Sounding Unit (AMSU and Special Sensor Microwave Imager/Sounder (SSMIS data. The spectral gradient ratio is defined as the difference over the sum of the SSMIS brightness temperatures at 18 and 36 GHz vertical linear polarisation (GR1836. The GR1836 is related to the emissivity at the atmospheric temperature sounding channels at around 50 GHz. Furthermore, the brightness temperatures and the polarisation ratio (PR at the neighbouring 18, 36 and 50 GHz channels are highly correlated. Both the gradient ratio at 18 and 36 GHz and the PR at 36 GHz measured by SSMIS are input into the model predicting the 50 GHz emissivity for horizontal and vertical linear polarisations and incidence angles between 0° and 60° The simulated emissivity is compared to the emissivity derived with alternative methods. The fit to real AMSU observations is investigated using the different emissivity estimates for simulating the observations with atmospheric data from a regional weather prediction model.

Cloud System Evolution in the Trades—CSET

Science.gov (United States)

Albrecht, B. A.; Zuidema, P.; Bretherton, C. S.; Wood, R.; Ghate, V. P.

2015-12-01

The Cloud System Evolution in the Trades (CSET) study was designed to describe and explain the evolution of the boundary layer aerosol, cloud, and thermodynamic structures along trajectories within the north-Pacific trade-winds. The observational component of this study centered on 7 round-trips made by the NSF NCAR Gulfstream V (GV) between Sacramento, CA and Kona, Hawaii between 1 July and 15 August 2015. The CSET observing strategy used a Lagrangian approach to sample aerosol, cloud, and boundary layer properties upwind from the transition zone over the North Pacific and to resample these areas two days later. GFS forecast trajectories were used to plan the outbound flight to Hawaii and then updated forecast trajectories helped set the return flight plan two days later. Two key elements of the CSET observing system were the newly developed HIAPER Cloud Radar (HCR) and the HIAPER Spectral Resolution Lidar (HSRL). Together they provided unprecedented characterizations of aerosol, cloud and precipitation structures. A full suite of probes on the aircraft were used for in situ measurements of aerosol, cloud, precipitation, and turbulence properties during the low-level aircraft profiling portions of the flights. A wide range of boundary layer structures and aerosol, cloud, and precipitation conditions were observed during CSET. The cloud systems sampled included solid stratocumulus infused with smoke from Canadian wildfires, mesoscale (100-200 km) cloud-precipitation complexes, and patches of shallow cumuli in environments with accumulation mode aerosol concentrations of less than 50 cm-3. Ultra clean layers (UCLs with accumulation mode concentrations of less than 10 cm-3) were observed frequently near the top of the boundary layer and were often associated with shallow, gray (optically thin) layered clouds—features that are the subject of focused investigations by the CSET science team. The extent of aerosol, cloud, drizzle and boundary layer sampling that was

77 FR 48097 - Operation of Radar Systems in the 76-77 GHz Band

Science.gov (United States)

2012-08-13

... modify the emission limits for vehicular radar systems operating within the 76-77 GHz band. Specifically.... 15.253 of the rules for vehicular radar systems operating in the 76-77 GHz band. Vehicular radars can... sensors operating in the 76-77 GHz band, the spectrum shall be investigated up to 231 GHz. (f) Fundamental...

Cloud-Top Entrainment in Stratocumulus Clouds

Science.gov (United States)

Mellado, Juan Pedro

2017-01-01

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

Optical Spectra of Radio Planetary Nebulae in the Large Magellanic Cloud

Directory of Open Access Journals (Sweden)

Payne, J. L.

2008-12-01

Full Text Available We present 11 spectra from 12 candidate radio sources co-identified with known planetary nebulae (PNe in the Large Magellanic Cloud (LMC. Originally found in Australia Telescope Compact Array (ATCA LMC surveys at 1.4, 4.8 and 8.64~GHz and confirmed by new high resolution ATCA images at 6 and 3~cm (4arcsec/2arcsec, these complement data recently presented for candidate radio PNe in the Small Magellanic Cloud (SMC. Their spectra were obtained using the Radcliffe 1.9-meter telescope in Sutherland (South Africa. All of the optical PNe and radio candidates are within 2arcsec and may represent a population of selected radio bright sample only. Nebular ionized masses of these objects are estimated to be as high as 1.8~$M_odot$, supporting the idea that massive PNe progenitor central stars lose much of their mass in the asymptotic giant branch (AGB phase or prior. We also identify a sub-population (33\\% of radio PNe candidates with prominent ionized iron emission lines.

Flare-generated clouds as compact force-free toroidal configurations: magnetic measurements by the Vega-1 and Vega-2 space probes

International Nuclear Information System (INIS)

Ivanov, K.G.; Kharshiladze, A.F.; Eroshenko, E.G.; Styazhkin, V.A.

1988-01-01

Magnetic field experimental profiles, obtained during Vega-I and Vega-2 space vehicles passing through interplanetary cloud on the 16.02.1986, are compared with approximate theoretical profiles, taken from different hypotheses about such clouds structure. Maximum correlation of the theory and experiment is obtained with cloud presentation as flattened compact force-free toroid, which equatorial plane is approximately parallel to great circle plane, passing through flare on the 14.02.86 parallel to magnetic axis nearest to bipolar group flare

Radiative effects of global MODIS cloud regimes

Science.gov (United States)

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

2018-01-01

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

Radiative Effects of Global MODIS Cloud Regimes

Science.gov (United States)

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

2016-01-01

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

A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

Science.gov (United States)

Goldsmith, K. J. A.; Pittard, J. M.

2018-05-01

The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

Multi-gigabit wireless data transfer at 60 GHz

International Nuclear Information System (INIS)

Soltveit, H K; Schöning, A; Wiedner, D; Brenner, R

2012-01-01

In this paper we describe the status of the first prototype of the 60 GHz wireless Multi-gigabit data transfer topology currently under development at University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60 GHz band is very suitable for high data rate and short distance applications. One application can be a wireless multi Gbps radial data transmission inside the ATLAS silicon strip detector, making a first level track trigger feasible. The wireless transceiver consists of a transmitter and a receiver. The transmitter includes an On-Off Keying (OOK) modulator, a Local Oscillator (LO), a Power Amplifier (PA) and a Band-pass Filter (BPF). The receiver part is composed of a Band-pass Filter (BPF), a Low Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local Oscillator (LO), then a BPF to remove the mixer introduced noise, an Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting amplifier. The first prototype would be able to handle a data-rate of about 3.5 Gbps over a link distance of 1 m. The first simulations of the LNA show that a Noise figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB bandwidth of more than 20 GHz with a power consumption 11 mW are achieved. Simulations of the PA show an output referred compression point P1dB of 19.7 dB at 60 GHz.

Cloud Computing, Tieto Cloud Server Model

OpenAIRE

Suikkanen, Saara

2013-01-01

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

Phase-partitioning in mixed-phase clouds - An approach to characterize the entire vertical column

Science.gov (United States)

Kalesse, H.; Luke, E. P.; Seifert, P.

2017-12-01

The characterization of the entire vertical profile of phase-partitioning in mixed-phase clouds is a challenge which can be addressed by synergistic profiling measurements with ground-based polarization lidars and cloud radars. While lidars are sensitive to small particles and can thus detect supercooled liquid (SCL) layers, cloud radar returns are dominated by larger particles (like ice crystals). The maximum lidar observation height is determined by complete signal attenuation at a penetrated optical depth of about three. In contrast, cloud radars are able to penetrate multiple liquid layers and can thus be used to expand the identification of cloud phase to the entire vertical column beyond the lidar extinction height, if morphological features in the radar Doppler spectrum can be related to the existence of SCL. Relevant spectral signatures such as bimodalities and spectral skewness can be related to cloud phase by training a neural network appropriately in a supervised learning scheme, with lidar measurements functioning as supervisor. The neural network output (prediction of SCL location) derived using cloud radar Doppler spectra can be evaluated with several parameters such as liquid water path (LWP) detected by microwave radiometer (MWR) and (liquid) cloud base detected by ceilometer or Raman lidar. The technique has been previously tested on data from Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) instruments in Barrow, Alaska and is in this study utilized for observations from the Leipzig Aerosol and Cloud Remote Observations System (LACROS) during the Analysis of the Composition of Clouds with Extended Polarization Techniques (ACCEPT) field experiment in Cabauw, Netherlands in Fall 2014. Comparisons to supercooled-liquid layers as classified by CLOUDNET are provided.

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Science.gov (United States)

2010-10-01

... exceed 3000 microvolts/meter/MHz at 3 meters in any direction. Further, an AVIS, when in its operating position, shall not produce a field strength greater than 400 microvolts/meter/MHz at 3 meters in any... maximum of 100 microvolts/meter/MHz at 3 meters, measured from 30 MHz to 20 GHz for the complete system...

Towards low-cost gigabit wireless systems at 60 GHz

NARCIS (Netherlands)

Yang, Haibing

2008-01-01

The world-wide availability of the huge amount of license-free spectral space in the 60 GHz band provides wide room for gigabit-per-second (Gb/s) wireless applications. A commercial (read: low-cost) 60-GHz transceiver will, however, provide limited system performance due to the stringent link budget

Statistical thermodynamics and the size distributions of tropical convective clouds.

Science.gov (United States)

Garrett, T. J.; Glenn, I. B.; Krueger, S. K.; Ferlay, N.

2017-12-01

Parameterizations for sub-grid cloud dynamics are commonly developed by using fine scale modeling or measurements to explicitly resolve the mechanistic details of clouds to the best extent possible, and then to formulating these behaviors cloud state for use within a coarser grid. A second is to invoke physical intuition and some very general theoretical principles from equilibrium statistical thermodynamics. This second approach is quite widely used elsewhere in the atmospheric sciences: for example to explain the heat capacity of air, blackbody radiation, or even the density profile or air in the atmosphere. Here we describe how entrainment and detrainment across cloud perimeters is limited by the amount of available air and the range of moist static energy in the atmosphere, and that constrains cloud perimeter distributions to a power law with a -1 exponent along isentropes and to a Boltzmann distribution across isentropes. Further, the total cloud perimeter density in a cloud field is directly tied to the buoyancy frequency of the column. These simple results are shown to be reproduced within a complex dynamic simulation of a tropical convective cloud field and in passive satellite observations of cloud 3D structures. The implication is that equilibrium tropical cloud structures can be inferred from the bulk thermodynamic structure of the atmosphere without having to analyze computationally expensive dynamic simulations.

Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds

Energy Technology Data Exchange (ETDEWEB)

Turner, David, D.; Ferrare, Richard, A.

2011-07-06

The 'Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds' project focused extensively on the analysis and utilization of water vapor and aerosol profiles derived from the ARM Raman lidar at the Southern Great Plains ARM site. A wide range of different tasks were performed during this project, all of which improved quality of the data products derived from the lidar or advanced the understanding of atmospheric processes over the site. These activities included: upgrading the Raman lidar to improve its sensitivity; participating in field experiments to validate the lidar aerosol and water vapor retrievals; using the lidar aerosol profiles to evaluate the accuracy of the vertical distribution of aerosols in global aerosol model simulations; examining the correlation between relative humidity and aerosol extinction, and how these change, due to horizontal distance away from cumulus clouds; inferring boundary layer turbulence structure in convective boundary layers from the high-time-resolution lidar water vapor measurements; retrieving cumulus entrainment rates in boundary layer cumulus clouds; and participating in a field experiment that provided data to help validate both the entrainment rate retrievals and the turbulent profiles derived from lidar observations.

A Physically Based Algorithm for Non-Blackbody Correction of Cloud-Top Temperature and Application to Convection Study

Science.gov (United States)

Wang, Chunpeng; Lou, Zhengzhao Johnny; Chen, Xiuhong; Zeng, Xiping; Tao, Wei-Kuo; Huang, Xianglei

2014-01-01

Cloud-top temperature (CTT) is an important parameter for convective clouds and is usually different from the 11-micrometers brightness temperature due to non-blackbody effects. This paper presents an algorithm for estimating convective CTT by using simultaneous passive [Moderate Resolution Imaging Spectroradiometer (MODIS)] and active [CloudSat 1 Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] measurements of clouds to correct for the non-blackbody effect. To do this, a weighting function of the MODIS 11-micrometers band is explicitly calculated by feeding cloud hydrometer profiles from CloudSat and CALIPSO retrievals and temperature and humidity profiles based on ECMWF analyses into a radiation transfer model.Among 16 837 tropical deep convective clouds observed by CloudSat in 2008, the averaged effective emission level (EEL) of the 11-mm channel is located at optical depth; approximately 0.72, with a standard deviation of 0.3. The distance between the EEL and cloud-top height determined by CloudSat is shown to be related to a parameter called cloud-top fuzziness (CTF), defined as the vertical separation between 230 and 10 dBZ of CloudSat radar reflectivity. On the basis of these findings a relationship is then developed between the CTF and the difference between MODIS 11-micrometers brightness temperature and physical CTT, the latter being the non-blackbody correction of CTT. Correction of the non-blackbody effect of CTT is applied to analyze convective cloud-top buoyancy. With this correction, about 70% of the convective cores observed by CloudSat in the height range of 6-10 km have positive buoyancy near cloud top, meaning clouds are still growing vertically, although their final fate cannot be determined by snapshot observations.

Aerosol-Cloud Interactions During Puijo Cloud Experiments - The effects of weather and local sources

Science.gov (United States)

Komppula, Mika; Portin, Harri; Leskinen, Ari; Romakkaniemi, Sami; Brus, David; Neitola, Kimmo; Hyvärinen, Antti-Pekka; Kortelainen, Aki; Hao, Liqing; Miettinen, Pasi; Jaatinen, Antti; Ahmad, Irshad; Lihavainen, Heikki; Laaksonen, Ari; Lehtinen, Kari E. J.

2013-04-01

The Puijo measurement station has provided continuous data on aerosol-cloud interactions since 2006. The station is located on top of the Puijo observation tower (306 m a.s.l, 224 m above the surrounding lake level) in Kuopio, Finland. The top of the tower is covered by cloud about 15 % of the time, offering perfect conditions for studying aerosol-cloud interactions. With a twin-inlet setup (total and interstitial inlets) we are able to separate the activated particles from the interstitial (non-activated) particles. The continuous twin-inlet measurements include aerosol size distribution, scattering and absorption. In addition cloud droplet number and size distribution are measured continuously with weather parameters. During the campaigns the twin-inlet system was additionally equipped with aerosol mass spectrometer (AMS) and Single Particle Soot Photometer (SP-2). This way we were able to define the differences in chemical composition of the activated and non-activated particles. Potential cloud condensation nuclei (CCN) in different supersaturations were measured with two CCN counters (CCNC). The other CCNC was operated with a Differential Mobility Analyzer (DMA) to obtain size selected CCN spectra. Other additional measurements included Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) for particle hygroscopicity. Additionally the valuable vertical wind profiles (updraft velocities) are available from Halo Doppler lidar during the 2011 campaign. Cloud properties (droplet number and effective radius) from MODIS instrument onboard Terra and Aqua satellites were retrieved and compared with the measured values. This work summarizes the two latest intensive campaigns, Puijo Cloud Experiments (PuCE) 2010 & 2011. We study especially the effect of the local sources on the cloud activation behaviour of the aerosol particles. The main local sources include a paper mill, a heating plant, traffic and residential areas. The sources can be categorized and identified

Supporting the scientific lifecycle through cloud services

Science.gov (United States)

Gensch, S.; Klump, J. F.; Bertelmann, R.; Braune, C.

2014-12-01

can benefit from the provision of standard services, like weblog and website creation, virtual machine deployments, and groupware provision using cloud based app store-like portals. And, other than in an industrial environment, researchers will want to keep their existing user profile when moving from one institution to another.

Exploring the Effects of Clouds on Hot Jupiter Atmospheres

Science.gov (United States)

Robinson, Jenna; Line, Michael

2018-01-01

Secondary eclipse spectroscopy of transiting exoplanets allows us to probe the atmospheric properties on the daysides of tidally locked planets. Specifically, eclipse spectra combined with atmospheric retrieval models permit constraints on the molecular abundances and vertical thermal profiles of the planetary dayside. Eclipse spectra from HST WFC3 are typically interpreted assuming that all of the near infrared light is due solely to the thermal emission of the planet. However, recent evidence suggests that reflected stellar light from clouds on the planetary daysides might contaminate the near-IR spectrum. Here, we aim to explore how reflected light from clouds within in a simplified cloud framework will alter the shape of the near infrared spectra and how they will influence our determinations of dayside temperatures and abundances. Specifically, we will use atmospheric retrieval tools to determine the biases in abundances and temperature profiles if reflected light is not taken into account. We will explore the influence of reflected light on interpretation of WFC3 spectra of the well-observed exoplanets, HD209458b and WASP-43b. We will then investigate how reflected light in the near-IR will influence our interpretation of JWST spectra.

Precision and resolution on Tore-Supra ECE electron temperature profile measurements

International Nuclear Information System (INIS)

Segui, J.L.; Molina, D.; Goniche, M.

2003-01-01

A 16-channel heterodyne radiometer, 2 GHz spaced, is used on Tore-Supra to measure the electron cyclotron emission in the frequency range 78-110 GHz for the O mode and 94 -126 GHz for the X mode. In the equatorial plane, a dual polarisation Gaussian optics lens antenna, with a perpendicular line of sight (with respect to the magnetic field), gives ECE measurements with very low refraction and Doppler effects. A separate O/X mode RF front-end allows the use of an IF electronic mode selector. This improves time stability calibration and gives the potentiality of simultaneous O/X mode measurements in the 94 -110 GHz RF band for polarisation studies. RF and IF filters reject the gyrotron frequency (118 GHz) in order to perform temperature measurements during ECRH plasmas. A precise absolute spectral calibration is performed outside the vacuum vessel by using a 600 deg. C black body, a digital signal averaging on the waveform generated by a mechanical chopper placed directly in front of it, and a simulation window without Fabry-Perot effects. The calibration precision leads to ECE temperature profiles which are very consistent with Thomson scattering measurements and guarantees a good stability of the ECE profiles for small changes on the magnetic field (absolute precision ± 6%, relative precision between channels ± 3%). Post-pulse data processing takes routinely into account the total magnetic field (B vacuum with ripple, B para , B dia , B pol , all with analytical formulations), the radial relativistic shift (analytical formulation is used), the refraction, not described in this paper, (cut-off detection with safety margin to avoid strong refraction), the nonthermal ECE spectra, not described in this paper, during LHCD (using an electron density threshold criterion). These previous analytical formulations are compatible with real time processing. Relativistic radial broadening simulations show that it is useful to fulfill 32 channels (1 GHz spaced). (authors)

Precision and resolution on Tore-Supra ECE electron temperature profile measurements

Energy Technology Data Exchange (ETDEWEB)

Segui, J.L.; Molina, D.; Goniche, M. [Association EURATOM -CEA, CEA/DSM/DRFC CEA-Cadarache, 13108 St Paul-lez-Durance (France)

2003-07-01

A 16-channel heterodyne radiometer, 2 GHz spaced, is used on Tore-Supra to measure the electron cyclotron emission in the frequency range 78-110 GHz for the O mode and 94 -126 GHz for the X mode. In the equatorial plane, a dual polarisation Gaussian optics lens antenna, with a perpendicular line of sight (with respect to the magnetic field), gives ECE measurements with very low refraction and Doppler effects. A separate O/X mode RF front-end allows the use of an IF electronic mode selector. This improves time stability calibration and gives the potentiality of simultaneous O/X mode measurements in the 94 -110 GHz RF band for polarisation studies. RF and IF filters reject the gyrotron frequency (118 GHz) in order to perform temperature measurements during ECRH plasmas. A precise absolute spectral calibration is performed outside the vacuum vessel by using a 600 deg. C black body, a digital signal averaging on the waveform generated by a mechanical chopper placed directly in front of it, and a simulation window without Fabry-Perot effects. The calibration precision leads to ECE temperature profiles which are very consistent with Thomson scattering measurements and guarantees a good stability of the ECE profiles for small changes on the magnetic field (absolute precision {+-} 6%, relative precision between channels {+-} 3%). Post-pulse data processing takes routinely into account the total magnetic field (B{sub vacuum} with ripple, B{sub para}, B{sub dia}, B{sub pol}, all with analytical formulations), the radial relativistic shift (analytical formulation is used), the refraction, not described in this paper, (cut-off detection with safety margin to avoid strong refraction), the nonthermal ECE spectra, not described in this paper, during LHCD (using an electron density threshold criterion). These previous analytical formulations are compatible with real time processing. Relativistic radial broadening simulations show that it is useful to fulfill 32 channels (1 GHz

Planck intermediate results XXVIII. Interstellar gas and dust in the Chamaeleon clouds as seen by Fermi LAT and Planck

DEFF Research Database (Denmark)

Ade, P. A. R.; Aghanim, N.; Aniano, G.

2015-01-01

the clouds. We have separated clouds at local, intermediate, and Galactic velocities in H i and 12CO line emission to model in parallel the γ-ray intensity recorded between 0.4 and 100 GeV; the dust optical depth at 353 GHz, τ353; the thermal radiance of the large grains; and an estimate of the dust...... extinction, AVQ, empirically corrected for the starlight intensity. The dust and gamma-models have been coupled to account for the DNM gas. The consistent γ-emissivity spectra recorded in the different phases confirm that the GeV-TeV cosmic rays probed by the LAT uniformly permeate all gas phases up...... in the gamma-versus dust calibration of XCO, but they confirm the factor of 2 difference found between the XCO estimates in nearby clouds and in the neighbouring spiral arms....

Horizontal Variability of Water and Its Relationship to Cloud Fraction near the Tropical Tropopause: Using Aircraft Observations of Water Vapor to Improve the Representation of Grid-scale Cloud Formation in GEOS-5

Science.gov (United States)

Selkirk, Henry B.; Molod, Andrea M.

2014-01-01

Large-scale models such as GEOS-5 typically calculate grid-scale fractional cloudiness through a PDF parameterization of the sub-gridscale distribution of specific humidity. The GEOS-5 moisture routine uses a simple rectangular PDF varying in height that follows a tanh profile. While below 10 km this profile is informed by moisture information from the AIRS instrument, there is relatively little empirical basis for the profile above that level. ATTREX provides an opportunity to refine the profile using estimates of the horizontal variability of measurements of water vapor, total water and ice particles from the Global Hawk aircraft at or near the tropopause. These measurements will be compared with estimates of large-scale cloud fraction from CALIPSO and lidar retrievals from the CPL on the aircraft. We will use the variability measurements to perform studies of the sensitivity of the GEOS-5 cloud-fraction to various modifications to the PDF shape and to its vertical profile.

Gravitational fragmentation caught in the act: the filamentary Musca molecular cloud

Science.gov (United States)

Kainulainen, J.; Hacar, A.; Alves, J.; Beuther, H.; Bouy, H.; Tafalla, M.

2016-02-01

Context. Filamentary structures are common in molecular clouds. Explaining how they fragment to dense cores is a missing step in understanding their role in star formation. Aims: We perform a case study of whether low-mass filaments are close to hydrostatic prior to their fragmentation, and whether their fragmentation agrees with gravitational fragmentation models. To accomplish this, we study the ~6.5 pc long Musca molecular cloud, which is an ideal candidate for a filament at an early stage of fragmentation. Methods: We employ dust extinction mapping, in conjunction with near-infrared JHKS-band data from the CTIO/NEWFIRM instrument, and 870 μm dust continuum emission data from the APEX/LABOCA instrument to estimate column densities in Musca. We use the data to identify fragments from the cloud and to determine the radial density distribution of its filamentary part. We compare the cloud's morphology with 13CO and C18O line emission observed with the APEX/SHeFI instrument. Results: The Musca cloud is pronouncedly fragmented at its ends, but harbors a remarkably well-defined, ~1.6 pc long filament in its center region. The line mass of the filament is 21-31 M⊙ pc-1 and the full width at half maximum (FWHM) 0.07 pc. The radial profile of the filament can be fitted with a Plummer profile, which has the power-index of 2.6 ± 11% and is flatter than that of an infinite hydrostatic filament. The profile can also be fitted with a hydrostatic cylinder truncated by external pressure. These models imply a central density of ~5-10 × 104 cm-3. The fragments in the cloud have a mean separation of ~0.4 pc, in agreement with gravitational fragmentation. These properties, together with the subsonic and velocity-coherent nature of the cloud, suggest a scenario in which an initially hydrostatic cloud is currently gravitationally fragmenting. The fragmentation started a few tenths of a Myr ago from the ends of the cloud, leaving its center still relatively nonfragmented

Multiparty quantum secret sharing based on GHZ states

Energy Technology Data Exchange (ETDEWEB)

Hwang, Tzonelih; Hwang, Cheng-Chieh [Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan, 701 Taiwan (China); Li, Chuan-Ming, E-mail: hwangtl@ismail.csie.ncku.edu.tw [Department of Information Management, Shu-Zen College of Medicine and Management, Kaohsiung, 821 Taiwan (China)

2011-04-15

Gao (2009 Commun. Theor. Phys. 52 421-4) has proposed an efficient multiparty quantum secret sharing (MQSS) with two-photon three-dimensional Einstein-Podolsky-Rosen (EPR) pairs. This work shows that a similar idea can also be used to construct an MQSS using the Greenberger-Horne-Zeilinger (GHZ) states. Compared to other MQSSs using GHZ-related states, the newly proposed protocol is more efficient in the aspect of qubit utilization.

+Cloud: An Agent-Based Cloud Computing Platform

OpenAIRE

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

2017-01-01

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

Remote Determination of Cloud Temperature and Transmittance from Spectral Radiance Measurements: Method and Results

Science.gov (United States)

1996-10-01

atmospherics temperatura and humidity profiles. Validation tests performed on experimental spectra demonstrate the occuracy of the method with typical...indicated as with the title.) Passive Remota Sensing Infrared Spectra Cloud Temperatura Cloud Transmittance FTIR Spectrometer Icing Hazard Detection (DCD03E.IFO - 95.02.22) UNCLASSIFIED SECURITY CLASSIFICATION OF FORM

Design of a 17.14 GHz quasi-optical pulse compressor

International Nuclear Information System (INIS)

Petelin, M. I.; Kuzikov, S. V.; Danilov, Yu. Yu.; Granatstein, V. L.; Nusinovich, G. S.

1999-01-01

A quasi-optical version of the ring cavity pulse compressor is considered. This concept is based on the coupling of the input wave to a whispering gallery mode of a barrel-like cavity due to helical corrugations of the cavity wall. Low-power tests of the prototype were carried out at 11.4 GHz and demonstrated reasonable agree-ment between experimental data and theoretical predictions. The design of a similar pulse compressor at 17.14 GHz compatible with the 17.14 GHz, 100 MW gyroklystron currently under development at the University of Maryland is presented

Silicon Photonics Cloud (SiCloud)

DEFF Research Database (Denmark)

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

2015-01-01

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

Analisis Kelayakan Implementasi Teknologi LTE 1.8 GHz Bagi Operator Seluler di Indonesia [Feasibility Analysis of LTE 1.8 GHz for Mobile Operators in Indonesia

Directory of Open Access Journals (Sweden)

Sri Ariyanti

2015-06-01

Full Text Available Peningkatan kebutuhan layanan data mendorong operator telekomunikasi berusaha mengimplementasikan jaringan akses broadband yang lebih handal.  Teknologi LTE merupakan salah satu teknologi dengan kecepatan mencapai tiga kali dibanding teknologi HSDPA, sehingga diharapkan dapat memenuhi kebutuhan pelanggan data mobile. Refarming frekuensi 1.8 GHz  untuk penerapan teknologi LTE memberikan efisiensi karena tidak perlu membayar BHP lagi untuk menyewa frekuensi baru. Teknologi 2G GSM selama ini juga semakin ditinggalkan, masyarakat di daerah perkotaan cenderung lebih banyak menggunakan layanan data.  Sebelum diterapkannya teknologi LTE pada frekuensi 1.8 GHz perlu adanya kajian untuk mengetahui kelayakan teknologi LTE pada frekuensi 1.8 GHz. Penelitian ini bertujuan untuk melakukan cost-benefit analysis implementasi LTE pada frekuensi 1.8 GHz.  Metode penelitian menggunakan pendekatan kualitataif yang didukung dengan data kuantitatif.  Hasil penelitian menunjukkan bahwa minimal bandiwdth yang diperlukan agar implementasi LTE layak digunakan adalah 15 MHz.  Meskipun tanpa Global Frequency Returning, penggunaan bandwidth 10 MHz tidak layak digunakan untuk implementasi LTE.      *****The incresing of data demand drives mobile operators to implement more reliable broadband access network. LTE technology has downlink peak rate up to three times than HSDPA,  hence it may fulfill the mobile data user requirement. Frequency 1.8 GHz refarming can be implemented to provide efficiency because They do not need to pay licence fee for leasing new frequency. GSM technology will be abandoned since it is not growing anymore. Besides that, dense urban users tend to use data mobile.  Before implementing LTE technology  on 1.8 GHz frequency, It is necessary to analysis the feasibility such technology. This research used qualitative method supported by quantitative  approach.  The result of this research showed that minimum bandwidth to implement 1.8 GHz LTE

Evaluating Microphysics in Cloud-Resolving Models using TRMM and Ground-based Precipitation Radar Observations

Science.gov (United States)

Krueger, S. K.; Zulauf, M. A.; Li, Y.; Zipser, E. J.

2005-05-01

conclusion can be reached by comparing the simulated microwave brightness temperatures with observed brightness temperatures at 85 GHz and 37 GHz. In each case, the simulations are more extreme than all observed MCSs in the region over the 5 year period. The situation is similar but less egregious for the southern Great Plains simulation. Inspection of the cloud microphysics output files reveals the source of the discrepancy between simulation and observations in the upper troposphere. The simulations have very large graupel concentrations between about 5-10 km, as high as 10 g/kg graupel mixing ratio. This guarantees that there are very high radar reflectivities extending into the upper troposphere, and unrealistically low microwave brightness temperatures. We also performed a set of short (6-h) numerical simulations of the life cycle of a single convection cell to examine the sensitivity of the simulated graupel fields to the intercept parameter and the density of the graupel. The control case used the same values as the ARM and KWAJEX simulations. Reducing the intercept parameter by a factor of 100 reduced the maximum graupel mixing ratios but increased the maximum dBZ values. This suggests that the discrepencies between the simulations and the observations must involve the graupel growth rates.

Cloud Properties of CERES-MODIS Edition 4 and CERES-VIIRS Edition 1

Science.gov (United States)

Sun-Mack, Sunny; Minnis, Patrick; Chang, Fu-Lung; Hong, Gang; Arduini, Robert; Chen, Yan; Trepte, Qing; Yost, Chris; Smith, Rita; Brown, Ricky;

Cloud Processed CCN Suppress Stratus Cloud Drizzle

Science.gov (United States)

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

2017-12-01

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

The 1.4 GHZ light curve of GRB 970508

NARCIS (Netherlands)

Galama, TJ; Wijers, RAMJ; Groot, PJ; Strom, RG; De Bruyn, AG; Kouveliotou, C; Robinson, CR; van Paradus, J

1998-01-01

We report on Westerbork 1.4 GHz radio observations of the radio counterpart to gamma-ray burst GRB 970508, between 0.80 and 138 days after this event. The 1.4 GHz light curve shows a transition from optically thick to thin emission between 39 and 54 days after the event. We derive the slope p of the

Observational demonstration of a high image rejection SIS mixer receiver using a new waveguide filter at 230 GHz

Science.gov (United States)

Hasegawa, Yutaka; Asayama, Shinichiro; Harada, Ryohei; Tokuda, Kazuki; Kimura, Kimihiro; Ogawa, Hideo; Onishi, Toshikazu

2017-12-01

A new sideband separation method was developed for use in millimeter-/submillimeter-band radio receivers using a novel waveguide frequency separation filter (FSF), which consists of two branch line hybrid couplers and two waveguide high-pass filters. The FSF was designed to allow the radio frequency (RF) signal to pass through to an output port when the frequency is higher than a certain value (225 GHz), and to reflect the RF signal back to another output port when the frequency is lower. The FSF is connected to two double sideband superconductor-insulator-superconductor (SIS) mixers, and an image rejection ratio (IRR) is determined by the FSF characteristics. With this new sideband separation method, we can achieve good and stable IRR without the balancing two SIS mixers such as is necessary for conventional sideband-separating SIS mixers. To demonstrate the applicability of this method, we designed and developed an FSF for simultaneous observations of the J = 2-1 rotational transition lines of three CO isotopes (12CO, 13CO, and C18O): the 12CO line is in the upper sideband and the others are in the lower sideband with an intermediate-frequency range of 4-8 GHz at the radio frequency of 220/230 GHz. This FSF was then installed in the receiver system of the 1.85 m radio telescope of Osaka Prefecture University, and was used during the 2014 observation season. The observation results indicate that the IRR of the proposed receiver is 25 dB or higher for the 12CO line, and no significant fluctuation larger than 1 dB in the IRR was observed throughout the season. These results demonstrate the practical utility of the FSF receiver for observations like extensive molecular cloud surveys in specified lines with a fixed frequency setting.

Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

Science.gov (United States)

Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

2009-01-01

Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

Cloud Physics Lidar Optical Measurements During the SAFARI-2000 Field Campaign

Science.gov (United States)

Hlavka, Dennis L.; McGill, Matt; Hart, William D.; Spinhirne, James D.; Starr, David OC. (Technical Monitor)

2002-01-01

In this presentation, we will show new optical data processing results from the Cloud Physics War during SAFARI-2000. Retrieved products include aerosol and cloud layer location and identification, layer optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary layer and occasional elevated aerosol layers found in southern Africa during August and September 2000.

Monitoring water phase dynamics in winter clouds

Science.gov (United States)

Campos, Edwin F.; Ware, Randolph; Joe, Paul; Hudak, David

2014-10-01

This work presents observations of water phase dynamics that demonstrate the theoretical Wegener-Bergeron-Findeisen concepts in mixed-phase winter storms. The work analyzes vertical profiles of air vapor pressure, and equilibrium vapor pressure over liquid water and ice. Based only on the magnitude ranking of these vapor pressures, we identified conditions where liquid droplets and ice particles grow or deplete simultaneously, as well as the conditions where droplets evaporate and ice particles grow by vapor diffusion. The method is applied to ground-based remote-sensing observations during two snowstorms, using two distinct microwave profiling radiometers operating in different climatic regions (North American Central High Plains and Great Lakes). The results are compared with independent microwave radiometer retrievals of vertically integrated liquid water, cloud-base estimates from a co-located ceilometer, reflectivity factor and Doppler velocity observations by nearby vertically pointing radars, and radiometer estimates of liquid water layers aloft. This work thus makes a positive contribution toward monitoring and nowcasting the evolution of supercooled droplets in winter clouds.

Carbon pellet cloud striations

International Nuclear Information System (INIS)

Parks, P.B.

1989-01-01

Fine scale striations, with alternating rows of bright and dark zones, have been observed in the ablation clouds of carbon pellets injected into the TEXT tokamak. The striations extend along the magnetic field for about 1 cm with quite regular cross-field variations characterized by a wavelength of a few mm. Their potential as a diagnostic tool for measuring q-profiles in tokamaks provides motivation for investigating the origin of the striations. The authors propose that the striations are not due to a sequence of high and low ablation rates because of the finite thermal magnetic islands localized at rational surfaces, q = m/n, would be responsible for reducing the electron flux to the pellet region; the length of the closed field line which forms the local magnetic axis of the island is too long to prevent a depletion of plasma electrons in a flux tube intercepting the pellet for the duration 2 rp / vp . Instead, they propose that striations are the manifestation of the saturated state of growing fluctuations inside the cloud. The instability is generated by E x B rotation of the ablation cloud. The outward centrifugal force points down the ablation density gradient inducing the Rayleigh-Taylor instability. The instability is not present for wave numbers along the field lines, which may explain why the striations are long and uniform in that direction. The E field develops inside the ablation cloud as a result of cold electron return currents which are induced to cancel the incoming hot plasma electron current streaming along the field lines

Cloud Statistics and Discrimination in the Polar Regions

Science.gov (United States)

Chan, M.; Comiso, J. C.

2012-12-01

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

HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

International Nuclear Information System (INIS)

Potter, T. M.; Staveley-Smith, L.; Zanardo, G.; Ng, C.-Y.; Gaensler, B. M.; Ball, Lewis; Kesteven, M. J.; Manchester, R. N.; Tzioumis, A. K.

2009-01-01

The aftermath of supernova (SN) 1987A continues to provide spectacular insights into the interaction between an SN blastwave and its circumstellar environment. We here present 36 GHz observations from the Australia Telescope Compact Array of the radio remnant of SN 1987A. These new images, taken in 2008 April and 2008 October, substantially extend the frequency range of an ongoing monitoring and imaging program conducted between 1.4 and 20 GHz. Our 36.2 GHz images have a diffraction-limited angular resolution of 0.''3-0.''4, which covers the gap between high resolution, low dynamic range VLBI images of the remnant and low resolution, high dynamic range images at frequencies between 1 and 20 GHz. The radio morphology of the remnant at 36 GHz is an elliptical ring with enhanced emission on the eastern and western sides, similar to that seen previously at lower frequencies. Model fits to the data in the Fourier domain show that the emitting region is consistent with a thick inclined torus of mean radius 0.''85, and a 2008 October flux density of 27 ± 6 mJy at 36.2 GHz. The spectral index for the remnant at this epoch, determined between 1.4 GHz and 36.2 GHz, is α = -0.83. There is tentative evidence for an unresolved central source with flatter spectral index.

COMPARISON OF POINT CLOUDS DERIVED FROM AERIAL IMAGE MATCHING WITH DATA FROM AIRBORNE LASER SCANNING

Directory of Open Access Journals (Sweden)

Dominik Wojciech

2017-04-01

Full Text Available The aim of this study was to invest igate the properties of point clouds derived from aerial image matching and to compare them with point clouds from airborne laser scanning. A set of aerial images acquired in years 2010 - 2013 over the city of Elblag were used for the analysis. Images were acquired with the use of three digital cameras: DMC II 230, DMC I and DigiCAM60 with a GSD varying from 4.5 cm to 15 cm. Eight sets of images that were used in the study were acquired at different stages of the growing season – from March to December. Two L iDAR point clouds were used for the comparison – one with a density of 1.3 p/m 2 and a second with a density of 10 p/m 2 . Based on the input images point clouds were created with the use of the semi - global matching method. The properties of the obtained poi nt clouds were analyzed in three ways: – b y the comparison of the vertical accuracy of point clouds with reference to a terrain profile surveyed on bare ground with GPS - RTK method – b y visual assessment of point cloud profiles generated both from SGM and LiDAR point clouds – b y visual assessment of a digital surface model generated from a SGM point cloud with reference to a digital surface model generated from a LiDAR point cloud. The conducted studies allowed a number of observations about the quality o f SGM point clouds to be formulated with respect to different factors. The main factors having influence on the quality of SGM point clouds are GSD and base/height ratio. The essential problem related to SGM point clouds are areas covered with vegetation w here SGM point clouds are visibly worse in terms of both accuracy and the representation of terrain surface. It is difficult to expect that in these areas SG M point clouds could replace LiDAR point clouds. This leads to a general conclusion that SGM point clouds are less reliable, more unpredictable and are dependent on more factors than LiDAR point clouds. Nevertheless, SGM point

Handoff Management in Radio over Fiber 60 GHz Indoor Networks

NARCIS (Netherlands)

Bien, V.Q.

2014-01-01

Because of high data rate multimedia applications such as HD and UHDTV, online games, etc., the future home networks are expected to support short-range gigabit transmission. With the worldwide availability of 5 GHz spectrum at the 60 GHz band, it creates the opportunity for a promising air

Results of RIKEN superconducting electron cyclotron resonance ion source with 28 GHz.

Science.gov (United States)

Higurashi, Y; Ohnishi, J; Nakagawa, T; Haba, H; Tamura, M; Aihara, T; Fujimaki, M; Komiyama, M; Uchiyama, A; Kamigaito, O

2012-02-01

We measured the beam intensity of highly charged heavy ions and x-ray heat load for RIKEN superconducting electron cyclotron resonance ion source with 28 GHz microwaves under the various conditions. The beam intensity of Xe(20+) became maximum at B(min) ∼ 0.65 T, which was ∼65% of the magnetic field strength of electron cyclotron resonance (B(ECR)) for 28 GHz microwaves. We observed that the heat load of x-ray increased with decreasing gas pressure and field gradient at resonance zone. It seems that the beam intensity of highly charged heavy ions with 28 GHz is higher than that with 18 GHz at same RF power.

Electron-beam buncher to operate over the frequency range 1-4 GHz

International Nuclear Information System (INIS)

Goldberg, D.A.; Arthur, A.A.; Flood, W.S.; Voelker, F.

1983-03-01

We present a description of an electron buncher to be installed in the terminal of a Van de Graaff, which is to produce a modulated beam over the frequency range 1-4 GHz. The modulator geometry has been optimized so that the modulation amplitude should be nearly constant over the frequency ranges 1-2 GHz and 2-4 GHz. Preliminary results indicate the device works as predicted

GHz Yb:KYW oscillators in time-resolved spectroscopy

Science.gov (United States)

Li, Changxiu; Krauß, Nico; Schäfer, Gerhard; Ebner, Lukas; Kliebisch, Oliver; Schmidt, Johannes; Winnerl, Stephan; Hettich, Mike; Dekorsy, Thomas

2018-02-01

A high-speed asynchronous optical sampling system (ASOPS) based on Yb:KYW oscillators with 1-GHz repetition rate is reported. Two frequency-offset-stabilized diode-pumped Yb:KYW oscillators are employed as pump and probe source, respectively. The temporal resolution of this system within 1-ns time window is limited to 500 fs and the noise floor around 10-6 (ΔR/R) close to the shot-noise level is obtained within an acquisition time of a few seconds. Coherent acoustic phonons are investigated by measuring multilayer semiconductor structures with multiple quantum wells and aluminum/silicon membranes in this ASOPS system. A wavepacket-like phonon sequence at 360 GHz range is detected in the semiconductor structures and a decaying sequence of acoustic oscillations up to 200 GHz is obtained in the aluminum/silicon membranes. Coherent acoustic phonons generated from semiconductor structures are further manipulated by a double pump scheme through pump time delay control.

Observations of Co-variation in Cloud Properties and their Relationships with Atmospheric State

Science.gov (United States)

Sinclair, K.; van Diedenhoven, B.; Fridlind, A. M.; Arnold, T. G.; Yorks, J. E.; Heymsfield, G. M.; McFarquhar, G. M.; Um, J.

2017-12-01

Radiative properties of upper tropospheric ice clouds are generally not well represented in global and cloud models. Cloud top height, cloud thermodynamic phase, cloud optical thickness, cloud water path, particle size and ice crystal shape all serve as observational targets for models to constrain cloud properties. Trends or biases in these cloud properties could have profound effects on the climate since they affect cloud radiative properties. Better understanding of co-variation between these cloud properties and linkages with atmospheric state variables can lead to better representation of clouds in models by reducing biases in their micro- and macro-physical properties as well as their radiative properties. This will also enhance our general understanding of cloud processes. In this analysis we look at remote sensing, in situ and reanalysis data from the MODIS Airborne Simulator (MAS), Cloud Physics Lidar (CPL), Cloud Radar System (CRS), GEOS-5 reanalysis data and GOES imagery obtained during the Tropical Composition, Cloud and Climate Coupling (TC4) airborne campaign. The MAS, CPL and CRS were mounted on the ER-2 high-altitude aircraft during this campaign. In situ observations of ice size and shape were made aboard the DC8 and WB57 aircrafts. We explore how thermodynamic phase, ice effective radius, particle shape and radar reflectivity vary with altitude and also investigate how these observed cloud properties vary with cloud type, cloud top temperature, relative humidity and wind profiles. Observed systematic relationships are supported by physical interpretations of cloud processes and any unexpected differences are examined.

Processes that generate and deplete liquid water and snow in thin midlevel mixed-phase clouds

Science.gov (United States)

Smith, Adam J.; Larson, Vincent E.; Niu, Jianguo; Kankiewicz, J. Adam; Carey, Lawrence D.

2009-06-01

This paper uses a numerical model to investigate microphysical, radiative, and dynamical processes in mixed-phase altostratocumulus clouds. Three cloud cases are chosen for study, each of which was observed by aircraft during the fifth or ninth Complex Layered Cloud Experiment (CLEX). These three clouds are numerically modeled using large-eddy simulation (LES). The observed and modeled clouds consist of a mixed-phase layer with a quasi-adiabatic profile of liquid, and a virga layer below that consists of snow. A budget of cloud (liquid) water mixing ratio is constructed from the simulations. It shows that large-scale ascent/descent, radiative cooling/heating, turbulent transport, and microphysical processes are all significant. Liquid is depleted indirectly via depositional growth of snow (the Bergeron-Findeisen process). This process is more influential than depletion of liquid via accretional growth of snow. Also constructed is a budget of snow mixing ratio, which turns out to be somewhat simpler. It shows that snow grows by deposition in and below the liquid (mixed-phase) layer, and sublimates in the remainder of the virga region below. The deposition and sublimation are balanced primarily by sedimentation, which transports the snow from the growth region to the sublimation region below. In our three clouds, the vertical extent of the virga layer is influenced more by the profile of saturation ratio below the liquid (mixed-phase) layer than by the mixing ratio of snow at the top of the virga layer.

Improvement of the spectroscopic investigation of pellet ablation clouds

International Nuclear Information System (INIS)

Koubiti, M.; Ferri, S.; Godbert-Mouret, L.; Marandet, Y.; Rosato, J.; Stamm, R.; Goto, M.; Morita, S.

2012-11-01

The method allowing the characterization of the so-called ablation cloud of a pellet from its spectroscopic emission lines (intensities and shapes) is described. It is illustrated using measurements concerning carbon and aluminum pellets injected in the Large Helical Devices (LHD). The electron densities in pellet ablation clouds are sufficiently high that the energy levels of the main emitting species are at Local Thermodynamic Equilibrium (LTE). This justifies the electron temperature determination from the measured intensities using Boltzmann plots. In the case of carbon pellet, the C II 723 nm line was previously fitted with a convolution of a Lorentzian and a Gaussian profiles to determine the electron density. It is proposed here to use more elaborate theoretical profiles accounting for the Stark-Zeeman contributions in order to obtain more accurate plasma parameters especially for the high-resolution spectra in which both Zeeman and Stark features are visible. We present some preliminary comparisons with such spectra which were measured recently in LHD and discuss the possible improvement of the considered investigation technique once all the contributions to the line profile are effectively included. (author)

Test result of 5 GHz, 500 kW CW prototype klystron for KSTAR LHCD system

Energy Technology Data Exchange (ETDEWEB)

Do, H., E-mail: heejindo@nfri.re.kr [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Park, S. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Jeong, J.H.; Bae, Y.S.; Yang, H.L. [National Fusion Research Institute, Daejeon 350-333 (Korea, Republic of); Delpech, L.; Magne, R.; Hoang, G.T. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Park, H.; Cho, M.H.; Namkung, W. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2011-10-15

A 5 GHz LHCD system is being designed for current drive and profile modification necessary for AT mode and steady-state operation of the KSTAR tokamak. A prototype 500 kW CW klystron operating at 5 GHz was developed for the steady-state RF source. In this klystron, a multi-cell cavity is introduced to reduce cavity voltage and ohmic power loss. The klystron is designed with a triode system for optimization of gain, efficiency and beam control. The high voltage for the cathode is turned by using a thyristor switching system at the low voltage transformer unit. For anode voltage control, a mod-anode voltage divider system is used which utilize the parallel-circuit of the FET switch and Zener diodes. The RF output power of the klystron was 300 kW for 800 s and 450 kW for 20 s. The maximal temperature at collector top surface was 83 deg. C and power loss at the tube body did not exceed 10 kW, the interlock level for the protection of the klystron. Detailed results of the klystron system test and commissioning are presented.

A CMOS frequency generation module for 60-GHz applications

International Nuclear Information System (INIS)

Zhou Chunyuan; Zhang Lei; Wang Hongrui; Qian He

2012-01-01

A frequency generation module for 60-GHz transceivers and phased array systems is presented in this paper. It is composed of a divide-by-2 current mode logic divider (CML) and a doubler in push-push configuration. Benefiting from the CML structure and push-push configuration, the proposed frequency generation module has a wide operating frequency range to cover process, voltage, and temperature variation. It is implemented in a 90-nm CMOS process, and occupies a chip area of 0.64 × 0.65 mm 2 including pads. The measurement results show that the designed frequency generation module functions properly with input frequency over 15 GHz to 25 GHz. The whole chip dissipates 12.1 mW from a 1.2-V supply excluding the output buffers. (semiconductor integrated circuits)

Balloon-borne aerosol measurements in the planetary boundary layer: particle production associated with a continental stratiform cloud

Energy Technology Data Exchange (ETDEWEB)

Kuetz, S. [Inst. for Tropospheric Res., Leipzig (Germany); Dubois, R. [Inst. for Tropospheric Res., Leipzig (Germany)

1997-05-01

Vertical profiles of submicrometer Aitken nuclei (AN), temperature, humidity, wind speed and direction have been measured using a tethered balloon as a platform for the instrumentation. Daytime soundings up to 700 m above ground were done over Eastern Germany during a strong and persistent wintertime temperature inversion on 18th January 1996. The inversion at 650 m above ground topped a closed stratus deck with a diffuse cloud base at 250 m. The profiles of temperature, humidity and AN concentrations indicate that the layer below the inversion was well mixed. An upper limit to cloud droplet number concentration of 700 p/cm{sup 3} was inferred from the AN measurements. At the top of the cloud distinct AN concentration maxima were observed. Their evolution as a function of time and space with respect to the profiles of temperature, humidity and wind indicated new particle production. Concurrent with the balloon soundings, continuous ground based measurements of wind by SODAR and of SO{sub 2} were also performed. (orig.)

Single-footprint retrievals of temperature, water vapor and cloud properties from AIRS

Science.gov (United States)

Irion, Fredrick W.; Kahn, Brian H.; Schreier, Mathias M.; Fetzer, Eric J.; Fishbein, Evan; Fu, Dejian; Kalmus, Peter; Wilson, R. Chris; Wong, Sun; Yue, Qing

2018-02-01

Single-footprint Atmospheric Infrared Sounder spectra are used in an optimal estimation-based algorithm (AIRS-OE) for simultaneous retrieval of atmospheric temperature, water vapor, surface temperature, cloud-top temperature, effective cloud optical depth and effective cloud particle radius. In a departure from currently operational AIRS retrievals (AIRS V6), cloud scattering and absorption are in the radiative transfer forward model and AIRS single-footprint thermal infrared data are used directly rather than cloud-cleared spectra (which are calculated using nine adjacent AIRS infrared footprints). Coincident MODIS cloud data are used for cloud a priori data. Using single-footprint spectra improves the horizontal resolution of the AIRS retrieval from ˜ 45 to ˜ 13.5 km at nadir, but as microwave data are not used, the retrieval is not made at altitudes below thick clouds. An outline of the AIRS-OE retrieval procedure and information content analysis is presented. Initial comparisons of AIRS-OE to AIRS V6 results show increased horizontal detail in the water vapor and relative humidity fields in the free troposphere above the clouds. Initial comparisons of temperature, water vapor and relative humidity profiles with coincident radiosondes show good agreement. Future improvements to the retrieval algorithm, and to the forward model in particular, are discussed.

Multistatic Aerosol Cloud Lidar in Space: A Theoretical Perspective

Science.gov (United States)

Mishchenko, Michael I.; Alexandrov, Mikhail D.; Cairns, Brian; Travis, Larry D.

2016-01-01

Accurate aerosol and cloud retrievals from space remain quite challenging and typically involve solving a severely ill-posed inverse scattering problem. In this Perspective, we formulate in general terms an aerosol and aerosol-cloud interaction space mission concept intended to provide detailed horizontal and vertical profiles of aerosol physical characteristics as well as identify mutually induced changes in the properties of aerosols and clouds. We argue that a natural and feasible way of addressing the ill-posedness of the inverse scattering problem while having an exquisite vertical-profiling capability is to fly a multistatic (including bistatic) lidar system. We analyze theoretically the capabilities of a formation-flying constellation of a primary satellite equipped with a conventional monostatic (backscattering) lidar and one or more additional platforms each hosting a receiver of the scattered laser light. If successfully implemented, this concept would combine the measurement capabilities of a passive multi-angle multi-spectral polarimeter with the vertical profiling capability of a lidar; address the ill-posedness of the inverse problem caused by the highly limited information content of monostatic lidar measurements; address the ill-posedness of the inverse problem caused by vertical integration and surface reflection in passive photopolarimetric measurements; relax polarization accuracy requirements; eliminate the need for exquisite radiative-transfer modeling of the atmosphere-surface system in data analyses; yield the day-and-night observation capability; provide direct characterization of ground-level aerosols as atmospheric pollutants; and yield direct measurements of polarized bidirectional surface reflectance. We demonstrate, in particular, that supplementing the conventional backscattering lidar with just one additional receiver flown in formation at a scattering angle close to 170deg can dramatically increase the information content of the

Role of mixed precipitating cloud systems on the typhoon rainfall

Directory of Open Access Journals (Sweden)

C. J. Pan

2010-01-01

Full Text Available L-band wind profiler data are utilized to diagnose the vertical structure of the typhoon precipitating cloud systems in Taiwan. For several typhoons, a pronounced bright band (BB around 5 km is commonly observed from the observation. Since strong convection within typhoon circulation may disturb and/or disrupt the melting layer, the BB shall not appear persistently. Hence, an understanding of the vertical structure of the BB region is important because it holds extensive hydrometeors information on the type of precipitation and its variability. Wind profiler observational results suggest that the mixture of convective and stratiform (embedded type clouds are mostly associated with typhoons. In the case of one typhoon, BB is appeared around 5.5 km with embedded precipitation and also BB height of 1 km higher than ordinary showery precipitation. This is evident from the long-term observations of wind profiler and Tropical Rainfall Measuring Mission. The Doppler velocity profiles show hydrometers (ice/snow at 6 km but liquid below 5 km for typhoons and 4 km for showery precipitation. In the BB region the melting particles accelerations of 5.8 ms−1 km−1 and 3.2 ms−1 km−1 are observed for typhoon and showery precipitation, respectively.

A browser-based 3D Visualization Tool designed for comparing CERES/CALIOP/CloudSAT level-2 data sets.

Science.gov (United States)

Chu, C.; Sun-Mack, S.; Chen, Y.; Heckert, E.; Doelling, D. R.

2017-12-01

In Langley NASA, Clouds and the Earth's Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) are merged with Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat Cloud Profiling Radar (CPR). The CERES merged product (C3M) matches up to three CALIPSO footprints with each MODIS pixel along its ground track. It then assigns the nearest CloudSat footprint to each of those MODIS pixels. The cloud properties from MODIS, retrieved using the CERES algorithms, are included in C3M with the matched CALIPSO and CloudSat products along with radiances from 18 MODIS channels. The dataset is used to validate the CERES retrieved MODIS cloud properties and the computed TOA and surface flux difference using MODIS or CALIOP/CloudSAT retrieved clouds. This information is then used to tune the computed fluxes to match the CERES observed TOA flux. A visualization tool will be invaluable to determine the cause of these large cloud and flux differences in order to improve the methodology. This effort is part of larger effort to allow users to order the CERES C3M product sub-setted by time and parameter as well as the previously mentioned visualization capabilities. This presentation will show a new graphical 3D-interface, 3D-CERESVis, that allows users to view both passive remote sensing satellites (MODIS and CERES) and active satellites (CALIPSO and CloudSat), such that the detailed vertical structures of cloud properties from CALIPSO and CloudSat are displayed side by side with horizontally retrieved cloud properties from MODIS and CERES. Similarly, the CERES computed profile fluxes whether using MODIS or CALIPSO and CloudSat clouds can also be compared. 3D-CERESVis is a browser-based visualization tool that makes uses of techniques such as multiple synchronized cursors, COLLADA format data and Cesium.

Feasibility of automotive radar at frequencies beyond 100 GHz

OpenAIRE

Köhler, Mike; Hasch, Jürgen; Blöcher, Hans Ludwig; Schmidt, Lorenz-Peter

2014-01-01

Radar sensors are used widely in modern driver assistance systems. Available sensors nowadays often operate in the 77 GHz band and can accurately provide distance, velocity, and angle information about remote objects. Increasing the operation frequency allows improving the angular resolution and accuracy. In this paper, the technical feasibility to move the operation frequency beyond 100 GHz is discussed, by investigating dielectric properties of radome materials, the attenuation of rain and ...

Stratocumulus Cloud Top Radiative Cooling and Cloud Base Updraft Speeds

Science.gov (United States)

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

2017-12-01

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

Cloud attenuation studies of the six major climatic zones of Africa for Ka and V satellite system design

Directory of Open Access Journals (Sweden)

Temidayo Victor Omotosho

2014-01-01

Full Text Available Normal 0 false false false EN-GB X-NONE X-NONE Cloud cover statistics, cloud base and top height, cloud temperature, frequency of precipitation, freezing height, total cloud liquid water content (TCLWC and cloud attenuation data have been obtained for the six major climatic zones of Africa. The present results reveal a strong positive correlation between the monthly distribution of low cloud cover, cloud top height, cloud temperature, and frequency of precipitation in the six zones. The cumulative distribution of the TCLWC derived from radiosonde measurement in each climatic zone shows a departure from the TCLWC recommended by the ITU Study Group 3 data, with an exceedance percentage difference of 32% to 90% occurring 0.01% to 10% of the time. The underestimation of the TCLWC is greatest in the tropical rain forest. A comparison of the cloud attenuation cumulative distribution in the Ka and V bands reveals that the International Telecommunication Union – Region (ITU-R is an intergovernmental organization that develops rain model based on collected data around the world. This model underestimates the cloud attenuation in all of the six climatic zones by 2.0 dB and 4.7 dB for the arid Sahara desert, 1.3 dB and 3.0 dB in semi-arid North Africa, 1.3 dB and 1.5 dB in savannah North Africa, 2.0 dB and 3.6 dB in the tropical rain forest, 1.3 dB and 2.9 dB in savannah South Africa and 0.9 dB and 2.6 dB in semi-arid South Africa, respectively, at 30 and 50 GHz. Overall, the cloud attenuation in the tropical rain-forest zone is very high because of the high annual total cloud cover (98%, high annual frequency of precipitation (4.5, low annual clear sky amount (8%, high cloud depth (10,937 m, high 0°C isotherm height (4.7 km, high TCLWC (4.0 kg/m2 at 0.01% and low seasonal cloud base height (356 m.

Design, Development & Functional Validation of Magnets system in support of 42 GHz Gyrotron in India

Directory of Open Access Journals (Sweden)

Pradhan S.

2017-01-01

Full Text Available A multi institutional initiative is underway towards the development of 42 GHz, 200 kW gyrotron system in India under the frame work of Department of Science and Technology, Government of India. Indigenous realization comprising of design, fabrication, prototypes and functional validations of an appropriate Magnet System is one of the primary technological objective of these initiatives. The 42 GHz gyrotron magnet system comprises of a warm gun magnet, a NbTi/Cu based high homogenous superconducting cavity magnet and three warm collector magnets. The superconducting cavity magnet has been housed inside a low loss cryostat. The magnet system has been designed in accordance with gyrotron physics and engineering considerations respecting highly homogenous spatial field profile as well as maintaining steep gradient as per the compression and velocity ratios between the emission and resonator regions. The designed magnet system further ensures the co-linearity of the magnetic axis with that of the beam axis with custom winding techniques apart from a smooth collection of beam with the collector magnet profiles. The designed magnets have been wound after several R & D validations. The superconducting magnet has been housed inside a low loss designed cryostat with in-built radial and axial alignment flexibilities to certain extent. The cryostat further houses liquid helium port, liquid nitrogen ports, current communication ports, ports for monitoring helium level and other instrumentations apart from over-pressure safety intensive burst disks etc. The entire magnet system comprising of warm and superconducting magnets has been installed and integrated in the Gyrotron test set-up. The magnet system has been aligned in both warm and when the superconducting cavity magnet is cold. The integrated geometric axes have been experimentally ensured as well as the field profiles have been measured with the magnets being charged. Under experimental conditions

The Role of Emissivity in the Detection of Arctic Night Clouds

Directory of Open Access Journals (Sweden)

Filomena Romano

2017-04-01

Full Text Available Detection of clouds over polar areas from satellite radiometric measurements in the visible and IR atmospheric window region is rather difficult because of the high albedo of snow, possible ice covered surfaces, very low humidity, and the usual presence of atmospheric temperature inversion. Cold and highly reflective polar surfaces provide little thermal and visible contrast between clouds and the background surface. Moreover, due to the presence of temperature inversion, clouds are not always identifiable as being colder than the background. In addition, low humidity often causes polar clouds to be optically thin. Finally, polar clouds are usually composed of a mixture of ice and water, which leads to an unclear spectral signature. Single and bi-spectral threshold methods are sometimes inappropriate due to a large variability of surface emissivity and cloud conditions. The objective of this study is to demonstrate the crucial role played by surface emissivity in the detection of polar winter clouds and the potential improvement offered by infrared hyperspectral observations, such as from the Infrared Atmospheric Sounding Interferometer (IASI. In this paper a new approach for cloud detection is proposed and validated exploiting active measurements from satellite sensors, i.e., the CloudSat cloud profiling radar (CPR and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO. For a homogenous IASI field of view (FOVs, the proposed cloud detection scheme tallies with the combined CPR and CALIOP product in classifying 98.11% of the FOVs as cloudy and also classifies 97.54% of the FOVs as clear. The Hansen Kuipers discriminant reaches 0.95.

High power, 140 GHz gyrotron

International Nuclear Information System (INIS)

Kreischer, K.E.; Temkin, R.J.; Mulligan, W.J.; MacCabe, S.; Chaplya, R.

1982-01-01

The design and construction of a pulsed 100 kW, 140 GHz gyrotron is described. Initial gyrotron operation is expected in early 1982. Advances in gyrotron theory have also been carried out in support of this experimental research. The application of gyrotrons to plasma diagnostics is also under investigation. (author)

Cloud networking understanding cloud-based data center networks

CERN Document Server

Lee, Gary

2014-01-01

Cloud Networking: Understanding Cloud-Based Data Center Networks explains the evolution of established networking technologies into distributed, cloud-based networks. Starting with an overview of cloud technologies, the book explains how cloud data center networks leverage distributed systems for network virtualization, storage networking, and software-defined networking. The author offers insider perspective to key components that make a cloud network possible such as switch fabric technology and data center networking standards. The final chapters look ahead to developments in architectures

Steganalysis and improvement of a quantum steganography protocol via a GHZ4 state

International Nuclear Information System (INIS)

Xu Shu-Jiang; Chen Xiu-Bo; Niu Xin-Xin; Yang Yi-Xian

2013-01-01

Quantum steganography that utilizes the quantum mechanical effect to achieve the purpose of information hiding is a popular topic of quantum information. Recently, El Allati et al. proposed a new quantum steganography using the GHZ 4 state. Since all of the 8 groups of unitary transformations used in the secret message encoding rule change the GHZ 4 state into 6 instead of 8 different quantum states when the global phase is not considered, we point out that a 2-bit instead of a 3-bit secret message can be encoded by one group of the given unitary transformations. To encode a 3-bit secret message by performing a group of unitary transformations on the GHZ 4 state, we give another 8 groups of unitary transformations that can change the GHZ 4 state into 8 different quantum states. Due to the symmetry of the GHZ 4 state, all the possible 16 groups of unitary transformations change the GHZ 4 state into 8 different quantum states, so the improved protocol achieves a high efficiency

37 GHz METHANOL MASERS : HORSEMEN OF THE APOCALYPSE FOR THE CLASS II METHANOL MASER PHASE?

International Nuclear Information System (INIS)

Ellingsen, S. P.; Breen, S. L.; Sobolev, A. M.; Voronkov, M. A.; Caswell, J. L.; Lo, N.

2011-01-01

We report the results of a search for class II methanol masers at 37.7, 38.3, and 38.5 GHz toward a sample of 70 high-mass star formation regions. We primarily searched toward regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesized to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.

Tropical cloud buoyancy is the same in a world with or without ice

Science.gov (United States)

Seeley, Jacob T.; Romps, David M.

2016-04-01

When convective clouds grow above the melting line, where temperatures fall below 0°C, condensed water begins to freeze and water vapor is deposited. These processes release the latent heat of fusion, which warms cloud air, and many previous studies have suggested that this heating from fusion increases cloud buoyancy in the upper troposphere. Here we use numerical simulations of radiative-convective equilibrium with and without ice processes to argue that tropical cloud buoyancy is not systematically higher in a world with fusion than in a world without it. This insensitivity results from the fact that the environmental temperature profile encountered by developing tropical clouds is itself determined by convection. We also offer a simple explanation for the large reservoir of convective available potential energy in the tropical upper troposphere that does not invoke ice.

24 GHz cmWave Radio Propagation Through Vegetation

DEFF Research Database (Denmark)

Rodriguez, Ignacio; Abreu, Renato Barbosa; Portela Lopes de Almeida, Erika

2016-01-01

This paper presents a measurement-based analysis of cm-wave radio propagation through vegetation at 24 GHz. A set of dedicated directional measurements were performed with horn antennas located close to street level inside a densely-vegetated area illuminated from above. The full azimuth was exam......This paper presents a measurement-based analysis of cm-wave radio propagation through vegetation at 24 GHz. A set of dedicated directional measurements were performed with horn antennas located close to street level inside a densely-vegetated area illuminated from above. The full azimuth...

Molecular astronomy using heterodyne detection at 691 GHz

International Nuclear Information System (INIS)

Fetterman, H.R.; Buhl, D.

1984-01-01

Observations of the CO J 6 - 5 transition at 691 GHz in new interstellar and planetary sources have been made. The heterodyne receiver uses an optically pumped laser local oscillator and a quasi-optical Schottky diode mixer, with measured noise temperatures consistently under 4000 K (double sideband). Continued improvements in system performance and antenna coupling have made possible the mapping of 691 GHz emission from W3, and the detection of CO J 5 - 6 absorption in the atmosphere of Venus. A detailed description of the instrumentation and recent observational data are provided. 14 references

TWT design requirements for 30/20 GHz digital communications' satellite

Science.gov (United States)

Stankiewicz, N.; Anzic, G.

1979-01-01

The rapid growth of communication traffic (voice, data, and video) requires the development of additional frequency bands before the 1990's. The frequencies currently in use for satellite communications at 6/4 GHz are crowded and demands for 14/12 GHz systems are increasing. Projections are that these bands will be filled to capacity by the late 1980's. The next higher frequency band allocated for satellite communications is at 30/20 GHz. For interrelated reasons of efficiency, power level, and system reliability criteria, a candidate for the downlink amplifier in a 30/20 GHz communications' satellite is a dual mode traveling wave tube (TWT) equipped with a highly efficient depressed collector. A summary is given of the analyses which determine the TWT design requirements. The overall efficiency of such a tube is then inferred from a parametric study and from experimental data on multistaged depressed collectors. The expected TWT efficiency at 4 dB below output saturation is 24 percent in the high mode and 22 percent in the low mode.

New Satellite Estimates of Mixed-Phase Cloud Properties: A Synergistic Approach for Application to Global Satellite Imager Data

Science.gov (United States)

Smith, W. L., Jr.; Spangenberg, D.; Fleeger, C.; Sun-Mack, S.; Chen, Y.; Minnis, P.

2016-12-01

Determining accurate cloud properties horizontally and vertically over a full range of time and space scales is currently next to impossible using data from either active or passive remote sensors or from modeling systems. Passive satellite imagers provide horizontal and temporal resolution of clouds, but little direct information on vertical structure. Active sensors provide vertical resolution but limited spatial and temporal coverage. Cloud models embedded in NWP can produce realistic clouds but often not at the right time or location. Thus, empirical techniques that integrate information from multiple observing and modeling systems are needed to more accurately characterize clouds and their impacts. Such a strategy is employed here in a new cloud water content profiling technique developed for application to satellite imager cloud retrievals based on VIS, IR and NIR radiances. Parameterizations are developed to relate imager retrievals of cloud top phase, optical depth, effective radius and temperature to ice and liquid water content profiles. The vertical structure information contained in the parameterizations is characterized climatologically from cloud model analyses, aircraft observations, ground-based remote sensing data, and from CloudSat and CALIPSO. Thus, realistic cloud-type dependent vertical structure information (including guidance on cloud phase partitioning) circumvents poor assumptions regarding vertical homogeneity that plague current passive satellite retrievals. This paper addresses mixed phase cloud conditions for clouds with glaciated tops including those associated with convection and mid-latitude storm systems. Novel outcomes of our approach include (1) simultaneous retrievals of ice and liquid water content and path, which are validated with active sensor, microwave and in-situ data, and yield improved global cloud climatologies, and (2) new estimates of super-cooled LWC, which are demonstrated in aviation safety applications and

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

Science.gov (United States)

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

2010-01-01

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

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

Directory of Open Access Journals (Sweden)

I. Koren

2010-05-01

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

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

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

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

The Effect of Cumulus Cloud Field Anisotropy on Domain-Averaged Solar Fluxes and Atmospheric Heating Rates

Science.gov (United States)

Hinkelman, Laura M.; Evans, K. Franklin; Clothiaux, Eugene E.; Ackerman, Thomas P.; Stackhouse, Paul W., Jr.

2006-01-01

Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies of the interaction of cumulus clouds and radiation have assumed these clouds to be isotropic. This paper describes an investigation of the effect of fair-weather cumulus cloud field anisotropy on domain-averaged solar fluxes and atmospheric heating rate profiles. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of cloud scenes from a large eddy simulation. Progressively greater degrees of x-z plane tilting and horizontal stretching were imposed on each of these scenes, so that an ensemble of scenes was produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo radiative transfer model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. The mechanisms by which anisotropy interacts with solar fluxes were investigated by comparisons to independent pixel approximation and tilted independent pixel approximation computations for the same scenes. Cumulus anisotropy was found to most strongly impact solar radiative transfer by changing the effective cloud fraction, i.e., the cloud fraction when the field is projected on a surface perpendicular to the direction of the incident solar beam.

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

Energy Technology Data Exchange (ETDEWEB)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J [MIT - Plasma Science and Fusion Center, NW16-186, 167 Albany Street, Cambridge, MA 02139 (United States)

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3{mu}s) at an efficiency of 42% in the TE{sub 22,6} mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%.

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

International Nuclear Information System (INIS)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3μs) at an efficiency of 42% in the TE 22,6 mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%

TES/Aura L2 Summary Profiles V005

Data.gov (United States)

National Aeronautics and Space Administration — Atmospheric vertical profile estimates, along with retrieved surface temperature, cloud effective optical depth, column estimates, quality flags, and a priori...

TES/Aura L2 Summary Profiles V003

Data.gov (United States)

National Aeronautics and Space Administration — Atmospheric vertical profile estimates, along with retrieved surface temperature, cloud effective optical depth, column estimates, quality flags, and a priori...

Miniature Packaging Concept for LNAs in the 200-300 GHz Range

Science.gov (United States)

Samoska, Lorene; Fung, Andy; Varonen, Mikko; Lin, Robert; Peralta, Alejandro; Soria, Mary; Lee, Choonsup; Padmanabhan, Sharmila; Sarkozy, Stephen; Lai, Richard

2016-01-01

In this work, we describe new miniaturized low noise amplifier modules which we developed for incorporation in small-scale satellites or Cubesats, and which exhibit similar or better performance compared to previously reported LNAs in the literature. We have targeted the WR4 (170-260 GHz) and WR3 (220-325 GHz) waveguide bands for the module development. The modules include two different methods of E-plane probes which have been developed for low loss, and stability at high frequencies. MMIC LNAs were also developed for these frequency ranges and fabricated in Northrop Grumman Corporation's 35 nm InP HEMT technology, and we have experimentally verified that noise performance is lower than reported in prior work. The best results include a miniature LNA module with 550K noise at 224 GHz, and a wideband LNA module with 15 dB gain from 230-280 GHz.

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

International Nuclear Information System (INIS)

Shinohara, Naoki; Hatano, Ken

2014-01-01

In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

Science.gov (United States)

Shinohara, Naoki; Hatano, Ken

2014-11-01

In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation.

A program of high power microwave source research and development from 8 GHz to 600 GHz

International Nuclear Information System (INIS)

Granatstein, V.L.; Antonsen, T.M. Jr.; Bidwell, S.; Booske, J.; Carmel, Y.; Destler, W.W.; Kehs, R.A.; Latham, P.E.; Levush, B.; Lou, W.R.; Mayergoyz, I.D.; Minami, K.; Radack, D.J.

1990-01-01

We review research results both on a plasma filled, backward wave oscillator (BWO), and on a free electron laser (FEL) driven by a sheet electron beam. Recently, it was demonstrated that a plasma filled BWO driven by an intense relativistic electron beam can generate hundreds of megawatts of microwave radiation at an unusually high efficiency of 40% compared with a typical efficiency of ∼10% in a BWO without a background plasma. Furthermore, the enhanced efficiency can be maintained even for large electron beam currents approaching the vacuum space charge limiting current, and we anticipate this might hold even for larger current values. Theoretical studies and numerical simulations indicate that the enhanced efficiency as well as a lower value for the start oscillation current in the linear regime may be due to the finite length of the BWO circuit coupled with modification of the dispersion relation due to the background plasma. In the case of our FEL studies, we present designs for a 1 MW, CW, tapered FEL amplifier operating at frequencies of 280 GHz and 560 GHz. A short wiggler period (ell w ∼ 1 cm) is combined with a sheet beam of electrons having energy ∼1 MeV. Depressed collector techniques would allow the main power supply rating to be reduced to ∼200 kV. Efficient sheet beam transport (>99%) has been demonstrated through 10 wiggler periods, and transport through 60 wiggler periods is currently under study. Finally, plans for a proof-of-principle tapered FEL amplifier experiment at 94 GHz are presented. 8 refs., 7 figs

SIMPLE HEURISTIC ALGORITHM FOR DYNAMIC VM REALLOCATION IN IAAS CLOUDS

Directory of Open Access Journals (Sweden)

Nikita A. Balashov

2018-03-01

Full Text Available The rapid development of cloud technologies and its high prevalence in both commercial and academic areas have stimulated active research in the domain of optimal cloud resource management. One of the most active research directions is dynamic virtual machine (VM placement optimization in clouds build on Infrastructure-as-a-Service model. This kind of research may pursue different goals with energy-aware optimization being the most common goal as it aims at a urgent problem of green cloud computing - reducing energy consumption by data centers. In this paper we present a new heuristic algorithm of dynamic reallocation of VMs based on an approach presented in one of our previous works. In the algorithm we apply a 2-rank strategy to classify VMs and servers corresponding to the highly and lowly active VMs and solve four tasks: VM classification, host classification, forming a VM migration map and VMs migration. Dividing all of the VMs and servers into two classes we attempt to implement the possibility of risk reduction in case of hardware overloads under overcommitment conditions and to reduce the influence of the occurring overloads on the performance of the cloud VMs. Presented algorithm was developed based on the workload profile of the JINR cloud (a scientific private cloud with the goal of maximizing its usage, but it can also be applied in both public and private commercial clouds to organize the simultaneous use of different SLA and QoS levels in the same cloud environment by giving each VM rank its own level of overcommitment.

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

International Nuclear Information System (INIS)

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

1987-01-01

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

Improved retrieval of cloud base heights from ceilometer using a non-standard instrument method

Science.gov (United States)

Wang, Yang; Zhao, Chuanfeng; Dong, Zipeng; Li, Zhanqing; Hu, Shuzhen; Chen, Tianmeng; Tao, Fa; Wang, Yuzhao

2018-04-01

Cloud-base height (CBH) is a basic cloud parameter but has not been measured accurately, especially under polluted conditions due to the interference of aerosol. Taking advantage of a comprehensive field experiment in northern China in which a variety of advanced cloud probing instruments were operated, different methods of detecting CBH are assessed. The Micro-Pulse Lidar (MPL) and the Vaisala ceilometer (CL51) provided two types of backscattered profiles. The latter has been employed widely as a standard means of measuring CBH using the manufacturer's operational algorithm to generate standard CBH products (CL51 MAN) whose quality is rigorously assessed here, in comparison with a research algorithm that we developed named value distribution equalization (VDE) algorithm. It was applied to both the profiles of lidar backscattering data from the two instruments. The VDE algorithm is found to produce more accurate estimates of CBH for both instruments and can cope with heavy aerosol loading conditions well. By contrast, CL51 MAN overestimates CBH by 400 m and misses many low level clouds under such conditions. These findings are important given that CL51 has been adopted operationally by many meteorological stations in China.

160 Gbit/s photonics wireless transmission in the 300-500 GHz band

Directory of Open Access Journals (Sweden)

X. Yu

2016-11-01

Full Text Available To accommodate the ever increasing wireless traffic in the access networks, considerable efforts have been recently invested in developing photonics-assisted wireless communication systems with very high data rates. Superior to photonic millimeter-wave systems, terahertz (THz band (300 GHz-10 THz provides a much larger bandwidth and thus promises an extremely high capacity. However, the capacity potential of THz wireless systems has by no means been achieved yet. Here, we successfully demonstrate 160 Gbit/s wireless transmission by using a single THz emitter and modulating 25 GHz spaced 8 channels (20 Gbps per channel in the 300-500 GHz band, which is the highest bitrate in the frequency band above 300 GHz, to the best of our knowledge.

H2 profiles of C-type bow shocks

International Nuclear Information System (INIS)

Smith, M.D.; Brand, P.W.J.L.

1990-01-01

We present emission-line profiles of molecular hydrogen from curved C-shocks within molecular clouds. Shock configurations arising from the supersonic motion of jets and bullets within a dense cloud are chosen. Bow shock speeds in the range υ w = 40-200 km s -1 are investigated. Breakdown through dissociation and self-ionization restricts the C-shock section to the bow tail. We find that profiles are essentially single-peaked and narrow with full widths (at 10 per cent maximum intensity, deconvolved) of up to about 50, 40 and 30 km s -1 for cones, hemispherical caps and paraboloids, respectively. Exceptional field alignments can produce lines as wide as 75 km s -1 in the conical shock model. (author)

Design of a 300 GHZ broadband coupler and RF-structure

International Nuclear Information System (INIS)

Krawczyk, F.L.; Carlsten, B.E.; Earley, L.M.; Sigler, F.E.; Potter, J.M.; Schulze, M.E.

2004-01-01

Recent LANL activities in millimeter wave structures focus on 95 and 300 GHz structures. They aim at power generation from low power (100W-2kW) with a round electron beam (120kV, 0.1-1.0 A) to high power (2-100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design of a 300 GHz RF-structure with a broadband (> 6% bandwidth) power coupler is presented. The choice of two input/output waveguides, a special coupling region and the structure parameters are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented. We are investigating planar micro-fabricated traveling-wave tube amplifiers as sources for the generation of millimeter waves from 95 to 300 GHz. While for low energy applications narrow structures with pencil beams are proposed, for high energy operation flat, thin sheet beams are required. For the latter vane-loaded rectangular waveguides that operate in a slow-wave mode matched to the velocity of the electron beam are especially well suited. The 300 GHz effort initially is limited to narrow structures for pencil beams. The main emphasis for this work are the study of fabrication issues and the understanding of features that allow a broadband operation (5-10% bandwidth).

A 90 GHz photoinjector

International Nuclear Information System (INIS)

Palmer, D.T.; Hogan, M.J.; Ferrario, M.; Serafini, L.

1999-01-01

Photocathode rf guns depend on mode locked laser systems to produce an electron beam at a given phase of the rf. In general, the laser pulse is less than σ 2 = 10'' of rf phase in length and the required stability is on the order of Δφ = 1 At 90 GHz (W-band), these requirements correspond to σ 2 = 333 fsec and Δφ = 33 fsec. Laser system with pulse lengths in the fsec regime are commercially available, the timing stability is a major concern. It is proposed a multi-cell W-band photoinjector that does not require a mode locked laser system. Thereby eliminating the stability requirements at W-band. The laser pulse is allowed to be many rf periods long. In principle, the photoinjector can now be considered as a thermionic rf gun. Instead of using an alpha magnet to compress the electron bunch, which would have a detrimental effect on the transverse hase space quality due to longitudinal phase space mixing, it is here proposed to use long pulse laser system and a pair of undulators to produce a low emittance, high current, ultra-short electron bunch for beam dynamics experiments in the 90 GHz regime

Cloud Computing Fundamentals

Science.gov (United States)

Furht, Borko

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

Smart learning services based on smart cloud computing.

Science.gov (United States)

Kim, Svetlana; Song, Su-Mi; Yoon, Yong-Ik

2011-01-01

Context-aware technologies can make e-learning services smarter and more efficient since context-aware services are based on the user's behavior. To add those technologies into existing e-learning services, a service architecture model is needed to transform the existing e-learning environment, which is situation-aware, into the environment that understands context as well. The context-awareness in e-learning may include the awareness of user profile and terminal context. In this paper, we propose a new notion of service that provides context-awareness to smart learning content in a cloud computing environment. We suggest the elastic four smarts (E4S)--smart pull, smart prospect, smart content, and smart push--concept to the cloud services so smart learning services are possible. The E4S focuses on meeting the users' needs by collecting and analyzing users' behavior, prospecting future services, building corresponding contents, and delivering the contents through cloud computing environment. Users' behavior can be collected through mobile devices such as smart phones that have built-in sensors. As results, the proposed smart e-learning model in cloud computing environment provides personalized and customized learning services to its users.

Smart Learning Services Based on Smart Cloud Computing

Directory of Open Access Journals (Sweden)

Yong-Ik Yoon

2011-08-01

Full Text Available Context-aware technologies can make e-learning services smarter and more efficient since context-aware services are based on the user’s behavior. To add those technologies into existing e-learning services, a service architecture model is needed to transform the existing e-learning environment, which is situation-aware, into the environment that understands context as well. The context-awareness in e-learning may include the awareness of user profile and terminal context. In this paper, we propose a new notion of service that provides context-awareness to smart learning content in a cloud computing environment. We suggest the elastic four smarts (E4S—smart pull, smart prospect, smart content, and smart push—concept to the cloud services so smart learning services are possible. The E4S focuses on meeting the users’ needs by collecting and analyzing users’ behavior, prospecting future services, building corresponding contents, and delivering the contents through cloud computing environment. Users’ behavior can be collected through mobile devices such as smart phones that have built-in sensors. As results, the proposed smart e-learning model in cloud computing environment provides personalized and customized learning services to its users.

Detection of single and multilayer clouds in an artificial neural network approach

Science.gov (United States)

Sun-Mack, Sunny; Minnis, Patrick; Smith, William L.; Hong, Gang; Chen, Yan

2017-10-01

Determining whether a scene observed with a satellite imager is composed of a thin cirrus over a water cloud or thick cirrus contiguous with underlying layers of ice and water clouds is often difficult because of similarities in the observed radiance values. In this paper an artificial neural network (ANN) algorithm, employing several Aqua MODIS infrared channels and the retrieved total cloud visible optical depth, is trained to detect multilayer ice-over-water cloud systems as identified by matched April 2009 CloudSat and CALIPSO (CC) data. The CC lidar and radar profiles provide the vertical structure that serves as output truth for a multilayer ANN, or MLANN, algorithm. Applying the trained MLANN to independent July 2008 MODIS data resulted in a combined ML and single layer hit rate of 75% (72%) for nonpolar regions during the day (night). The results are comparable to or more accurate than currently available methods. Areas of improvement are identified and will be addressed in future versions of the MLANN.

GHz band frequency hopping PLL-based frequency synthesizers

Institute of Scientific and Technical Information of China (English)

XU Yong; WANG Zhi-gong; GUAN Yu; XU Zhi-jun; QIAO Lu-feng

2005-01-01

In this paper we describe a full-integrated circuit containing all building blocks of a completed PLL-based synthesizer except for low pass filter(LPF).The frequency synthesizer is designed for a frequency hopping (FH) transceiver operating up to 1.5 GHz as a local oscillator. The architecture of Voltage Controlled Oscillator (VCO) is optimized to get better performance, and a phase noise of -111.85-dBc/Hz @ 1 MHz and a tuning range of 250 MHz are gained at a centre frequency of 1.35 GHz.A novel Dual-Modulus Prescaler(DMP) is designed to achieve a very low jitter and a lower power.The settling time of PLL is 80 μs while the reference frequency is 400 KHz.This monolithic frequency synthesizer is to integrate all main building blocks of PLL except for the low pass filter,with a maximum VCO output frequency of 1.5 GHz,and is fabricated with a 0.18 μm mixed signal CMOS process. Low power dissipation, low phase noise, large tuning range and fast settling time are gained in this design.

Scanning ARM Cloud Radars. Part II: Data Quality Control and Processing

Energy Technology Data Exchange (ETDEWEB)

Kollias, Pavlos; Jo, Ieng; Borque, Paloma; Tatarevic, Aleksandra; Lamer, Katia; Bharadwaj, Nitin; Widener, Kevin B.; Johnson, Karen L.; Clothiaux, Eugene E.

2014-03-01

The Scanning ARM Cloud Radars (SACR’s) are the primary instruments for documenting the four-dimensional structure and evolution of clouds within a 20-30 km radius from the ARM fixed and mobile sites. Here, the post-processing of the calibrated SACR measurements is discussed. First, a feature mask algorithm that objectively determines the presence of significant radar returns is described. The feature mask algorithm is based on the statistical properties of radar receiver noise. It accounts for atmospheric emission and is applicable even for SACR profiles with few or no signal-free range gates. Using the nearest-in-time atmospheric sounding, the SACR radar reflectivities are corrected for gaseous attenuation (water vapor and oxygen) using a line-by-line absorption model. Despite having a high pulse repetition frequency, the SACR has a narrow Nyquist velocity limit and thus Doppler velocity folding is commonly observed. An unfolding algorithm that makes use of a first guess for the true Doppler velocity using horizontal wind measurements from the nearest sounding is described. The retrieval of the horizontal wind profile from the HS-RHI SACR scan observations and/or nearest sounding is described. The retrieved horizontal wind profile can be used to adaptively configure SACR scan strategies that depend on wind direction. Several remaining challenges are discussed, including the removal of insect and second-trip echoes. The described algorithms significantly enhance SACR data quality and constitute an important step towards the utilization of SACR measurements for cloud research.

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. 25.250 Section 25.250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...

Validation of UARS Microwave Limb Sounder 183 GHz H2O Measurements

Science.gov (United States)

Lahoz, W. A.; Suttie, M. R.; Froidevaux, L.; Harwood, R. S.; Lau, C. L.; Lungu, T. A.; Peckham, G. E.; Pumphrey, H. C.; Read, W. G.; Shippony, Z.;

Clustering, randomness, and regularity in cloud fields: 2. Cumulus cloud fields

Science.gov (United States)

Zhu, T.; Lee, J.; Weger, R. C.; Welch, R. M.

1992-12-01

During the last decade a major controversy has been brewing concerning the proper characterization of cumulus convection. The prevailing view has been that cumulus clouds form in clusters, in which cloud spacing is closer than that found for the overall cloud field and which maintains its identity over many cloud lifetimes. This "mutual protection hypothesis" of Randall and Huffman (1980) has been challenged by the "inhibition hypothesis" of Ramirez et al. (1990) which strongly suggests that the spatial distribution of cumuli must tend toward a regular distribution. A dilemma has resulted because observations have been reported to support both hypotheses. The present work reports a detailed analysis of cumulus cloud field spatial distributions based upon Landsat, Advanced Very High Resolution Radiometer, and Skylab data. Both nearest-neighbor and point-to-cloud cumulative distribution function statistics are investigated. The results show unequivocally that when both large and small clouds are included in the cloud field distribution, the cloud field always has a strong clustering signal. The strength of clustering is largest at cloud diameters of about 200-300 m, diminishing with increasing cloud diameter. In many cases, clusters of small clouds are found which are not closely associated with large clouds. As the small clouds are eliminated from consideration, the cloud field typically tends towards regularity. Thus it would appear that the "inhibition hypothesis" of Ramirez and Bras (1990) has been verified for the large clouds. However, these results are based upon the analysis of point processes. A more exact analysis also is made which takes into account the cloud size distributions. Since distinct clouds are by definition nonoverlapping, cloud size effects place a restriction upon the possible locations of clouds in the cloud field. The net effect of this analysis is that the large clouds appear to be randomly distributed, with only weak tendencies towards

95 GHz methanol masers near DR 21 and DR 21(OH)

International Nuclear Information System (INIS)

Plambeck, R.L.; Menten, K.M.

1990-01-01

The BIMA array is used to map the 95-GHz 8(0) to 7 1A(+) transition of methanol and the 98-GHz J = 2-1 transition of CS toward the DR 21(OH) and DR 21 star-forming regions. Several strong methanol masers were found. The positions of the two brightest masers were measured with an accuracy of about + or - 0.3 arcsec. Toward DR 21(OH), the positions, velocities, and line shapes of the 95 GHz masers are in excellent agreement with those of the 84-GHz 5(-1) to 4 () methanol masers previously mapped by Batrla and Menten (1988), demonstrating that maser emission in both transitions originates from the same clumps of gas. The methanol masers are offset from CS emission peaks and from other known infrared and maser sources; they may possibly be clustered along the interface between outflows, traced by shock-excited H2 emission, and dense ambient gas, traced by CS emission. 25 refs

Gravity, turbulence and the scaling ``laws'' in molecular clouds

Science.gov (United States)

Ballesteros-Paredes, Javier

The so-called Larson (1981) scaling laws found empirically in molecular clouds have been generally interpreted as evidence that the clouds are turbulent and fractal. In the present contribution we discussed how recent observations and models of cloud formation suggest that: (a) these relations are the result of strong observational biases due to the cloud definition itself: since the filling factor of the dense structures is small, by thresholding the column density the computed mean density between clouds is nearly constant, and nearly the same as the threshold (Ballesteros-Paredes et al. 2012). (b) When accounting for column density variations, the velocity dispersion-size relation does not appears anymore. Instead, dense cores populate the upper-left corner of the δ v-R diagram (Ballesteros-Paredes et al. 2011a). (c) Instead of a δ v-R relation, a more appropriate relation seems to be δ v 2 / R = 2 GMΣ, which suggest that clouds are in collapse, rather than supported by turbulence (Ballesteros-Paredes et al. 2011a). (d) These results, along with the shapes of the star formation histories (Hartmann, Ballesteros-Paredes & Heitsch 2012), line profiles of collapsing clouds in numerical simulations (Heitsch, Ballesteros-Paredes & Hartmann 2009), core-to-core velocity dispersions (Heitsch, Ballesteros-Paredes & Hartmann 2009), time-evolution of the column density PDFs (Ballesteros-Paredes et al. 2011b), etc., strongly suggest that the actual source of the non-thermal motions is gravitational collapse of the clouds, so that the turbulent, chaotic component of the motions is only a by-product of the collapse, with no significant ``support" role for the clouds. This result calls into question if the scale-free nature of the motions has a turbulent, origin (Ballesteros-Paredes et al. 2011a; Ballesteros-Paredes et al. 2011b, Ballesteros-Paredes et al. 2012).

High-performance CPW MMIC LNA using GaAs-based metamorphic HEMTs for 94-GHz applications

International Nuclear Information System (INIS)

Ryu, Keun-Kwan; Kim, Sung-Chan; An, Dan; Rhee, Jin-Koo

2010-01-01

In this paper, we report on a high-performance low-noise amplifier (LNA) using metamorphic high-electron-mobility transistor (MHEMT) technology for 94-GHz applications. The 100 nm x 60 μm MHEMT devices for the coplanar MMIC LNA exhibited DC characteristics with a drain current density of 655 mA/mm and an extrinsic transconductance of 720 mS/mm. The current gain cutoff frequency (f T ) and the maximum oscillation frequency (f max ) were 195 GHz and 305 GHz, respectively. Based on this MHEMT technology, coplanar 94-GHz MMIC LNAs were realized, achieving a small signal gain of more than 13 dB between 90 and 100 GHz and a small signal gain of 14.8 dB and a noise figure of 4.7 dB at 94 GHz.

Improving Estimates of Cloud Radiative Forcing over Greenland

Science.gov (United States)

Wang, W.; Zender, C. S.

2014-12-01

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

Simultaneous retrieval of water vapour, temperature and cirrus clouds properties from measurements of far infrared spectral radiance over the Antarctic Plateau

Science.gov (United States)

Di Natale, Gianluca; Palchetti, Luca; Bianchini, Giovanni; Del Guasta, Massimo

2017-03-01

The possibility separating the contributions of the atmospheric state and ice clouds by using spectral infrared measurements is a fundamental step to quantifying the cloud effect in climate models. A simultaneous retrieval of cloud and atmospheric parameters from infrared wideband spectra will allow the disentanglement of the spectral interference between these variables. In this paper, we describe the development of a code for the simultaneous retrieval of atmospheric state and ice cloud parameters, and its application to the analysis of the spectral measurements acquired by the Radiation Explorer in the Far Infrared - Prototype for Applications and Development (REFIR-PAD) spectroradiometer, which has been in operation at Concordia Station on the Antarctic Plateau since 2012. The code performs the retrieval with a computational time that is comparable with the instrument acquisition time. Water vapour and temperature profiles and the cloud optical and microphysical properties, such as the generalised effective diameter and the ice water path, are retrieved by exploiting the 230-980 cm-1 spectral band. To simulate atmospheric radiative transfer, the Line-By-Line Radiative Transfer Model (LBLRTM) has been integrated with a specifically developed subroutine based on the δ-Eddington two-stream approximation, whereas the single-scattering properties of cirrus clouds have been derived from a database for hexagonal column habits. In order to detect ice clouds, a backscattering and depolarisation lidar, co-located with REFIR-PAD has been used, allowing us to infer the position and the cloud thickness to be used in the retrieval. A climatology of the vertical profiles of water vapour and temperature has been performed by using the daily radiosounding available at the station at 12:00 UTC. The climatology has been used to build an a priori profile correlation to constrain the fitting procedure. An optimal estimation method with the Levenberg-Marquardt approach has been

On the determination of the dynamic properties of a transformer oil based ferrofluid in the frequency range 0.1–20 GHz

International Nuclear Information System (INIS)

Fannin, P.C.; Vekas, L.; Marin, C.N.; Malaescu, I.

2017-01-01

Complex susceptibility measurements provide a unique and efficient means for the investigation and determination of the dynamic properties of magnetic fluids. In particular, measurement of the frequency, f(Hz), and field, H(kA/m), dependent, complex susceptibility, χ(ω, Η)= χ′(ω, Η)−iχ″(ω, Η), of magnetic fluids has proven to be a valuable and reliable technique for investigating such properties. The experimental data presented here was obtained from measurements of a transformer oil based ferrofluid, with measurements being performed over the frequency range 0.1–20 GHz and polarising fields 0–168 kA/m. In the case of transformer oil magnetic fluids, the normal measurement emphasis has been on the investigation of their dielectric properties, including the effects which lightning may have on these properties. Little has been reported on the measurement of the corresponding magnetic susceptibility, χ(ω), of such fluids and in this paper we address this fact. Thus we consider it worthwhile, in the case of a transformer with magnetic fluid transformer oil, being affected as a result of a lightening occurrence, to have knowledge of the fluids dynamic properties, at the microwave frequencies. In the process of determining the sample susceptibility profiles, it was found that the peak value of the χ″(ω) component, was approximately constant over the frequency range 2.4–6.3 GHz. From this it was determined that the fluid was effectively operating as a wideband absorber over a bandwidth of 3.9 GHz. - Highlights: • Complex magnetic susceptibility measurements in the frequency range 0.1–20 GHz. • Determination of the dynamic properties of a transformer oil based ferrofluid. • Wideband attenuator ( Absorber) in the frequency range 2.4–6.3 GHz.

Evaluation of RRTMG and Fu-Liou RTM Performance against LBLRTM-DISORT Simulations and CERES Data in terms of Ice Clouds Radiative Effects

Science.gov (United States)

Gu, B.; Yang, P.; Kuo, C. P.; Mlawer, E. J.

2017-12-01

Evaluation of RRTMG and Fu-Liou RTM Performance against LBLRTM-DISORT Simulations and CERES Data in terms of Ice Clouds Radiative Effects Boyan Gu1, Ping Yang1, Chia-Pang Kuo1, Eli J. Mlawer2 Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843, USA Atmospheric and Environmental Research (AER), Lexington, MA 02421, USA Ice clouds play an important role in climate system, especially in the Earth's radiation balance and hydrological cycle. However, the representation of ice cloud radiative effects (CRE) remains significant uncertainty, because scattering properties of ice clouds are not well considered in general circulation models (GCM). We analyze the strengths and weakness of the Rapid Radiative Transfer Model for GCM Applications (RRTMG) and Fu-Liou Radiative Transfer Model (RTM) against rigorous LBLRTM-DISORT (a combination of Line-By-Line Radiative Transfer Model and Discrete Ordinate Radiative Transfer Model) calculations and CERES (Clouds and the Earth's Radiant Energy System) flux observations. In total, 6 US standard atmospheric profiles and 42 atmospheric profiles from Atmospheric and Environmental Research (AER) Company are used to evaluate the RRTMG and Fu-Liou RTM by LBLRTM-DISORT calculations from 0 to 3250 cm-1. Ice cloud radiative effect simulations with RRTMG and Fu-Liou RTM are initialized using the ice cloud properties from MODIS collection-6 products. Simulations of single layer ice cloud CRE by RRTMG and LBLRTM-DISORT show that RRTMG, neglecting scattering, overestimates the TOA flux by about 0-15 W/m2 depending on the cloud particle size and optical depth, and the most significant overestimation occurs when the particle effective radius is small (around 10 μm) and the cloud optical depth is intermediate (about 1-10). The overestimation reduces significantly when the similarity rule is applied to RRTMG. We combine ice cloud properties from MODIS Collection-6 and atmospheric profiles from the Modern

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Science.gov (United States)

2010-10-01

...) Incorporation of ancillary terrestrial component base station into an L-band mobile-satellite service system... ancillary terrestrial component (ATC) base stations as defined in § 25.201 at its own risk and subject to... Applications and Licenses Earth Stations § 25.136 Licensing provisions for user transceivers in the 1.6/2.4 GHz...

Analysis of 38 GHz mmWave Propagation Characteristics of Urban Scenarios

DEFF Research Database (Denmark)

Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Sørensen, Troels Bundgaard

2015-01-01

The 38 GHz mm-wave frequency band is a strong candidate for the future deployment of wireless systems. Compared to lower frequency bands, propagation in the 38 GHz band is relatively unexplored for access networks in urban scenarios. This paper presents a detailed measurement-based analysis of ur...

Impact of aerosol intrusions on sea-ice melting rates and the structure Arctic boundary layer clouds

Science.gov (United States)

Cotton, W.; Carrio, G.; Jiang, H.

2003-04-01

The Los Alamos National Laboratory sea-ice model (LANL CICE) was implemented into the real-time and research versions of the Colorado State University-Regional Atmospheric Modeling System (RAMS@CSU). The original version of CICE was modified in its structure to allow module communication in an interactive multigrid framework. In addition, some improvements have been made in the routines involved in the coupling, among them, the inclusion of iterative methods that consider variable roughness lengths for snow-covered ice thickness categories. This version of the model also includes more complex microphysics that considers the nucleation of cloud droplets, allowing the prediction of mixing ratios and number concentrations for all condensed water species. The real-time version of RAMS@CSU automatically processes the NASA Team SSMI F13 25km sea-ice coverage data; the data are objectively analyzed and mapped to the model grid configuration. We performed two types of cloud resolving simulations to assess the impact of the entrainment of aerosols from above the inversion on Arctic boundary layer clouds. The first series of numerical experiments corresponds to a case observed on May 4 1998 during the FIRE-ACE/SHEBA field experiment. Results indicate a significant impact on the microstructure of the simulated clouds. When assuming polluted initial profiles above the inversion, the liquid water fraction of the cloud monotonically decreases, the total condensate paths increases and downward IR tends to increase due to a significant increase in the ice water path. The second set of cloud resolving simulations focused on the evaluation of the potential effect of aerosol concentration above the inversion on melting rates during spring-summer period. For these multi-month simulations, the IFN and CCN profiles were also initialized assuming the 4 May profiles as benchmarks. Results suggest that increasing the aerosol concentrations above the boundary layer increases sea-ice melting

Diseño y validación de un radar CW-FM a 94 GHz

OpenAIRE

Varela Agrelo, David

2013-01-01

Diseño y validación de un radar CW-FM a 9g GHz 94 GHz CW-FM radar design and mesurement campaign validation. Desarrollo de un radar CW-FM a 94GHz y verificación de los resultados obtenidos durante la etapa de medidas. Desevolupament d'un radar CW-FM a 94GHz i verificació dels resultat obteinguts durante l'etapa de mesures.

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

Science.gov (United States)

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

2017-08-01

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

Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM

Directory of Open Access Journals (Sweden)

B. Croft

2010-02-01

Full Text Available A diagnostic cloud nucleation scavenging scheme, which determines stratiform cloud scavenging ratios for both aerosol mass and number distributions, based on cloud droplet, and ice crystal number concentrations, is introduced into the ECHAM5-HAM global climate model. This scheme is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. The aerosol mass scavenged in stratiform clouds is found to be primarily (>90% scavenged by cloud nucleation processes for all aerosol species, except for dust (50%. The aerosol number scavenged is primarily (>90% attributed to impaction. 99% of this impaction scavenging occurs in clouds with temperatures less than 273 K. Sensitivity studies are presented, which compare aerosol concentrations, burdens, and deposition for a variety of in-cloud scavenging approaches: prescribed fractions, a more computationally expensive prognostic aerosol cloud processing treatment, and the new diagnostic scheme, also with modified assumptions about in-cloud impaction and nucleation scavenging. Our results show that while uncertainties in the representation of in-cloud scavenging processes can lead to differences in the range of 20–30% for the predicted annual, global mean aerosol mass burdens, and near to 50% for accumulation mode aerosol number burden, the differences in predicted aerosol mass concentrations can be up to one order of magnitude, particularly for regions of the middle troposphere with temperatures below 273 K where mixed and ice phase clouds exist. Different parameterizations for impaction scavenging changed the predicted global, annual mean number removal attributed to ice clouds by seven-fold, and the global, annual dust mass removal attributed to impaction by two orders of magnitude. Closer agreement with observations of black carbon profiles from aircraft (increases near to one order of magnitude for mixed phase clouds

Design of an O-mode frequency modulated reflectometry system for the measurement of Alborz Tokamak plasma density profile

Energy Technology Data Exchange (ETDEWEB)

Koohestani, Saeideh [Department of Energy Engineering and physics, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of); Amrollahi, Reza, E-mail: amrollahi@aut.ac.ir [Department of Energy Engineering and physics, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of); Moradi, Gholamreza [Department of Electrical Engineering, Amirkabir University of Technology, Tehran, 15875-4413, Islamic Republic of Iran (Iran, Islamic Republic of)

2016-12-15

Reflectometry is a common method for plasma diagnostic, in which microwaves are launched into the plasma and reflected at the critical surfaces. Comparing the reflected microwave signals with the launched waves would give rise to the plasma density profiles. In the present study, an ordinary mode (O-mode) frequency modulation (FM) reflectometry system has been designed for the electron density profile measurement of the Alborz Tokamak plasma. This system has been considered to operate at K-band (18–26.5 GHz) frequency range and scan the frequency band between 18 to 26 GHz in 40 μS. The density profile from major radius r = 47.9–51.55 cm can be measured in Alborz Tokamak plasma. Based on the Alborz Tokamak operational conditions, the characteristic frequencies, and some dimensional limitations, all parts of reflectometer have been designed so that an appropriate efficiency with minimum attenuation, especially in transmitting/receiving system would be achieved. A dual antenna and an oversized waveguide of X-band (8–12 GHz) for transmitting and receiving purposes and a balanced detector for absolute phase determination have been utilized. The details of the Alborz Tokamak FM reflectometry components focusing on the antenna and waveguide design and mounting are described in this paper. Additionally, the procedure of plasma profile reconstruction using the system output signal is discussed. This system uses signal phase shift to determine the position of the cutoff layer.

RADIO SOURCES FROM A 31 GHz SKY SURVEY WITH THE SUNYAEV-ZEL'DOVICH ARRAY

International Nuclear Information System (INIS)

Muchovej, Stephen; Hawkins, David; Lamb, James; Woody, David; Leitch, Erik; Carlstrom, John E.; Culverhouse, Thomas; Greer, Chris; Hennessy, Ryan; Loh, Michael; Marrone, Daniel P.; Pryke, Clem; Sharp, Matthew; Joy, Marshall; Miller, Amber; Mroczkowski, Tony

2010-01-01

We present the first sample of 31 GHz selected sources to flux levels of 1 mJy. From late 2005 to mid-2007, the Sunyaev-Zel'dovich Array observed 7.7 deg 2 of the sky at 31 GHz to a median rms of 0.18 mJy beam -1 . We identify 209 sources at greater than 5σ significance in the 31 GHz maps, ranging in flux from 0.7 mJy to ∼200 mJy. Archival NVSS data at 1.4 GHz and observations at 5 GHz with the Very Large Array are used to characterize the sources. We determine the maximum-likelihood integrated source count to be N(>S) = (27.2 ± 2.5)deg -2 x (S mJy ) -1.18±0.12 over the flux range 0.7-15 mJy. This result is significantly higher than predictions based on 1.4 GHz selected samples, a discrepancy which can be explained by a small shift in the spectral index distribution for faint 1.4 GHz sources. From comparison with previous measurements of sources within the central arcminute of massive clusters, we derive an overdensity of 6.8 ± 4.4, relative to field sources.

On the effects of rotation on interstellar molecular line profiles

International Nuclear Information System (INIS)

Adelson, L.M.; Chunming Leung

1988-01-01

Theoretical models are constructed to study the effects of systematic gas rotation on the emergent profiles of interstellar molecular lines, in particular the effects of optical depth and different velocity laws. Both rotational and radial motions (expansion or contraction) may produce similar asymmetric profiles, but the behaviour of the velocity centroid of the emergent profile over the whole cloud (iso-centroid maps) can be used to distinguish between these motions. Iso-centroid maps can also be used to determine the location and orientation of the rotation axis and of the equatorial axis. For clouds undergoing both radial and rotational motion, the component of the centroid due to the rotational motion can be separated from that due to the radial motion. Information on the form of the rotational velocity law can also be derived. (author)

New insight of Arctic cloud parameterization from regional climate model simulations, satellite-based, and drifting station data

Science.gov (United States)

Klaus, D.; Dethloff, K.; Dorn, W.; Rinke, A.; Wu, D. L.

2016-05-01

Cloud observations from the CloudSat and CALIPSO satellites helped to explain the reduced total cloud cover (Ctot) in the atmospheric regional climate model HIRHAM5 with modified cloud physics. Arctic climate conditions are found to be better reproduced with (1) a more efficient Bergeron-Findeisen process and (2) a more generalized subgrid-scale variability of total water content. As a result, the annual cycle of Ctot is improved over sea ice, associated with an almost 14% smaller area average than in the control simulation. The modified cloud scheme reduces the Ctot bias with respect to the satellite observations. Except for autumn, the cloud reduction over sea ice improves low-level temperature profiles compared to drifting station data. The HIRHAM5 sensitivity study highlights the need for improving accuracy of low-level (<700 m) cloud observations, as these clouds exert a strong impact on the near-surface climate.

Role of mixed precipitating cloud systems on the typhoon rainfall

Directory of Open Access Journals (Sweden)

C. J. Pan

2010-01-01

Full Text Available L-band wind profiler data are utilized to diagnose the vertical structure of the typhoon precipitating cloud systems in Taiwan. For several typhoons, a pronounced bright band (BB around 5 km is commonly observed from the observation. Since strong convection within typhoon circulation may disturb and/or disrupt the melting layer, the BB shall not appear persistently. Hence, an understanding of the vertical structure of the BB region is important because it holds extensive hydrometeors information on the type of precipitation and its variability. Wind profiler observational results suggest that the mixture of convective and stratiform (embedded type clouds are mostly associated with typhoons. In the case of one typhoon, BB is appeared around 5.5 km with embedded precipitation and also BB height of 1 km higher than ordinary showery precipitation. This is evident from the long-term observations of wind profiler and Tropical Rainfall Measuring Mission. The Doppler velocity profiles show hydrometers (ice/snow at 6 km but liquid below 5 km for typhoons and 4 km for showery precipitation. In the BB region the melting particles accelerations of 5.8 ms⁻¹ km⁻¹ and 3.2 ms⁻¹ km⁻¹ are observed for typhoon and showery precipitation, respectively.

Cloud-to-Ground Lightning Estimates Derived from SSMI Microwave Remote Sensing and NLDN

Science.gov (United States)

Winesett, Thomas; Magi, Brian; Cecil, Daniel

2015-01-01

present in the cloud and electric charge separation occurs. These ice particles efficiently scatter the microwave radiation at the 85 and 37 GHz frequencies, thus leading to large brightness temperature depressions. Lightning flash rate is related to the total amount of ice passing through the convective updraft regions of thunderstorms. Confirmation of this relationship using TRMM LIS and TMI data, however, remains constrained to TRMM observational limits of the tropics and subtropics. Satellites from the Defense Meteorology Satellite Program (DMSP) have global coverage and are equipped with passive microwave imagers that, like TMI, observe brightness temperatures at 85 and 37 GHz. Unlike the TRMM satellite, however, DMSP satellites do not have a lightning sensor, and the DMSP microwave data has never been used to derive global lightning. In this presentation, a relationship between DMSP Special Sensor Microwave Imager (SSMI) data and ground-based cloud-to-ground (CG) lightning data from NLDN is investigated to derive a spatially complete time history of CG lightning for the USA study area. This relationship is analogous to the established using TRMM LIS and TMI data. NLDN has the most spatially and temporally complete CG lightning data for the USA, and therefore provides the best opportunity to find geospatially coincident observations with SSMI sensors. The strongest thunderstorms generally have minimum 85 GHz Polarized Corrected brightness Temperatures (PCT) less than 150 K. Archived radar data was used to resolve the spatial extent of the individual storms. NLDN data for that storm spatial extent defined by radar data was used to calculate the CG flash rate for the storm. Similar to results using TRMM sensors, a linear model best explained the relationship between storm-specific CG flash rates and minimum 85 GHz PCT. However, the results in this study apply only to CG lightning. To extend the results to weaker storms, the probability of CG lightning (instead of the

Sensitivity of warm-frontal processes to cloud-nucleating aerosol concentrations

Science.gov (United States)

Igel, Adele L.; Van Den Heever, Susan C.; Naud, Catherine M.; Saleeby, Stephen M.; Posselt, Derek J.

2013-01-01

An extratropical cyclone that crossed the United States on 9-11 April 2009 was successfully simulated at high resolution (3-km horizontal grid spacing) using the Colorado State University Regional Atmospheric Modeling System. The sensitivity of the associated warm front to increasing pollution levels was then explored by conducting the same experiment with three different background profiles of cloud-nucleating aerosol concentration. To the authors' knowledge, no study has examined the indirect effects of aerosols on warm fronts. The budgets of ice, cloud water, and rain in the simulation with the lowest aerosol concentrations were examined. The ice mass was found to be produced in equal amounts through vapor deposition and riming, and the melting of ice produced approximately 75% of the total rain. Conversion of cloud water to rain accounted for the other 25%. When cloud-nucleating aerosol concentrations were increased, significant changes were seen in the budget terms, but total precipitation remained relatively constant. Vapor deposition onto ice increased, but riming of cloud water decreased such that there was only a small change in the total ice production and hence there was no significant change in melting. These responses can be understood in terms of a buffering effect in which smaller cloud droplets in the mixed-phase region lead to both an enhanced vapor deposition and decreased riming efficiency with increasing aerosol concentrations. Overall, while large changes were seen in the microphysical structure of the frontal cloud, cloud-nucleating aerosols had little impact on the precipitation production of the warm front.

The effect of cloud screening on MAX-DOAS aerosol retrievals.

Science.gov (United States)

Gielen, Clio; Van Roozendael, Michel; Hendrik, Francois; Fayt, Caroline; Hermans, Christian; Pinardi, Gaia; De Backer, Hugo; De Bock, Veerle; Laffineur, Quentin; Vlemmix, Tim

2014-05-01

In recent years, ground-based multi-axis differential absorption spectroscopy (MAX-DOAS) has shown to be ideally suited for the retrieval of tropospheric trace gases and deriving information on the aerosol properties. These measurements are invaluable to our understanding of the physics and chemistry of the atmospheric system, and the impact on the Earth's climate. Unfortunately, MAX-DOAS measurements are often performed under strong non-clear-sky conditions, causing strong data quality degradation and uncertainties on the retrievals. Here we present the result of our cloud-screening method, using the colour index (CI), on aerosol retrievals from MAX-DOAS measurements (AOD and vertical profiles). We focus on two large data sets, from the Brussels and Beijing area. Using the CI we define 3 different sky conditions: bad (=full thick cloud cover/extreme aerosols), mediocre (=thin clouds/aerosols) and good (=clear sky). We also flag the presence of broken/scattered clouds. We further compare our cloud-screening method with results from cloud-cover fractions derived from thermic infrared measurements. In general, our method shows good results to qualify the sky and cloud conditions of MAX-DOAS measurements, without the need for other external cloud-detection systems. Removing data under bad-sky and broken-cloud conditions results in a strongly improved agreement, in both correlation and slope, between the MAX-DOAS aerosol retrievals and data from other instruments (e.g. AERONET, Brewer). With the improved AOD retrievals, the seasonal and diurnal variations of the aerosol content and vertical distribution at both sites can be investigated in further detail. By combining with additional information derived by other instruments (Brewer, lidar, ...) operated at the stations, we will further study the observed aerosol characteristics, and their influence on and by meteorological conditions such as clouds and/or the boundary layer height.

Optical Spectra of Radio Planetary Nebulae in the Small Magellanic Cloud

Directory of Open Access Journals (Sweden)

Payne, J. L.

2008-06-01

Full Text Available We present preliminary results from spectral observations of four (4 candidate radio sources co-identified with known planetary nebulae (PNe in the Small Magellanic Cloud (SMC. These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA surveys of the SMC at 1.42 and 2.37~GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (4arcsec/2arcsec. Optical PNe and radio candidates are within 2arcsec and may represent a sub-population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6~$M_odot$ or greater, supporting the existence of PNe progenitor central stars with masses up to 8 $M_odot$.

Optical spectra of radio planetary nebulae in the small Magellanic cloud

Directory of Open Access Journals (Sweden)

Payne J.L.

2008-01-01

Full Text Available We present preliminary results from spectral observations of four (4 candidate radio sources co-identified with known planetary nebulae (PNe in the Small Magellanic Cloud (SMC. These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA surveys of the SMC at 1.42 and 2.37 GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (400 /200 . Optical PNe and radio candidates are within 200 and may represent a sub- population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6 Mo or greater, supporting the existence of PNe progenitor central stars with masses up to 8 Mo.

Interaction between the SNR Sagittarius A East and the 50-km s-1 Molecular Cloud

International Nuclear Information System (INIS)

Tsuboi, Masato; Okumura, Sachiko K; Miyazaki, Atsushi

2006-01-01

We performed high-resolution observations of the Galactic Center 50-km s -1 molecular cloud in the CS J = 1 - 0 line using the Nobeyama Millimeter Array. The 50-km s -1 molecular cloud corresponds to a break in the Sagittarius (Sgr) A east shell. A very broad and negative velocity wing feature is detected at an apparent contact spot between the molecular cloud and the Sgr A east shell. The velocity width of the wing feature is over 50-km s -1 . The width is three times wider than those of typical Galactic Center clouds. This strongly suggests that the shell is interacting physically with the molecular cloud. The asymmetric velocity profile of the wing feature indicates that the Sgr A east shell expands and crashes into the far side of the molecular cloud. About 50 clumps are identified in the cloud using CLUMPFIND. The velocity width-size relation and the mass spectrum of clumps in the cloud are similar to those in Central Molecular Zone (CMZ)

125-GHz Microwave Signal Generation Employing an Integrated Pulse Shaper

DEFF Research Database (Denmark)

Liao, Shasha; Ding, Yunhong; Dong, Jianji

2017-01-01

We propose and experimentally demonstrate an on-chip pulse shaper for 125-GHz microwave waveform generation. The pulse shaper is implemented based on a silicon-on-insulator (SOI) platform that has a structure with eight-tap finite impulse response (FIR) and there is an amplitude modulator on each...... of the generated microwave waveforms is larger than 100 GHz, and it has wide bandwidth when changing the time delay of the adjacent taps and compactness, capability for integration with electronics and small power consumption are also its merits.......We propose and experimentally demonstrate an on-chip pulse shaper for 125-GHz microwave waveform generation. The pulse shaper is implemented based on a silicon-on-insulator (SOI) platform that has a structure with eight-tap finite impulse response (FIR) and there is an amplitude modulator on each...

Contrasting Cloud Composition Between Coupled and Decoupled Marine Boundary Layer Clouds

Science.gov (United States)

WANG, Z.; Mora, M.; Dadashazar, H.; MacDonald, A.; Crosbie, E.; Bates, K. H.; Coggon, M. M.; Craven, J. S.; Xian, P.; Campbell, J. R.; AzadiAghdam, M.; Woods, R. K.; Jonsson, H.; Flagan, R. C.; Seinfeld, J.; Sorooshian, A.

2016-12-01

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (E-PEACE 2011, NiCE 2013, BOAS 2015). Decoupled clouds exhibited significantly lower overall mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and sub-cloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Non-refractory sub-micrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Total cloud water mass concentration in coupled clouds was dominated by sodium and chloride, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea salt constituents (e.g., Cl, Na, Mg, K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. These results suggest that an important variable is the extent to which clouds are coupled to the surface layer when interpreting microphysical data relevant to clouds and aerosol particles.

A novel technique for extracting clouds base height using ground based imaging

Directory of Open Access Journals (Sweden)

E. Hirsch

2011-01-01

Full Text Available The height of a cloud in the atmospheric column is a key parameter in its characterization. Several remote sensing techniques (passive and active, either ground-based or on space-borne platforms and in-situ measurements are routinely used in order to estimate top and base heights of clouds. In this article we present a novel method that combines thermal imaging from the ground and sounded wind profile in order to derive the cloud base height. This method is independent of cloud types, making it efficient for both low boundary layer and high clouds. In addition, using thermal imaging ensures extraction of clouds' features during daytime as well as at nighttime. The proposed technique was validated by comparison to active sounding by ceilometers (which is a standard ground based method, to lifted condensation level (LCL calculations, and to MODIS products obtained from space. As all passive remote sensing techniques, the proposed method extracts only the height of the lowest cloud layer, thus upper cloud layers are not detected. Nevertheless, the information derived from this method can be complementary to space-borne cloud top measurements when deep-convective clouds are present. Unlike techniques such as LCL, this method is not limited to boundary layer clouds, and can extract the cloud base height at any level, as long as sufficient thermal contrast exists between the radiative temperatures of the cloud and its surrounding air parcel. Another advantage of the proposed method is its simplicity and modest power needs, making it particularly suitable for field measurements and deployment at remote locations. Our method can be further simplified for use with visible CCD or CMOS camera (although nighttime clouds will not be observed.

Context-aware distributed cloud computing using CloudScheduler

Science.gov (United States)

Seuster, R.; Leavett-Brown, CR; Casteels, K.; Driemel, C.; Paterson, M.; Ring, D.; Sobie, RJ; Taylor, RP; Weldon, J.

2017-10-01

The distributed cloud using the CloudScheduler VM provisioning service is one of the longest running systems for HEP workloads. It has run millions of jobs for ATLAS and Belle II over the past few years using private and commercial clouds around the world. Our goal is to scale the distributed cloud to the 10,000-core level, with the ability to run any type of application (low I/O, high I/O and high memory) on any cloud. To achieve this goal, we have been implementing changes that utilize context-aware computing designs that are currently employed in the mobile communication industry. Context-awareness makes use of real-time and archived data to respond to user or system requirements. In our distributed cloud, we have many opportunistic clouds with no local HEP services, software or storage repositories. A context-aware design significantly improves the reliability and performance of our system by locating the nearest location of the required services. We describe how we are collecting and managing contextual information from our workload management systems, the clouds, the virtual machines and our services. This information is used not only to monitor the system but also to carry out automated corrective actions. We are incrementally adding new alerting and response services to our distributed cloud. This will enable us to scale the number of clouds and virtual machines. Further, a context-aware design will enable us to run analysis or high I/O application on opportunistic clouds. We envisage an open-source HTTP data federation (for example, the DynaFed system at CERN) as a service that would provide us access to existing storage elements used by the HEP experiments.

Measuring the service level in the 2.4 GHz ISM band

NARCIS (Netherlands)

van Bloem, J.W.H.; Schiphorst, Roelof

2011-01-01

In this report we provide the findings of the 2.4 GHz service level research. Here service level means the following: can all devices in the 2.4 GHz band fulfill their communication needs. In other words this corresponds to the overall Quality of Service (QoS). The project is a short research

AceCloud: Molecular Dynamics Simulations in the Cloud.

Science.gov (United States)

Harvey, M J; De Fabritiis, G

2015-05-26

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

VMware private cloud computing with vCloud director

CERN Document Server

Gallagher, Simon

2013-01-01

It's All About Delivering Service with vCloud Director Empowered by virtualization, companies are not just moving into the cloud, they're moving into private clouds for greater security, flexibility, and cost savings. However, this move involves more than just infrastructure. It also represents a different business model and a new way to provide services. In this detailed book, VMware vExpert Simon Gallagher makes sense of private cloud computing for IT administrators. From basic cloud theory and strategies for adoption to practical implementation, he covers all the issues. You'll lea

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

Science.gov (United States)

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

1990-01-01

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

Overview and sample applications of SMILES and Odin-SMR retrievals of upper tropospheric humidity and cloud ice mass

Directory of Open Access Journals (Sweden)

P. Eriksson

2014-12-01

Full Text Available Retrievals of cloud ice mass and humidity from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES and the Odin-SMR (Sub-Millimetre Radiometer limb sounder are presented and example applications of the data are given. SMILES data give an unprecedented view of the diurnal variation of cloud ice mass. Mean regional diurnal cycles are reported and compared to some global climate models. Some improvements in the models regarding diurnal timing and relative amplitude were noted, but the models' mean ice mass around 250 hPa is still low compared to the observations. The influence of the ENSO (El Niño–Southern Oscillation state on the upper troposphere is demonstrated using 12 years of Odin-SMR data. The same retrieval scheme is applied for both sensors, and gives low systematic differences between the two data sets. A special feature of this Bayesian retrieval scheme, of Monte Carlo integration type, is that values are produced for all measurements but for some atmospheric states retrieved values only reflect a priori assumptions. However, this "all-weather" capability allows a direct statistical comparison to model data, in contrast to many other satellite data sets. Another strength of the retrievals is the detailed treatment of "beam filling" that otherwise would cause large systematic biases for these passive cloud ice mass retrievals. The main retrieval inputs are spectra around 635/525 GHz from tangent altitudes below 8/9 km for SMILES/Odin-SMR, respectively. For both sensors, the data cover the upper troposphere between 30° S and 30° N. Humidity is reported as both relative humidity and volume mixing ratio. The vertical coverage of SMILES is restricted to a single layer, while Odin-SMR gives some profiling capability between 300 and 150 hPa. Ice mass is given as the partial ice water path above 260 hPa, but for Odin-SMR ice water content, estimates are also provided. Besides a smaller contrast between most dry and wet

Ultra-wideband and 60 GHz communications for biomedical applications

CERN Document Server

Yuce, Mehmet R

2013-01-01

This book investigates the design of devices, systems, and circuits for medical applications using the two recently established frequency bands: ultra-wideband (3.1-10.6 GHz) and 60 GHz ISM band. These two bands provide the largest bandwidths available for communication technologies and present many attractive opportunities for medical applications. The applications of these bands in healthcare are wireless body area network (WBAN), medical imaging, biomedical sensing, wearable and implantable devices, fast medical device connectivity, video data transmission, and vital signs monitoring. The r

Emittance studies of the 2.45 GHz permanent magnet ECR ion source

Science.gov (United States)

Zelenak, A.; Bogomolov, S. L.; Yazvitsky, N. Yu.

2004-05-01

During the past several years different types of permanent magnet 2.45 GHz (electron cyclotron resonance) ion sources were developed for production of singly charged ions. Ion sources of this type are used in the first stage of DRIBs project, and are planned to be used in the MASHA mass separator. The emittance of the beam provided by the source is one of the important parameters for these applications. An emittance scanner composed from a set of parallel slits and rotary wire beam profile monitor was used for the studying of the beam emittance characteristics. The emittance of helium and argon ion beams was measured with different shapes of the plasma electrode for several ion source parameters: microwave power, source potential, plasma aperture-puller aperture gap distance, gas pressure. The results of measurements are compared with previous simulations of ion optics.

Emittance studies of the 2.45 GHz permanent magnet ECR ion source

International Nuclear Information System (INIS)

Zelenak, A.; Bogomolov, S.L.; Yazvitsky, N.Yu.

2004-01-01

During the past several years different types of permanent magnet 2.45 GHz (electron cyclotron resonance) ion sources were developed for production of singly charged ions. Ion sources of this type are used in the first stage of DRIBs project, and are planned to be used in the MASHA mass separator. The emittance of the beam provided by the source is one of the important parameters for these applications. An emittance scanner composed from a set of parallel slits and rotary wire beam profile monitor was used for the studying of the beam emittance characteristics. The emittance of helium and argon ion beams was measured with different shapes of the plasma electrode for several ion source parameters: microwave power, source potential, plasma aperture-puller aperture gap distance, gas pressure. The results of measurements are compared with previous simulations of ion optics

10 GHz ECRIS for Warsaw Cyclotron

CERN Document Server

Sudlitz, K

1999-01-01

Cusp type, 10 GHz ECRIS has been built and tested earlier. For obtaining intensive beams, more relevant for cyclotron, cusp geometry has been replaced by hexapole. Discharge chamber (stainless steel, 50 mm diameter, 250 mm long) is an extension of a coaxial line, feeding RF (9,6 GHz, up to 200 W) to the plasma. The NdFeB hexapole (0,52 T on the surface) has been used. The axial magnetic field is created by water cooled coils. The axial injection line dedicated to K160 isochronous heavy ion cyclotron has been constructed. The line consists of Glaser lenses, double focusing magnet, solenoid and mirror type inflector. The system provides sufficient transmission of the beam from ECR ion source to the firsts orbits of the cyclotron for m/q ranging from 7 to 2. After successful initial tests which were done in July 1997 the ECRIS serves as an external source for Warsaw Cyclotron.

Characteristics of ocular temperature elevations after exposure to quasi- and millimeter waves (18-40 GHz)

Science.gov (United States)

Kojima, Masami; Suzuki, Yukihisa; Tsai, Cheng-Yu; Sasaki, Kensuke; Wake, Kanako; Watanabe, Soichi; Taki, Masao; Kamimura, Yoshitsugu; Hirata, Akimasa; Sasaki, Kazuyuki; Sasaki, Hiroshi

2015-04-01

In order to investigate changes in ocular temperature in rabbit eyes exposed to different frequencies (18 to 40 GHz) of quasi-millimeter waves, and millimeter waves (MMW). Pigmented rabbits were anesthetized with both general and topical anesthesia, and thermometer probes (0.5 mm in diameter) were inserted into their cornea (stroma), lens (nucleus) and vitreous (center of vitreous). The eyes were exposed unilaterally to 200 mW/cm2 by horn antenna for 3 min at 18, 22 and 26.5 GHz using a K band exposure system or 26.5, 35 and 40 GHz using a Ka band exposure system. Changes in temperature of the cornea, lens and vitreous were measured with a fluoroptic thermometer. Since the ocular temperatures after exposure to 26.5 GHz generated by the K band and Ka band systems were similar, we assumed that experimental data from these 2 exposure systems were comparable. The highest ocular temperature was induced by 40 GHz MMW, followed by 35 GHz. The 26.5 and 22 GHz corneal temperatures were almost the same. The lowest temperature was recorded at 18 GHz. The elevation in ocular temperature in response to exposure to 200 mW/cm2 MMW is dependent on MMW frequency. MMW exposure induced heat is conveyed not only to the cornea but also the crystalline lens.

Creating cloud-free Landsat ETM+ data sets in tropical landscapes: cloud and cloud-shadow removal

Science.gov (United States)

Sebastián Martinuzzi; William A. Gould; Olga M. Ramos Gonzalez

2007-01-01

Clouds and cloud shadows are common features of visible and infrared remotelysensed images collected from many parts of the world, particularly in humid and tropical regions. We have developed a simple and semiautomated method to mask clouds and shadows in Landsat ETM+ imagery, and have developed a recent cloud-free composite of multitemporal images for Puerto Rico and...

Using AMIE data to study cloud processes within the Madden-Julian Oscillation

Energy Technology Data Exchange (ETDEWEB)

Houze, Robert A. [Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences

2015-12-17

This study uses AMIE data to show how the small clouds in the Madden-Julian Oscillation first organize into lines and other patterns, how they develop the first rainshowers, how those showers deposit cool air over the ocean surface, how this cool air spreads and triggers deeper convection, how the deep convection develops into mesoscale systems, how the mesoscale systems modify the heating profile through the depth of the troposphere, and how the development of the clouds responds to and interacts with large-scale waves circumnavigating the globe at upper levels, and how equatorial trapped waves at lower levels modulates the development of the cloud population. The techniques used to analyze the radar and sounding data collected in AMIE to achieve the above results are innovative, and to obtain more general results we have used regional modeling with a variety of cloud microphysical schemes in combination with the data analyses.

Scanning ARM Cloud Radars Part II. Data Quality Control and Processing

Energy Technology Data Exchange (ETDEWEB)

Kollias, Pavlos [McGill Univ., Montreal, QC (Canada); Jo, Ieng [McGill Univ., Montreal, QC (Canada); Borque, Paloma [McGill Univ., Montreal, QC (Canada); Tatarevic, Aleksandra [McGill Univ., Montreal, QC (Canada); Lamer, Katia [McGill Univ., Montreal, QC (Canada); Bharadwaj, Nitin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Widener, Kevin B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Karen [Brookhaven National Lab. (BNL), Upton, NY (United States); Clothiaux, Eugene E. [Pennsylvania State Univ., State College, PA (United States)

2013-10-04

The Scanning ARM Cloud Radars (SACR’s) are the primary instruments for documenting the four-dimensional structure and evolution of clouds within a 20-30 km radius from the ARM fixed and mobile sites. Here, the post-processing of the calibrated SACR measurements is discussed. First, a feature mask algorithm that objectively determines the presence of significant radar returns is described. The feature mask algorithm is based on the statistical properties of radar receiver noise. It accounts for atmospheric emission and is applicable even for SACR profiles with few or no signal-free range gates. Using the nearest-in-time atmospheric sounding, the SACR radar reflectivities are corrected for gaseous attenuation (water vapor and oxygen) using a line-by-line absorption model. Despite having a high pulse repetition frequency, the SACR has a narrow Nyquist velocity limit and thus Doppler velocity folding is commonly observed. An unfolding algorithm that makes use of a first guess for the true Doppler velocity using horizontal wind measurements from the nearest sounding is described. The retrieval of the horizontal wind profile from the Hemispherical Sky – Range Height Indicator SACR scan observations and/or nearest sounding is described. The retrieved horizontal wind profile can be used to adaptively configure SACR scan strategies that depend on wind direction. Several remaining challenges are discussed, including the removal of insect and second-trip echoes. The described algorithms significantly enhance SACR data quality and constitute an important step towards the utilization of SACR measurements for cloud research.

Evaluation of cloud resolving model simulations of midlatitude cirrus with ARM and A-Train observations

Science.gov (United States)

Muehlbauer, A. D.; Ackerman, T. P.; Lawson, P.; Xie, S.; Zhang, Y.

2015-12-01

This paper evaluates cloud resolving model (CRM) and cloud system-resolving model (CSRM) simulations of a midlatitude cirrus case with comprehensive observations collected under the auspices of the Atmospheric Radiation Measurements (ARM) program and with spaceborne observations from the National Aeronautics and Space Administration (NASA) A-train satellites. Vertical profiles of temperature, relative humidity and wind speeds are reasonably well simulated by the CSRM and CRM but there are remaining biases in the temperature, wind speeds and relative humidity, which can be mitigated through nudging the model simulations toward the observed radiosonde profiles. Simulated vertical velocities are underestimated in all simulations except in the CRM simulations with grid spacings of 500m or finer, which suggests that turbulent vertical air motions in cirrus clouds need to be parameterized in GCMs and in CSRM simulations with horizontal grid spacings on the order of 1km. The simulated ice water content and ice number concentrations agree with the observations in the CSRM but are underestimated in the CRM simulations. The underestimation of ice number concentrations is consistent with the overestimation of radar reflectivity in the CRM simulations and suggests that the model produces too many large ice particles especially toward cloud base. Simulated cloud profiles are rather insensitive to perturbations in the initial conditions or the dimensionality of the model domain but the treatment of the forcing data has a considerable effect on the outcome of the model simulations. Despite considerable progress in observations and microphysical parameterizations, simulating the microphysical, macrophysical and radiative properties of cirrus remains challenging. Comparing model simulations with observations from multiple instruments and observational platforms is important for revealing model deficiencies and for providing rigorous benchmarks. However, there still is considerable

A 60 GHz Dual-Polarized Probe for Spherical Near-Field Measurements

DEFF Research Database (Denmark)

Popa, Paula Irina; Breinbjerg, Olav

2017-01-01

to waveguide adapters up to 67 GHz for OMT-switch connection. A 27 dBi gain conical horn is designed by using WIPL-D software and in-house manufactured. The 60 GHz probe system is being assembled and tested in planar near-field (PNF) setup at DTU. The results are validated by comparison with WIPL-D simulations...

BAECC Biogenic Aerosols - Effects on Clouds and Climate

Energy Technology Data Exchange (ETDEWEB)

Petäjä, Tuukka [Univ. of Helsinki (Finland); Moisseev, Dmitri [Univ. of Helsinki (Finland); Sinclair, Victoria [Univ. of Helsinki (Finland); O' Connor, Ewan J. [Finnish Meteorological Institute, Helsinki (Finland); Manninen, Antti J. [Univ. of Helsinki (Finland); Levula, Janne [Univ. of Helsinki (Finland); Väänänen, Riikka [Univ. of Helsinki (Finland); Heikkinen, Liine [Univ. of Helsinki (Finland); Äijälä, Mikko [Univ. of Helsinki (Finland); Aalto, Juho [Univ. of Helsinki (Finland); Bäck, Jaana [University of Helsinki, Finland

2015-11-01

“Biogenic Aerosols - Effects on Clouds and Climate (BAECC)”, featured the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Program’s 2nd Mobile Facility (AMF2) in Hyytiälä, Finland. It operated for an 8-month intensive measurement campaign from February to September 2014. The main research goal was to understand the role of biogenic aerosols in cloud formation. One of the reasons to perform BAECC study in Hyytiälä was the fact that it hosts SMEAR-II (Station for Measuring Forest Ecosystem-Atmosphere Relations), which is one of the world’s most comprehensive surface in-situ observation sites in a boreal forest environment. The station has been measuring atmospheric aerosols, biogenic emissions and an extensive suite of parameters relevant to atmosphere-biosphere interactions continuously since 1996. The BAECC enables combining vertical profiles from AMF2 with surface-based in-situ SMEAR-II observations and allows the processes at the surface to be directly related to processes occurring throughout the entire tropospheric column. With the inclusion of extensive surface precipitation measurements, and intensive observation periods involving aircraft flights and novel radiosonde launches, the complementary observations of AMF2 and SMEAR-II provide a unique opportunity for investigating aerosol-cloud interactions, and cloud-to-precipitation processes. The BAECC dataset will initiate new opportunities for evaluating and improving models of aerosol sources and transport, cloud microphysical processes, and boundary-layer structures.