Stratus Cloud Radiative Effects from Cloud Processed Bimodal CCN Distributions

NASA Astrophysics Data System (ADS)

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

2016-12-01

Inability to understand cloud processes is a large component of climate uncertainty. Increases in cloud condensation nuclei (CCN) concentrations are known to increase cloud droplet number concentrations (Nc). This aerosol-cloud interaction (ACI) produces greater Nc at smaller sizes, which brightens clouds. A lesser understood ACI is cloud processing of CCN. This improves CCN that then more easily activate at lower cloud supersaturations (S). Bimodal CCN distributions thus ensue from these evaporated cloud droplets. Hudson et al. (2015) related CCN bimodality to Nc. In stratus clouds, bimodal CCN created greater Nc whereas in cumulus less Nc. Thus, CCN distribution shape influences cloud properties; microphysics and radiative properties. Measured uni- and bimodal CCN distributions were input into an adiabatic droplet growth model using various specified vertical wind speeds (W). Bimodal CCN produced greater Nc (Fig. 1a) and smaller mean diameters (MD; Fig. 1b) at lower W typical of stratus clouds (<70 cm/s). Improved CCN (low critical S) were more easily activated at the lower S of stratus from low W, thus, creating greater Nc. Competition for condensate thus reduced MD and drizzle. At greater W, typical of cumulus clouds (>70 cm/s), bimodal CCN made lower Nc with larger MD thus enhancing drizzle whereas unimodal CCN made greater Nc with smaller MD, thus reducing drizzle. Thus, theoretical predictions of Nc and MD for uni- and bimodal CCN agree with the sense of the observations. Radiative effects were determined using a cloud grown to a 250-meter thickness. Bimodal CCN at low W reduced cloud effective radius (re), made greater cloud optical thickness (COT), and made greater cloud albedo (Fig. 1c). At very low W changes were as much as +9% for albedo, +17% for COT, and -12% for re. Stratus clouds typically have low W and cover large areas. Thus, these changes in cloud radiative properties at low W impact climate. Stratus cloud susceptibility to CCN distribution thus

Young stellar population and star formation history ofW4 HII region/Cluster Complex

NASA Astrophysics Data System (ADS)

Panwar, Neelam

2018-04-01

The HII region/cluster complex has been a subject of numerous investigations to study the feedback effect of massive stars on their surroundings. Massive stars not only alter the morphology of the parental molecular clouds, but also influence star formation, circumstellar disks and the mass function of low-mass stars in their vicinity. However, most of the studies of low-mass stellar content of the HII regions are limited only to the nearby regions. We study the star formation in the W4 HII region using deep optical observations obtained with the archival data from Canada - France - Hawaii Telescope, Two-Micron All Sky Survey, Spitzer, Herschel and Chandra. We investigate the spatial distribution of young stellar objects in the region, their association with the remnant molecular clouds, and search for the clustering to establish the sites of recent star formation. Our analysis suggests that the influence of massive stars on circumstellar disks is significant only to thei! r immediate neighborhood. The spatial correlation of the young stars with the distribution of gas and dust of the complex indicate that the clusters would have formed in a large filamentary cloud. The observing facilities at the 3.6-m Devasthal Optical Telescope (DOT), providing high-resolution spectral and imaging capabilities, will fulfill the major objectives in the study of HII regions.

STAR FORMATION ACROSS THE W3 COMPLEX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Román-Zúñiga, Carlos G.; Ybarra, Jason E.; Tapia, Mauricio

We present a multi-wavelength analysis of the history of star formation in the W3 complex. Using deep, near-infrared ground-based images combined with images obtained with Spitzer and Chandra observatories, we identified and classified young embedded sources. We identified the principal clusters in the complex and determined their structure and extension. We constructed extinction-limited samples for five principal clusters and constructed K-band luminosity functions that we compare with those of artificial clusters with varying ages. This analysis provided mean ages and possible age spreads for the clusters. We found that IC 1795, the centermost cluster of the complex, still hosts amore » large fraction of young sources with circumstellar disks. This indicates that star formation was active in IC 1795 as recently as 2 Myr ago, simultaneous to the star-forming activity in the flanking embedded clusters, W3-Main and W3(OH). A comparison with carbon monoxide emission maps indicates strong velocity gradients in the gas clumps hosting W3-Main and W3(OH) and shows small receding clumps of gas at IC 1795, suggestive of rapid gas removal (faster than the T Tauri timescale) in the cluster-forming regions. We discuss one possible scenario for the progression of cluster formation in the W3 complex. We propose that early processes of gas collapse in the main structure of the complex could have defined the progression of cluster formation across the complex with relatively small age differences from one group to another. However, triggering effects could act as catalysts for enhanced efficiency of formation at a local level, in agreement with previous studies.« less

Evaluation of Cloud Physical Properties of ECMWF Analysis and Re-Analysis (ERA-40 and ERA Interim) against CERES Tropical Deep Convective Cloud Object Observations

NASA Technical Reports Server (NTRS)

Xu, Kuan-Man

2008-01-01

This study presents an approach that converts the vertical profiles of grid-averaged cloud properties from large-scale models to probability density functions (pdfs) of subgrid-cell cloud physical properties measured at satellite footprints. Cloud physical and radiative properties, rather than just cloud and precipitation occurrences, of assimilated cloud systems by the European Center for Medium-range Weather Forecasts (ECMWF) operational analysis (EOA) and ECMWF Re-Analyses (ERA-40 and ERA Interim) are validated against those obtained from Earth Observing System satellite cloud object data for January-August 1998 and March 2000 periods. These properties include ice water path (IWP), cloud-top height and temperature, cloud optical depth and solar and infrared radiative fluxes. Each cloud object, a contiguous region with similar cloud physical properties, is temporally and spatially matched with EOA and ERA-40 data. Results indicate that most pdfs of EOA and ERA-40 cloud physical and radiative properties agree with those of satellite observations of the tropical deep convective cloud-object type for the January-August 1998 period. There are, however, significant discrepancies in selected ranges of the cloud property pdfs such as the upper range of EOA cloud top height. A major discrepancy is that the dependence of the pdfs on the cloud object size for both EOA and ERA-40 is not as strong as in the observations. Modifications to the cloud parameterization in ECMWF that occurred in October 1999 eliminate the clouds near the tropopause but shift power of the pdf to lower cloud-top heights and greatly reduce the ranges of IWP and cloud optical depth pdfs. These features persist in ERA-40 due to the use of the same cloud parameterizations. The downgrade of data assimilation technique and the lack of snow water content information in ERA-40, not the coarser horizontal grid resolution, are also responsible for the disagreements with observed pdfs of cloud physical

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

NASA Astrophysics Data System (ADS)

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 (<1 km) cloud occurrences in CCCM are larger over tropical oceans because the CCCM algorithm uses a more relaxed threshold of cloud-aerosol discrimination score for CALIPSO Vertical Feature Mask product. In contrast, midlevel (1-8 km) cloud occurrences in GEOPROF-LIDAR are larger than CCCM at high latitudes (>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.

Clouds Aerosols Internal Affaires: Increasing Cloud Fraction and Enhancing the Convection

NASA Technical Reports Server (NTRS)

Koren, Ilan; Kaufman, Yoram; Remer, Lorraine; Rosenfeld, Danny; Rudich, Yinon

2004-01-01

Clouds developing in a polluted environment have more numerous, smaller cloud droplets that can increase the cloud lifetime and liquid water content. Such changes in the cloud droplet properties may suppress low precipitation allowing development of a stronger convection and higher freezing level. Delaying the washout of the cloud water (and aerosol), and the stronger convection will result in higher clouds with longer life time and larger anvils. We show these effects by using large statistics of the new, 1km resolution data from MODIS on the Terra satellite. We isolate the aerosol effects from meteorology by regression and showing that aerosol microphysical effects increases cloud fraction by average of 30 presents for all cloud types and increases convective cloud top pressure by average of 35mb. We analyze the aerosol cloud interaction separately for high pressure trade wind cloud systems and separately for deep convective cloud systems. The resultant aerosol radiative effect on climate for the high pressure cloud system is: -10 to -13 W/sq m at the top of the atmosphere (TOA) and -11 to -14 W/sq m at the surface. For deeper convective clouds the forcing is: -4 to -5 W/sq m at the TOA and -6 to -7 W/sq m at the surface.

On the origin of the Orion and Monoceros molecular cloud complexes

NASA Technical Reports Server (NTRS)

Franco, J.; Tenorio-Tagle, G.; Bodenheimer, P.; Rozyczka, M.; Mirabel, I. F.

1988-01-01

A detailed model for the origin of the Orion and Monoceros cloud complexes is presented, showing that a single high-velocity H I cloud-galaxy collision can explain their main observed features. The collision generates massive shocked layers, and self-gravity can then provide the conditions for the transformation of these layers into molecular clouds. The clouds formed by the collision maintain the motion of their parental shocked gas and reach positions located far away from the plane. According to this model, both the Orion and Monoceros complexes were formed some 60 million yr ago, when the original shocked layer was fragmented by Galactic tidal forces.

Ambiguities in the identification of giant molecular cloud complexes from longitude-velocity diagrams

NASA Technical Reports Server (NTRS)

Adler, David S.; Roberts, William W., Jr.

1992-01-01

Techniques which use longitude-velocity diagrams to identify molecular cloud complexes in the disk of the Galaxy are investigated by means of model Galactic disks generated from N-body cloud-particle simulations. A procedure similar to the method used to reduce the low-level emission in Galactic l-v diagrams is employed to isolate complexes of emission in the model l-v diagram (LVCs) from the 'background'clouds. The LVCs produced in this manner yield a size-line-width relationship with a slope of 0.58 and a mass spectrum with a slope of 1.55, consistent with Galactic observations. It is demonstrated that associations identified as LVCs are often chance superpositions of clouds spread out along the line of sight in the disk of the model system. This indicates that the l-v diagram cannot be used to unambiguously determine the location of molecular cloud complexes in the model Galactic disk. The modeling results also indicate that the existence of a size-line-width relationship is not a reliable indicator of the physical nature of cloud complexes, in particular, whether the complexes are gravitationally bound objects.

EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

NASA Astrophysics Data System (ADS)

Falkovich, Gregory; Malinowski, Szymon P.

2008-07-01

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

Supernova Remnant W49B and Its Environment

NASA Astrophysics Data System (ADS)

Zhu, H.; Tian, W. W.; Zuo, P.

2014-10-01

We study gamma-ray supernova remnant (SNR) W49B and its environment using recent radio and infrared data. Spitzer Infrared Spectrograph low resolution data of W49B shows shocked excitation lines of H2 (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H2 gas is composed of two components with temperatures of ~260 K and ~1060 K, respectively. Various spectral lines from atomic and ionic particles are detected toward W49B. We suggest that the ionic phase has an electron density of ~500 cm-3 and a temperature of ~104 K by the spectral line diagnoses. The mid- and far-infrared data from MSX, Spitzer, and Herschel reveal a 151 ± 20 K hot dust component with a mass of 7.5 ± 6.6 × 10-4 M ⊙ and a 45 ± 4 K warm dust component with a mass of 6.4 ± 3.2 M ⊙. The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the H I absorption spectra of W49B and four nearby H II regions (W49A, G42.90+0.58, G42.43-0.26, and G43.19-0.53) and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 μm infrared and CO data. We therefore obtain a kinematic distance of ~10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s-1.

Siderophores in Cloud Waters and Potential Impact on Atmospheric Chemistry: Photoreactivity of Iron Complexes under Sun-Simulated Conditions.

PubMed

Passananti, Monica; Vinatier, Virginie; Delort, Anne-Marie; Mailhot, Gilles; Brigante, Marcello

2016-09-06

In the present work, the photoreactivity of a mixture of iron(III)–pyoverdin (Fe(III)–Pyo) complexes was investigated under simulated cloud conditions. Pyoverdins are expected to complex ferric ions naturally present in cloudwater, thus modifying their availability and photoreactivity. The spectroscopic properties and photoreactivity of Fe(III)-Pyo were investigated, with particular attention to their fate under solar irradiation, also studied through simulations. The photolysis of the Fe(III)–Pyo complex leads to the generation of Fe(II), with rates of formation (RFe(II)f) of 6.98 and 3.96 × 10–9 M s–1 at pH 4.0 and 6.0, respectively. Interestingly, acetate formation was observed during the iron-complex photolysis, suggesting that fragmentation can occur after the ligand-to-metal charge transfer (LMCT) via a complex reaction mechanism. Moreover, photogenerated Fe(II) represent an important source of hydroxyl radical via the Fenton reaction in cloudwater. This reactivity might be relevant for the estimation of the rates of formation and steady-state concentrations of the hydroxyl radical by cloud chemistry models and for organic matter speciation in the cloud aqueous phase. In fact, the conventional models, which describe the iron photoreactivity in terms of iron–aqua and oxalate complexes, are not in accordance with our results.

A resource management architecture based on complex network theory in cloud computing federation

NASA Astrophysics Data System (ADS)

Zhang, Zehua; Zhang, Xuejie

2011-10-01

Cloud Computing Federation is a main trend of Cloud Computing. Resource Management has significant effect on the design, realization, and efficiency of Cloud Computing Federation. Cloud Computing Federation has the typical characteristic of the Complex System, therefore, we propose a resource management architecture based on complex network theory for Cloud Computing Federation (abbreviated as RMABC) in this paper, with the detailed design of the resource discovery and resource announcement mechanisms. Compare with the existing resource management mechanisms in distributed computing systems, a Task Manager in RMABC can use the historical information and current state data get from other Task Managers for the evolution of the complex network which is composed of Task Managers, thus has the advantages in resource discovery speed, fault tolerance and adaptive ability. The result of the model experiment confirmed the advantage of RMABC in resource discovery performance.

Completing the Mapping of the W3 Giant Molecular Cloud; Testing Models and the Importance of Triggered Star Formation

NASA Astrophysics Data System (ADS)

Moore, Toby; Allsopp, James; Jones, Huw

2006-05-01

It is proposed to complete the R. Gehrz's mapping of W3 at both IRAC and MIPS 24um wavelengths. W3 is an outer galaxy Giant Molecular Cloud comprising of two regions; a quiescent, spontaneously star forming region and a region compressed by the W4 OB association containing the majority of star formation and all of the high mass star formation. Currently only the high-density region, Lada( put date) is mapped, but for a scientifically-valid comparision between the triggered and spontaneous modes we require the remainder of the cloud to be mapped. Triggered star formation is vitally important as it provides a mechanism for understanding the massive disparity between the low star formation efficiencies of galaxies such as our own andmore violent events such as galaxy mergers. Currently we have mapped the majority of the cloud at 850 um using SCUBA and the whole cloud using the CO(J=1-0) with the 12CO, 13CO and C18O isotomers. From these studies we have identified and measured the masses of 230 clumps. Without Spitzer data we have no way of determining which of these clumps have formed stars. This project forms the final crucial piece which when added to our current observations of the mass in the cloud will quantify the local star formation efficiency for each region. This is the first part of an ongoing much larger study into triggered star formation. We used Aztec (1.1mm continuum) on the JCMT in January 2006 to map two more clouds and Spitzer data on these from other observers has either been recently released or is about to be. In 2007, we will expand on the knowledge gained from this with the SCUBA2 JCMT Galactic Plane Survey (JPS) in which we are collaborators.

wFReDoW: A Cloud-Based Web Environment to Handle Molecular Docking Simulations of a Fully Flexible Receptor Model

PubMed Central

De Paris, Renata; Frantz, Fábio A.; Norberto de Souza, Osmar; Ruiz, Duncan D. A.

2013-01-01

Molecular docking simulations of fully flexible protein receptor (FFR) models are coming of age. In our studies, an FFR model is represented by a series of different conformations derived from a molecular dynamic simulation trajectory of the receptor. For each conformation in the FFR model, a docking simulation is executed and analyzed. An important challenge is to perform virtual screening of millions of ligands using an FFR model in a sequential mode since it can become computationally very demanding. In this paper, we propose a cloud-based web environment, called web Flexible Receptor Docking Workflow (wFReDoW), which reduces the CPU time in the molecular docking simulations of FFR models to small molecules. It is based on the new workflow data pattern called self-adaptive multiple instances (P-SaMIs) and on a middleware built on Amazon EC2 instances. P-SaMI reduces the number of molecular docking simulations while the middleware speeds up the docking experiments using a High Performance Computing (HPC) environment on the cloud. The experimental results show a reduction in the total elapsed time of docking experiments and the quality of the new reduced receptor models produced by discarding the nonpromising conformations from an FFR model ruled by the P-SaMI data pattern. PMID:23691504

Ultra-clean Layers (UCLs) and Low Albedo Clouds ("gray clouds") in the Marine Boundary Layer - CSET aircraft data, 2-D bin spectral cloud parcel model, large eddy simulation and satellite observations from CALIPSO, MODIS and COSMIC

NASA Astrophysics Data System (ADS)

O, K. T.; Wood, R.; Bretherton, C. S.; Eastman, R. M.; Tseng, H. H.

2016-12-01

During the 2015 Cloud System Evolution in the Trades (CSET) field program (CSET, Jul-Aug 2015, subtropical NE Pacific), the NSF/NCAR G-V aircraft frequently encountered ultra clean layers (hereafter UCLs) with extremely low accumulation mode aerosol (i.e. diameter da> 100nm) concentration (hereafter Na), and low albedo ( 0.2) warm clouds (termed "gray clouds" in our study) with low droplet concentration (hereafter Nd). The analysis of CSET aircraft data shows that (1) UCLs and gray clouds are mostly commonly found at a height of 1.5-2km, typically close to the top of the MBL, (2) UCLs and gray cloud coverage as high as 40-60% between 135W and 155W (i.e. Sc-Cu transition region) but occur very infrequently east of 130W (i.e. shallow, near-coastal stratocumulus region), and (3) UCLs and gray clouds exhibit remarkably low turbulence compared with non-UCL clear sky and clouds. It should be noted that most previous aircraft sampling of low clouds occurred close to the Californian coast, so the prevalence of UCLs and gray clouds has not been previously noted. Based on the analysis of aircraft data, we hypothesize that gray clouds result from detrainment of cloud close to the top of precipitating trade cumuli, and UCLs are remnants of these layers when gray clouds evaporates. The simulations in our study are performed using 2-D bin spectral cloud parcel model and version 6.9 of the System for Atmospheric Modeling (SAM). Our idealized simulations suggest that collision-coalescence plays a crucial role in reducing Nd such that gray clouds can easily form via collision-coalescence in layers detrained from the cloud top at trade cumulus regime, but can not form at stratocumulus regime. Upon evaporation of gray clouds, only few accumulation mode aerosols are returned to the clear sky, leaving horizontally-extensive UCLs (i.e. clean clear sky). Analysis of CSET flight data and idealized model simulations both suggest cloud top/PBL height may play an important role in the

Molecular Cloud Structures and Massive Star Formation in N159

NASA Astrophysics Data System (ADS)

Nayak, O.; Meixner, M.; Fukui, Y.; Tachihara, K.; Onishi, T.; Saigo, K.; Tokuda, K.; Harada, R.

2018-02-01

The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the 12CO, 13CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size–linewidth relation than the 12CO or 13CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the 13CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501 M ⊙ pc‑2, and the threshold for massive star formation in N159E is 794 M ⊙ pc‑2. We find that 13CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.

The Gould’s Belt Distances Survey (GOBELINS). III. The Distance to the Serpens/Aquila Molecular Complex

NASA Astrophysics Data System (ADS)

Ortiz-León, Gisela N.; Dzib, Sergio A.; Kounkel, Marina A.; Loinard, Laurent; Mioduszewski, Amy J.; Rodríguez, Luis F.; Torres, Rosa M.; Pech, Gerardo; Rivera, Juana L.; Hartmann, Lee; Boden, Andrew F.; Evans, Neal J., II; Briceño, Cesar; Tobin, John J.; Galli, Phillip A. B.

2017-01-01

We report on new distances and proper motions to seven stars across the Serpens/Aquila complex. The observations were obtained as part of the Gould’s Belt Distances Survey (GOBELINS) project between 2013 September and 2016 April with the Very Long Baseline Array (VLBA). One of our targets is the proto-Herbig AeBe object EC 95, which is a binary system embedded in the Serpens Core. For this system, we combined the GOBELINS observations with previous VLBA data to cover a total period of 8 years, and derive the orbital elements and an updated source distance. The individual distances to sources in the complex are fully consistent with each other, and the mean value corresponds to a distance of 436.0 ± 9.2 pc for the Serpens/W40 complex. Given this new evidence, we argue that Serpens Main, W40, and Serpens South are physically associated and form a single cloud structure.

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

NASA Astrophysics Data System (ADS)

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

Cloud Model-Based Artificial Immune Network for Complex Optimization Problem.

PubMed

Wang, Mingan; Feng, Shuo; Li, Jianming; Li, Zhonghua; Xue, Yu; Guo, Dongliang

2017-01-01

This paper proposes an artificial immune network based on cloud model (AINet-CM) for complex function optimization problems. Three key immune operators-cloning, mutation, and suppression-are redesigned with the help of the cloud model. To be specific, an increasing half cloud-based cloning operator is used to adjust the dynamic clone multipliers of antibodies, an asymmetrical cloud-based mutation operator is used to control the adaptive evolution of antibodies, and a normal similarity cloud-based suppressor is used to keep the diversity of the antibody population. To quicken the searching convergence, a dynamic searching step length strategy is adopted. For comparative study, a series of numerical simulations are arranged between AINet-CM and the other three artificial immune systems, that is, opt-aiNet, IA-AIS, and AAIS-2S. Furthermore, two industrial applications-finite impulse response (FIR) filter design and proportional-integral-differential (PID) controller tuning-are investigated and the results demonstrate the potential searching capability and practical value of the proposed AINet-CM algorithm.

Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex

NASA Astrophysics Data System (ADS)

Tremblay, Chenoa D.; Jordan, Christopher H.; Cunningham, Maria; Jones, Paul A.; Hurley-Walker, Natasha

2018-05-01

We detail tentative detections of low-frequency carbon radio recombination lines from within the Orion molecular cloud complex observed at 99-129 MHz. These tentative detections include one alpha transition and one beta transition over three locations and are located within the diffuse regions of dust observed in the infrared at 100 μm, the Hα emission detected in the optical, and the synchrotron radiation observed in the radio. With these observations, we are able to study the radiation mechanism transition from collisionally pumped to radiatively pumped within the H ii regions within the Orion molecular cloud complex.

Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds

NASA Astrophysics Data System (ADS)

Rowe, P. M.; Neshyba, S.; Walden, V. P.

2013-07-01

Simulations of cloud radiative properties for climate modeling and remote sensing rely on accurate knowledge of the complex refractive index (CRI) of water. Although conventional algorithms employ a temperature independent assumption (TIA), recent infrared measurements of supercooled water have demonstrated that the CRI becomes increasingly ice-like at lower temperatures. Here, we assess biases that result from ignoring this temperature dependence. We show that TIA-based cloud retrievals introduce spurious ice into pure, supercooled clouds, or underestimate cloud thickness and droplet size. TIA-based downwelling radiative fluxes are lower than those for the temperature-dependent CRI by as much as 1.7 W m-2 (in cold regions), while top-of-atmosphere fluxes are higher by as much as 3.4 W m-2 (in warm regions). Proper accounting of the temperature dependence of the CRI, therefore, leads to significantly greater local greenhouse warming due to supercooled clouds than previously predicted. The current experimental uncertainty in the CRI at low temperatures must be reduced to properly account for supercooled clouds in both climate models and cloud property retrievals.

Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds

NASA Astrophysics Data System (ADS)

Rowe, P. M.; Neshyba, S.; Walden, V. P.

2013-12-01

Simulations of cloud radiative properties for climate modeling and remote sensing rely on accurate knowledge of the complex refractive index (CRI) of water. Although conventional algorithms employ a temperature-independent assumption (TIA), recent infrared measurements of supercooled water have demonstrated that the CRI becomes increasingly ice-like at lower temperatures. Here, we assess biases that result from ignoring this temperature dependence. We show that TIA-based cloud retrievals introduce spurious ice into pure, supercooled clouds, or underestimate cloud optical thickness and droplet size. TIA-based downwelling radiative fluxes are lower than those for the temperature-dependent CRI by as much as 1.7 W m-2 (in cold regions), while top-of-atmosphere fluxes are higher by as much as 3.4 W m-2 (in warm regions). Proper accounting of the temperature dependence of the CRI, therefore, leads to significantly greater local greenhouse warming due to supercooled clouds than previously predicted. The current experimental uncertainty in the CRI at low temperatures must be reduced to account for supercooled clouds properly in both climate models and cloud-property retrievals.

Geometries and properties of bimetallic phosphido-bridged complex Cp(CO) 2W(μ-PPh 2)W(CO) 5 and Cp(CO) 3W(μ-PPh 2)W(CO) 5

NASA Astrophysics Data System (ADS)

Wang, Fang; Yang, Hongmei; Yang, Zuoyin; Zhang, Jingchang; Cao, Weiliang

2007-01-01

Complete geometry optimizations were carried out by HF and DFT methods to study the molecular structure of binuclear transition-metal compounds (Cp(CO) 3W(μ-PPh 2)W(CO) 5) (I) and (Cp(CO) 2W(μ-PPh 2)W(CO) 5) (II). A comparison of the experimental data and calculated structural parameters demonstrates that the most accurate geometry parameters are predicted by the MPW1PW91/LANL2DZ among the three DFT methods. Topological properties of molecular charge distributions were analyzed with the theory of atoms in molecules. (3, -1) critical points, namely bond critical point, were found between the two tungsten atoms, and between W1 and C10 in complex II, which confirms the existence of the metal-metal bond and a semi-bridging CO between the two tungsten atoms. The result provided a theoretical guidance of detailed study on the binuclear phosphido-bridged complex containing transition metal-metal bond, which could be useful in the further study of the heterobimetallic phosphido-bridged complexes.

Complex Clouds

Atmospheric Science Data Center

2013-04-16

... article title:  Multi-layer Clouds Over the South Indian Ocean     View Larger Image ... System-2 path 155. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission ...

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

NASA Astrophysics Data System (ADS)

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

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

NASA Astrophysics Data System (ADS)

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.

2016-12-01

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

Cloud Model-Based Artificial Immune Network for Complex Optimization Problem

PubMed Central

Wang, Mingan; Li, Jianming; Guo, Dongliang

2017-01-01

This paper proposes an artificial immune network based on cloud model (AINet-CM) for complex function optimization problems. Three key immune operators—cloning, mutation, and suppression—are redesigned with the help of the cloud model. To be specific, an increasing half cloud-based cloning operator is used to adjust the dynamic clone multipliers of antibodies, an asymmetrical cloud-based mutation operator is used to control the adaptive evolution of antibodies, and a normal similarity cloud-based suppressor is used to keep the diversity of the antibody population. To quicken the searching convergence, a dynamic searching step length strategy is adopted. For comparative study, a series of numerical simulations are arranged between AINet-CM and the other three artificial immune systems, that is, opt-aiNet, IA-AIS, and AAIS-2S. Furthermore, two industrial applications—finite impulse response (FIR) filter design and proportional-integral-differential (PID) controller tuning—are investigated and the results demonstrate the potential searching capability and practical value of the proposed AINet-CM algorithm. PMID:28630620

HOBYS and W43-HERO: Two more steps toward a Galaxy-wide understanding of high-mass star formation

NASA Astrophysics Data System (ADS)

Motte, Frédérique; Bontemps, Sylvain; Tigé, Jérémy

The Herschel/HOBYS key program allows to statistically study the formation of 10-20 M ⊙ stars. The IRAM/W43-HERO large program is itself dedicated to the much more extreme W43 molecular complex, which forms stars up to 50 M ⊙. Both reveal high-density cloud filaments of several pc3, which are forming clusters of OB-type stars. Given their activity, these so-called mini-starburst cloud ridges could be seen as ``miniature and instant models'' of starburst galaxies. Both surveys also strongly suggest that high-mass prestellar cores do not exist, in agreement with the dynamical formation of cloud ridges. The HOBYS and W43 surveys are necessary steps towards Galaxy-wide studies of high-mass star formation.

1.0 Mm Maps and Radial Density Distributions of Southern Hii/molecular Cloud Complexes

NASA Technical Reports Server (NTRS)

Cheung, L. H.; Frogel, J. A.; Gezar, D. Y.; Hauser, M. G.

1980-01-01

Several 1.0 continuum mapping observations were made of seven southern hemisphere h12/molecular cloud complexes with 65 arcsec resolution. The radial density distribution of the clouds with central luminosity sources was determined observationally. Strong similarities in morphology and general physical conditions were found to exist among all of the southern clouds in the sample.

Similar complex kinematics within two massive, filamentary infrared dark clouds

NASA Astrophysics Data System (ADS)

Barnes, A. T.; Henshaw, J. D.; Caselli, P.; Jiménez-Serra, I.; Tan, J. C.; Fontani, F.; Pon, A.; Ragan, S.

2018-04-01

Infrared dark clouds (IRDCs) are thought to be potential hosts of the elusive early phases of high-mass star formation. Here, we conduct an in-depth kinematic analysis of one such IRDC, G034.43+00.24 (Cloud F), using high sensitivity and high spectral resolution IRAM-30m N2H+ (1-0) and C18O (1-0) observations. To disentangle the complex velocity structure within this cloud, we use Gaussian decomposition and hierarchical clustering algorithms. We find that four distinct coherent velocity components are present within Cloud F. The properties of these components are compared to those found in a similar IRDC, G035.39-00.33 (Cloud H). We find that the components in both clouds have high densities (inferred by their identification in N2H+), trans-to-supersonic non-thermal velocity dispersions with Mach numbers of ˜1.5-4, a separation in velocity of ˜3 km s-1, and a mean red-shift of ˜0.3 km s-1 between the N2H+ (dense gas) and C18O emission (envelope gas). The latter of these could suggest that these clouds share a common formation scenario. We investigate the kinematics of the larger-scale Cloud F structures, using lower-density-tracing 13CO(1-0) observations. A good correspondence is found between the components identified in the IRAM-30m observations and the most prominent component in the 13CO data. We find that the IRDC Cloud F is only a small part of a much larger structure, which appears to be an inter-arm filament of the Milky Way.

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

NASA Astrophysics Data System (ADS)

Hang, A.; L'Ecuyer, T.

2017-12-01

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

40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 2 2010-07-01 2010-07-01 false Guideline on Air Quality Models W Appendix W to Part 51 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS Pt. 51, App. W Appendix W to Part 51—Guideline on Air Quality Models...

Hierarchical Model for the Evolution of Cloud Complexes

NASA Astrophysics Data System (ADS)

Sánchez D., Néstor M.; Parravano, Antonio

1999-01-01

The structure of cloud complexes appears to be well described by a tree structure (i.e., a simplified ``stick man'') representation when the image is partitioned into ``clouds.'' In this representation, the parent-child relationships are assigned according to containment. Based on this picture, a hierarchical model for the evolution of cloud complexes, including star formation, is constructed. The model follows the mass evolution of each substructure by computing its mass exchange with its parent and children. The parent-child mass exchange (evaporation or condensation) depends on the radiation density at the interphase. At the end of the ``lineage,'' stars may be born or die, so that there is a nonstationary mass flow in the hierarchical structure. For a variety of parameter sets the system follows the same series of steps to transform diffuse gas into stars, and the regulation of the mass flux in the tree by previously formed stars dominates the evolution of the star formation. For the set of parameters used here as a reference model, the system tends to produce initial mass functions (IMFs) that have a maximum at a mass that is too high (~2 Msolar) and the characteristic times for evolution seem too long. We show that these undesired properties can be improved by adjusting the model parameters. The model requires further physics (e.g., allowing for multiple stellar systems and clump collisions) before a definitive comparison with observations can be made. Instead, the emphasis here is to illustrate some general properties of this kind of complex nonlinear model for the star formation process. Notwithstanding the simplifications involved, the model reveals an essential feature that will likely remain if additional physical processes are included, that is, the detailed behavior of the system is very sensitive to the variations on the initial and external conditions, suggesting that a ``universal'' IMF is very unlikely. When an ensemble of IMFs corresponding to a

Optical properties of marine stratocumulus clouds modified by ships

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, M.D.; Radke, L.F.; Hobbs, P.V.

1993-02-20

The angular distribution of scattered radiation deep within a cloud layer was measured in marine stratocumulus clouds modified by the emissions from ships. These observations, obtained at 13 discrete wavelengths between 0.5 and 2.3 [mu]m, were acquired as the University of Washington C-131A aircraft flew through a pair of roughly parallel ship track signatures produced in clouds off the coast of southern California on July 10, 1987. In the first of these ship tracks, the nadir (upwelling) intensity increased from 40 to 110 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] at 0.744 [mu]m. The second ship track produced a lessmore » dramatic, but more uniform, increase in the upwelling intensity. In contrast, the nadir intensity at 2.20 [mu]m decreased from 1 to 0.13 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] in the first ship track and to 0.6 W m[sup [minus]2] [mu]m[sup [minus]1] sr[sup [minus]1] in the second ship track. The relative angular distribution of the intensity field at each wavelength was used to determine the similarity parameter, and hence single scattering albedo, of the cloud using the diffusion domain method. Besides the spectral similarity parameter, these measurements provide a good estimate of the optical depth of the cloud layer both above and below the aircraft. Results of this analysis are presented for a 120-km section of marine stratocumulus cloud including both ship tracks. This analysis shows that the total optical thickness of the cloud layer increased in the ship tracks, in contrast to the similarity parameter which decreased. The decrease in absorption was a direct consequence of the reduction in cloud droplet size that occurred within the ship tracks. 34 refs., 11 figs., 2 tabs.« less

Synthesis, Characterization, and Some Properties of Cp*W(NO)(H)(η(3)-allyl) Complexes.

PubMed

Baillie, Rhett A; Holmes, Aaron S; Lefèvre, Guillaume P; Patrick, Brian O; Shree, Monica V; Wakeham, Russell J; Legzdins, Peter; Rosenfeld, Devon C

2015-06-15

Sequential treatment at low temperatures of Cp*W(NO)Cl2 in THF with 1 equiv of a binary magnesium allyl reagent, followed by an excess of LiBH4, affords three new Cp*W(NO)(H)(η(3)-allyl) complexes, namely, Cp*W(NO)(H)(η(3)-CH2CHCMe2) (1), Cp*W(NO)(H)(η(3)-CH2CHCHPh) (2), and Cp*W(NO)(H)(η(3)-CH2CHCHMe) (3). Complexes 1-3 are isolable as air-stable, analytically pure yellow solids in good to moderate yields by chromatography or fractional crystallization. In solutions, complex 1 exists as two coordination isomers in an 83:17 ratio differing with respect to the endo/exo orientation of the allyl ligand. In contrast, complexes 2 and 3 each exist as four coordination isomers, all differing by the orientation of their allyl ligands which can have either an endo or an exo orientation with the phenyl or methyl groups being either proximal or distal to the nitrosyl ligand. A DFT computational analysis using the major isomer of Cp*W(NO)(H)(η(3)-CH2CHCHMe) (3a) as the model complex has revealed that its lowest-energy thermal-decomposition pathway involves the intramolecular isomerization of 3a to the 16e η(2)-alkene complex, Cp*W(NO)(η(2)-CH2═CHCH2Me). Such η(2)-alkene complexes are isolable as their 18e PMe3 adducts when compounds 1-3 are thermolyzed in neat PMe3, the other organometallic products formed during these thermolyses being Cp*W(NO)(PMe3)2 (5) and, occasionally, Cp*W(NO)(H)(η(1)-allyl)(PMe3). All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

Distinct Impacts of Aerosols on an Evolving Continental Cloud Complex during the RACORO Field Campaign

DOE PAGES

Lin, Yun; Wang, Yuan; Pan, Bowen; ...

2016-08-26

In this study, a continental cloud complex, consisting of shallow cumuli, a deep convective cloud (DCC), and stratus, is simulated by a cloud-resolving Weather Research and Forecasting Model to investigate the aerosol microphysical effect (AME) and aerosol radiative effect (ARE) on the various cloud regimes and their transitions during the Department of Energy Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) campaign. Under an elevated aerosol loading with AME only, a reduced cloudiness for the shallow cumuli and stratus resulted from more droplet evaporation competing with suppressed precipitation, but an enhanced cloudinessmore » for the DCC is attributed to more condensation. With the inclusion of ARE, the shallow cumuli are suppressed owing to the thermodynamic effects of light-absorbing aerosols. The responses of DCC and stratus to aerosols are monotonic with AME only but nonmonotonic with both AME and ARE. The DCC is invigorated because of favorable convection and moisture conditions at night induced by daytime ARE, via the so-called aerosol-enhanced conditional instability mechanism. Finally, the results reveal that the overall aerosol effects on the cloud complex are distinct from the individual cloud types, highlighting that the aerosol–cloud interactions for diverse cloud regimes and their transitions need to be evaluated to assess the regional and global climatic impacts.« less

SMA OBSERVATIONS OF THE W3(OH) COMPLEX: PHYSICAL AND CHEMICAL DIFFERENTIATION BETWEEN W3(H{sub 2}O) AND W3(OH)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Sheng-Li; Schilke, Peter; Sánchez-Monge, Álvaro

2015-04-10

We report on the Submillimeter Array (SMA) observations of molecular lines at 270 GHz toward the W3(OH) and W3(H{sub 2}O) complex. Although previous observations already resolved the W3(H{sub 2}O) into two or three sub-components, the physical and chemical properties of the two sources are not well constrained. Our SMA observations clearly resolved the W3(OH) and W3(H{sub 2}O) continuum cores. Taking advantage of the line fitting tool XCLASS, we identified and modeled a rich molecular spectrum in this complex, including multiple CH{sub 3}CN and CH{sub 3}OH transitions in both cores. HDO, C{sub 2}H{sub 5}CN, O{sup 13}CS, and vibrationally excited lines ofmore » HCN, CH{sub 3}CN, and CH{sub 3}OCHO were only detected in W3(H{sub 2}O). We calculate gas temperatures and column densities for both cores. The results show that W3(H{sub 2}O) has higher gas temperatures and larger column densities than W3(OH) as previously observed, suggesting physical and chemical differences between the two cores. We compare the molecular abundances in W3(H{sub 2}O) to those in the Sgr B2(N) hot core, the Orion KL hot core, and the Orion Compact Ridge, and discuss the chemical origin of specific species. An east–west velocity gradient is seen in W3(H{sub 2}O), and the extension is consistent with the bipolar outflow orientation traced by water masers and radio jets. A north–south velocity gradient across W3(OH) is also observed. However, with current observations we cannot be assured whether the velocity gradients are caused by rotation, outflow, or radial velocity differences of the sub-components of W3(OH)« less

Molecular Gas toward the Gemini OB1 Molecular Cloud Complex. II. CO Outflow Candidates with Possible WISE Associations

NASA Astrophysics Data System (ADS)

Li, Yingjie; Li, Fa-Cheng; Xu, Ye; Wang, Chen; Du, Xin-Yu; Yang, Wenjin; Yang, Ji

2018-03-01

We present a large-scale survey of CO outflows in the Gem OB1 molecular cloud complex and its surroundings, using the Purple Mountain Observatory Delingha 13.7 m telescope. A total of 198 outflow candidates were identified over a large area (∼58.5 square degrees), of which 193 are newly detected. Approximately 68% (134/198) are associated with the Gem OB1 molecular cloud complex, including clouds GGMC 1, GGMC 2, BFS 52, GGMC 3, and GGMC 4. Other regions studied are: the Local arm (Local Lynds, West Front), Swallow, Horn, and Remote cloud. Outflow candidates in GGMC 1, BFS 52, and Swallow are mainly located at ring-like or filamentary structures. To avoid excessive uncertainty in distant regions (≳3.8 kpc), we only estimated the physical parameters for clouds in the Gem OB1 molecular cloud complex and in the Local arm. In those clouds, the total kinetic energy and the energy injection rate of the identified outflow candidates are ≲1% and ≲3% of the turbulent energy and the turbulent dissipation rate of each cloud, indicating that the identified outflow candidates cannot provide enough energy to balance turbulence of their host cloud at the scale of the entire cloud (several to dozens of parsecs). The gravitational binding energy of each cloud is ≳135 times the total kinetic energy of the identified outflow candidates within the corresponding cloud, indicating that the identified outflow candidates cannot cause major disruptions to the integrity of their host cloud at the scale of the entire cloud.

Nucleoprotein Complexes Containing Replicating Simian Virus 40 DNA: Comparison with Polyoma Nucleoprotein Complexes

PubMed Central

Hall, Mark R.; Meinke, William; Goldstein, David A.

1973-01-01

Procedures for isolating nucleoprotein complexes containing replicating polyoma DNA from infected mouse cells were used to prepare short-lived nucleoprotein complexes (r-SV40 complexes) containing replicating simian virus 40 (SV40) DNA from infected monkey cells. Like the polyoma complexes, r-SV40 complexes were only partially released from nuclei by cell lysis but could be extracted from nuclei by prolonged treatment with solutions containing Triton X-100. r-SV40 complexes sedimented faster than complexes containing SV40 supercoiled DNA (SV40 complex) in sucrose gradients, and both types of SV40 nucleoprotein complexes sedimented ahead of polyoma complexes containing supercoiled polyoma DNA (py complex). The sedimentation rates of py complex and SV40 complex were 56 and 61S, respectively, based on the sedimentation rate of the mouse large ribosomal subunit as a marker. r-SV40 complexes sedimented as multiple peaks between 56 and 75S. Sedimentation and buoyant density measurements indicated that protein is bound to all forms of SV40 DNA at about the same ratio of protein to DNA (1-2/1) as was reported for polyoma nucleoproteins. PMID:4359958

40 CFR Table W - 1A of Subpart W-Default Whole Gas Emission Factors for Onshore Petroleum and Natural Gas Production

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 22 2012-07-01 2012-07-01 false 1A of Subpart W-Default Whole Gas Emission Factors for Onshore Petroleum and Natural Gas Production W Table W Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING...

The Cloud Detection and UV Monitoring Experiment (CLUE)

NASA Technical Reports Server (NTRS)

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

2004-01-01

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

Cloud Radiative Effect to Downward Longwave Radiation in the Polar Regions

NASA Astrophysics Data System (ADS)

Yamada, K.; Hayasaka, T.

2014-12-01

Downward longwave radiation is important factor to affect climate change. In polar regions, estimation of the radiative effect of cloud on the downward longwave radiation has large uncertainty. Relatively large cloud effect to the radiation occurs there due to low temperature, small amount of water vapor, and strong inversion layer. The cloud effect is, however, not evaluated sufficiently because the long term polar night and high surface albedo make satellite retrieval difficult. The intent of the present study is to quantify cloud radiative effect for downward longwave radiation in the polar regions by in-situ observation and radiative transfer calculation. The observation sites in this study are Ny-Ålesund (NYA), Syowa (SYO), and South Pole (SPO). These stations belong to the Baseline Surface Radiation Network. The period of data analysis is from 2003 to 2012. The effect of cloud on the downward longwave radiation is evaluated by subtraction of calculated downward longwave radiation under clear-sky condition from observed value under all-sky condition. Radiative transfer model was used for the evaluation of clear sky radiation with vertical temperature and humidity profile obtained by radiosonde observations. Calculated result shows good correlation with observation under clear-sky condition. The RMSE is +0.83±5.0. The cloud effect varied from -10 - +110 W/m2 (-10 - +40 %). Cloud effect increased with increasing of cloud fraction and decreasing of cloud base height and precipitable water. In SYO negative effects were sometimes obtained. The negative cloud effect emerged under dry and temperature inversion condition lower than 2 km. One of reasons of negative effect is considered to be existence of cloud at temperature inversion altitude. When the cloud effect is smaller than -5 W/m2 (standard deviation between calculation and observation), 50 % of them have a condition with cloud base height estimated by micro pulse lidar lower than 2 km.

SMA observations of the W3(OH) complex: Dynamical differentiation between W3(H2O) and W3(OH)

NASA Astrophysics Data System (ADS)

Qin, Sheng-Li; Schilke, Peter; Wu, Jingwen; Liu, Tie; Wu, Yuefang; Sánchez-Monge, Álvaro; Liu, Ying

2016-03-01

We present Submillimeter Array observations of the HCN (3-2) and HCO+ (3-2) molecular lines towards the W3(H2O) and W3(OH) star-forming complexes. Infall and outflow motions in the W3(H2O) have been characterized by observing HCN and HCO+ transitions. High-velocity blue/red-shifted emission, tracing the outflow, show multiple knots, which might originate in episodic and precessing outflows. `Blue-peaked' line profiles indicate that gas is infalling on to the W3(H2O) dust core. The measured large mass accretion rate, 2.3 × 10-3 M⊙ yr-1, together with the small free-fall time-scale, 5 × 103 yr, suggest W3(H2O) is in an early evolutionary stage of the process of formation of high-mass stars. For the W3(OH), a two-layer model fit to the HCN and HCO+ spectral lines and Spizter/Infrared Array Camera (IRAC) images support that the W3(OH) H II region is expanding and interacting with the ambient gas, with the shocked neutral gas being expanding with an expansion time-scale of 6.4 × 103 yr. The observations suggest different kinematical time-scales and dynamical states for the W3(H2O) and W3(OH).

Observed Cloud Properties Above the Northern Indian Ocean During CARDEX 2012

NASA Astrophysics Data System (ADS)

Gao, L.; Wilcox, E. M.

2016-12-01

An analysis of cloud microphysical, macrophysical and radiative properties during the dry winter monsoon season above the northern Indian Ocean is presented. The Cloud Aerosol Radiative Forcing Experiment (CARDEX), conducted from 16 February to 30 March 2012 at the Maldives Climate Observatory on Hanimaadhoo (MCOH), used autonomous unmanned aerial vehicles (UAVs) to measure the aerosol profiles, water vapor flux and cloud properties concurrent with continuous ground measurements of surface aerosol and meteorological variables as well as the total-column precipitable water vapor (PWV) and the cloud liquid water path (LWP). Here we present the cloud properties only for the cases with lower atmospheric water vapor using the criterion that the PWV less than 40 kg/m2. This criterion acts to filter the data to control for the natural meteorological variability in the region according to previous studies. The high polluted case is found to correlate with warmer temperature, higher relative humidity in boundary layer and lower lifted condensation level (LCL). Micro Pulse Lidar (MPL) retrieved cloud base height coincides with calculated LCL height which is lower for high polluted case. Meanwhile satellite retrieved cloud top height didn't show obvious variation indicating cloud deepening which is consistent with the observed greater cloud LWP in high polluted case. Those high polluted clouds are associated with more cloud droplets and smaller effective radius and are generally becoming narrower due to the stronger cloud side evaporation-entrainment effect and becoming deeper due to more moist static energy. Clouds in high polluted condition become brighter with higher albedo which can cause a net shortwave forcing over -40 W/m2 in this region.

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

NASA Astrophysics Data System (ADS)

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

2012-07-01

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

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

NASA Astrophysics Data System (ADS)

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 FIRST DISTANCE CONSTRAINT ON THE RENEGADE HIGH-VELOCITY CLOUD COMPLEX WD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peek, J. E. G.; Roman-Duval, Julia; Tumlinson, Jason

2016-09-10

We present medium-resolution, near-ultraviolet Very Large Telescope/FLAMES observations of the star USNO-A0600-15865535. We adapt a standard method of stellar typing to our measurement of the shape of the Balmer ϵ absorption line to demonstrate that USNO-A0600-15865535 is a blue horizontal branch star, residing in the lower stellar halo at a distance of 4.4 kpc from the Sun. We measure the H and K lines of singly ionized calcium and find two isolated velocity components, one originating in the disk, and one associated with the high-velocity cloud complex WD. This detection demonstrated that complex WD is closer than ∼4.4 kpc andmore » is the first distance constraint on the +100 km s{sup −1} Galactic complex of clouds. We find that complex WD is not in corotation with the Galactic disk, which has been assumed for decades. We examine a number of scenarios and find that the most likely scenario is that complex WD was ejected from the solar neighborhood and is only a few kiloparsecs from the Sun.« less

Giant Spin Hall Effect and Switching Induced by Spin-Transfer Torque in a W /Co40Fe40B20/MgO Structure with Perpendicular Magnetic Anisotropy

NASA Astrophysics Data System (ADS)

Hao, Qiang; Xiao, Gang

2015-03-01

We obtain robust perpendicular magnetic anisotropy in a β -W /Co40Fe40B20/MgO structure without the need of any insertion layer between W and Co40Fe40B20 . This is achieved within a broad range of W thicknesses (3.0-9.0 nm), using a simple fabrication technique. We determine the spin Hall angle (0.40) and spin-diffusion length for the bulk β form of tungsten with a large spin-orbit coupling. As a result of the giant spin Hall effect in β -W and careful magnetic annealing, we significantly reduce the critical current density for the spin-transfer-torque-induced magnetic switching in Co40Fe40B20 . The elemental β -W is a superior candidate for magnetic memory and spin-logic applications.

Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhien

2010-06-29

The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processesmore » is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model

Cloud Geometry Analysis of the Smoke Week III Obscuration Trials.

DTIC Science & Technology

1982-01-01

GRAPIC 1LJu 4 Cf . .444,44 44- 0. 15, 25, TltME( SErs AOEDET. . **** *HEI HT0F CENTER OP MASS ABOVE DET. PT 42 SMOKE III EVENT # 07 1313 Z 08-12-80 STATION...PORTION OF CLOUD ATMOSPHEdIC SCIENCES LABORATORY WHITE SANDS MISSILE RANGE, N.M. 119 CLI-J000000 ) .0 0 1a 40 M M M MMMMMMMM ul zo w -ZIxJ z z w 0 L- CF ... CF -R (CPT James M. Watson) Dugway, UT 84022 Port Sill, OK 73503 Commander Commandant US Army Dugway Proving Ground US Army Field Artillery School ATTN

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

NASA Astrophysics Data System (ADS)

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.

Cloud Structure of Galactic OB Cluster-forming Regions from Combining Ground- and Space-based Bolometric Observations

NASA Astrophysics Data System (ADS)

Lin, Yuxin; Liu, Hauyu Baobab; Li, Di; Zhang, Zhi-Yu; Ginsburg, Adam; Pineda, Jaime E.; Qian, Lei; Galván-Madrid, Roberto; McLeod, Anna Faye; Rosolowsky, Erik; Dale, James E.; Immer, Katharina; Koch, Eric; Longmore, Steve; Walker, Daniel; Testi, Leonardo

2016-09-01

We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground-based (CSO, JCMT, APEX, and IRAM-30 m) and space telescopes (Herschel and Planck). For the seven luminous (L\\gt {10}6 L ⊙) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, and G10.3-0.1, we have performed single-component, modified blackbody fits to each pixel of the combined (sub)millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The ˜10″ resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3 kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed ˜10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (I.e., the enclosed mass profile, the column density probability distribution function (N-PDF), the two-point correlation function of column density, and the probability distribution function of clump/core separations). In particular, the massive molecular gas clumps located at the center of G10.6-0.4 and

A satellite-based 13-year climatology of net cloud radiative forcing over the Indian monsoon region

NASA Astrophysics Data System (ADS)

Saud, Trailokya; Dey, Sagnik; Das, Sushant; Dutta, Soumi

2016-12-01

We present a satellite-based 13-year (Mar. 2000-Feb. 2013) climatology of net cloud radiative forcing (CRF) over the Indian monsoon region (0-40°N, 60-100°E) using the Clouds and Earth's Radiant Energy System (CERES) radiation data and explained the net CRF variability in terms of cloud properties retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS). Mean (± 1σ) seasonal shortwave (SW) CRF values averaged over the region are - 82.7 ± 24.5, - 32.1 ± 12.1, - 17.2 ± 5.3 and - 30.2 ± 16.2 W m- 2 respectively for the monsoon (JJAS), post-monsoon (ON), winter (DJF) and pre-monsoon (MAM) seasons; while the corresponding longwave (LW) CRF values are 53.7 ± 14.2, 27.9 ± 10.0, 15.8 ± 7.0 and 25.2 ± 9.1 W m- 2. Regional analysis reveals the largest (least) negative net CRF over the northeast (northwest) rainfall homogeneous zone throughout the year due to the dominance of optically thick high clouds (low cloud fraction, fc). Mean JJAS fc is found to increase (by > 0.01 per year) over large parts of the Arabian Sea, Bay of Bengal and the northwest region. Mean annual net CRF values for cumulus, stratocumulus and stratus (low level), altocumulus, altostratus and nimbostratus (mid-level clouds) and cirrus, cirrostratus and deep-convective (high level) clouds over the Indian monsoon region are estimated to be - 0.8, - 4.7, - 6.9, + 3.3, - 6.3, - 23.3, + 5.4, - 23.3 and - 42.1 W m- 2 respectively. Across a wide range of cloud optical depth (COD) and fc < 0.6, near cancellation of SW cooling by LW warming, is observed for low clouds. Net CRF drops below - 15 W m- 2 for clouds evolving above 400 hPa, mainly in the monsoon season. Our results demonstrate that net CRF variability in the Indian monsoon region can be explained by variability in Cloud Top Pressure (CTP), COD and fc. The study highlights the need for resolving a multi-layer cloud field in the future.

Changes in Stratiform Clouds of Mesoscale Convective Complex Introduced by Dust Aerosols

NASA Technical Reports Server (NTRS)

Lin, B.; Min, Q.-L.; Li, R.

2010-01-01

Aerosols influence the earth s climate through direct, indirect, and semi-direct effects. There are large uncertainties in quantifying these effects due to limited measurements and observations of aerosol-cloud-precipitation interactions. As a major terrestrial source of atmospheric aerosols, dusts may serve as a significant climate forcing for the changing climate because of its effect on solar and thermal radiation as well as on clouds and precipitation processes. Latest satellites measurements enable us to determine dust aerosol loadings and cloud distributions and can potentially be used to reduce the uncertainties in the estimations of aerosol effects on climate. This study uses sensors on various satellites to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective complex (MCC). A trans-Atlantic dust outbreak of Saharan origin occurring in early March 2004 is considered. For the observed MCCs under a given convective strength, small hydrometeors were found more prevalent in the dusty stratiform regions than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust regions, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of clouds and precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the size spectrum of precipitation-sized hydrometeors from heavy precipitation to light precipitation and ultimately to suppress precipitation and increase the lifecycle of cloud systems, especially over stratiform areas.

Measurements of Ocean Surface Scattering Using an Airborne 94-GHz Cloud Radar: Implication for Calibration of Airborne and Spaceborne W-band Radars

NASA Technical Reports Server (NTRS)

Li, Li-Hua; Heymsfield, Gerald M.; Tian, Lin; Racette, Paul E.

2004-01-01

Scattering properties of the Ocean surface have been widely used as a calibration reference for airborne and spaceborne microwave sensors. However, at millimeter-wave frequencies, the ocean surface backscattering mechanism is still not well understood, in part, due to the lack of experimental measurements. During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE), measurements of ocean surface backscattering were made using a 94-GHz (W-band) cloud radar onboard a NASA ER-2 high-altitude aircraft. The measurement set includes the normalized Ocean surface cross section over a range of the incidence angles under a variety of wind conditions. Analysis of the radar measurements shows good agreement with a quasi-specular scattering model. This unprecedented dataset enhances our knowledge about the Ocean surface scattering mechanism at 94 GHz. The results of this work support the proposition of using the Ocean surface as a calibration reference for airborne millimeter-wave cloud radars and for the ongoing NASA CloudSat mission, which will use a 94-GHz spaceborne cloud radar for global cloud measurements.

Heterobimetallic complexes of palladium and platinum containing a redox-active W[SNS]2 metalloligand.

PubMed

Rosenkoetter, Kyle E; Ziller, Joseph W; Heyduk, Alan F

2017-05-02

Complexes of the general formula W[SNS] 2 M(dppe) (M = Pd, Pt; [SNS]H 3 = bis(2-mercapto-p-tolyl)amine; dppe = 1,2-bis(diphenylphosphino)ethane) were prepared by combining the corresponding (dppe)MCl 2 synthon with W[SNS] 2 under reducing conditions. X-ray diffraction studies revealed the formation of a heterobimetallic complex supported by a single thiolate bridging ligand and a short metal-metal bond between the tungsten and palladium or platinum. Electrochemical and computational results show that the frontier orbitals lie predominantly on the W[SNS] 2 fragment suggesting that it behaves as a redox-active metalloligand in these complexes.

W49A: A Massive Molecular Cloud Forming a Massive Star Cluster in the Galactic Disk

NASA Astrophysics Data System (ADS)

Galvan-Madrid, Roberto; Liu, Hauyu Baobab; Pineda, Jaime E.; Zhang, Zhi-Yu; Ginsburg, Adam; Roman-Zuñiga, Carlos; Peters, Thomas

2015-08-01

I summarize our current results of the MUSCLE survey of W49A, the most luminous star formation region in the Milky Way. Our approach emphasizes multi-scale, multi-resolution imaging in dust, ionized-, and molecular gas, to trace the multiple gas components from <0.1 pc (core scale) all the way up to the scale of the entire giant molecular cloud (GMC), ˜100 pc. The 106 M⊙ GMC is structured in a radial network of filaments that converges toward the central 'hub' with ˜2x105 M⊙, which contains within a few pc a deeply embedded young massive cluster (YMC) of stellar mass ~5x104 M⊙. We also discuss the dynamics of the filamentary network, the role of turbulence in the formation of this YMC, and how objects like W49A can link Milky Way and extragalactic star formation relations.

Blowing in the Milky Way Wind: Neutral Hydrogen Clouds Tracing the Galactic Nuclear Outflow

NASA Astrophysics Data System (ADS)

Di Teodoro, Enrico M.; McClure-Griffiths, N. M.; Lockman, Felix J.; Denbo, Sara R.; Endsley, Ryan; Ford, H. Alyson; Harrington, Kevin

2018-03-01

We present the results of a new sensitive survey of neutral hydrogen above and below the Galactic Center with the Green Bank Telescope. The observations extend up to Galactic latitude | b| < 10^\\circ with an effective angular resolution of 9.‧5 and an average rms brightness temperature noise of 40 mK in a 1 {km} {{{s}}}-1 channel. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of about 1.5 kpc from the Galactic plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities | {V}LSR}| ≲ 360 {km} {{{s}}}-1, and assuming a Galactic Center origin, they have sizes of a few tens of parsec and neutral hydrogen masses spanning 10{--}{10}5 {M}ȯ . Accounting for selection effects, the cloud population is symmetric in longitude, latitude, and V LSR. We model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocity {V}{{w}}≃ 330 {km} {{{s}}}-1 distributed throughout a bicone with opening angle α > 140^\\circ . This simple model implies an outflow luminosity {L}{{w}}> 3× {10}40 erg s‑1 over the past 10 Myr, consistent with star formation feedback in the inner region of the Milky Way, with a cold gas mass-loss rate ≲ 0.1 {{M}ȯ {yr}}-1. These clouds may represent the cold gas component accelerated in the nuclear wind driven by our Galaxy, although some of the derived properties challenge current theoretical models of the entrainment process.

Present-day Galactic Evolution: Low-metallicity, Warm, Ionized Gas Inflow Associated with High-velocity Cloud Complex A

NASA Astrophysics Data System (ADS)

Barger, K. A.; Haffner, L. M.; Wakker, B. P.; Hill, Alex. S.; Madsen, G. J.; Duncan, A. K.

2012-12-01

The high-velocity cloud Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin Hα Mapper kinematically resolved observations of Complex A over the velocity range of -250 to -50 km s-1 in the local standard of rest reference frame. These observations include the first full Hα intensity map of Complex A across (\\mathit {l, b}) = (124{^\\circ }, 18{^\\circ }) to (171°, 53°) and deep targeted observations in Hα, [S II] λ6716, [N II] λ6584, and [O I] λ6300 toward regions with high H I column densities, background quasars, and stars. The Hα data imply that the masses of neutral and ionized material in the cloud are similar, both being greater than 106 M ⊙. We find that the Bland-Hawthorn & Maloney model for the intensity of the ionizing radiation near the Milky Way is consistent with the known distance of the high-latitude part of Complex A and an assumed cloud geometry that puts the lower-latitude parts of the cloud at a distance of 7-8 kpc. This compatibility implies a 5% ionizing photon escape fraction from the Galactic disk. We also provide the nitrogen and sulfur upper abundance solutions for a series of temperatures, metallicities, and cloud configurations for purely photoionized gas; these solutions are consistent with the sub-solar abundances found by previous studies, especially for temperatures above 104 K or for gas with a high fraction of singly ionized nitrogen and sulfur.

Models of the global cloud structure on Venus derived from Venus Express observations

NASA Astrophysics Data System (ADS)

Barstow, J. K.; Tsang, C. C. C.; Wilson, C. F.; Irwin, P. G. J.; Taylor, F. W.; McGouldrick, K.; Drossart, P.; Piccioni, G.; Tellmann, S.

2012-02-01

. Spectrosc. Radiat. Trans. 109, 1136-1150). The sulfuric acid concentration in the cloud particles is found to be higher in regions of optically thick cloud. The cloud base altitude shows a dependence on latitude, reaching a maximum height near -50°. The increased average particle size near the pole found by Wilson et al. (Wilson, C.F., Guerlet, S., Irwin, P.G.J., Tsang, C.C.C., Taylor, F.W., Carlson, R.W., Drossart, P., Piccioni, G. [2008]. J. Geophys. Res. (Planets) 113, E12) and the finding of spatially variable water vapor abundance at35-40 km altitude first reported by Tsang et al. (Tsang, C.C.C., Wilson, C.F., Barstow, J.K., Irwin, P.G.J., Taylor, F.W., McGouldrick, K., Piccioni, G., Drossart, P., Svedhem, H. [2010]. Geophys. Res. Lett. 37, L02202) are both confirmed. The implications of these improved descriptions of cloud structure and variability for the chemistry, meteorology, and radiative energy balance on Venus are briefly discussed.

Cloud-Top Entrainment in Stratocumulus Clouds

NASA Astrophysics Data System (ADS)

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.

Alterations of Cloud Microphysics Due to Cloud Processed CCN

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Unveiling aerosol-cloud interactions - Part 1: Cloud contamination in satellite products enhances the aerosol indirect forcing estimate

NASA Astrophysics Data System (ADS)

Christensen, Matthew W.; Neubauer, David; Poulsen, Caroline A.; Thomas, Gareth E.; McGarragh, Gregory R.; Povey, Adam C.; Proud, Simon R.; Grainger, Roy G.

2017-11-01

Increased concentrations of aerosol can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of aerosol statistics near clouds. Aerosol retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the aerosol field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud-aerosol pairing algorithm (CAPA) to link cloud observations to the nearest aerosol retrieval within the satellite image. The distance between each aerosol retrieval and nearest cloud is also computed in CAPA. Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic aerosol indirect radiative forcing when selecting aerosol pairs that are located farther away from the clouds (-0.28±0.26 W m-2) compared to those including pairs that are within 15 km of the nearest cloud (-0.49±0.18 W m-2). The larger aerosol optical depths in closer proximity to cloud artificially enhance the relationship between aerosol-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the aerosol located near clouds.

Laser-diode pumped 40-W Yb:YAG ceramic laser.

PubMed

Hao, Qiang; Li, Wenxue; Pan, Haifeng; Zhang, Xiaoyi; Jiang, Benxue; Pan, Yubai; Zeng, Heping

2009-09-28

We demonstrated a high-power continuous-wave (CW) polycrystalline Yb:YAG ceramic laser pumped by fiber-pigtailed laser diode at 968 nm with 400 mum fiber core. The Yb:YAG ceramic laser performance was compared for different Yb(3+) ion concentrations in the ceramics by using a conventional end-pump laser cavity consisting of two flat mirrors with output couplers of different transmissions. A CW laser output of 40 W average power with M(2) factor of 5.8 was obtained with 5 mol% Yb concentration under 120 W incident pump power. This is to the best of our knowledge the highest output power in end-pumped bulk Yb:YAG ceramic laser.

Discovery of Temperate Latitude Clouds on Titan

NASA Astrophysics Data System (ADS)

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

2005-01-01

Until now, all the clouds imaged in Titan's troposphere have been found at far southern latitudes (60°-90° south). The occurrence and location of these clouds is thought to be the result of convection driven by the maximum annual solar heating of Titan's surface, which occurs at summer solstice (2002 October) in this south polar region. We report the first observations of a new recurring type of tropospheric cloud feature, confined narrowly to ~40° south latitude, which cannot be explained by this simple insolation hypothesis. We propose two classes of formation scenario, one linked to surface geography and the other to seasonally evolving circulation, which will be easily distinguished with continued observations over the next few years. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

PRESENT-DAY GALACTIC EVOLUTION: LOW-METALLICITY, WARM, IONIZED GAS INFLOW ASSOCIATED WITH HIGH-VELOCITY CLOUD COMPLEX A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barger, K. A.; Haffner, L. M.; Wakker, B. P.

2012-12-20

The high-velocity cloud Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin H{alpha} Mapper kinematically resolved observations of Complex A over the velocity range of -250 to -50 km s{sup -1} in the local standard of rest reference frame. These observations include the first full H{alpha} intensity map of Complex A across (l, b) = (124 Degree-Sign , 18 Degree-Sign ) to (171 Degree-Sign , 53 Degree-Sign ) and deep targeted observationsmore » in H{alpha}, [S II] {lambda}6716, [N II] {lambda}6584, and [O I] {lambda}6300 toward regions with high H I column densities, background quasars, and stars. The H{alpha} data imply that the masses of neutral and ionized material in the cloud are similar, both being greater than 10{sup 6} M{sub Sun }. We find that the Bland-Hawthorn and Maloney model for the intensity of the ionizing radiation near the Milky Way is consistent with the known distance of the high-latitude part of Complex A and an assumed cloud geometry that puts the lower-latitude parts of the cloud at a distance of 7-8 kpc. This compatibility implies a 5% ionizing photon escape fraction from the Galactic disk. We also provide the nitrogen and sulfur upper abundance solutions for a series of temperatures, metallicities, and cloud configurations for purely photoionized gas; these solutions are consistent with the sub-solar abundances found by previous studies, especially for temperatures above 10{sup 4} K or for gas with a high fraction of singly ionized nitrogen and sulfur.« less

Insights on Chemistry of Mercury Species in Clouds over Northern China: Complexation and Adsorption.

PubMed

Li, Tao; Wang, Yan; Mao, Huiting; Wang, Shuxiao; Talbot, Robert W; Zhou, Ying; Wang, Zhe; Nie, Xiaoling; Qie, Guanghao

2018-05-01

Cloud effects on heterogeneous reactions of atmospheric mercury (Hg) are poorly understood due to limited knowledge of cloudwater Hg chemistry. Here we quantified Hg species in cloudwater at the summit of Mt. Tai in northern China. Total mercury (THg) and methylmercury (MeHg) in cloudwater were on average 70.5 and 0.15 ng L -1 , respectively, and particulate Hg (PHg) contributed two-thirds of THg. Chemical equilibrium modeling simulations suggested that Hg complexes by dissolved organic matter (DOM) dominated dissolved Hg (DHg) speciation, which was highly pH dependent. Hg concentrations and speciation were altered by cloud processing, during which significant positive correlations of PHg and MeHg with cloud droplet number concentration ( N d ) were observed. Unlike direct contribution to PHg from cloud scavenging of aerosol particles, abiotic DHg methylation was the most likely source of MeHg. Hg adsorption coefficients K ad (5.9-362.7 L g -1 ) exhibited an inverse-power relationship with cloud residues content. Morphology analyses indicated that compared to mineral particles, fly ash particles could enhance Hg adsorption due to more abundant carbon binding sites on the surface. Severe particulate air pollution in northern China may bring substantial Hg into cloud droplets and impact atmospheric Hg geochemical cycling by aerosol-cloud interactions.

Improving Representation of Tropical Cloud Overlap in GCMs Based on Cloud-Resolving Model Data

NASA Astrophysics Data System (ADS)

Jing, Xianwen; Zhang, Hua; Satoh, Masaki; Zhao, Shuyun

2018-04-01

The decorrelation length ( L cf) has been widely used to describe the behavior of vertical overlap of clouds in general circulation models (GCMs); however, it has been a challenge to associate L cf with the large-scale meteorological conditions during cloud evolution. This study explored the relationship between L cf and the strength of atmospheric convection in the tropics based on output from a global cloud-resolving model. L cf tends to increase with vertical velocity in the mid-troposphere ( w 500) at locations of ascent, but shows little or no dependency on w 500 at locations of descent. A representation of L cf as a function of vertical velocity is obtained, with a linear regression in ascending regions and a constant value in descending regions. This simple and dynamic-related representation of L cf leads to a significant improvement in simulation of both cloud cover and radiation fields compared with traditional overlap treatments. This work presents a physically justifiable approach to depicting cloud overlap in the tropics in GCMs.

Real-time complex event processing for cloud resources

NASA Astrophysics Data System (ADS)

Adam, M.; Cordeiro, C.; Field, L.; Giordano, D.; Magnoni, L.

2017-10-01

The ongoing integration of clouds into the WLCG raises the need for detailed health and performance monitoring of the virtual resources in order to prevent problems of degraded service and interruptions due to undetected failures. When working in scale, the existing monitoring diversity can lead to a metric overflow whereby the operators need to manually collect and correlate data from several monitoring tools and frameworks, resulting in tens of different metrics to be constantly interpreted and analyzed per virtual machine. In this paper we present an ESPER based standalone application which is able to process complex monitoring events coming from various sources and automatically interpret data in order to issue alarms upon the resources’ statuses, without interfering with the actual resources and data sources. We will describe how this application has been used with both commercial and non-commercial cloud activities, allowing the operators to quickly be alarmed and react to misbehaving VMs and LHC experiments’ workflows. We will present the pattern analysis mechanisms being used, as well as the surrounding Elastic and REST API interfaces where the alarms are collected and served to users.

Testing cloud microphysics parameterizations in NCAR CAM5 with ISDAC and M-PACE observations

NASA Astrophysics Data System (ADS)

Liu, Xiaohong; Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Shi, Xiangjun; Wang, Zhien; Lin, Wuyin; Ghan, Steven J.; Earle, Michael; Liu, Peter S. K.; Zelenyuk, Alla

2011-01-01

Arctic clouds simulated by the National Center for Atmospheric Research (NCAR) Community Atmospheric Model version 5 (CAM5) are evaluated with observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Indirect and Semi-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its North Slope of Alaska site in April 2008 and October 2004, respectively. Model forecasts for the Arctic spring and fall seasons performed under the Cloud-Associated Parameterizations Testbed framework generally reproduce the spatial distributions of cloud fraction for single-layer boundary-layer mixed-phase stratocumulus and multilayer or deep frontal clouds. However, for low-level stratocumulus, the model significantly underestimates the observed cloud liquid water content in both seasons. As a result, CAM5 significantly underestimates the surface downward longwave radiative fluxes by 20-40 W m-2. Introducing a new ice nucleation parameterization slightly improves the model performance for low-level mixed-phase clouds by increasing cloud liquid water content through the reduction of the conversion rate from cloud liquid to ice by the Wegener-Bergeron-Findeisen process. The CAM5 single-column model testing shows that changing the instantaneous freezing temperature of rain to form snow from -5°C to -40°C causes a large increase in modeled cloud liquid water content through the slowing down of cloud liquid and rain-related processes (e.g., autoconversion of cloud liquid to rain). The underestimation of aerosol concentrations in CAM5 in the Arctic also plays an important role in the low bias of cloud liquid water in the single-layer mixed-phase clouds. In addition, numerical issues related to the coupling of model physics and time stepping in CAM5 are responsible for the model biases and will be explored in future studies.

An Estimate of Low-Cloud Feedbacks from Variations of Cloud Radiative and Physical Properties with Sea Surface Temperature on Interannual Time Scales

NASA Technical Reports Server (NTRS)

Eitzen, Zachary A.; Xu, Kuan-Man; Wong, Takmeng

2011-01-01

Simulations of climate change have yet to reach a consensus on the sign and magnitude of the changes in physical properties of marine boundary layer clouds. In this study, the authors analyze how cloud and radiative properties vary with SST anomaly in low-cloud regions, based on five years (March 2000 - February 2005) of Clouds and the Earth s Radiant Energy System (CERES) -- Terra monthly gridded data and matched European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological reanalaysis data. In particular, this study focuses on the changes in cloud radiative effect, cloud fraction, and cloud optical depth with SST anomaly. The major findings are as follows. First, the low-cloud amount (-1.9% to -3.4% /K) and the logarithm of low-cloud optical depth (-0.085 to -0.100/K) tend to decrease while the net cloud radiative effect (3.86 W/m(exp 2)/ K) becomes less negative as SST anomalies increase. These results are broadly consistent with previous observational studies. Second, after the changes in cloud and radiative properties with SST anomaly are separated into dynamic, thermodynamic, and residual components, changes in the dynamic component (taken as the vertical velocity at 700 hPa) have relatively little effect on cloud and radiative properties. However, the estimated inversion strength decreases with increasing SST, accounting for a large portion of the measured decreases in cloud fraction and cloud optical depth. The residual positive change in net cloud radiative effect (1.48 W/m(exp 2)/ K) and small changes in low-cloud amount (-0.81% to 0.22% /K) and decrease in the logarithm of optical depth (-0.035 to -0.046/ K) with SST are interpreted as a positive cloud feedback, with cloud optical depth feedback being the dominant contributor. Last, the magnitudes of the residual changes differ greatly among the six low-cloud regions examined in this study, with the largest positive feedbacks (approximately 4 W/m(exp 2)/ K) in the southeast and northeast

Structures of GMC W 37

NASA Astrophysics Data System (ADS)

Zhan, Xiao-Liang; Jiang, Zhi-Bo; Chen, Zhi-Wei; Zhang, Miao-Miao; Song, Chao

2016-04-01

We carried out observations toward the giant molecular cloud W 37 with the J = 1 - 0 transitions of 12CO, 13CO and C18O using the 13.7m single-dish telescope at the Delingha station of Purple Mountain Observatory. Based on these CO lines, we calculated the column densities and cloud masses for molecular clouds with radial velocities around +20 km s-1. The gas mass of W 37, calculated from 13 CO emission, is 1.7 × 105 M⊙, above the criterion to be considered a giant molecular cloud. The dense ridge of W 37 is a dense filament, which is supercritical in terms of linear mass ratio. Dense clumps found by C18O emission are aligned along the dense ridge at regular intervals of about 2.8 pc, similar to the clump separation caused by large-scale ‘sausage instability’. We confirm the identification of the giant molecular filament (GMF) G 18.0-16.8 and find a new giant filament, G 16.5-15.8, located ˜ 0.7° to the west of G 18.0-16.8. Both GMFs are not gravitationally bound, as indicated by their low linear mass ratio (˜ 80 M⊙ pc-1). We compared the gas temperature map with the dust temperature map from Herschel images, and found similar structures. The spatial distributions of class I objects and the dense clumps are reminiscent of triggered star formation occurring in the northwestern part of W 37, which is close to NGC 6611.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

Cloud radar Doppler spectra offer much information about cloud processes. By analyzing millimeter radar Doppler spectra from cloud-top to -base in mixed-phase clouds in which super-cooled liquid-layers are present we try to tell the microphysical evolution story of particles that are present by disentangling the contributions of the solid and liquid particles to the total radar returns. Instead of considering vertical profiles, dynamical effects are taken into account by following the particle population evolution along slanted paths which are caused by horizontal advection of the cloud. The goal is to identify regions in which different microphysical processes such as new particle formation (nucleation), water vapor deposition, aggregation, riming, or sublimation occurr. Cloud radar measurements are supplemented by Doppler lidar and Raman lidar observations as well as observations with MWR, wind profiler, and radio sondes. The presence of super-cooled liquid layers is identified by positive liquid water paths in MWR measurements, the vertical location of liquid layers (in non-raining systems and below lidar extinction) is derived from regions of high-backscatter and low depolarization in Raman lidar observations. In collocated cloud radar measurements, we try to identify cloud phase in the cloud radar Doppler spectrum via location of the Doppler peak(s), the existence of multi-modalities or the spectral skewness. Additionally, within the super-cooled liquid layers, the radar-identified liquid droplets are used as air motion tracer to correct the radar Doppler spectrum for vertical air motion w. These radar-derived estimates of w are validated by independent estimates of w from collocated Doppler lidar measurements. A 35 GHz vertically pointing cloud Doppler radar (METEK MIRA-35) in linear depolarization (LDR) mode is used. Data is from the deployment of the Leipzig Aerosol and Cloud Remote Observations System (LACROS) during the Analysis of the Composition of

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

NASA Technical Reports Server (NTRS)

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

1995-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2006-01-01

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

Interferometric molecular line observations of W51

NASA Technical Reports Server (NTRS)

Rudolph, Alexander; Welch, William J.; Palmer, Patrick; Dubrulle, Berengere

1989-01-01

Observations are presented of the H II region complex in W51 made with a mm interferometer. W51 is a region of massive star formation approx. 7 kpc distant from the sun. This region has been well studied in both the IR and submillimeter, the radio, as well as the maser transitions. These previous observations have revealed three regions of interest: (1) W51MAIN, a know of bright maser emission near two compact H II regions W51e1 and W51e2 (W51MAIN is also the peak of the 400 micron emission indicating that the bulk of the mass is centered there; (2) W51IRS1 is a long curving structure seen at 20 micron and at 2 and 6 cm but not at 400 micron; (3) W51IRS2 (also known as W51NORTH) is another compact H II region slightly offset from an 8 and a 20 micron peak and a collection of masers. Some conclusions are as follows: (1) SO and H(13)CN emission are similar and coincide with outflow activity; (2) HCO+ spectra show evidence for overall collapse of the W51 cloud toward W51MAIN; (3) A previously undetected continuum peak, W51DUST, coincides with the molecular peak H(13)CN-4; and (4) Dust emission at 3.4 mm reveals that about half of the 400 micron emission comes from the ultracompact H II region e2, and the rest from W51e1 and W51DUST.

Molecular-cloud-scale Chemical Composition. II. Mapping Spectral Line Survey toward W3(OH) in the 3 mm Band

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Yuri; Watanabe, Yoshimasa; Yamamoto, Satoshi

To study a molecular-cloud-scale chemical composition, we conducted a mapping spectral line survey toward the Galactic molecular cloud W3(OH), which is one of the most active star-forming regions in the Perseus arm. We conducted our survey through the use of the Nobeyama Radio Observatory 45 m telescope, and observed the area of 16′ × 16′, which corresponds to 9.0 pc × 9.0 pc. The observed frequency ranges are 87–91, 96–103, and 108–112 GHz. We prepared the spectrum averaged over the observed area, in which eight molecular species (CCH, HCN, HCO{sup +}, HNC, CS, SO, C{sup 18}O, and {sup 13}CO) aremore » identified. On the other hand, the spectrum of the W3(OH) hot core observed at a 0.17 pc resolution shows the lines of various molecules such as OCS, H{sub 2}CS CH{sub 3}CCH, and CH{sub 3}CN in addition to the above species. In the spatially averaged spectrum, emission of the species concentrated just around the star-forming core, such as CH{sub 3}OH and HC{sub 3}N, is fainter than in the hot core spectrum, whereas emission of the species widely extended over the cloud such as CCH is relatively brighter. We classified the observed area into five subregions according to the integrated intensity of {sup 13}CO, and evaluated the contribution to the averaged spectrum from each subregion. The CCH, HCN, HCO{sup +}, and CS lines can be seen even in the spectrum of the subregion with the lowest {sup 13}CO integrated intensity range (<10 K km s{sup −1}). Thus, the contributions of the spatially extended emission is confirmed to be dominant in the spatially averaged spectrum.« less

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

DOE PAGES

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

2017-10-24

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

The CENP-T/-W complex is a binding partner of the histone chaperone FACT

PubMed Central

Prendergast, Lisa; Müller, Sebastian; Liu, Yiwei; Huang, Hongda; Dingli, Florent; Loew, Damarys; Vassias, Isabelle; Patel, Dinshaw J.; Sullivan, Kevin F.; Almouzni, Geneviève

2016-01-01

The CENP-T/-W histone fold complex, as an integral part of the inner kinetochore, is essential for building a proper kinetochore at the centromere in order to direct chromosome segregation during mitosis. Notably, CENP-T/-W is not inherited at centromeres, and new deposition is absolutely required at each cell cycle for kinetochore function. However, the mechanisms underlying this new deposition of CENP-T/-W at centromeres are unclear. Here, we found that CENP-T deposition at centromeres is uncoupled from DNA synthesis. We identified Spt16 and SSRP1, subunits of the H2A–H2B histone chaperone facilitates chromatin transcription (FACT), as CENP-W binding partners through a proteomic screen. We found that the C-terminal region of Spt16 binds specifically to the histone fold region of CENP-T/-W. Furthermore, depletion of Spt16 impairs CENP-T and CENP-W deposition at endogenous centromeres, and site-directed targeting of Spt16 alone is sufficient to ensure local de novo CENP-T accumulation. We propose a model in which the FACT chaperone stabilizes the soluble CENP-T/-W complex in the cell and promotes dynamics of exchange, enabling CENP-T/-W deposition at centromeres. PMID:27284163

The CENP-T/-W complex is a binding partner of the histone chaperone FACT.

PubMed

Prendergast, Lisa; Müller, Sebastian; Liu, Yiwei; Huang, Hongda; Dingli, Florent; Loew, Damarys; Vassias, Isabelle; Patel, Dinshaw J; Sullivan, Kevin F; Almouzni, Geneviève

2016-06-01

The CENP-T/-W histone fold complex, as an integral part of the inner kinetochore, is essential for building a proper kinetochore at the centromere in order to direct chromosome segregation during mitosis. Notably, CENP-T/-W is not inherited at centromeres, and new deposition is absolutely required at each cell cycle for kinetochore function. However, the mechanisms underlying this new deposition of CENP-T/-W at centromeres are unclear. Here, we found that CENP-T deposition at centromeres is uncoupled from DNA synthesis. We identified Spt16 and SSRP1, subunits of the H2A-H2B histone chaperone facilitates chromatin transcription (FACT), as CENP-W binding partners through a proteomic screen. We found that the C-terminal region of Spt16 binds specifically to the histone fold region of CENP-T/-W. Furthermore, depletion of Spt16 impairs CENP-T and CENP-W deposition at endogenous centromeres, and site-directed targeting of Spt16 alone is sufficient to ensure local de novo CENP-T accumulation. We propose a model in which the FACT chaperone stabilizes the soluble CENP-T/-W complex in the cell and promotes dynamics of exchange, enabling CENP-T/-W deposition at centromeres. © 2016 Prendergast et al.; Published by Cold Spring Harbor Laboratory Press.

40 CFR 89.916 - Emergency-vessel exemption for marine engines below 37 kW.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Emergency-vessel exemption for marine engines below 37 kW. 89.916 Section 89.916 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... ENGINES Exemption Provisions § 89.916 Emergency-vessel exemption for marine engines below 37 kW. The...

40 CFR 89.916 - Emergency-vessel exemption for marine engines below 37 kW.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Emergency-vessel exemption for marine engines below 37 kW. 89.916 Section 89.916 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... ENGINES Exemption Provisions § 89.916 Emergency-vessel exemption for marine engines below 37 kW. The...

40 CFR 89.916 - Emergency-vessel exemption for marine engines below 37 kW.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Emergency-vessel exemption for marine engines below 37 kW. 89.916 Section 89.916 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... ENGINES Exemption Provisions § 89.916 Emergency-vessel exemption for marine engines below 37 kW. The...

40 CFR 89.916 - Emergency-vessel exemption for marine engines below 37 kW.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Emergency-vessel exemption for marine engines below 37 kW. 89.916 Section 89.916 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... ENGINES Exemption Provisions § 89.916 Emergency-vessel exemption for marine engines below 37 kW. The...

40 CFR 89.916 - Emergency-vessel exemption for marine engines below 37 kW.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Emergency-vessel exemption for marine engines below 37 kW. 89.916 Section 89.916 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... ENGINES Exemption Provisions § 89.916 Emergency-vessel exemption for marine engines below 37 kW. The...

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varble, Adam; Nesbitt, Steve; Salio, Paola

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

Height Distribution Between Cloud and Aerosol Layers from the GLAS Spaceborne Lidar in the Indian Ocean Region

NASA Technical Reports Server (NTRS)

Hart, William D.; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis L.

2005-01-01

The Geoscience Laser Altimeter System (GLAS), a nadir pointing lidar on the Ice Cloud and land Elevation Satellite (ICESat) launched in 2003, now provides important new global measurements of the relationship between the height distribution of cloud and aerosol layers. GLAS data have the capability to detect, locate, and distinguish between cloud and aerosol layers in the atmosphere up to 40 km altitude. The data product algorithm tests the product of the maximum attenuated backscatter coefficient b'(r) and the vertical gradient of b'(r) within a layer against a predetermined threshold. An initial case result for the critical Indian Ocean region is presented. From the results the relative height distribution between collocated aerosol and cloud shows extensive regions where cloud formation is well within dense aerosol scattering layers at the surface. Citation: Hart, W. D., J. D. Spinhime, S. P. Palm, and D. L. Hlavka (2005), Height distribution between cloud and aerosol layers from the GLAS spaceborne lidar in the Indian Ocean region,

Surface tension and quasi-emulsion of cavitation bubble cloud.

PubMed

Bai, Lixin; Chen, Xiaoguang; Zhu, Gang; Xu, Weilin; Lin, Weijun; Wu, Pengfei; Li, Chao; Xu, Delong; Yan, Jiuchun

2017-03-01

A quasi-emulsion phenomenon of cavitation structure in a thin liquid layer (the thin liquid layer is trapped between a radiating surface and a hard reflector) is investigated experimentally with high-speed photography. The transformation from cloud-in-water (c/w) emulsion to water-in-cloud (w/c) emulsion is related to the increase of cavitation bubble cloud. The acoustic field in the thin liquid layer is analyzed. It is found that the liquid region has higher acoustic pressure than the cloud region. The bubbles are pushed from liquid region to cloud region by the primary Bjerknes forces. The rate of change of CSF increased with the increase of CSF. The cavitation bubbles on the surface of cavitation cloud are attracted by the cavitation bubbles inside the cloud due to secondary Bjerknes forces. The existence of surface tension on the interface of liquid region and cloud region is proved. The formation mechanism of disc-shaped liquid region and cloud region are analysed by surface tension and incompressibility of cavitation bubble cloud. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermal Chemistry of Cp*W(NO)(CH2CMe3)(H)(L) Complexes (L = Lewis Base).

PubMed

Fabulyak, Diana; Handford, Rex C; Holmes, Aaron S; Levesque, Taleah M; Wakeham, Russell J; Patrick, Brian O; Legzdins, Peter; Rosenfeld, Devon C

2017-01-03

The complexes trans-Cp*W(NO)(CH 2 CMe 3 )(H)(L) (Cp* = η 5 -C 5 Me 5 ) result from the treatment of Cp*W(NO)(CH 2 CMe 3 ) 2 in n-pentane with H 2 (∼1 atm) in the presence of a Lewis base, L. The designation of a particular geometrical isomer as cis or trans indicates the relative positions of the alkyl and hydrido ligands in the base of a four-legged piano-stool molecular structure. The thermal behavior of these complexes is markedly dependent on the nature of L. Some of them can be isolated at ambient temperatures [e.g., L = P(OMe) 3 , P(OPh) 3 , or P(OCH 2 ) 3 CMe]. Others undergo reductive elimination of CMe 4 via trans to cis isomerization to generate the 16e reactive intermediates Cp*W(NO)(L). These intermediates can intramolecularly activate a C-H bond of L to form 18e cis complexes that may convert to the thermodynamically more stable trans isomers [e.g., Cp*W(NO)(PPh 3 ) initially forms cis-Cp*W(NO)(H)(κ 2 -PPh 2 C 6 H 4 ) that upon being warmed in n-pentane at 80 °C isomerizes to trans-Cp*W(NO)(H)(κ 2 -PPh 2 C 6 H 4 )]. Alternatively, the Cp*W(NO)(L) intermediates can effect the intermolecular activation of a substrate R-H to form trans-Cp*W(NO)(R)(H)(L) complexes [e.g., L = P(OMe) 3 or P(OCH 2 ) 3 CMe; R-H = C 6 H 6 or Me 4 Si] probably via their cis isomers. These latter activations are also accompanied by the formation of some Cp*W(NO)(L) 2 disproportionation products. An added complication in the L = P(OMe) 3 system is that thermolysis of trans-Cp*W(NO)(CH 2 CMe 3 )(H)(P(OMe) 3 ) results in it undergoing an Arbuzov-like rearrangement and being converted mainly into [Cp*W(NO)(Me)(PO(OMe) 2 )] 2 , which exists as a mixture of two isomers. All new complexes have been characterized by conventional and spectroscopic methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

Optical properties of marine stratocumulus clouds modified by ship track effluents

NASA Technical Reports Server (NTRS)

King, Michael D.; Nakajima, Teruyuki

1990-01-01

The angular distribution of scattered radiation deep within a cloud layer was measured in marine stratocumulus clouds modified by the emissions from ships. These observations, obtained at thirteen discrete wavelengths between 0.5 and 2.3 microns, were obtained as the University of Washington Convair C-131A aircraft flew through a pair of roughly parallel ship tracks off the coast of southern California on 10 July 1987. In the first of these ship tracks, the cloud droplet concentration increased from 40 to 107/cu cm (125/cu cm in the second ship track). Simultaneous to this spectacular change, the aircraft measured interstitial aerosol (Aitken nucleus) concentration that increased from 400 to 1000/cu cm and cloud liquid water content that increased from 0.03 to 0.75 g/cu m. Broadband pyranometer measurements showed that the upwelling flux density increased from 150 to 280 W/sq m. These in-situ microphysics and broadband pyranometer results, together with AVHRR satellite images obtained with the NOAA-10 satellite, are described in detail by Radke et al., (1989). Internal scattered radiation measurements at selected wavelengths obtained with the cloud absorption radiometer (King et al., 1986) for a 100 km section of marine stratocumulus clouds containing these two ship track features are presented.

LARGE-SCALE CO MAPS OF THE LUPUS MOLECULAR CLOUD COMPLEX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tothill, N. F. H.; Loehr, A.; Stark, A. A.

2009-11-01

Fully sampled degree-scale maps of the {sup 13}CO 2-1 and CO 4-3 transitions toward three members of the Lupus Molecular Cloud Complex-Lupus I, III, and IV-trace the column density and temperature of the molecular gas. Comparison with IR extinction maps from the c2d project requires most of the gas to have a temperature of 8-10 K. Estimates of the cloud mass from {sup 13}CO emission are roughly consistent with most previous estimates, while the line widths are higher, around 2 km s{sup -1}. CO 4-3 emission is found throughout Lupus I, indicating widespread dense gas, and toward Lupus III andmore » IV. Enhanced line widths at the NW end and along the edge of the B 228 ridge in Lupus I, and a coherent velocity gradient across the ridge, are consistent with interaction between the molecular cloud and an expanding H I shell from the Upper-Scorpius subgroup of the Sco-Cen OB Association. Lupus III is dominated by the effects of two HAe/Be stars, and shows no sign of external influence. Slightly warmer gas around the core of Lupus IV and a low line width suggest heating by the Upper-Centaurus-Lupus subgroup of Sco-Cen, without the effects of an H I shell.« less

Leaf gas exchange of understory spruce-fir saplings in relict cloud forests, southern Appalachian Mountains, USA.

PubMed

Reinhardt, Keith; Smith, William K

2008-01-01

The southern Appalachian spruce-fir (Picea rubens Sarg. and Abies fraseri (Pursh) Poir.) forest is found only on high altitude mountain tops that receive copious precipitation ( > 2000 mm year(-1)) and experience frequent cloud immersion. These high-elevation, temperate rain forests are immersed in clouds on approximately 65% of the total growth season days and for 30-40% of a typical summer day, and cloud deposition accounts for up to 50% of their annual water budget. We investigated environmental influences on understory leaf gas exchange and water relations at two sites: Mt. Mitchell, NC (MM; 35 degrees 45'53'' N, 82 degrees 15'53'' W, 2028 m elevation) and Whitetop Mtn., VA (WT; 36 degrees 38'19'' N, 81 degrees 36'19'' W, 1685 m elevation). We hypothesized that the cool, moist and cloudy conditions at these sites exert a strong influence on leaf gas exchange. Maximum photosynthesis (A(max)) varied between 1.6 and 4.0 micromol CO(2) m(-2) s(-1) for both spruce and fir and saturated at irradiances between approximately 200 and 400 micromol m(-2) s(-1) at both sites. Leaf conductance (g) ranged between 0.05 and 0.25 mol m(-2) s(-1) at MM and between 0.15 and 0.40 mol m(-2) s(-1) at WT and was strongly associated with leaf-to-air vapor pressure difference (LAVD). At both sites, g decreased exponentially as LAVD increased, with an 80-90% reduction in g between 0 and 0.5 kPa. Predawn leaf water potentials remained between -0.25 and -0.5 MPa for the entire summer, whereas late afternoon values declined to between -1.25 and -1.75 MPa by late summer. Thus, leaf gas exchange appeared tightly coupled to the response of g to LAVD, which maintained high water status, even at the relatively low LAVD of these cloud forests. Moreover, the cloudy, humid environment of these refugial forests appears to exert a strong influence on tree leaf gas exchange and water relations. Because global climate change is predicted to increase regional cloud ceiling levels, more research on

Environmental Controls on Stratocumulus Cloud Fraction

NASA Astrophysics Data System (ADS)

Burleyson, Casey Dale

Marine stratocumulus clouds are widespread, low, optically thick, and persist for long periods of time. Their high albedo allows stratocumulus clouds to reflect large amounts of incoming shortwave radiation. Understanding the processes that lead to changes in stratocumulus cloud fraction is critically important in capturing the effects of stratocumulus in global climate models (GCMs). This research presents two analyses which seek to better understand the governing processes that drive variability in the stratocumulus-topped boundary layer system. The diurnal cycle of marine stratocumulus in cloud-topped boundary layers is examined using ship-based meteorological data obtained during the 2008 VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx). The high temporal and spatial continuity of the ship data, as well as the 31-day sample size, allows us to resolve the diurnal transition in degree of coupling of the stratocumulus-topped boundary layer. The amplitude of diurnal variation was comparable to the magnitude of longitudinal differences between regions east and west of 80°W for most of the cloud, surface, and precipitation variables examined. The diurnal cycle of precipitation is examined in terms of areal coverage, number of drizzle cells, and estimated rain rate. East of 80°W, the drizzle cell frequency and drizzle area peaks just prior to sunrise. West of 80°W, total drizzle area peaks at 3:00 am, 2-3 hours before sunrise. Peak drizzle cell frequency is three times higher west of 80°W compared to east of 80°W. The waning of drizzle several hours prior to the ramp up of shortwave fluxes may be related to the higher peak drizzle frequencies in the west. The ensemble effect of localized subcloud evaporation of precipitation may make drizzle a self-limiting process where the areal density of drizzle cells is sufficiently high. The daytime reduction in vertical velocity variance in a less coupled boundary layer is accompanied by enhanced

Stability and structure in [alpha]- and [beta]-keggin heteropolytungstates, [Xn+W12O40](8-n)-, X = p-block cation

Treesearch

Wade A. Neiwert; Jennifer J. Cowan; Kenneth I. Hardcastle; Craig L. Hill; Ira A. Weinstock

2002-01-01

[Beta]-[SiW12O40]4- (C3v symmetry) is sufficiently higher in energy than its [alpha]-isomer analogue that effectively complete conversion to [alpha]-[SiW12O40]4- (Td) is observed. By contrast, [beta]- and [alpha]-[AlW12O40]5- ([beta]- and [alpha]-1; C3v and Td, respectively) are sufficiently close in energy that both isomers are readily seen in 27Al NMR spectra of...

Factors leading to the formation of arc cloud complexes

NASA Technical Reports Server (NTRS)

Welshinger, Mark John; Brundidge, Kenneth C.

1987-01-01

A total of 12 mesoscale convective systems (MCSs) were investigated. The duration of the gust front, produced by each MCS, was used to classify the MCSs. Category 1 MCSs were defined as ones that produced a gust front and the gust front lasted for more than 6 h. There were 7 category 1 MCSs in the sample. Category 2 MCSs were defined as ones that produced a gust front and the gust front lasted for 6 h or less. There were 4 category 2 MCSs. The MCS of Case 12 was not categorized because the precipitation characteristics were similar to a squall line, rather than an MCS. All of the category 1 MCSs produced arc cloud complexes (ACCs), while only one of the category 2 MCSs produced an ACC. To determine if there were any differences in the characteristics between the MCSs of the two categories, composite analyses were accomplished. The analyses showed that there were significant differences in the characteristics of category 1 and 2 MCSs. Category 1 MCSs, on average, had higher thunderstorm heights, greater precipitation intensities, colder cloud top temperatures and produced larger magnitudes of surface divergence than category 2 MCSs.

Cosmic-ray ionisation of dense molecular clouds

NASA Astrophysics Data System (ADS)

Vaupre, Solenn

2015-07-01

Cosmic rays (CR) are of tremendous importance in the dynamical and chemical evolution of interstellar molecular clouds, where stars and planets form. CRs are likely accelerated in the shells of supernova remnants (SNR), thus molecular clouds nearby can be irradiated by intense fluxes of CRs. CR protons have two major effects on dense molecular clouds: 1) when they encounter the dense medium, high-energy protons (>280 MeV) create pions that decay into gamma-rays. This process makes SNR-molecular cloud associations intense GeV and/or TeV sources whose spectra mimic the CR spectrum. 2) at lower energies, CRs penetrate the cloud and ionise the gas, leading to the formation of molecular species characteristic of the presence of CRs, called tracers of the ionisation. Studying these tracers gives information on low-energy CRs that are unaccessible to any other observations. I studied the CR ionisation of molecular clouds next to three SNRs: W28, W51C and W44. These SNRs are known to be interacting with the nearby clouds, from the presence of shocked gas, OH masers and pion-decay induced gamma-ray emission. My work includes millimeter observations and chemical modeling of tracers of the ionisation in these dense molecular clouds. In these three regions, we determined an enhanced CR ionisation rate, supporting the hypothesis of an origin of the CRs in the SNR nearby. The evolution of the CR ionisation rate with the distance to the SNR brings valuable constraints on the propagation properties of low-energy CRs. The method used relies on observations of the molecular ions HCO+ and DCO+, which shows crucial limitations at high ionisation. Therefore, I investigated, both through modeling and observations, the chemical abundances of several other species to try and identity alternative tracers of the ionisation. In particular, in the W44 region, observations of N2H+ bring additional constraints on the physical conditions, volatile abundances in the cloud, and the ionisation

The Legionella IcmS-IcmW protein complex is important for Dot/Icm-mediated protein translocation.

PubMed

Ninio, Shira; Zuckman-Cholon, Deborah M; Cambronne, Eric D; Roy, Craig R

2005-02-01

The intracellular pathogen Legionella pneumophila can infect and replicate within macrophages of a human host. To establish infection, Legionella require the Dot/Icm secretion system to inject protein substrates directly into the host cell cytoplasm. The mechanism by which substrate proteins are engaged and translocated by the Dot/Icm system is not well understood. Here we show that two cytosolic components of the Dot/Icm secretion machinery, the proteins IcmS and IcmW, play an important role in substrate translocation. Biochemical analysis indicates that IcmS and IcmW form a stable protein complex. In Legionella, the IcmW protein is rapidly degraded in the absence of the IcmS protein. Substrate proteins translocated into mammalian host cells by the Dot/Icm system were identified using the IcmW protein as bait in a yeast two-hybrid screen. It was determined that the IcmS-IcmW complex interacts with these substrates and plays an important role in translocation of these proteins into mammalian cells. These data are consistent with the IcmS-IcmW complex being involved in the recognition and Dot/Icm-dependent translocation of substrate proteins during Legionella infection of host cells.

Dichroic Filter for Separating W-Band and Ka-Band

NASA Technical Reports Server (NTRS)

Epp, Larry W.; Durden, Stephen L.; Jamnejad, Vahraz; Long, Ezra M.; Sosnowski, John B.; Higuera, Raymond J.; Chen, Jacqueline C.

2012-01-01

The proposed Aerosol/Cloud/Ecosystems (ACEs) mission development would advance cloud profiling radar from that used in CloudSat by adding a 35-GHz (Ka-band) channel to the 94-GHz (W-band) channel used in CloudSat. In order to illuminate a single antenna, and use CloudSat-like quasi-optical transmission lines, a spatial diplexer is needed to add the Ka-band channel. A dichroic filter separates Ka-band from W-band by employing advances in electrical discharge machining (EDM) and mode-matching analysis techniques developed and validated for designing dichroics for the Deep Space Network (DSN), to develop a preliminary design that both met the requirements of frequency separation and mechanical strength. First, a mechanical prototype was built using an approximately 102-micron-diameter EDM process, and tolerances of the hole dimensions, wall thickness, radius, and dichroic filter thickness measured. The prototype validated the manufacturing needed to design a dichroic filter for a higher-frequency usage than previously used in the DSN. The initial design was based on a Ka-band design, but thicker walls are required for mechanical rigidity than one obtains by simply scaling the Ka-band dichroic filter. The resulting trade of hole dimensions for mechanical rigidity (wall thickness) required electrical redesign of the hole dimensions. Updates to existing codes in the linear solver decreased the analysis time using mode-matching, enabling the electrical design to be realized quickly. This work is applicable to missions and instruments that seek to extend W-band cloud profiling measurements to other frequencies. By demonstrating a dichroic filter that passes W-band, but reflects a lower frequency, this opens up the development of instruments that both compare to and enhance CloudSat.

Ongoing cosmic ray acceleration in the supernova remnant W51C revealed with the MAGIC telescopes

NASA Astrophysics Data System (ADS)

Krause, J.; Reichardt, I.; Carmona, E.; Gozzini, S. R.; Jankowski, F.; MAGIC Collaboration

2012-12-01

The supernova remnant (SNR) W51C interacts with the molecular clouds of the star-forming region W51B, making the W51 complex one of the most promising targets to study cosmic ray acceleration. Gamma-ray emission from this region was discovered by Fermi/LAT and H.E.S.S., although its location was compatible with the SNR shell, the molecular cloud (MC) and a pulsar wind nebula (PWN) candidate. The modeling of the spectral energy distribution presented by the Fermi/LAT collaboration suggests a hadronic emission mechanism. Furthermore indications of an enhanced flux of low energy cosmic rays in the interaction region between SNR and MC have been reported based on ionization measurements in the mm regime. MAGIC conducted deep observations of W51, yielding a detection of an extended emission with more than 11 standard deviations. We extend the spectrum from the highest Fermi/LAT energies to ~5 TeV and find that it follows a single power law with an index of 2.58+/-0.07stat+/-0.22syst. We restrict the main part of the emission region to the zone where the SNR interacts with the molecular clouds. We also find a tail extending towards the PWN candidate CXO J192318.5+140305, possibly contributing up to 20% of the total flux. The broad band spectral energy distribution can be explained with a hadronic model that implies proton acceleration at least up to 50 TeV. This result, together with the morphology of the source, suggests that we observe ongoing acceleration of ions in the interaction zone between the SNR and the cloud.

Eddy correlation measurements of size-dependent cloud droplet turbulent fluxes to complex terrain

NASA Astrophysics Data System (ADS)

Vong, Richard J.; Kowalski, Andrew S.

1995-07-01

An eddy correlation technique was used to measure the turbulent flux of cloud droplets to complex, forested terrain near the coast of Washington State during the spring of 1993. Excellent agreement was achieved for cloud liquid water content measured by two instruments. Substantial downward liquid water fluxes of 1mm per 24 h were measured at night during "steady and continuous" cloud events, about twice the magnitude of those measured by Beswick etal. in Scotland. Cloud water chemical fluxes were estimated to represent up to 50% of the chemical deposition associated with precipitation at the site. An observed size-dependence in the turbulent liquid water fluxes suggested that both droplet impaction, which leads to downward fluxes, and phase change processes, which can lead to upward fluxes, consistently are important contributors to the eddy correlation results. The diameter below which phase change processes were important to observed fluxes was shown to depend upon σL, the relative standard deviation of the liquid water content (LWC) within a 30-min averaging period. The crossover from upward to downward LW flux occurs at 8µm for steady and continuous cloud events but at 13µm for events with a larger degree of LWC variability. This comparison of the two types of cloud events suggested that evaporation was the most likely cause of upward droplet fluxes for the smaller droplets (dia<13µm) during cloud with variable LWC (σL>0.3).

Daytime Cirrus Cloud Top-of-Atmosphere Radiative Forcing Properties at a Midlatitude Site and their Global Consequence

NASA Technical Reports Server (NTRS)

Campbell, James R.; Lolli, Simone; Lewis, Jasper R.; Gu, Yu; Welton, Ellsworth J.

2016-01-01

One year of continuous ground-based lidar observations (2012) is analyzed for single-layer cirrus clouds at the NASA Micro Pulse Lidar Network site at the Goddard Space Flight Center to investigate top-of-the-atmosphere (TOA) annual net daytime radiative forcing properties. A slight positive net daytime forcing is estimated (i.e., warming): 0.070.67 W m(exp -2) in sample-relative terms, which reduces to 0.030.27 W m(exp -2) in absolute terms after normalizing to unity based on a 40% midlatitude occurrence frequency rate estimated from satellite data. Results are based on bookend solutions for lidar extinction-to-backscatter (20 and 30 sr) and corresponding retrievals of the 532-nm cloud extinction coefficient. Uncertainties due to cloud under sampling, attenuation effects, sample selection, and lidar multiple scattering are described. A net daytime cooling effect is found from the very thinnest clouds (cloud optical depth of less than or equal to 0.01), which is attributed to relatively high solar zenith angles. A relationship involving positive negative daytime cloud forcing is demonstrated as a function of solar zenith angle and cloud-top temperature. These properties, combined with the influence of varying surface albedos, are used to conceptualize how daytime cloud forcing likely varies with latitude and season, with cirrus clouds exerting less positive forcing and potentially net TOA cooling approaching the summer poles (not ice and snow covered) versus greater warming at the equator. The existence of such a gradient would lead cirrus to induce varying daytime TOA forcing annually and seasonally, making it a far greater challenge than presently believed to constrain the daytime and diurnal cirrus contributions to global radiation budgets.

HYDROGEN CHLORIDE IN DIFFUSE INTERSTELLAR CLOUDS ALONG THE LINE OF SIGHT TO W31C (G10.6-0.4)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monje, R. R.; Lis, D. C.; Phillips, T. G.

2013-04-10

We report the detection of hydrogen chloride, HCl, in diffuse molecular clouds on the line of sight toward the star-forming region W31C (G10.6-0.4). The J = 1-0 lines of the two stable HCl isotopologues, H{sup 35}Cl and H{sup 37}Cl, are observed using the 1b receiver of the Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory. The HCl line is detected in absorption, over a wide range of velocities associated with diffuse clouds along the line of sight to W31C. The analysis of the absorption strength yields a total HCl column density of a few 10{sup 13}more » cm{sup -2}, implying that HCl accounts for {approx}0.6% of the total gas-phase chlorine, which exceeds the theoretical model predictions by a factor of {approx}6. This result is comparable to those obtained from the chemically related species H{sub 2}Cl{sup +} and HCl{sup +}, for which large column densities have also been reported on the same line of sight. The source of discrepancy between models and observations is still unknown; however, the detection of these Cl-bearing molecules provides key constraints for the chlorine chemistry in the diffuse gas.« less

Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds

DOE PAGES

Kuo, Chia-Pang; Yang, Ping; Huang, Xianglei; ...

2017-12-13

General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in longwave (LW) spectral bands. In this study, the flux and heating rate biases due to neglecting the scattering of LW radiation by clouds are quantified by using advanced cloud optical property models, and satellite data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Clouds and the Earth's Radiant Energy System (CERES), and Moderatemore » Resolution Imaging Spectrometer (MODIS) merged products (CCCM). From the products, information about the atmosphere and clouds (microphysical and buck optical properties, and top and base heights) is used to simulate fluxes and heating rates. One-year global simulations for 2010 show that the LW scattering decreases top-of-atmosphere (TOA) upward flux and increases surface downward flux by 2.6 and 1.2 W/m 2, respectively, or approximately 10% and 5% of the TOA and surface LW cloud radiative effect, respectively. Regional TOA upward flux biases are as much as 5% of global averaged outgoing longwave radiation (OLR). LW scattering causes approximately 0.018 K/d cooling at the tropopause and about 0.028 K/d heating at the surface. Furthermore, over 40% of the total OLR bias for ice clouds is observed in 350–500 cm -1. Overall, the radiative effects associated with neglecting LW scattering are comparable to the counterpart due to doubling atmospheric CO 2 under clear-sky conditions.« less

Theoretical studies on the electronic and optoelectronic properties of [A.2AP(w)/A*.2AP(WC)/C.2AP(w)/C*.2AP(WC)/C.A(w)/C*.A(WC)]-Au8 mismatch nucleobase complexes

NASA Astrophysics Data System (ADS)

Srivastava, Ruby

2018-01-01

The electronic and optoelectronic properties of [A.2AP(w)/A*.2AP(WC)/C.2AP(w)/C*.2AP(WC)/C.A(w)/ C*.A(WC)]-Au8 metal-mismatch nucleobase complexes are investigated by means of density functional theory and time-dependent methods. We selected these mispairs as 2-aminopurine (2AP) produces incorporation errors when binding with cytosine (C) into the wobble (w) C.2AP(w) mispair, and is tautomerised into Watson-Crick (WC)-like base mispair C*.2AP(WC) and less effectively produces A.2AP(w)/A*.2AP(WC) mispairs. The vertical ionisation potential, vertical electron affinity, hardness and electrophilicity index of these complexes have also been discussed. The modifications of energy levels and charge density distributions of the frontier orbitals are also analysed. The absorption spectra of these complexes lie in the visible region, which suggests their application in fluorescent-bio imaging. The mechanism of cooperativity effect is studied by molecular orbital potential (MEP), atoms-in-molecules (AIM) and natural bond orbital analyses. Most metalated pairs have smaller HOMO-LUMO band gaps than the isolated mismatch nucleobases which suggest interesting consequences for electron transfer through DNA duplexes.

Characterizing the W40 Cluster Region with the UKIDSS Galactic Plane Survey

NASA Astrophysics Data System (ADS)

Yu, Ka Chun; Shuping, Ralph

2018-01-01

W40 is a region of thermal radio continuum emission in the Aquila Rift, and is one of only a few high-mass star forming regions within 1 kpc of the Sun. We use the Galactic Plane Survey from the UKIDDS Data Release 10 in JHK to study the stellar population in a 30' x 30' field centered on the W40 star-forming region. With imaging deeper than previous surveys (down to a depth of K=18), we identify ~1500 stars with K-band excess that are likely young stars with protostellar disks (Class II-III), more than has been found in previous surveys of this region. We use the NIR photometry of ~50,000 stars to create a high resolution 0.5' optical extinction map, which is used in conjunction with nearby control fields to assess contamination by background sources. Like in previous studies, we find an embedded cluster of reddened sources centered on the handful of late-O/early-B type stars at the center of W40. We fit their spatial distribution using a 2D gaussian profile with $\\sigma$ ~ 1' (0.37 pc at a distance of 440 pc), and a central stellar density of 510 stars/pc^2. After removing foreground stars, we identify 217 total stars within $3\\sigma$ of the cluster center, of which ~100 have K-band excess indicative of Class II-III YSOs, consistent with previous work. We discuss possible background contamination as well as the spatial distribution of young stars throughout the region.

Structural insights into the roles of the IcmS-IcmW complex in the type IVb secretion system of Legionella pneumophila.

PubMed

Xu, Jianpo; Xu, Dandan; Wan, Muyang; Yin, Li; Wang, Xiaofei; Wu, Lijie; Liu, Yanhua; Liu, Xiaoyun; Zhou, Yan; Zhu, Yongqun

2017-12-19

The type IVb secretion system (T4BSS) of Legionella pneumophila is a multiple-component apparatus that delivers ∼300 virulent effector proteins into host cells. The injected effectors modulate host cellular processes to promote bacterial infection and proliferation. IcmS and IcmW are two conserved small, acidic adaptor proteins that form a binary complex to interact with many effectors and facilitate their translocation. IcmS and IcmW can also interact with DotL, an ATPase of the type IV coupling protein complex (T4CP). However, how IcmS-IcmW recognizes effectors, and what the roles of IcmS-IcmW are in T4BSSs are unclear. In this study, we found that IcmS and IcmW form a 1:1 heterodimeric complex to bind effector substrates. Both IcmS and IcmW adopt new structural folds and have no structural similarities with known effector chaperones. IcmS has a compact global structure with an α/β fold, while IcmW adopts a fully α-folded, relatively loose architecture. IcmS stabilizes IcmW by binding to its two C-terminal α-helices. Photocrosslinking assays revealed that the IcmS-IcmW complex binds its cognate effectors via an extended hydrophobic surface, which can also interact with the C terminus of DotL. A crystal structure of the DotL-IcmS-IcmW complex reveals extensive and highly stable interactions between DotL and IcmS-IcmW. Moreover, IcmS-IcmW recruits LvgA to DotL and assembles a unique T4CP. These data suggest that IcmS-IcmW also functions as an inseparable integral component of the DotL-T4CP complex in the bacterial inner membrane. This study provides molecular insights into the dual roles of the IcmS-IcmW complex in T4BSSs.

CO Column Density and Extinction in the Chamaeleon II--III Dark-Cloud Complex

NASA Astrophysics Data System (ADS)

Hayakawa, Takahiro; Cambrésy, Laurent; Onishi, Toshikazu; Mizuno, Akira; Fukui, Yasuo

2001-12-01

We carried out 13CO (J = 1 -- 0) and C18O (J = 1 -- 0) observations of the Chamaeleon II--III dark-cloud complex with the NANTEN radio telescope. The column densities of both molecular isotopes were derived assuming LTE. The AV values were obtained by scaling the AV values that were derived using an adaptive-grid star-count method applied to the DENIS J-band data. We established the AV--CO isotope column-density relations in Cha II and III, and compared them with those in Cha I. The slopes of the AV--13CO relations for Cha II and III are steeper than that for Cha I. Those of the AV -- C18O relations are similar among the three clouds. The total column density ratio, N(13O) / N(C18O, in Cha I tends to be small compared with those in Cha II or Cha III; the ratios range from ~ 5 to ~ 25 at low extinction in Cha II and III, but at most ~ 10 in Cha I. We suggest that the increase of N(13CO) due to the 13CO formation process causes cloud-to-cloud variations in the AV -- N(13CO) correlation.

New particle formation leads to cloud dimming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, Ryan C.; Crippa, Paola; Matsui, Hitoshi

New particle formation (NPF), nucleation of condensable vapors to the solid or liquid phase, is a significant source of atmospheric aerosol particle number concentrations. With sufficient growth, these nucleated particles may be a significant source of cloud condensation nuclei (CCN), thus altering cloud albedo, structure, and lifetimes, and insolation reaching the Earth's surface. Herein we present one of the first numerical experiments to quantify the impact of NPF on cloud radiative properties that is conducted at a convection permitting resolution and that explicitly simulates cloud droplet number concentrations. Consistent with observations, these simulations suggest that in spring over the Midwesternmore » U.S.A., NPF occurs frequently and on regional scales. However, the simulations suggest that NPF is not associated with enhancement of regional cloud albedos as would be expected from an increase of CCN. These simulations indicate that NPF reduces ambient sulfuric acid concentrations sufficiently to inhibit growth of preexisting particles to CCN sizes. This reduction in CCN-sized particles reduces cloud albedo, resulting in a domain average positive top of atmosphere cloud radiative forcing of 10 W m-2 and up to ~ 50 W m-2 in individual grid cells relative to a simulation in which NPF is excluded.« less

H I, CO, and Planck/IRAS dust properties in the high latitude cloud complex, MBM 53, 54, 55 and HLCG 92 – 35. Possible evidence for an optically thick H I envelope around the CO clouds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukui, Yasuo; Okamoto, Ryuji; Kaji, Ryohei

We present an analysis of the H I and CO gas in conjunction with the Planck/IRAS submillimeter/far-infrared dust properties toward the most outstanding high latitude clouds MBM 53, 54, 55 and HLCG 92 – 35 at b = –30° to – 45°. The CO emission, dust opacity at 353 GHz (τ{sub 353}), and dust temperature (T {sub d}) show generally good spatial correspondence. On the other hand, the correspondence between the H I emission and the dust properties is less clear than in CO. The integrated H I intensity W{sub H} {sub I} and τ{sub 353} show a large scattermore » with a correlation coefficient of ∼0.6 for a T {sub d} range from 16 K to 22 K. We find, however, that W{sub H} {sub I} and τ{sub 353} show better correlation for smaller ranges of T {sub d} every 0.5 K, generally with a correlation coefficient of 0.7-0.9. We set up a hypothesis that the H I gas associated with the highest T {sub d} ≥ 21.5 K is optically thin, whereas the H I emission is generally optically thick for T {sub d} lower than 21.5 K. We have determined a relationship for the optically thin H I gas between atomic hydrogen column density and τ{sub 353}, N{sub H} {sub I} (cm{sup −2})=(1.5×10{sup 26})⋅τ{sub 353}, under the assumption that the dust properties are uniform and we have applied this to estimate N{sub H} {sub I} from τ{sub 353} for the whole cloud. N{sub H} {sub I} was then used to solve for T {sub s} and τ{sub H} {sub I} over the region. The result shows that the H I is dominated by optically thick gas having a low spin temperature of 20-40 K and a density of 40-160 cm{sup –3}. The H I envelope has a total mass of ∼1.2 × 10{sup 4} M {sub ☉}, an order of magnitude larger than that of the CO clouds. The H I envelope properties derived by this method do not rule out a mixture of H I and H{sub 2} in the dark gas, but we present indirect evidence that most of the gas mass is in the atomic state.« less

AMF3 CloudSat Overpasses Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matrosov, Sergey; Hardin, Joseph; De Boer, Gijs

Synergy between ground-based and satellite radar observations of clouds and precipitation is important for refining the algorithms to retrieve hydrometeor microphysical parameters, improvements in the retrieval accuracy, and better understanding the advantages and limitations of different retrieval approaches. The new dual-frequency (Ka- and W-band, 35 GHz and 94 GHz) fully polarimetric scanning U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Research Facility cloud radars (SACRs-2) are advanced sensors aimed to significantly enhance remote sensing capabilities (Kollias et al. 2016). One of these radars was deployed as part of the third ARM Mobile Facility (AMF3) at Oliktok Point, Alaska (70.495omore » N, 149.886oW). The National Aeronautics and Space Administration (NASA) CloudSat satellite, which is part of the polar-orbiting A-train satellite constellation, passes over the vicinity of the AMF3 location (typically within 0-7 km depending on a particular overpass) on a descending orbit every 16 days at approximately 13:21 UTC. The nadir pointing W-band CloudSat cloud profiling radar (CPR) provides vertical profiles of reflectivity that are then used for retrievals of hydrometeor parameters (Tanelli et al. 2008). The main objective of the AMF3 CloudSat overpasses intensive operating period (IOP) campaign was to collect approximately collocated in space and time radar data from the SACR-2 and the CloudSat CPR measurements for subsequent joint analysis of radar variables and microphysical retrievals of cloud and precipitation parameters. Providing the reference for the SACR-2 absolute calibration from the well-calibrated CloudSat CPR was another objective of this IOP. The IOP objectives were achieved by conducting seven special SACR-2 scans during the 10.5-min period centered at the exact time of the CloudSat overpass over the AMF3 (~1321 UTC) on six dates of the CloudSat overpasses during the three-month period allocated to this IOP. These

Identification of protein W, the elusive sixth subunit of the Rhodopseudomonas palustris reaction center-light harvesting 1 core complex.

PubMed

Jackson, Philip J; Hitchcock, Andrew; Swainsbury, David J K; Qian, Pu; Martin, Elizabeth C; Farmer, David A; Dickman, Mark J; Canniffe, Daniel P; Hunter, C Neil

2018-02-01

The X-ray crystal structure of the Rhodopseudomonas (Rps.) palustris reaction center-light harvesting 1 (RC-LH1) core complex revealed the presence of a sixth protein component, variably referred to in the literature as helix W, subunit W or protein W. The position of this protein prevents closure of the LH1 ring, possibly to allow diffusion of ubiquinone/ubiquinol between the RC and the cytochrome bc 1 complex in analogous fashion to the well-studied PufX protein from Rhodobacter sphaeroides. The identity and function of helix W have remained unknown for over 13years; here we use a combination of biochemistry, mass spectrometry, molecular genetics and electron microscopy to identify this protein as RPA4402 in Rps. palustris CGA009. Protein W shares key conserved sequence features with PufX homologs, and although a deletion mutant was able to grow under photosynthetic conditions with no discernible phenotype, we show that a tagged version of protein W pulls down the RC-LH1 complex. Protein W is not encoded in the photosynthesis gene cluster and our data indicate that only approximately 10% of wild-type Rps. palustris core complexes contain this non-essential subunit; functional and evolutionary consequences of this observation are discussed. The ability to purify uniform RC-LH1 and RC-LH1-protein W preparations will also be beneficial for future structural studies of these bacterial core complexes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Automated Visibility & Cloud Cover Measurements with a Solid State Imaging System

DTIC Science & Technology

1989-03-01

GL-TR-89-0061 SIO Ref. 89-7 MPL-U-26/89 AUTOMATED VISIBILITY & CLOUD COVER MEASUREMENTS WITH A SOLID-STATE IMAGING SYSTEM C) to N4 R. W. Johnson W. S...include Security Classification) Automated Visibility & Cloud Measurements With A Solid State Imaging System 12. PERSONAL AUTHOR(S) Richard W. Johnson...based imaging systems , their ics and control algorithms, thus they ar.L discussed sepa- initial deployment and the preliminary application of rately

High-resolution Near-infrared Observations of a Small Cluster Associated with a Bright-rimmed Cloud in W5

NASA Astrophysics Data System (ADS)

Imai, Rieko; Sugitani, Koji; Miao, Jingqi; Fukuda, Naoya; Watanabe, Makoto; Kusune, Takayoshi; Pickles, Andrew J.

2017-08-01

We carried out near-infrared (IR) observations to examine star formation toward the bright-rimmed cloud SFO 12, of which the main exciting star is O7V star in W5-W. We found a small young stellar object (YSO) cluster of six members embedded in the head of SFO 12 facing its exciting star, aligned along the UV radiation incident direction from the exciting star. We carried out high-resolution near-IR observations with the Subaru adaptive optics (AO) system and revealed that three of the cluster members appear to have circumstellar envelopes, one of which shows an arm-like structure in its envelope. Our near-IR and {L}\\prime -band photometry and Spitzer IRAC data suggest that formation of two members at the tip side occurred in advance of other members toward the central part, under our adopted assumptions. Our near-IR data and previous studies imply that more YSOs are distributed in the region just outside the cloud head on the side of the main exciting star, but there is little sign of star formation toward the opposite side. We infer that star formation has been sequentially occurring from the exciting star side to the central part. We examined archival data of far-infrared and CO (J=3-2) which reveals that, unlike in the optical image, SFO 12 has a head-tail structure that is along the UV incident direction. This suggests that SFO 12 is affected by strong UV from the main exciting star. We discuss the formation of this head-tail structure and star formation there by comparing with a radiation-driven implosion (RDI) model.

Height Dependency of Aerosol-Cloud Interaction Regimes: Height Dependency of ACI Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jingyi; Liu, Yangang; Zhang, Minghua

This study investigates the height dependency of aerosol-cloud interaction regimes in terms of the joint dependence of the key cloud microphysical properties (e.g. cloud droplet number concentration, cloud droplet relative dispersion, etc.) on aerosol number concentration (N a) and vertical velocity (w). The three distinct regimes with different microphysical features are the aerosol-limited regime, the updraft-limited regime, and the transitional regime. The results reveal two new phenomena in updraft-limited regime: 1) The “condensational broadening” of cloud droplet size distribution in contrast to the well-known “condensational narrowing” in the aerosol-limited regime; 2) Above the level of maximum supersaturation, some cloud dropletsmore » are deactivated into interstitial aerosols in the updraft-limited regime whereas all droplets remain activated in the aerosol-limited regime. Further analysis shows that the particle equilibrium supersaturation plays important role in understanding these unique features. Also examined is the height of warm rain initiation and its dependence on N a and w. The rain initiation height is found to depend primarily on either N a or w or both in different N a-w regimes, thus suggesting a strong regime dependence of the second aerosol indirect effect.« less

Height Dependency of Aerosol-Cloud Interaction Regimes: Height Dependency of ACI Regime

DOE PAGES

Chen, Jingyi; Liu, Yangang; Zhang, Minghua; ...

2018-01-10

This study investigates the height dependency of aerosol-cloud interaction regimes in terms of the joint dependence of the key cloud microphysical properties (e.g. cloud droplet number concentration, cloud droplet relative dispersion, etc.) on aerosol number concentration (N a) and vertical velocity (w). The three distinct regimes with different microphysical features are the aerosol-limited regime, the updraft-limited regime, and the transitional regime. The results reveal two new phenomena in updraft-limited regime: 1) The “condensational broadening” of cloud droplet size distribution in contrast to the well-known “condensational narrowing” in the aerosol-limited regime; 2) Above the level of maximum supersaturation, some cloud dropletsmore » are deactivated into interstitial aerosols in the updraft-limited regime whereas all droplets remain activated in the aerosol-limited regime. Further analysis shows that the particle equilibrium supersaturation plays important role in understanding these unique features. Also examined is the height of warm rain initiation and its dependence on N a and w. The rain initiation height is found to depend primarily on either N a or w or both in different N a-w regimes, thus suggesting a strong regime dependence of the second aerosol indirect effect.« less

Morphological and spectral properties of the W51 region measured with the MAGIC telescopes

NASA Astrophysics Data System (ADS)

Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado Mendez, C.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido, D.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Huber, B.; Jankowski, F.; Jogler, T.; Kadenius, V.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Niedzwiecki, A.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paiano, S.; Paneque, D.; Paoletti, R.; Pardo, S.; Paredes, J. M.; Partini, S.; Perez-Torres, M. A.; Persic, M.; Pilia, M.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puerto Gimenez, I.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Sun, S.; Surić, T.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.

2012-05-01

Context. The W51 complex hosts the supernova remnant W51C which is known to interact with the molecular clouds in the star forming region W51B. In addition, a possible pulsar wind nebula CXO J192318.5+140305 was found likely associated with the supernova remnant. Gamma-ray emission from this region was discovered by Fermi/LAT (between 0.2 and 50 GeV) and H.E.S.S. (>1 TeV). The spatial distribution of the events could not be used to pinpoint the location of the emission among the pulsar wind nebula, the supernova remnant shell and/or the molecular cloud. However, the modeling of the spectral energy distribution presented by the Fermi/LAT collaboration suggests a hadronic emission mechanism. The possibility that the gamma-ray emission from such an object is of hadronic origin can contribute to solvingthe long-standing problem of the contribution to galactic cosmic rays by supernova remnants. Aims: Our aim is to determine the morphology of the very-high-energy gamma-ray emission of W51 and measure its spectral properties. Methods: We performed observations of the W51 complex with the MAGIC telescopes for more than 50 h. The energy range accessible with MAGIC extends from 50 GeV to several TeV, allowing for the first spectral measurement at these energies. In addition, the good angular resolution in the medium (few hundred GeV) to high (above 1 TeV) energies allow us to perform morphological studies. We look for underlying structures by means of detailed morphological studies. Multi-wavelength data from this source have been sampled to model the emission with both leptonic and hadronic processes. Results: We detect an extended emission of very-high-energy gamma rays, with a significance of 11 standard deviations. We extend the spectrum from the highest Fermi/LAT energies to ~5 TeV and find that it follows a single power law with an index of 2.58 ± 0.07stat ± 0.22syst. The main part of the emission coincides with the shocked cloud region, while we find a feature

Representation of Arctic mixed-phase clouds and the Wegener-Bergeron-Findeisen process in climate models: Perspectives from a cloud-resolving study

NASA Astrophysics Data System (ADS)

Fan, Jiwen; Ghan, Steven; Ovchinnikov, Mikhail; Liu, Xiaohong; Rasch, Philip J.; Korolev, Alexei

2011-01-01

Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, regimes of cloud particle growth, including the Wegener-Bergeron-Findeisen (WBF) process, and the relationships among properties/processes in mixed-phase clouds are examined to gain insights for improving their representation in General Circulation Models (GCMs). The PDF of the simulated w is well represented by a Gaussian function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. The PDFs of liquid and ice water contents can be approximated by Gamma functions, and a Gaussian function can describe the total water distribution, but a fixed variance assumption should be avoided in both cases. The CRM results support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor near liquid saturation. Thus, ice continues to grow throughout the stratiform cloud but the WBF process occurs in about 50% of cloud volume where liquid and ice co-exist, predominantly in downdrafts. In updrafts, liquid and ice particles grow simultaneously. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The simplified size-independent capacitance of ice particles used in GCMs could lead to large deviations in ice depositional growth.

Arctic ocean radiative fluxes and cloud forcing estimated from the ISCCP C2 cloud dataset, 1983-1990

NASA Technical Reports Server (NTRS)

Schweiger, Axel J.; Key, Jeffrey R.

1994-01-01

Radiative fluxes and cloud forcings for the ocean areas of the Arctic are computed from the monthly cloud product of the International Satellite Cloud Climatology Project (ISCCP) for 1983-90. Spatially averaged short-wave fluxes are compared well with climatological values, while downwelling longwave fluxes are significantly lower. This is probably due to the fact that the ISCCP cloud amounts are underestimates. Top-of-the-atmosphere radiative fluxes are in excellent agreement with measurements from the Earth Radiation Budget Experiment (ERBE). Computed cloud forcings indicate that clouds have a warming effect at the surface and at the top of the atmosphere during winter and a cooling effect during summer. The net radiative effect of clouds is larger at the surface during winter but greater at the top of the atmosphere during summer. Overall the net radiative effect of clouds at the top of the atmosphere is one of cooling. This is in contrast to a previous result from ERBE data showing arctic cloud forcings have a net warming effect. Sensitivities to errors in input parameters are generally greater during winter with cloud amount being the most important paarameter. During summer the surface radiation balance is most sensitive to errors in the measurements of surface reflectance. The results are encouraging, but the estimated error of 20 W/sq m in surface net radiative fluxes is too large, given that estimates of the net radiative warming effect due to a doubling of CO2 are on the order of 4 W/sq m. Because it is difficult to determine the accuracy of results with existing in situ observations, it is recommended that the development of improved algorithms for the retrieval of surface radiative properties be accompanied by the simultaneous assembly of validation datasets.

Inhibitory effects of α-Na8SiW11CoO40 on tyrosinase and its application in controlling browning of fresh-cut apples.

PubMed

Chen, Bing-Nian; Xing, Rui; Wang, Fang; Zheng, A-Ping; Wang, Li

2015-12-01

α-Na8SiW11CoO40 was synthesized and characterized. The inhibitory effects of α-Na8SiW11CoO40 on the activity of mushroom tyrosinase and the effects of α-Na8SiW11CoO40 on the browning of fresh-cut apples were studied. The Native-PAGE result showed that α-Na8SiW11CoO40 had a significant inhibitory effect on tyrosinase. Kinetic analyses showed that α-Na8SiW11CoO40 was an irreversible and competitive inhibitor. The inhibitor concentration leading to a 50% reduction in activity (IC50) was estimated to be 0.239 mM. Additionally, the results also showed that α-Na8SiW11CoO40 treatment could significantly decrease the browning process of apple slices and inhibit the polyphenol oxidase (PPO) activity. Moreover, application of α-Na8SiW11CoO40 resulted in higher peroxidase activity and promoted high amounts of phenolic compounds and ascorbic acid. This study may provide a promising method for the use of polyoxometalates to inhibit tyrosinase activity and control the browning of fresh-cut apples. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

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

A 94 GHz RF Electronics Subsystem for the CloudSat Cloud Profiling Radar

NASA Technical Reports Server (NTRS)

LaBelle, Remi C.; Girard, Ralph; Arbery, Graham

2003-01-01

The CloudSat spacecraft, scheduled for launch in 2004, will carry the 94 GHz Cloud Profiling Radar (CPR) instrument. The design, assembly and test of the flight Radio Frequency Electronics Subsystem (RFES) for this instrument has been completed and is presented here. The RFES consists of an Upconverter (which includes an Exciter and two Drive Amplifiers (DA's)), a Receiver, and a Transmitter Calibrator assembly. Some key performance parameters of the RFES are as follows: dual 100 mW pulse-modulated drive outputs at 94 GHz, overall Receiver noise figure < 5.0 dB, a highly stable W-band noise source to provide knowledge accuracy of Receiver gain of < 0.4 dB over the 2 year mission life, and a W-band peak power detector to monitor the transmitter output power to within 0.5 dB over life. Some recent monolithic microwave integrated circuit (MMIC) designs were utilized which implement the DA's in 0.1 micron GaAs high electron-mobility transistor (HEMT) technology and the Receiver low-noise amplifier (LNA) in 0.1 micron InP HEMT technology.

Nonlinear eigen-structures in star-forming gyratory nonthermal complex molecular clouds

NASA Astrophysics Data System (ADS)

Karmakar, Pralay Kumar; Dutta, Pranamika

2018-01-01

This paper deals with the nonlinear gravito-electrostatic fluctuations in star-forming rotating complex partially ionized dust molecular clouds, evolutionarily well-governed by a derived pair of the Korteweg-de Vries (KdV) equations of a unique analytical shape, in a bi-fluidic-model fabric. The lighter constituent species, such as electrons and ions, are considered thermo-statistically as the nonthermal ones in nature, governed by the anti-equilibrium kappa-distribution laws, due to inherent nonlocal gradient effects stemming from large-scale inhomogeneity. The heavier species, such as the constitutive identical neutral and charged dust micro-spheres, are treated as separate turbulent viscous fluids in the Larson logatropic tapestry. Application of a standard technique of multiple scale analysis over the nonlinearly perturbed cloud procedurally yields the pair KdV system. It comprises of the gravitational KdV and electrostatic KdV equations with exclusive constructs of diversified multi-parametric coefficients. A numerical constructive platform is provided to see the excitation and propagatory dynamics of gravitational rarefactive periodic soliton-trains and electrostatic rarefactive aperiodic damped soliton-trains of distinctive patterns as the pair-KdV-supported discrete coherent eigen-mode structures illustratively. The varied key stabilizing and tonality destabilizing factors behind the cloud dynamics are identified. An elaborated contrast of the eigen-mode conjugacy is reconnoitered. The main implications and applications of the semi-analytical results explored here are summarily outlined in the real astro-space-cosmic statuses.

Cloud Control

ERIC Educational Resources Information Center

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

2011-01-01

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

CHEMICAL ANALYSIS OF A DIFFUSE CLOUD ALONG A LINE OF SIGHT TOWARD W51: MOLECULAR FRACTION AND COSMIC-RAY IONIZATION RATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.

2012-10-20

Absorption lines from the molecules OH{sup +}, H{sub 2}O{sup +}, and H{sup +} {sub 3} have been observed in a diffuse molecular cloud along a line of sight near W51 IRS2. We present the first chemical analysis that combines the information provided by all three of these species. Together, OH{sup +} and H{sub 2}O{sup +} are used to determine the molecular hydrogen fraction in the outskirts of the observed cloud, as well as the cosmic-ray ionization rate of atomic hydrogen. H{sup +} {sub 3} is used to infer the cosmic-ray ionization rate of H{sub 2} in the molecular interior ofmore » the cloud, which we find to be {zeta}{sub 2} = (4.8 {+-} 3.4) Multiplication-Sign 10{sup -16} s{sup -1}. Combining the results from all three species we find an efficiency factor-defined as the ratio of the formation rate of OH{sup +} to the cosmic-ray ionization rate of H-of {epsilon} = 0.07 {+-} 0.04, much lower than predicted by chemical models. This is an important step in the future use of OH{sup +} and H{sub 2}O{sup +} on their own as tracers of the cosmic-ray ionization rate.« less

Tiny, Dusty, Galactic HI Clouds: The GALFA-HI Compact Cloud Catalog

NASA Astrophysics Data System (ADS)

Saul, Destry R.; Putman, M. E.; Peek, J. G.

2013-01-01

The recently published GALFA-HI Compact Cloud Catalog contains 2000 nearby neutral hydrogen clouds under 20' in angular size detected with a machine-vision algorithm in the Galactic Arecibo L-Band Feed Array HI survey (GALFA-HI). At a distance of 1kpc, the compact clouds would typically be 1 solar mass and 1pc in size. We observe that nearly all of the compact clouds that are classified as high velocity (> 90 km/s) are near previously-identified high velocity complexes. We separate the compact clouds into populations based on velocity, linewidth, and position. We have begun to search for evidence of dust in these clouds using IRIS and have detections in several populations.

40 CFR 721.5325 - Nickel acrylate complex.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Nickel acrylate complex. 721.5325... Substances § 721.5325 Nickel acrylate complex. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nickel acrylate complex (PMN P-85-1034) is subject to reporting under...

40 CFR 721.5325 - Nickel acrylate complex.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nickel acrylate complex. 721.5325... Substances § 721.5325 Nickel acrylate complex. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nickel acrylate complex (PMN P-85-1034) is subject to reporting under...

40 CFR 721.5325 - Nickel acrylate complex.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Nickel acrylate complex. 721.5325... Substances § 721.5325 Nickel acrylate complex. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nickel acrylate complex (PMN P-85-1034) is subject to reporting under...

40 CFR 721.5325 - Nickel acrylate complex.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nickel acrylate complex. 721.5325... Substances § 721.5325 Nickel acrylate complex. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nickel acrylate complex (PMN P-85-1034) is subject to reporting under...

Ice Cloud Properties And Their Radiative Effects: Global Observations And Modeling

NASA Astrophysics Data System (ADS)

Hong, Yulan

Ice clouds are crucial to the Earth's radiation balance. They cool the Earth-atmosphere system by reflecting solar radiation back to space and warm it by blocking outgoing thermal radiation. However, there is a lack of an observation-based climatology of ice cloud properties and their radiative effects. Two active sensors, the CloudSat radar and the CALIPSO lidar, for the first time provide vertically resolved ice cloud data on a global scale. Using synergistic signals of these two sensors, it is possible to obtain both optically thin and thick ice clouds as the radar excels in probing thick clouds while the lidar is better to detect the thin ones. First, based on the CloudSat radar and CALIPSO lidar measurements, we have derived a climatology of ice cloud properties. Ice clouds cover around 50% of the Earth surface, and their global-mean optical depth, ice water path, and effective radius are approximately 2 (unitless), 109 g m. {-2} and 48 \\mum, respectively. Ice cloud occurrence frequency not only depends on regions and seasons, but also on the types of ice clouds as defined by optical depth (tau) values. Optically thin ice clouds (tau < 3) are most frequently observed in the tropics around 15 km and in the midlatitudes below 5 km, while the thicker clouds (tau > 3) occur frequently in the tropical convective areas and along the midlatitude storm tracks. Using ice retrievals derived from combined radar-lidar measurements, we conducted radiative transfer modeling to study ice cloud radiative effects. The combined effects of ice clouds warm the earth-atmosphere system by approximately 5 W m-2, contributed by a longwave warming effect of about 21.8 W m-2 and a shortwave cooling effect of approximately -16.7 W m-2. Seasonal variations of ice cloud radiative effects are evident in the midlatitudes where the net effect changes from warming during winter to cooling during summer, and the net warming effect occurs year-round in the tropics (˜ 10 W m-2). Ice cloud

40 CFR 721.5325 - Nickel acrylate complex.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Nickel acrylate complex. 721.5325... Substances § 721.5325 Nickel acrylate complex. Link to an amendment published at 79 FR 34637, June 18, 2014... nickel acrylate complex (PMN P-85-1034) is subject to reporting under this section for the significant...

Comparative Phylogeographic Analyses Illustrate the Complex Evolutionary History of Threatened Cloud Forests of Northern Mesoamerica

PubMed Central

Ornelas, Juan Francisco; Sosa, Victoria; Soltis, Douglas E.; Daza, Juan M.; González, Clementina; Soltis, Pamela S.; Gutiérrez-Rodríguez, Carla; de los Monteros, Alejandro Espinosa; Castoe, Todd A.; Bell, Charles; Ruiz-Sanchez, Eduardo

2013-01-01

Comparative phylogeography can elucidate the influence of historical events on current patterns of biodiversity and can identify patterns of co-vicariance among unrelated taxa that span the same geographic areas. Here we analyze temporal and spatial divergence patterns of cloud forest plant and animal species and relate them to the evolutionary history of naturally fragmented cloud forests–among the most threatened vegetation types in northern Mesoamerica. We used comparative phylogeographic analyses to identify patterns of co-vicariance in taxa that share geographic ranges across cloud forest habitats and to elucidate the influence of historical events on current patterns of biodiversity. We document temporal and spatial genetic divergence of 15 species (including seed plants, birds and rodents), and relate them to the evolutionary history of the naturally fragmented cloud forests. We used fossil-calibrated genealogies, coalescent-based divergence time inference, and estimates of gene flow to assess the permeability of putative barriers to gene flow. We also used the hierarchical Approximate Bayesian Computation (HABC) method implemented in the program msBayes to test simultaneous versus non-simultaneous divergence of the cloud forest lineages. Our results show shared phylogeographic breaks that correspond to the Isthmus of Tehuantepec, Los Tuxtlas, and the Chiapas Central Depression, with the Isthmus representing the most frequently shared break among taxa. However, dating analyses suggest that the phylogeographic breaks corresponding to the Isthmus occurred at different times in different taxa. Current divergence patterns are therefore consistent with the hypothesis of broad vicariance across the Isthmus of Tehuantepec derived from different mechanisms operating at different times. This study, coupled with existing data on divergence cloud forest species, indicates that the evolutionary history of contemporary cloud forest lineages is complex and often lineage

High-efficiency 3 W/40 K single-stage pulse tube cryocooler for space application

NASA Astrophysics Data System (ADS)

Zhang, Ankuo; Wu, Yinong; Liu, Shaoshuai; Liu, Biqiang; Yang, Baoyu

2018-03-01

Temperature is an extremely important parameter for space-borne infrared detectors. To develop a quantum-well infrared photodetector (QWIP), a high-efficiency Stirling-type pulse tube cryocooler (PTC) has been designed, manufactured and experimentally investigated for providing a large cooling power at 40 K cold temperature. Simulated and experimental studies were carried out to analyse the effects of low temperature on different energy flows and losses, and the performance of the PTC was improved by optimizing components and parameters such as regenerator and operating frequency. A no-load lowest temperature of 26.2 K could be reached at a frequency of 51 Hz, and the PTC could efficiently offer cooling power of 3 W at 40 K cold temperature when the input power was 225 W. The efficiency relative to the Carnot efficiency was approximately 8.4%.

Cloud Macroscopic Organization: Order Emerging from Randomness

NASA Technical Reports Server (NTRS)

Yuan, Tianle

2011-01-01

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

Satellite-based solar radiation mapping over complex terrain: Validation in the Alps and possible improvements

NASA Astrophysics Data System (ADS)

Castelli, Mariapina; Stoeckli, Reto; Tetzlaff, Anke; Ernst Wagner, Jochen; Zardi, Dino; Petitta, Marcello

2013-04-01

Solar radiation is an essential variable for applications such as the climate monitoring or the planning of systems exploiting solar energy. This study presents a validation of surface irradiance derived from MSG (Meteosat second generation) satellite data with an extended version of the Heliosat algorithm [3] in the Alps. The algorithm implemented by MeteoSwiss is based on the clear-sky LUT (look up table) approach proposed by Müller et al., 2009 [2], and a probabilistic cloud mask adapted to MSG from the scheme of Khlopenkov and Trishchenko, 2007 [1]. The validation study focuses on the accuracy of the diffuse/direct components of irradiance and suggests possible improvements. We performed a detailed analysis at three locations, i.e. two Alpine sites - Bolzano (IT), at low altitude, and Davos (CH), at high altitude - and Payerne (CH), in the Swiss Plateau, comparing the hourly, daily, monthly and seasonal bias of the satellite estimation against ground measurements. Results indicate, in terms of MBD (mean bias deviation) and MAD (mean absolute deviation), that the algorithm reproduces precisely the yearly cycle, especially for global irradiance (MBD between -1 and 6 W/m2, MAD between 3 and 13 W/m2). On a daily time scale the all-sky MAD is below 15 W/m2 for all the components of radiation, while it is above 40 W/m2 at the hourly scale. In the mean daily cycle diffuse irradiance is overestimated (10-20 W/m2) for the two stations based on a valley floor, while it is underestimated in the other one. We noticed that cloud free conditions are affected by the biggest absolute error, especially in summer. We therefore investigated the role of aerosols in the clear-sky uncertainty. By including in the radiative transfer model adopted for the simulations either ground or satellite daily atmospheric input on aerosol and water vapor, the estimation of the hourly averages of diffuse radiation improves significantly (MAD < 10 W/m2) compared to the satellite estimate

Microphysical Model Studies of Venus Clouds

NASA Astrophysics Data System (ADS)

Meade, P. E.; Bullock, M. A.; Grinspoon, D. H.

2004-11-01

We have adapted a standard cloud microphysics model to construct a self-consistent microphysical model of Venus' cloud layer which reproduces and extends previous studies (e.g. James et al. 1997). Our model is based on the Community Aerosol and Radiation Model Atmosphere (CARMA), which is a widely used computer code for terrestrial cloud microphysics, derived from the work of Toon et al. (1988). The standard code has been adapted to treat H2O and H2SO4 as co-condensing vapor species onto aqueous H2SO4 cloud droplets, as well as the nucleation of condensation nuclei to droplets. Vapor condensation and evaporation follows the method of James et al. (1997). Microphysical processes included in this model include nucleation of condensation nuclei, condensation and evaporation of H2O and H2SO4 vapor, and droplet coagulation. Vertical transport occurs though advection, eddy diffusion, sedimentation for both droplets and condensation nuclei. The cloud model is used to explore the sensitivity of Venus' cloud layer to environmental changes. Observations of the Venus' lower cloud from the Pioneer Venus, Venera, and Galileo spacecraft have suggested that the properties of the lower cloud may be time-variable, and at times may be entirely absent (Carlson et al. 1993, Grinspoon et al. 1993, Esposito et al. 1997). Our model explores the dependence of such behavior on environment factors such as variations in water or SO2 abundance. We have also calculated the optical properties of the model atmosphere using both the conventional optical constants for H2SO4 (Palmer and Williams, 1975), and the new data of Tisdale et al. (1998). This work has been supported by NASA's Exobiology Program. References Carlson, R.W., et al., 1993. Planetary and Space Science, 41, 477-486. Esposito, L.W., et al., 1997. In Venus II, eds. S.W. Bougher et al., pp. 415-458, University of Arizona Press, Tucson. Grinspoon, D.H., et al., 1993. Planetary and Space Science, 41 (July 1993), 515-542. James, E. P

40 CFR Table 1 to Subpart W of... - General Provisions Applicability to Subpart W

Code of Federal Regulations, 2010 CFR

2010-07-01

... Subpart W 1 Table 1 to Subpart W of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Polyamides Production Pt. 63, Subpt. W, Table 1 Table 1 to Subpart W of Part 63—General Provisions Applicability to Subpart W Reference Applies to subpart W BLR WSR WSR alternative standard, and BLR equipment...

A 40-kW fuel cell field test summary utilities activities report

NASA Astrophysics Data System (ADS)

Racine, W. C.; Londos, T. C.

1987-07-01

Forty six 40 kW fuel cell power plants were field tested by 37 host participants at 42 sites in a variety of commercial, light industrial and multifamily residential applications. The participants obtained over 300,000 hours of operating experience with the power plants covering a diverse range of applications for power plant electricity and heat utilization in both single and multiple unit installations.

Ross Ice Shelf, Antarctic Ice and Clouds

NASA Technical Reports Server (NTRS)

1991-01-01

In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

Marine cloud brightening – as effective without clouds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahlm, Lars; Jones, Andy; Stjern, Camilla W.

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

Marine cloud brightening – as effective without clouds

DOE PAGES

Ahlm, Lars; Jones, Andy; Stjern, Camilla W.; ...

2017-11-06

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

Cost-effective cloud computing: a case study using the comparative genomics tool, roundup.

PubMed

Kudtarkar, Parul; Deluca, Todd F; Fusaro, Vincent A; Tonellato, Peter J; Wall, Dennis P

2010-12-22

Comparative genomics resources, such as ortholog detection tools and repositories are rapidly increasing in scale and complexity. Cloud computing is an emerging technological paradigm that enables researchers to dynamically build a dedicated virtual cluster and may represent a valuable alternative for large computational tools in bioinformatics. In the present manuscript, we optimize the computation of a large-scale comparative genomics resource-Roundup-using cloud computing, describe the proper operating principles required to achieve computational efficiency on the cloud, and detail important procedures for improving cost-effectiveness to ensure maximal computation at minimal costs. Utilizing the comparative genomics tool, Roundup, as a case study, we computed orthologs among 902 fully sequenced genomes on Amazon's Elastic Compute Cloud. For managing the ortholog processes, we designed a strategy to deploy the web service, Elastic MapReduce, and maximize the use of the cloud while simultaneously minimizing costs. Specifically, we created a model to estimate cloud runtime based on the size and complexity of the genomes being compared that determines in advance the optimal order of the jobs to be submitted. We computed orthologous relationships for 245,323 genome-to-genome comparisons on Amazon's computing cloud, a computation that required just over 200 hours and cost $8,000 USD, at least 40% less than expected under a strategy in which genome comparisons were submitted to the cloud randomly with respect to runtime. Our cost savings projections were based on a model that not only demonstrates the optimal strategy for deploying RSD to the cloud, but also finds the optimal cluster size to minimize waste and maximize usage. Our cost-reduction model is readily adaptable for other comparative genomics tools and potentially of significant benefit to labs seeking to take advantage of the cloud as an alternative to local computing infrastructure.

Cost-Effective Cloud Computing: A Case Study Using the Comparative Genomics Tool, Roundup

PubMed Central

Kudtarkar, Parul; DeLuca, Todd F.; Fusaro, Vincent A.; Tonellato, Peter J.; Wall, Dennis P.

2010-01-01

Background Comparative genomics resources, such as ortholog detection tools and repositories are rapidly increasing in scale and complexity. Cloud computing is an emerging technological paradigm that enables researchers to dynamically build a dedicated virtual cluster and may represent a valuable alternative for large computational tools in bioinformatics. In the present manuscript, we optimize the computation of a large-scale comparative genomics resource—Roundup—using cloud computing, describe the proper operating principles required to achieve computational efficiency on the cloud, and detail important procedures for improving cost-effectiveness to ensure maximal computation at minimal costs. Methods Utilizing the comparative genomics tool, Roundup, as a case study, we computed orthologs among 902 fully sequenced genomes on Amazon’s Elastic Compute Cloud. For managing the ortholog processes, we designed a strategy to deploy the web service, Elastic MapReduce, and maximize the use of the cloud while simultaneously minimizing costs. Specifically, we created a model to estimate cloud runtime based on the size and complexity of the genomes being compared that determines in advance the optimal order of the jobs to be submitted. Results We computed orthologous relationships for 245,323 genome-to-genome comparisons on Amazon’s computing cloud, a computation that required just over 200 hours and cost $8,000 USD, at least 40% less than expected under a strategy in which genome comparisons were submitted to the cloud randomly with respect to runtime. Our cost savings projections were based on a model that not only demonstrates the optimal strategy for deploying RSD to the cloud, but also finds the optimal cluster size to minimize waste and maximize usage. Our cost-reduction model is readily adaptable for other comparative genomics tools and potentially of significant benefit to labs seeking to take advantage of the cloud as an alternative to local computing

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

NASA Astrophysics Data System (ADS)

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

2015-02-01

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

Water and complex organic chemistry in the cold dark cloud Barnard 5: Observations and Models

NASA Astrophysics Data System (ADS)

Wirström, Eva; Charnley, Steven B.; Taquet, Vianney; Persson, Carina M.

2015-08-01

Studies of complex organic molecule (COM) formation have traditionally been focused on hot cores in regions of massive star formation, where chemistry is driven by the elevated temperatures - evaporating ices and allowing for endothermic reactions in the gas-phase. As more sensitive instruments have become available, the types of objects known to harbour COMs like acetaldehyde (CH3CHO), dimethyl ether (CH3OCH3), methyl formate (CH3OCHO), and ketene (CH2CO) have expanded to include low mass protostars and, recently, even pre-stellar cores. We here report on the first in a new category of objects harbouring COMs: the cold dark cloud Barnard 5 where non-thermal ice desorption induce complex organic chemistry entirely unrelated to local star-formation.Methanol, which only forms efficiently on the surfaces of dust grains, provide evidence of efficient non-thermal desorption of ices in the form of prominent emission peaks offset from protostellar activity and high density tracers in cold molecular clouds. A study with Herschel targeting such methanol emission peaks resulted in the first ever detection of gas-phase water offset from protostellar activity in a dark cloud, at the so called methanol hotspot in Barnard 5.To model the effect a transient injection of ices into the gas-phase has on the chemistry of a cold, dark cloud we have included gas-grain interactions in an existing gas-phase chemical model and connected it to a chemical reaction network updated and expanded to include the formation and destruction paths of the most common COMs. Results from this model will be presented.Ground-based follow-up studies toward the methanol hotspot in B5 have resulted in the detection of a number of COMs, including CH2CO, CH3CHO, CH3OCH3, and CH3OCHO, as well as deuterated methanol (CH2DOH). Observations have also confirmed that COM emission is extended and not localised to a core structure. The implications of these observational and theoretical studies of B5 will be discussed

Mononuclear Sulfido-Tungsten(V) Complexes: Completing the Tp*MEXY (M = Mo, W; E = O, S) Series.

PubMed

Sproules, Stephen; Eagle, Aston A; George, Graham N; White, Jonathan M; Young, Charles G

2017-05-01

Orange Tp*WSCl 2 has been synthesized from the reactions of Tp*WOCl 2 with boron sulfide in refluxing toluene or Tp*WS 2 Cl with PPh 3 in dichloromethane at room temperature. Mononuclear sulfido-tungsten(V) complexes, Tp*WSXY {X = Y = Cl, OPh, SPh, SePh; X = Cl, Y = OPh; XY = toluene-3,4-dithiolate (tdt), quinoxaline-2,3-dithiolate (qdt); and Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate} were prepared by metathesis of Tp*WSCl 2 with the respective alkali metal salt of X - /XY 2- , or [NHEt 3 ] 2 (qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, and infrared (IR), electron paramagnetic resonance (EPR) and electronic absorption spectroscopies. The molecular structures of Tp*WS(OPh) 2 , Tp*WS(SePh) 2 , and Tp*WS(tdt) have been determined by X-ray crystallography. The six-coordinate, distorted-octahedral W centers are coordinated by terminal sulfido (W≡S = 2.128(2) - 2.161(1) Å), terdentate facial Tp*, and monodentate/bidentate O/S/Se-donor ligands. The sulfido-W(V) complexes are characterized by lower energy electronic transitions, smaller g iso , and larger A iso ( 183 W) values, and more positive reduction potentials compared with their oxo-W(V) counterparts. This series has been probed by sulfur K-edge X-ray absorption spectroscopy (XAS), the spectra being assigned by comparison to Tp*WOXY (X = Y = SPh; XY = tdt, qdt) and time-dependent density functional theoretical (TD-DFT) calculations. This study provides insight into the electronic nature and chemistry of the catalytically and biologically important sulfido-W unit.

A comparison between CloudSat and aircraft data for a multilayer, mixed phase cloud system during the Canadian CloudSat-CALIPSO Validation Project

NASA Astrophysics Data System (ADS)

Barker, H. W.; Korolev, A. V.; Hudak, D. R.; Strapp, J. W.; Strawbridge, K. B.; Wolde, M.

2008-04-01

Reflectivities recorded by the W-band Cloud Profiling Radar (CPR) aboard NASA's CloudSat satellite and some of CloudSat's retrieval products are compared to Ka-band radar reflectivities and in situ cloud properties gathered by instrumentation on the NRC's Convair-580 aircraft. On 20 February 2007, the Convair flew several transects along a 60 nautical mile stretch of CloudSat's afternoon ground track over southern Quebec. On one of the transects it was well within CloudSat's radar's footprint while in situ sampling a mixed phase boundary layer cloud. A cirrus cloud was also sampled before and after overpass. Air temperature and humidity profiles from ECMWF reanalyses, as employed in CloudSat's retrieval stream, agree very well with those measured by the Convair. The boundary layer cloud was clearly visible, to the eye and lidar, and dominated the region's solar radiation budget. It was, however, often below or near the Ka-band's distance-dependent minimum detectable signal. In situ samples at overpass revealed it to be composed primarily of small, supercooled droplets at the south end and increasingly intermixed with ice northward. Convair and CloudSat CPR reflectivities for the low cloud agree well, but while CloudSat properly ascribed it as overcast, mixed phase, and mostly liquid near the south end, its estimates of liquid water content LWC (and visible extinction coefficient κ) and droplet effective radii are too small and large, respectively. The cirrus consisted largely of irregular crystals with typical effective radii ˜150 μm. While both CPR reflectivities agree nicely, CloudSat's estimates of crystal number concentrations are too large by a factor of 5. Nevertheless, distributions of ice water content and κ deduced from in situ data agree quite well with values retrieved from CloudSat algorithms.

Possible influences of Asian dust aerosols on cloud properties and radiative forcing observed from MODIS and CERES

NASA Astrophysics Data System (ADS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2006-03-01

The effects of dust storms on cloud properties and Radiative Forcing (RF) are analyzed over Northwestern China from April 2001 to June 2004 using data collected by the MODerate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. Due to changes in cloud microphysics, the instantaneous net RF is increased from -161.6 W/m2 for dust-free clouds to -118.6 W/m2 for dust-contaminated clouds.

The Effect of Asian Dust Aerosols on Cloud Properties and Radiative Forcing from MODIS and CERES

NASA Technical Reports Server (NTRS)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Wang, Tianhe; Yi, Yuhong; Hu, Yongxiang; Sun-Mack, Sunny; Ayers, Kirk

2005-01-01

The effects of dust storms on cloud properties and radiative forcing are analyzed over northwestern China from April 2001 to June 2004 using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Aqua and Terra satellites. On average, ice cloud effective particle diameter, optical depth and ice water path of the cirrus clouds under dust polluted conditions are 11%, 32.8%, and 42% less, respectively, than those derived from ice clouds in dust-free atmospheric environments. The humidity differences are larger in the dusty region than in the dust-free region, and may be caused by removal of moisture by wet dust precipitation. Due to changes in cloud microphysics, the instantaneous net radiative forcing is reduced from -71.2 W/m2 for dust contaminated clouds to -182.7 W/m2 for dust-free clouds. The reduced cooling effects of dusts may lead to a net warming of 1 W/m2, which, if confirmed, would be the strongest aerosol forcing during later winter and early spring dust storm seasons over the studied region.

A comparison of the optical pulse characteristics of intracloud and cloud-to-ground lightning as observed above clouds

NASA Technical Reports Server (NTRS)

Goodman, Steven J.; Christian, Hugh J.; Rust, W. David

1988-01-01

The optical-pulse characteristics of intracloud (IC) and cloud-to-ground (CG) lightning flashes were investigated. The time-resolved optical waveforms at 777.4 nm and electric-field changes produced by lightning flashes were measured aboard a U2 aircraft flying above clouds at the same time that ground-based lightning measurements were carried out. The pulse shapes and intensities of IC and CG flashes, as viewed from above cloud, were found to exhibit remarkably similar waveshapes, radiances, and radiant energy densities. The median radiance at cloud top was found to be about 0.007 W/sq m per sr, and the median energy density about 0.000003 J/sq m per sr.

Aircraft-Measured Indirect Cloud Effects from Biomass Burning Smoke in the Arctic and Subarctic

NASA Technical Reports Server (NTRS)

Zamora, L. M.; Kahn, R. A.; Cubison, M. J.; Diskin, G. S.; Jimenez, J. L.; Kondo, Y.; McFarquhar, G. M.; Nenes, A.; Thornhill, K. L.; Wisthaler, A.;

Overcoming Constraints in Healthcare with Cloud Technology.

PubMed

Hucíková, Anežka; Babic, Ankica

2016-01-01

Transitioning enterprise operations to the cloud brings a variety of opportunities and challenges. Such step requires a deep and complex understanding of all elements related to the technology as well as defining the manner in which specific cloud challenges can be dealt with. To provide a better understanding of these opportunities and challenges within healthcare, systematic literature overview and industrial cases review is used. Results of the two methods show interconnection between cloud deployment advantages and constrains. However, healthcare case studies provide interesting insights emphasizing cloud complexity and superposition which seems to balance organizational limitations.

A comparison of the interaction of nitric oxide with the heteropolytungstic acids H{sub 3}PW{sub 12}O{sub 40}, H{sub 0.5}Cs{sub 2.5}PW{sub 12}O{sub 40}, HMgPW{sub 12}O{sub 40}, H{sub 8}SiW{sub 11}O{sub 38}, H{sub 4}SiW{sub 12}O{sub 40}, and H{sub 10}CoW{sub 12}O{sub 42}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herring, A.M.; McCormick, R.L.; Boonrueng, S.R.

2000-05-18

The interaction between NO and the heteropolytungstic acids (HPAs) H{sub 3}PW{sub 12}O{sub 40} (HPW), H{sub 0.5}Cs{sub 2.5}PW{sub 12}O{sub 40} (HCsPW), HMgPW{sub 12}O{sub 40} (HMgPW), H{sub 8}SiW{sub 11}O{sub 38} (HSiW{sub 11}), H{sub 4}SiW{sub 12}O{sub 40} (HSiW), and H{sub 10}CoW{sub 12}{sub 42}(HCoW) in the presence of O{sub 2}(g) was investigated. The tools employed were in situ diffuse reflectance infrared spectroscopy, X-ray powder diffraction, and solid-state {sup 1}H NMR. It was determined that protons may either be present in the HPAs secondary structure as anhydrous protons or be bound to one or two water molecules as H{sub 3}O{sup +} or H{sub 5}O{sub 2}{supmore » +}, respectively. A previous investigation found that HPW sorbed NO into its bulk structure as NOH{sup +}, whereas the anhydrous potassium salt of HPW exhibited weak chemisorption of NO on its surface. In the present study, it was found that NO chemisorbed weakly on the surface of the anhydrous HCsPW. For HMgPW and HSiW, IR and NMR evidence suggests that water is present as H{sub 3}O{sup +}, and the formation of surface-bound NOH{sup +} was observed. Inclusion of NO into the secondary structure as NOH{sup +} was observed for HPW, HSiW{sub 11}, and HCoW. Literature data for HPW, as well as IR and NMR results reported here, indicate that these HPAs contain water as H{sub 5}O{sub 2}{sup +}. The presence of H{sub 5}O{sub 2}{sup +} is, therefore, a prerequisite for NO incorporation as NOH{sup +} in the HPA secondary structure. These HPAs exhibited two modes of NO bonding in the secondary structure: a strongly hydrogen-bound hydrated form, NOH{sup +}{center_dot}H{sub 2}O, and a more weakly bound anhydrous form, NOH{sup +}. Evidence suggests that it is the hydrated form that decomposes, yielding N{sub 2} upon rapid heating. Both NO-containing species interact with terminal and corner-sharing oxygen atoms of the Keggin ion. Anions that are held apart by terminal oxygen-hydrogen bonds have a larger

40 CFR 230.45 - Riffle and pool complexes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Riffle and pool complexes. 230.45... Impacts on Special Aquatic Sites § 230.45 Riffle and pool complexes. (a) Steep gradient sections of streams are sometimes characterized by riffle and pool complexes. Such stream sections are recognizable by...

40 CFR 230.45 - Riffle and pool complexes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Riffle and pool complexes. 230.45... Impacts on Special Aquatic Sites § 230.45 Riffle and pool complexes. (a) Steep gradient sections of streams are sometimes characterized by riffle and pool complexes. Such stream sections are recognizable by...

Synthesis, properties and crystal structure of (Gly) 2H 4SiW 12O 40·5.5H 2O

NASA Astrophysics Data System (ADS)

Lihua, Bi; Qizhuang, He; Qiong, Jia; Enbo, Wang

2001-10-01

A novel polyoxometalate containing Glycine (Gly), (Gly)2H4SiW12O40·5.5H2O (I), has been synthesized and characterized by single-crystal X-ray diffraction, elemental analyzes, IR spectrum, cyclic voltammograms and thermogravimetric analysis. The compound crystallizes in the monoclinic space group C2/C with a=40.362 (8) Å, b=12.478 (3) Å, c=19.879 (4) Å, β=96.22 (3)°, V=9953 (4) Å3, Z=8 and R1 (wR2)=0.0699 (0.1609). The crystal structure consists of [SiW12O40]4- units linked together with Gly molecules through hydrogen bonding. The electrochemical properties of I showed that the electrode reaction is surface-controlled. The compound has photosensitivity under irradiation of sunlight to result in charge transfer by oxidation of Gly and the reduction of SiW12O404-. We also found that the compound exhibited effectiveness in preventing cucumber mosaic virus (CMV).

A Multi-Frequency Wide-Swath Spaceborne Cloud and Precipitation Imaging Radar

NASA Technical Reports Server (NTRS)

Li, Lihua; Racette, Paul; Heymsfield, Gary; McLinden, Matthew; Venkatesh, Vijay; Coon, Michael; Perrine, Martin; Park, Richard; Cooley, Michael; Stenger, Pete;

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

NASA Technical Reports Server (NTRS)

Varnai, Tamas; Yang, Weidong; Marshak, Alexander

2016-01-01

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

Star formation in a hierarchical model for Cloud Complexes

NASA Astrophysics Data System (ADS)

Sanchez, N.; Parravano, A.

The effects of the external and initial conditions on the star formation processes in Molecular Cloud Complexes are examined in the context of a schematic model. The model considers a hierarchical system with five predefined phases: warm gas, neutral gas, low density molecular gas, high density molecular gas and protostars. The model follows the mass evolution of each substructure by computing its mass exchange with their parent and children. The parent-child mass exchange depends on the radiation density at the interphase, which is produced by the radiation coming from the stars that form at the end of the hierarchical structure, and by the external radiation field. The system is chaotic in the sense that its temporal evolution is very sensitive to small changes in the initial or external conditions. However, global features such as the star formation efficience and the Initial Mass Function are less affected by those variations.

Towards a Three-Dimensional Near-Real Time Cloud Product for Aviation Safety and Weather Diagnoses

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Nguyen, Louis; Palikonda, Rabindra; Spangeberg, Douglas; Nordeen, Michele L.; Yi, Yu-Hong; Ayers, J. Kirk

2004-01-01

Satellite data have long been used for determining the extent of cloud cover and for estimating the properties at the cloud tops. The derived properties can also be used to estimate aircraft icing potential to improve the safety of air traffic in the region. Currently, cloud properties and icing potential are derived in near-real time over the United States of America (USA) from the Geostationary Operational Environmental Satellite GOES) imagers at 75 W and 135 W. Traditionally, the results have been given in two dimensions because of the lack of knowledge about the vertical extent of clouds and the occurrence of overlapping clouds. Aircraft fly in a three-dimensional space and require vertical as well as horizontal information about clouds, their intensity, and their potential for icing. To improve the vertical component of the derived cloud and icing parameters, this paper explores various methods and datasets for filling in the three-dimensional space over the USA with cloud water.

Aerosol Indirect Effects on Cirrus Clouds in Global Aerosol-Climate Models

NASA Astrophysics Data System (ADS)

Liu, X.; Zhang, K.; Wang, Y.; Neubauer, D.; Lohmann, U.; Ferrachat, S.; Zhou, C.; Penner, J.; Barahona, D.; Shi, X.

2015-12-01

Cirrus clouds play an important role in regulating the Earth's radiative budget and water vapor distribution in the upper troposphere. Aerosols can act as solution droplets or ice nuclei that promote ice nucleation in cirrus clouds. Anthropogenic emissions from fossil fuel and biomass burning activities have substantially perturbed and enhanced concentrations of aerosol particles in the atmosphere. Global aerosol-climate models (GCMs) have now been used to quantify the radiative forcing and effects of aerosols on cirrus clouds (IPCC AR5). However, the estimate uncertainty is very large due to the different representation of ice cloud formation and evolution processes in GCMs. In addition, large discrepancies have been found between model simulations in terms of the spatial distribution of ice-nucleating aerosols, relative humidity, and temperature fluctuations, which contribute to different estimates of the aerosol indirect effect through cirrus clouds. In this presentation, four GCMs with the start-of-the art representations of cloud microphysics and aerosol-cloud interactions are used to estimate the aerosol indirect effects on cirrus clouds and to identify the causes of the discrepancies. The estimated global and annual mean anthropogenic aerosol indirect effect through cirrus clouds ranges from 0.1 W m-2 to 0.3 W m-2 in terms of the top-of-the-atmosphere (TOA) net radiation flux, and 0.5-0.6 W m-2 for the TOA longwave flux. Despite the good agreement on global mean, large discrepancies are found at the regional scale. The physics behind the aerosol indirect effect is dramatically different. Our analysis suggests that burden of ice-nucleating aerosols in the upper troposphere, ice nucleation frequency, and relative role of ice formation processes (i.e., homogeneous versus heterogeneous nucleation) play key roles in determining the characteristics of the simulated aerosol indirect effects. In addition to the indirect effect estimate, we also use field campaign

Aerosol Radiative Effects on Deep Convective Clouds and Associated Radiative Forcing

NASA Technical Reports Server (NTRS)

Fan, J.; Zhang, R.; Tao, W.-K.; Mohr, I.

2007-01-01

The aerosol radiative effects (ARE) on the deep convective clouds are investigated by using a spectral-bin cloud-resolving model (CRM) coupled with a radiation scheme and an explicit land surface model. The sensitivity of cloud properties and the associated radiative forcing to aerosol single-scattering albedo (SSA) are examined. The ARE on cloud properties is pronounced for mid-visible SSA of 0.85. Relative to the case excluding the ARE, cloud fraction and optical depth decrease by about 18% and 20%, respectively. Cloud droplet and ice particle number concentrations, liquid water path (LWP), ice water path (IWP), and droplet size decrease significantly when the ARE is introduced. The ARE causes a surface cooling of about 0.35 K and significantly high heating rates in the lower troposphere (about 0.6K/day higher at 2 km), both of which lead to a more stable atmosphere and hence weaker convection. The weaker convection and the more desiccation of cloud layers explain the less cloudiness, lower cloud optical depth, LWP and IWP, smaller droplet size, and less precipitation. The daytime-mean direct forcing induced by black carbon is about 2.2 W/sq m at the top of atmosphere (TOA) and -17.4 W/sq m at the surface for SSA of 0.85. The semi-direct forcing is positive, about 10 and 11.2 W/sq m at the TOA and surface, respectively. Both the TOA and surface total radiative forcing values are strongly negative for the deep convective clouds, attributed mostly to aerosol indirect forcing. Aerosol direct and semi-direct effects are very sensitive to SSA. Because the positive semi-direct forcing compensates the negative direct forcing at the surface, the surface temperature and heat fluxes decrease less significantly with the increase of aerosol absorption (decreasing SSA). The cloud fraction, optical depth, convective strength, and precipitation decrease with the increase of absorption, resulting from a more stable and dryer atmosphere due to enhanced surface cooling and

Isolating signatures of major cloud-cloud collisions using position-velocity diagrams

NASA Astrophysics Data System (ADS)

Haworth, T. J.; Tasker, E. J.; Fukui, Y.; Torii, K.; Dale, J. E.; Shima, K.; Takahira, K.; Habe, A.; Hasegawa, K.

2015-06-01

Collisions between giant molecular clouds are a potential mechanism for triggering the formation of massive stars, or even super star clusters. The trouble is identifying this process observationally and distinguishing it from other mechanisms. We produce synthetic position-velocity diagrams from models of cloud-cloud collisions, non-interacting clouds along the line of sight, clouds with internal radiative feedback and a more complex cloud evolving in a galactic disc, to try and identify unique signatures of collision. We find that a broad bridge feature connecting two intensity peaks, spatially correlated but separated in velocity, is a signature of a high-velocity cloud-cloud collision. We show that the broad bridge feature is resilient to the effects of radiative feedback, at least to around 2.5 Myr after the formation of the first massive (ionizing) star. However for a head-on 10 km s-1 collision, we find that this will only be observable from 20 to 30 per cent of viewing angles. Such broad-bridge features have been identified towards M20, a very young region of massive star formation that was concluded to be a site of cloud-cloud collision by Torii et al., and also towards star formation in the outer Milky Way by Izumi et al.

Short-range prediction of a heavy precipitation event by assimilating Chinese CINRAD-SA radar reflectivity data using complex cloud analysis

NASA Astrophysics Data System (ADS)

Sheng, C.; Gao, S.; Xue, M.

2006-11-01

With the ARPS (Advanced Regional Prediction System) Data Analysis System (ADAS) and its complex cloud analysis scheme, the reflectivity data from a Chinese CINRAD-SA Doppler radar are used to analyze 3D cloud and hydrometeor fields and in-cloud temperature and moisture. Forecast experiments starting from such initial conditions are performed for a northern China heavy rainfall event to examine the impact of the reflectivity data and other conventional observations on short-range precipitation forecast. The full 3D cloud analysis mitigates the commonly known spin-up problem with precipitation forecast, resulting a significant improvement in precipitation forecast in the first 4 to 5 hours. In such a case, the position, timing and amount of precipitation are all accurately predicted. When the cloud analysis is used without in-cloud temperature adjustment, only the forecast of light precipitation within the first hour is improved. Additional analysis of surface and upper-air observations on the native ARPS grid, using the 1 degree real-time NCEP AVN analysis as the background, helps improve the location and intensity of rainfall forecasting slightly. Hourly accumulated rainfall estimated from radar reflectivity data is found to be less accurate than the model predicted precipitation when full cloud analysis is used.

Validation of Quasi-Invariant Ice Cloud Radiative Quantities with MODIS Satellite-Based Cloud Property Retrievals

NASA Technical Reports Server (NTRS)

Ding, Jiachen; Yang, Ping; Kattawar, George W.; King, Michael D.; Platnick, Steven; Meyer, Kerry G.

2017-01-01

Similarity relations applied to ice cloud radiance calculations are theoretically analyzed and numerically validated. If t(1v) and t(1vg) are conserved where t is optical thickness, v the single-scattering albedo, and g the asymmetry factor, it is possible that substantially different phase functions may give rise to similar radiances in both conservative and non-conservative scattering cases, particularly in the case of large optical thicknesses. In addition to theoretical analysis, this study uses operational ice cloud optical thickness retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) Level 2 Collection5 (C5) and Collection 6 (C6) cloud property products to verify radiative similarity relations. It is found that, if the MODIS C5 and C6 ice cloud optical thickness values are multiplied by their respective (1wg)factors, the resultant products referred to as the effective optical thicknesses become similar with their ratio values around unity. Furthermore, the ratios of the C5 and C6 ice cloud effective optical thicknesses display an angular variation pattern similar to that of the corresponding ice cloud phase function ratios. The MODIS C5 and C6 values of ice cloud similarity parameter, defined as [(1w)(1(exp. 1/2)wg)]12, also tend to be similar.

Exploring Stratocumulus Cloud-Top Entrainment Processes and Parameterizations by Using Doppler Cloud Radar Observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Bruce; Fang, Ming; Ghate, Virendra

2016-02-01

the parameterizations to give hourly estimates of the entrainment rates using the radar derived vertical velocity variance and dissipation rates. Hourly entrainment rates were estimated from a convective velocity w* parameterization depends on the local surface buoyancy fluxes and the calculated radiative flux divergence, parameterization using a bulk coefficient obtained from the mean inversion height budget. The hourly rates from the cloud turbulence estimates and the w* parameterization, which is independent of the radar observations, are compared with the hourly we values from the budget. All show rough agreement with each other and capture the entrainment variability associated with substantial changes in the surface flux and radiative divergence at cloud top. Major uncertainties in the hourly estimates from the height budget and w* are discussed. The results indicate a strong potential for making entrainment rate estimates directly from the radar vertical velocity variance and the EDR measurements—a technique that has distinct advantages over other methods for estimating entrainment rates. Calculations based on the EDR alone can provide high temporal resolution (for averaging intervals as small as 10 minutes) of the entrainment processes and do not require an estimate of the boundary layer depth, which can be difficult to define when the boundary layer is decoupled.« less

A cloud collision model for water maser excitation.

PubMed

Tarter, J C; Welch, W J

1986-06-01

High-velocity collisions between small, dense, neutral clouds or between a dense cloud and a dense shell can provide the energy source required to excite H2O maser emission. The radiative precursor from the surface of the collisional shock front rapidly diffuses through the cloud, heating the dust grains but leaving the H2 molecules cool. Transient maser emission occurs as the conditions for the Goldreich and Kwan "hot-dust cold-gas" maser pump scheme are realized locally within the cloud. In time the local maser action quenches due to the heating of the H2 molecules by collisions against the grains. Although this model cannot explain the very long-lived steady maser features, it is quite successful in explaining a number of the observed properties of the high-velocity features in such sources as Orion, W51, and W49. In particular, it provides a natural explanation for the rapid time variations, the narrow line widths, juxtaposition of high- and low-velocity features, and the short lifetimes which are frequently observed for the so-called high-velocity maser "bullets" thought to be accelerated by strong stellar winds.

Large Eddy Simulation of Cirrus Clouds

NASA Technical Reports Server (NTRS)

Wu, Ting; Cotton, William R.

1999-01-01

heating could be comparable in magnitude in the cloudy layer. This implies that latent heating cannot be neglected in the construction of a cirrus cloud model. The probability density function (PDF) of w was analyzed to assist in the parameterization of cloud-scale velocities in large-scale models. For the more radiatively-driven, thin cirrus case, the PDFs are approximately Gaussian. However, in the interior of the deep, convectively unstable case, the PDFs of w are multi-modal and very broad, indicating that parameterizing cloud-scale motions for such clouds can be very challenging. The results of this research are described in detail in a paper submitted to the Journal of Atmospheric Science (Wu and Cotton, 1999), which is enclosed as Appendix 2. Using soundings extracted from a mesoscale simulation of the November 26, 1991 cirrus event, the radiative effects on vapor deposition/sublimation of ice crystals was studied using a two-dimensional cloud-resolving model (CRM) version of RAMS, coupled to an explicit bin-resolving microphysics. The CRM simulations of the November 26, 1991 cirrus event demonstrate that the radiative impact on the diffusional growth (or sublimation) of ice crystals is significant. In this case, the ice particles experienced radiative warming. Model results show that radiative feedbacks in the diffusional growth of ice particles can be very complex. Radiative warming of an ice particle will restrict the particle's diffusional growth. In the case of radiative warming, ice particles larger than a certain size will experience so much radiative warming that surface ice saturation vapor pressures become large enough to cause sublimation of the larger crystals, while smaller crystals are growing by vapor deposition. However, ice mass production can be enhanced in the case of radiative cooling of an ice particle. For the November 26, 1991 cirrus event, radiative feedback results in significant reduction in the total ice mass, especially in the production

The Complex Point Cloud for the Knowledge of the Architectural Heritage. Some Experiences

NASA Astrophysics Data System (ADS)

Aveta, C.; Salvatori, M.; Vitelli, G. P.

2017-05-01

The present paper aims to present a series of experiences and experimentations that a group of PhD from the University of Naples Federico II conducted over the past decade. This work has concerned the survey and the graphic restitution of monuments and works of art, finalized to their conservation. The targeted query of complex point cloud acquired by 3D scanners, integrated with photo sensors and thermal imaging, has allowed to explore new possibilities of investigation. In particular, we will present the scientific results of the experiments carried out on some important historical artifacts with distinct morphological and typological characteristics. According to aims and needs that emerged during the connotative process, with the support of archival and iconographic historical research, the laser scanner technology has been used in many different ways. New forms of representation, obtained directly from the point cloud, have been tested for the elaboration of thematic studies for documenting the pathologies and the decay of materials, for correlating visible aspects with invisible aspects of the artifact.

The Endoplasmic Reticulum Is a Reservoir for WAVE/SCAR Regulatory Complex Signaling in the Arabidopsis Leaf1[W][OA

PubMed Central

Zhang, Chunhua; Mallery, Eileen; Reagan, Sara; Boyko, Vitaly P.; Kotchoni, Simeon O.; Szymanski, Daniel B.

2013-01-01

During plant cell morphogenesis, signal transduction and cytoskeletal dynamics interact to locally organize the cytoplasm and define the geometry of cell expansion. The WAVE/SCAR (for WASP family verprolin homologous/suppressor of cyclic AMP receptor) regulatory complex (W/SRC) is an evolutionarily conserved heteromeric protein complex. Within the plant kingdom W/SRC is a broadly used effector that converts Rho-of-Plants (ROP)/Rac small GTPase signals into Actin-Related Protein2/3 and actin-dependent growth responses. Although the components and biochemistry of the W/SRC pathway are well understood, a basic understanding of how cells partition W/SRC into active and inactive pools is lacking. In this paper, we report that the endoplasmic reticulum (ER) is an important organelle for W/SRC regulation. We determined that a large intracellular pool of the core W/SRC subunit NAP1, like the known positive regulator of W/SRC, the DOCK family guanine nucleotide-exchange factor SPIKE1 (SPK1), localizes to the surface of the ER. The ER-associated NAP1 is inactive because it displays little colocalization with the actin network, and ER localization requires neither activating signals from SPK1 nor a physical association with its W/SRC-binding partner, SRA1. Our results indicate that in Arabidopsis (Arabidopsis thaliana) leaf pavement cells and trichomes, the ER is a reservoir for W/SRC signaling and may have a key role in the early steps of W/SRC assembly and/or activation. PMID:23613272

Fusion and quasifission studies for the 40Ca+186W,192Os reactions

NASA Astrophysics Data System (ADS)

Prasad, E.; Hinde, D. J.; Williams, E.; Dasgupta, M.; Carter, I. P.; Cook, K. J.; Jeung, D. Y.; Luong, D. H.; Palshetkar, C. S.; Rafferty, D. C.; Ramachandran, K.; Simenel, C.; Wakhle, A.

2017-09-01

Background: All elements above atomic number 113 have been synthesized using hot fusion reactions with calcium beams on statically deformed actinide target nuclei. Quasifission and fusion-fission are the two major mechanisms responsible for the very low production cross sections of superheavy elements. Purpose: To achieve a quantitative measurement of capture and quasifission characteristics as a function of beam energy in reactions forming heavy compound systems using calcium beams as projectiles. Methods: Fission fragment mass-angle distributions were measured for the two reactions 40Ca+186W and 40C+192Os, populating 226Pu and 232Cm compound nuclei, respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Mass ratio distributions, angular distributions, and total fission cross sections were obtained from the experimental data. Simulations to match the features of the experimental mass-angle distributions were performed using a classical phenomenological approach. Results: Both 40Ca+186W and 40C+192Os reactions show strong mass-angle correlations at all energies measured. A maximum fusion probability of 60 -70 % is estimated for the two reactions in the energy range of the present study. Coupled-channels calculations assuming standard Woods-Saxon potential parameters overpredict the capture cross sections. Large nuclear potential diffuseness parameters ˜1.5 fm are required to fit the total capture cross sections. The presence of a weak mass-asymmetric quasifission component attributed to the higher angular momentum events can be reproduced with a shorter average sticking time but longer mass-equilibration time constant. Conclusions: The deduced above-barrier capture cross sections suggest that the dissipative processes are already occurring outside the capture barrier. The mass-angle correlations indicate that a compact shape is not achieved for deformation aligned collisions with lower capture barriers

Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds.

PubMed

Fan, Jiwen; Leung, L Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

2013-11-26

Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol's thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ~27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3-5 W m(-2)) and a surface cooling (-5 to -8 W m(-2)). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments.

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

NASA Astrophysics Data System (ADS)

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.

40 CFR 721.10104 - Halophosphate mixed metal complex (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halophosphate mixed metal complex... Specific Chemical Substances § 721.10104 Halophosphate mixed metal complex (generic). (a) Chemical... as halophosphate mixed metal complex (PMN P-04-254) is subject to reporting under this section for...

40 CFR 721.10104 - Halophosphate mixed metal complex (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halophosphate mixed metal complex... Specific Chemical Substances § 721.10104 Halophosphate mixed metal complex (generic). (a) Chemical... as halophosphate mixed metal complex (PMN P-04-254) is subject to reporting under this section for...

40 CFR 721.10104 - Halophosphate mixed metal complex (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halophosphate mixed metal complex... Specific Chemical Substances § 721.10104 Halophosphate mixed metal complex (generic). (a) Chemical... as halophosphate mixed metal complex (PMN P-04-254) is subject to reporting under this section for...

40 CFR 721.10104 - Halophosphate mixed metal complex (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halophosphate mixed metal complex... Specific Chemical Substances § 721.10104 Halophosphate mixed metal complex (generic). (a) Chemical... as halophosphate mixed metal complex (PMN P-04-254) is subject to reporting under this section for...

40 CFR 721.10104 - Halophosphate mixed metal complex (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halophosphate mixed metal complex... Specific Chemical Substances § 721.10104 Halophosphate mixed metal complex (generic). (a) Chemical... as halophosphate mixed metal complex (PMN P-04-254) is subject to reporting under this section for...

Evidence for a Neutral Iron Line Generated by MeV Protons from Supernova Remnants Interacting with Molecular Clouds

NASA Astrophysics Data System (ADS)

Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Koyama, Katsuji; Yamauchi, Shigeo; Uchiyama, Hideki; Okon, Hiromichi; Tanaka, Takaaki; Uchida, Hiroyuki; Tsuru, Takeshi G.

2018-02-01

Supernova remnants (SNRs) have been prime candidates for Galactic cosmic-ray accelerators. When low-energy cosmic-ray protons (LECRp) collide with interstellar gas, they ionize neutral iron atoms and emit the neutral iron line (Fe I Kα) at 6.40 keV. We search for the iron K-shell line in seven SNRs from the Suzaku archive data of the Galactic plane in the 6^\\circ ≲ l≲ 40^\\circ ,| b| < 1^\\circ region. All of these SNRs interact with molecular clouds. We discover Fe I Kα line emissions from five SNRs (W28, Kes 67, Kes 69, Kes 78, and W44). The spectra and morphologies suggest that the Fe I Kα line is produced by interactions between LECRp and the adjacent cold gas. The proton energy density is estimated to be ≳10–100 eV cm‑3, which is more than 10 times higher than that in the ambient interstellar medium.

Refinement of the CALIOP cloud mask algorithm

NASA Astrophysics Data System (ADS)

Katagiri, Shuichiro; Sato, Kaori; Ohta, Kohei; Okamoto, Hajime

2018-04-01

A modified cloud mask algorithm was applied to the CALIOP data to have more ability to detect the clouds in the lower atmosphere. In this algorithm, we also adopt the fully attenuation discrimination and the remain noise estimation using the data obtained at an altitude of 40 km to avoid contamination of stratospheric aerosols. The new cloud mask shows an increase in the lower cloud fraction. Comparison of the results to the data observed with a PML ground observation was also made.

Learning in the Clouds?

ERIC Educational Resources Information Center

Butin, Dan W.

2013-01-01

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

Rain-shadow: An area harboring "Gray Ocean" clouds

NASA Astrophysics Data System (ADS)

Padmakumari, B.; Maheskumar, R. S.; Harikishan, G.; Morwal, S. B.; Kulkarni, J. R.

2018-06-01

The characteristics of monsoon convective clouds over the rain-shadow region of north peninsular India have been investigated using in situ aircraft cloud microphysical observations collected during Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX). The parameters considered for characterization are: liquid water content (LWC), cloud vertical motion (updraft, downdraft: w), cloud droplet number concentration (CDNC) and effective radius (Re). The results are based on 15 research flights which were conducted from the base station Hyderabad during summer monsoon season. The clouds studied were developing congestus. The clouds have low CDNC and low updraft values resembling the oceanic convective clouds. The super-saturation in clouds is found to be low (≤0.2%) due to low updrafts. The land surface behaves like ocean surface during monsoon as deduced from Bowen ratio. Microphysically the clouds showed oceanic characteristics. However, these clouds yield low rainfall due to their low efficiency (mean 14%). The cloud parameters showed a large variability; hence their characteristic values are reported in terms of median values. These values will serve the numerical models for rainfall simulations over the region and also will be useful as a scientific basis for cloud seeding operations to increase the rainfall efficiency. The study revealed that monsoon convective clouds over the rain-shadow region are of oceanic type over the gray land, and therefore we christen them as "Gray Ocean" clouds.

Further Research on the Electrification of Pyrocumulus Clouds

NASA Technical Reports Server (NTRS)

Lang, Timothy J.; Laroche, Kendell; Baum, Bryan; Bateman, Monte; Mach, Douglas

2015-01-01

Past research on pyrocumulus electrification has demonstrated that a variety of lightning types can occur, including cloud-to-ground (CG) flashes, sometimes of dominant positive polarity, as well as small intra-cloud (IC) discharges in the upper levels of the pyro-cloud. In Colorado during summer 2012, the first combined polarimetric radar, multi-Doppler radar, and three-dimensional lightning mapping array (LMA) observations of lightning-producing pyrocumulus were obtained. These observations suggested that the National Lightning Detection Network (NLDN) was not sensitive enough to detect the small IC flashes that appear to be the dominant mode of lightning in these clouds. However, after an upgrade to the network in late 2012, the NLDN began detecting some of this pyrocumulus lightning. Multiple pyrocumulus clouds documented by the University of Wisconsin for various fires in 2013 and 2014 (including over the Rim, West Fork Complex, Yarnell Hill, Hardluck, and several other incidents) are examined and reported on here. This study exploits the increased-sensitivity NLDN as well as the new nationwide U.S. network of polarimetric Next-generation Radars (NEXRADs). These observations document the common occurrence of a polarimetric "dirty ice" signature - modest reflectivities (20-40+ dBZ), near-zero differential reflectivity, and reduced correlation coefficient (less than 0.9) - prior to the production of lightning. This signature is indicative of a mixture of ash and ice particles in the upper levels of the pyro-cloud (less than -20 C), with the ice interpreted as being necessary for pyro-cloud electrification. Pseudo-Geostationary Lightning Mapper (GLM) data will be produced from the 2012 LMA observations, and the ability of GLM to detect small pyrocumulus ICs will be assessed. The utility of lightning and polarimetric radar for documenting rapid wildfire growth, as well as for documenting pyrocumulus impacts on the composition of the upper troposphere

An eight-month climatology of marine stratocumulus cloud fraction, albedo, and integrated liquid water

NASA Technical Reports Server (NTRS)

Fairall, C. W.; Hare, J. E.; Snider, Jack B.

1990-01-01

As part of the FIRE/Extended Time Observations (ETO) program, extended time observations were made at San Nicolas Island (SNI) from March to October, 1987. Hourly averages of air temperature, relative humidity, wind speed and direction, solar irradiance, and downward longwave irradiance were recorded. The radiation sensors were standard Eppley pyranometers (shortwave) and pyrgeometers (longwave). The SNI data were processed in several ways to deduce properties of the stratocumulus covered marine boundary layer (MBL). For example, from the temperature and humidity the lifting condensation level, which is an estimate of the height of the cloud bottom, can be computed. A combination of longwave irradiance statistics can be used to estimate fractional cloud cover. An analysis technique used to estimate the integrated cloud liquid water content (W) and the cloud albedo from the measured solar irradiance is also described. In this approach, the cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the same hour on a cloudless day. From the transmittance and the zenith angle, values of cloud albedo and W are computed using the radiative transfer parameterizations of Stephens (1978). These analysis algorithms were evaluated with 17 days of simultaneous and colocated mm-wave (20.6 and 31.65 GHz) radiometer measurements of W and lidar ceilometer measurements of cloud fraction and cloudbase height made during the FIRE IFO. The algorithms are then applied to the entire data set to produce a climatology of these cloud properties for the eight month period.

Titan Lingering Clouds

NASA Image and Video Library

2009-06-03

Lots of clouds are visible in this infrared image of Saturn's moon Titan. These clouds form and move much like those on Earth, but in a much slower, more lingering fashion, new results from NASA's Cassini spacecraft show. Scientists have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. The way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing—clouds are still noticeable in the southern hemisphere while fall is approaching. Three false-color images make up this mosaic and show the clouds at 40 to 50 degrees mid-latitude. The images were taken by Cassini's visual and infrared mapping spectrometer during a close flyby of Titan on Sept. 7, 2006, known as T17. For a similar view see PIA12005. Each image is a color composite, with red shown at the 2-micron wavelength, green at 1.6 microns, and blue at 2.8 microns. An infrared color mosaic is also used as a background (red at 5 microns, green at 2 microns and blue at 1.3 microns). The characteristic elongated mid-latitude clouds, which are easily visible in bright bluish tones are still active even late into 2006-2007. According to climate models, these clouds should have faded out since 2005. http://photojournal.jpl.nasa.gov/catalog/PIA12004

40 CFR 721.4594 - Substituted azo metal complex dye.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted azo metal complex dye. 721... Substances § 721.4594 Substituted azo metal complex dye. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted azo metal complex...

40 CFR 721.4594 - Substituted azo metal complex dye.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Substituted azo metal complex dye. 721... Substances § 721.4594 Substituted azo metal complex dye. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted azo metal complex...

Implications of the Khrgian-Mazin Distribution Function for Water Clouds and Distribution Consistencies With Aerosols and Rain

DTIC Science & Technology

1991-12-06

Preprints 14th Radar Meteorology Conf. Tucson, Amer. Meteor. Soc. 413-418. Findeisen , W. (1932) Measurement of the size and number of cloud drops for the...study of coagulation in non-homogeneous clouds. Gerl. Beitr. z Geophys. 35:295-340. Findeisen , W. (1938) Die kolloid-meteorologischen vorgtnge bei...der nieder-schlagsbildung. Meteor. Z. 55:12 1-135. Findeisen , W. (1939) Zur Frage der Regentropfenbildung in reinen Wasserwolken. Meteor. Z. 56:365-368

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

DOE PAGES

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

2017-05-08

A near-global aquaplanet cloud-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate cloud feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S–N. It produces plausible mean distributions of clouds, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO 2. The Intertropical Convergence Zone width and tropical cloud covermore » are not strongly affected by SST warming or CO 2 increase, except for the expected upward shift in high clouds with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low cloud fraction and in-cloud liquid water content but decreases midlatitude cloud, yielding slightly positive domain-mean shortwave cloud feedbacks. CO 2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low cloud fraction. Warming-induced low cloud changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary layer radiative cooling in the warmer climate accompanies the robust subtropical low cloud increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

A near-global aquaplanet cloud-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate cloud feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S–N. It produces plausible mean distributions of clouds, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO 2. The Intertropical Convergence Zone width and tropical cloud covermore » are not strongly affected by SST warming or CO 2 increase, except for the expected upward shift in high clouds with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low cloud fraction and in-cloud liquid water content but decreases midlatitude cloud, yielding slightly positive domain-mean shortwave cloud feedbacks. CO 2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low cloud fraction. Warming-induced low cloud changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary layer radiative cooling in the warmer climate accompanies the robust subtropical low cloud increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate.« less

A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho-Gaia Astrometric Solution

NASA Astrophysics Data System (ADS)

Voirin, Jordan; Manara, Carlo F.; Prusti, Timo

2018-03-01

Context. The determination of the distance to dark star-forming clouds is a key parameter to derive the properties of the cloud itself and of its stellar content. This parameter is still loosely constrained even in nearby star-forming regions. Aim. We want to determine the distances to the clouds in the Chamaeleon-Musca complex and explore the connection between these clouds and the large-scale cloud structures in the Galaxy. Methods: We used the newly estimated distances obtained from the parallaxes measured by the Gaia satellite and included in the Tycho-Gaia Astrometric Solution catalog. When known members of a region are included in this catalog we used their distances to infer the distance to the cloud. Otherwise, we analyzed the dependence of the color excess on the distance of the stars and looked for a turn-on of this excess, which is a proxy of the position of the front-edge of the star-forming cloud. Results: We are able to measure the distance to the three Chamaeleon clouds. The distance to Chamaeleon I is 179-10-10+11+11 pc, where the quoted uncertainties are statistical and systematic uncertainties, respectively, 20 pc further away than previously assumed. The Chamaeleon II cloud is located at the distance of 181-5-10+6+11 pc, which agrees with previous estimates. We are able to measure for the first time a distance to the Chamaeleon III cloud of 199-7-11+8+12 pc. Finally, the distance of the Musca cloud is smaller than 603-70-92+91+133 pc. These estimates do not allow us to distinguish between the possibility that the Chamaeleon clouds are part of a sheet of clouds parallel to the Galactic plane, or perpendicular to it. Conclusions: We measured a larger distance to the Chamaeleon I cloud than assumed in the past, confirmed the distance to the Chamaeleon II region, and measured for the first time the distance to the Chamaleon III cloud. These values are consistent with the scenario in which the three clouds are part of a single large-scale structure

Mie Lidar for Aerosols and Clouds Monitoring at Otlica Observatory

NASA Astrophysics Data System (ADS)

Gao, F.; Stanič, S.; Bergant, K.; Filipčič, A.; Veberič, D.; Forte, B.

2009-04-01

Aerosol and cloud densities are the most important atmospheric parameters, which significantly influence the atmospheric conditions. The study of their spatial and temporal properties can provide detailed information about the transport processes of the air masses. In recent years, lidar techniques for remote sensing of the atmospheric parameters have been greatly improved. Like the lidar systems of the Pierre Auger Observatory in Argentina (35.2S, 69.1W, 1400 m a.s.l.), the Mie lidar built at Otlica Observatory (45.93N, 13.91E, 945 m a.s.l.) in Slovenia employs the same hardware, including the transmitter, the receiver, and the DAQ system. Due to its high-power laser, large-diameter telescope, and photon-counting data-acquisition technique, the Mie lidar has the potential ability to measure the tropospheric and stratospheric atmospheric conditions, and is suitable for monitoring the changes of the cirrus clouds and atmospheric boundary layer. We have been performing routine atmospheric monitoring experiments with the Otlica Mie lidar since September 2008. Using the techniques of event-averaging, noise-elimination, and data-gluing, the far end of lidar probing range is extended from 30 km up to 40 km. The extinction profiles are calculated using the Klett method and the time-height-intensity plots were made. They clearly show the evolution of atmospheric conditions, especially the motion of the cirrus clouds above Otlica.

CLUSTOM-CLOUD: In-Memory Data Grid-Based Software for Clustering 16S rRNA Sequence Data in the Cloud Environment.

PubMed

Oh, Jeongsu; Choi, Chi-Hwan; Park, Min-Kyu; Kim, Byung Kwon; Hwang, Kyuin; Lee, Sang-Heon; Hong, Soon Gyu; Nasir, Arshan; Cho, Wan-Sup; Kim, Kyung Mo

2016-01-01

High-throughput sequencing can produce hundreds of thousands of 16S rRNA sequence reads corresponding to different organisms present in the environmental samples. Typically, analysis of microbial diversity in bioinformatics starts from pre-processing followed by clustering 16S rRNA reads into relatively fewer operational taxonomic units (OTUs). The OTUs are reliable indicators of microbial diversity and greatly accelerate the downstream analysis time. However, existing hierarchical clustering algorithms that are generally more accurate than greedy heuristic algorithms struggle with large sequence datasets. To keep pace with the rapid rise in sequencing data, we present CLUSTOM-CLOUD, which is the first distributed sequence clustering program based on In-Memory Data Grid (IMDG) technology-a distributed data structure to store all data in the main memory of multiple computing nodes. The IMDG technology helps CLUSTOM-CLOUD to enhance both its capability of handling larger datasets and its computational scalability better than its ancestor, CLUSTOM, while maintaining high accuracy. Clustering speed of CLUSTOM-CLOUD was evaluated on published 16S rRNA human microbiome sequence datasets using the small laboratory cluster (10 nodes) and under the Amazon EC2 cloud-computing environments. Under the laboratory environment, it required only ~3 hours to process dataset of size 200 K reads regardless of the complexity of the human microbiome data. In turn, one million reads were processed in approximately 20, 14, and 11 hours when utilizing 20, 30, and 40 nodes on the Amazon EC2 cloud-computing environment. The running time evaluation indicates that CLUSTOM-CLOUD can handle much larger sequence datasets than CLUSTOM and is also a scalable distributed processing system. The comparative accuracy test using 16S rRNA pyrosequences of a mock community shows that CLUSTOM-CLOUD achieves higher accuracy than DOTUR, mothur, ESPRIT-Tree, UCLUST and Swarm. CLUSTOM-CLOUD is written in JAVA

CLUSTOM-CLOUD: In-Memory Data Grid-Based Software for Clustering 16S rRNA Sequence Data in the Cloud Environment

PubMed Central

Park, Min-Kyu; Kim, Byung Kwon; Hwang, Kyuin; Lee, Sang-Heon; Hong, Soon Gyu; Nasir, Arshan; Cho, Wan-Sup; Kim, Kyung Mo

2016-01-01

High-throughput sequencing can produce hundreds of thousands of 16S rRNA sequence reads corresponding to different organisms present in the environmental samples. Typically, analysis of microbial diversity in bioinformatics starts from pre-processing followed by clustering 16S rRNA reads into relatively fewer operational taxonomic units (OTUs). The OTUs are reliable indicators of microbial diversity and greatly accelerate the downstream analysis time. However, existing hierarchical clustering algorithms that are generally more accurate than greedy heuristic algorithms struggle with large sequence datasets. To keep pace with the rapid rise in sequencing data, we present CLUSTOM-CLOUD, which is the first distributed sequence clustering program based on In-Memory Data Grid (IMDG) technology–a distributed data structure to store all data in the main memory of multiple computing nodes. The IMDG technology helps CLUSTOM-CLOUD to enhance both its capability of handling larger datasets and its computational scalability better than its ancestor, CLUSTOM, while maintaining high accuracy. Clustering speed of CLUSTOM-CLOUD was evaluated on published 16S rRNA human microbiome sequence datasets using the small laboratory cluster (10 nodes) and under the Amazon EC2 cloud-computing environments. Under the laboratory environment, it required only ~3 hours to process dataset of size 200 K reads regardless of the complexity of the human microbiome data. In turn, one million reads were processed in approximately 20, 14, and 11 hours when utilizing 20, 30, and 40 nodes on the Amazon EC2 cloud-computing environment. The running time evaluation indicates that CLUSTOM-CLOUD can handle much larger sequence datasets than CLUSTOM and is also a scalable distributed processing system. The comparative accuracy test using 16S rRNA pyrosequences of a mock community shows that CLUSTOM-CLOUD achieves higher accuracy than DOTUR, mothur, ESPRIT-Tree, UCLUST and Swarm. CLUSTOM-CLOUD is written in

Impact of varying lidar measurement and data processing techniques in evaluating cirrus cloud and aerosol direct radiative effects

NASA Astrophysics Data System (ADS)

Lolli, Simone; Madonna, Fabio; Rosoldi, Marco; Campbell, James R.; Welton, Ellsworth J.; Lewis, Jasper R.; Gu, Yu; Pappalardo, Gelsomina

2018-03-01

In the past 2 decades, ground-based lidar networks have drastically increased in scope and relevance, thanks primarily to the advent of lidar observations from space and their need for validation. Lidar observations of aerosol and cloud geometrical, optical and microphysical atmospheric properties are subsequently used to evaluate their direct radiative effects on climate. However, the retrievals are strongly dependent on the lidar instrument measurement technique and subsequent data processing methodologies. In this paper, we evaluate the discrepancies between the use of Raman and elastic lidar measurement techniques and corresponding data processing methods for two aerosol layers in the free troposphere and for two cirrus clouds with different optical depths. Results show that the different lidar techniques are responsible for discrepancies in the model-derived direct radiative effects for biomass burning (0.05 W m-2 at surface and 0.007 W m-2 at top of the atmosphere) and dust aerosol layers (0.7 W m-2 at surface and 0.85 W m-2 at top of the atmosphere). Data processing is further responsible for discrepancies in both thin (0.55 W m-2 at surface and 2.7 W m-2 at top of the atmosphere) and opaque (7.7 W m-2 at surface and 11.8 W m-2 at top of the atmosphere) cirrus clouds. Direct radiative effect discrepancies can be attributed to the larger variability of the lidar ratio for aerosols (20-150 sr) than for clouds (20-35 sr). For this reason, the influence of the applied lidar technique plays a more fundamental role in aerosol monitoring because the lidar ratio must be retrieved with relatively high accuracy. In contrast, for cirrus clouds, with the lidar ratio being much less variable, the data processing is critical because smoothing it modifies the aerosol and cloud vertically resolved extinction profile that is used as input to compute direct radiative effect calculations.

Aerosol-Cloud Interactions and Cloud Microphysical Properties in the Asir Region of Saudi Arabia

NASA Astrophysics Data System (ADS)

Kucera, P. A.; Axisa, D.; Burger, R. P.; Li, R.; Collins, D. R.; Freney, E. J.; Buseck, P. R.

2009-12-01

In recent advertent and inadvertent weather modification studies, a considerable effort has been made to understand the impact of varying aerosol properties and concentration on cloud properties. Significant uncertainties exist with aerosol-cloud interactions for which complex microphysical processes link the aerosol and cloud properties. Under almost all environmental conditions, increased aerosol concentrations within polluted air masses will enhance cloud droplet concentration relative to that in unperturbed regions. The interaction between dust particles and clouds are significant, yet the conditions in which dust particles become cloud condensation nuclei (CCN) are uncertain. In order to quantify this aerosol effect on clouds and precipitation, a field campaign was launched in the Asir region, located adjacent to the Red Sea in the southwest region of Saudi Arabia. Ground measurements of aerosol size distributions, hygroscopic growth factors, CCN concentrations as well as aircraft measurements of cloud hydrometeor size distributions were observed in the Asir region in August 2009. The presentation will include a summary of the analysis and results with a focus on aerosol-cloud interactions and cloud microphysical properties observed during the convective season in the Asir region.

DEAD-box helicase DDX27 regulates 3′ end formation of ribosomal 47S RNA and stably associates with the PeBoW-complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kellner, Markus; Rohrmoser, Michaela; Forné, Ignasi

PeBoW, a trimeric complex consisting of pescadillo (Pes1), block of proliferation (Bop1), and the WD repeat protein 12 (WDR12), is essential for processing and maturation of mammalian 5.8S and 28S ribosomal RNAs. Applying a mass spectrometric analysis, we identified the DEAD-box helicase DDX27 as stably associated factor of the PeBoW-complex. DDX27 interacts with the PeBoW-complex via an evolutionary conserved F×F motif in the N-terminal domain and is recruited to the nucleolus via its basic C-terminal domain. This recruitment is RNA-dependent and occurs independently of the PeBoW-complex. Interestingly, knockdown of DDX27, but not of Pes1, induces the accumulation of an extendedmore » form of the primary 47S rRNA. We conclude that DDX27 can interact specifically with the Pes1 and Bop1 but fulfils critical function(s) for proper 3′ end formation of 47S rRNA independently of the PeBoW-complex. - Highlights: • DEAD-box helicase DDX27 is a new constituent of the PeBoW-complex. • The N-terminal F×F motif of DDX27 interacts with the PeBoW components Pes1 and Bop1. • Nucleolar anchoring of DDX27 via its basic C-terminal domain is RNA dependent. • Knockdown of DDX27 induces a specific defect in 3′ end formation of 47S rRNA.« less

Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Cloud Classification System

NASA Astrophysics Data System (ADS)

Hong, Yang

Precipitation estimation from satellite information (VISIBLE , IR, or microwave) is becoming increasingly imperative because of its high spatial/temporal resolution and board coverage unparalleled by ground-based data. After decades' efforts of rainfall estimation using IR imagery as basis, it has been explored and concluded that the limitations/uncertainty of the existing techniques are: (1) pixel-based local-scale feature extraction; (2) IR temperature threshold to define rain/no-rain clouds; (3) indirect relationship between rain rate and cloud-top temperature; (4) lumped techniques to model high variability of cloud-precipitation processes; (5) coarse scales of rainfall products. As continuing studies, a new version of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network (PERSIANN), called Cloud Classification System (CCS), has been developed to cope with these limitations in this dissertation. CCS includes three consecutive components: (1) a hybrid segmentation algorithm, namely Hierarchically Topographical Thresholding and Stepwise Seeded Region Growing (HTH-SSRG), to segment satellite IR images into separated cloud patches; (2) a 3D feature extraction procedure to retrieve both pixel-based local-scale and patch-based large-scale features of cloud patch at various heights; (3) an ANN model, Self-Organizing Nonlinear Output (SONO) network, to classify cloud patches into similarity-based clusters, using Self-Organizing Feature Map (SOFM), and then calibrate hundreds of multi-parameter nonlinear functions to identify the relationship between every cloud types and their underneath precipitation characteristics using Probability Matching Method and Multi-Start Downhill Simplex optimization techniques. The model was calibrated over the Southwest of United States (100°--130°W and 25°--45°N) first and then adaptively adjusted to the study region of North America Monsoon Experiment (65°--135°W and 10°--50°N) using

Explicit prediction of ice clouds in general circulation models

NASA Astrophysics Data System (ADS)

Kohler, Martin

1999-11-01

) and falling snow (diagnosed) components. An empirical parameterization of the effect of upward turbulent water fluxes in cloud layers is obtained from the CRM simulations by (1) identifying the time-scale of conversion of cloud ice to snow as the key parameter, and (2) regressing it onto cloud differential IR heating and environmental static stability. The updated UCLA-GCM achieves close agreement with observations in global mean top of atmosphere fluxes (within 1--4 W/m2). Artificially suppressing the impact of cloud turbulent fluxes reduces the global mean ice water path by a factor of 3 and produces errors in each of solar and IR fluxes at the top of atmosphere of about 5--6 W/m2.

W-band spaceborne radar observations of atmospheric river events

NASA Astrophysics Data System (ADS)

Matrosov, S. Y.

2010-12-01

While the main objective of the world first W-band radar aboard the CloudSat satellite is to provide vertically resolved information on clouds, it proved to be a valuable tool for observing precipitation. The CloudSat radar is generally able to resolve precipitating cloud systems in their vertical entirety. Although measurements from the liquid hydrometer layer containing rainfall are strongly attenuated, special retrieval approaches can be used to estimate rainfall parameters. These approaches are based on vertical gradients of observed radar reflectivity factor rather than on absolute estimates of reflectivity. Concurrent independent estimations of ice cloud parameters in the same vertical column allow characterization of precipitating systems and provide information on coupling between clouds and rainfall they produce. The potential of CloudSat for observations atmospheric river events affecting the West Coast of North America is evaluated. It is shown that spaceborne radar measurements can provide high resolution information on the height of the freezing level thus separating areas of rainfall and snowfall. CloudSat precipitation rate estimates complement information from the surface-based radars. Observations of atmospheric rivers at different locations above the ocean and during landfall help to understand evolutions of atmospheric rivers and their structures.

THE O- AND B-TYPE STELLAR POPULATION IN W3: BEYOND THE HIGH-DENSITY LAYER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiminki, Megan M.; Kim, Jinyoung Serena; Bagley, Micaela B.

2015-11-01

We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an R{sub V} of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecularmore » cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H ii region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8–10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially variable nebular emission.« less

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

NASA Astrophysics Data System (ADS)

Yun, Yuxing; Penner, Joyce E.

2012-04-01

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

Looking Down Through the Clouds – Optical Attenuation through Real-Time Clouds

NASA Astrophysics Data System (ADS)

Burley, J.; Lazarewicz, A.; Dean, D.; Heath, N.

Detecting and identifying nuclear explosions in the atmosphere and on the surface of the Earth is critical for the Air Force Technical Applications Center (AFTAC) treaty monitoring mission. Optical signals, from surface or atmospheric nuclear explosions detected by satellite sensors, are attenuated by the atmosphere and clouds. Clouds present a particularly complex challenge as they cover up to seventy percent of the earth's surface. Moreover, their highly variable and diverse nature requires physics-based modeling. Determining the attenuation for each optical ray-path is uniquely dependent on the source geolocation, the specific optical transmission characteristics along that ray path, and sensor detection capabilities. This research details a collaborative AFTAC and AFIT effort to fuse worldwide weather data, from a variety of sources, to provide near-real-time profiles of atmospheric and cloud conditions and the resulting radiative transfer analysis for virtually any wavelength(s) of interest from source to satellite. AFIT has developed a means to model global clouds using the U.S. Air Force’s World Wide Merged Cloud Analysis (WWMCA) cloud data in a new toolset that enables radiance calculations through clouds from UV to RF wavelengths.

The influence of Cloud Longwave Scattering together with a state-of-the-art Ice Longwave Optical Parameterization in Climate Model Simulations

NASA Astrophysics Data System (ADS)

Chen, Y. H.; Kuo, C. P.; Huang, X.; Yang, P.

2017-12-01

Clouds play an important role in the Earth's radiation budget, and thus realistic and comprehensive treatments of cloud optical properties and cloud-sky radiative transfer are crucial for simulating weather and climate. However, most GCMs neglect LW scattering effects by clouds and tend to use inconsistent cloud SW and LW optical parameterizations. Recently, co-authors of this study have developed a new LW optical properties parameterization for ice clouds, which is based on ice cloud particle statistics from MODIS measurements and state-of-the-art scattering calculation. A two-stream multiple-scattering scheme has also been implemented into the RRTMG_LW, a widely used longwave radiation scheme by climate modeling centers. This study is to integrate both the new LW cloud-radiation scheme for ice clouds and the modified RRTMG_LW with scattering capability into the NCAR CESM to improve the cloud longwave radiation treatment. A number of single column model (SCM) simulations using the observation from the ARM SGP site on July 18 to August 4 in 1995 are carried out to assess the impact of new LW optical properties of clouds and scattering-enabled radiation scheme on simulated radiation budget and cloud radiative effect (CRE). The SCM simulation allows interaction between cloud and radiation schemes with other parameterizations, but the large-scale forcing is prescribed or nudged. Comparing to the results from the SCM of the standard CESM, the new ice cloud optical properties alone leads to an increase of LW CRE by 26.85 W m-2 in average, as well as an increase of the downward LW flux at surface by 6.48 W m-2. Enabling LW cloud scattering further increases the LW CRE by another 3.57 W m-2 and the downward LW flux at the surface by 0.2 W m-2. The change of LW CRE is mainly due to an increase of cloud top height, which enhances the LW CRE. A long-term simulation of CESM will be carried out to further understand the impact of such changes on simulated climates.

Spitzer c2d Legacy, Circumstellar Disks around wTT Stars

NASA Astrophysics Data System (ADS)

Wahhaj, Zahed; c2d Legacy Team

2007-05-01

The Spitzer Legacy Project From "Molecular Cores to Planet-forming Disks" conducted a 3.6 to 70um photometric survey of roughly 160 weak- line TTauri Stars (wTTs) and 20 classical TTauri stars (cTTs) in the nearby star-forming regions Chamaeleon, Lupus, Ophiuchus and Taurus. WTTs are so named because they possess weaker H-alpha emission lines signifying weaker disk accretion on to the star than cTTs. The evolution of dust disks around these young stars (Age 10 Myrs) is key to understanding planet formation. From the observed infrared excesses, we infer the presence of circumstellar disks around 12% of wTTs and 75% of cTTs. However, when considering on-cloud sources only, the wTTs disk fraction is 22%, while it is only 6% for off- cloud sources, suggesting an older age for the latter. WTTs, while not discernibly younger than cTTs in age diagnostics, in general have disks which exhibit lower fractional luminosities and larger inner clearings. However, quite a few wTTs systems have fractional disk luminosities as high as cTTs systems. In light of these findings, wTTs seem to be transitional objects between cTTs and debris disks.

Downward solar global irradiance at the surface in São Paulo city—The climatological effects of aerosol and clouds

NASA Astrophysics Data System (ADS)

Yamasoe, M. A.; do Rosário, N. M. E.; Barros, K. M.

2017-01-01

We analyzed the variability of downward solar irradiance reaching the surface at São Paulo city, Brazil, and estimated the climatological aerosol and cloud radiative effects. Eleven years of irradiance were analyzed, from 2005 to 2015. To distinguish the aerosol from the cloud effect, the radiative transfer code LibRadtran was used to calculate downward solar irradiance. Two runs were performed, one considering only ozone and water vapor daily variability, with AOD set to zero and the second allowing the three variables to change, according to mean climatological values. The difference of the 24 h mean irradiance calculated with and without aerosol resulted in the shortwave aerosol direct radiative effect, while the difference between the measured and calculated, including the aerosol, represented the cloud effect. Results showed that, climatologically, clouds can be 4 times more effective than aerosols. The cloud shortwave radiative effect presented a maximum reduction of about -170 W m-2 in January and a minimum in July, of -37 W m-2. The aerosol direct radiative effect was maximum in spring, when the transport of smoke from the Amazon and central parts of South America is frequent toward São Paulo. Around mid-September, the 24 h radiative effect due to aerosol only was estimated to be -50 W m-2. Throughout the rest of the year, the mean aerosol effect was around -20 W m-2 and was attributed to local urban sources. The effect of the cloud fraction on the cloud modification factor, defined as the ratio of all-sky irradiation to cloudless sky irradiation, showed dependence on the cloud height. Low clouds presented the highest impact while the presence of high clouds only almost did not affect solar transmittance, even in overcast conditions.

Zero-gravity cloud physics.

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

Thin ice clouds in the Arctic: cloud optical depth and particle size retrieved from ground-based thermal infrared radiometry

NASA Astrophysics Data System (ADS)

Blanchard, Yann; Royer, Alain; O'Neill, Norman T.; Turner, David D.; Eloranta, Edwin W.

2017-06-01

Multiband downwelling thermal measurements of zenith sky radiance, along with cloud boundary heights, were used in a retrieval algorithm to estimate cloud optical depth and effective particle diameter of thin ice clouds in the Canadian High Arctic. Ground-based thermal infrared (IR) radiances for 150 semitransparent ice clouds cases were acquired at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada (80° N, 86° W). We analyzed and quantified the sensitivity of downwelling thermal radiance to several cloud parameters including optical depth, effective particle diameter and shape, water vapor content, cloud geometric thickness and cloud base altitude. A lookup table retrieval method was used to successfully extract, through an optimal estimation method, cloud optical depth up to a maximum value of 2.6 and to separate thin ice clouds into two classes: (1) TIC1 clouds characterized by small crystals (effective particle diameter ≤ 30 µm), and (2) TIC2 clouds characterized by large ice crystals (effective particle diameter > 30 µm). The retrieval technique was validated using data from the Arctic High Spectral Resolution Lidar (AHSRL) and Millimeter Wave Cloud Radar (MMCR). Inversions were performed over three polar winters and results showed a significant correlation (R2 = 0.95) for cloud optical depth retrievals and an overall accuracy of 83 % for the classification of TIC1 and TIC2 clouds. A partial validation relative to an algorithm based on high spectral resolution downwelling IR radiance measurements between 8 and 21 µm was also performed. It confirms the robustness of the optical depth retrieval and the fact that the broadband thermal radiometer retrieval was sensitive to small particle (TIC1) sizes.

Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

NASA Astrophysics Data System (ADS)

Tang, Wenjun; Qin, Jun; Yang, Kun; Liu, Shaomin; Lu, Ning; Niu, Xiaolei

2016-03-01

Cloud parameters (cloud mask, effective particle radius, and liquid/ice water path) are the important inputs in estimating surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy, but their temporal resolution is too low to obtain high-temporal-resolution SSR retrievals. In order to obtain hourly cloud parameters, an artificial neural network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multifunctional Transport Satellite (MTSAT) geostationary satellite signals. In addition, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone) are input to the model, we can derive SSR at high spatiotemporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (or 5.4 %); the RMSEs in daily and monthly mean SSR estimates are 34.2 W m-2 (or 19.1 %) and 22.1 W m-2 (or 12.3 %), respectively. The accuracy is comparable to or even higher than two other radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

NASA Astrophysics Data System (ADS)

Tang, W.; Qin, J.; Yang, K.; Liu, S.; Lu, N.; Niu, X.

2015-12-01

Cloud parameters (cloud mask, effective particle radius and liquid/ice water path) are the important inputs in determining surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy but their temporal resolution is too low to obtain high temporal resolution SSR retrievals. In order to obtain hourly cloud parameters, the Artificial Neural Network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multi-functional Transport Satellite (MTSAT) geostationary satellite signals. Meanwhile, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone and so on) are input to the model, we can derive SSR at high spatio-temporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River Basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (5.4 %); the RMSEs in daily and monthly-mean SSR estimates are 34.2 W m-2 (19.1 %) and 22.1 W m-2 (12.3 %), respectively. The accuracy is comparable or even higher than other two radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

AIRS Water Vapor and Cloud Products Validate and Explain Recent Short Term Decreases in Global and Tropical OLR as Observed by CERES

NASA Technical Reports Server (NTRS)

Susskind, Joel; Molnar, Gyula; Iredell, Lena

2010-01-01

A strong equatorial SST cooling occurred from 160E westward to 120W during the period of September 2002 through August 2010, surrounded by a weaker warming ring to the west. This is the result of a transition from a strong El Nino in late 2002 to a strong La Nina in 2008. Late 2009 is characterized by the beginning of another El Nino. Average rates of change (ARC's) in 500mb specific humidity and cloud cover are in phase with those in the Sea surface temperature (SST). In the El Nino and surrounding region causing outgoing longwave radiation (OLR), to decrease significantly near the dateline and increase in the vicinity of Indonesia. Tropical OLR ARC's in these two areas cancel each other to first order. The negative zonal mean tropical OLR ARC from a drop in equatorial OLR in region 1 from 140W to 40E. This results from increasing water vapor and cloud cover in this area during La Nina with the reverse holding during El Nino.

Discovery of lake-effect clouds on Titan

USGS Publications Warehouse

Brown, M.E.; Schaller, E.L.; Roe, H.G.; Chen, C.; Roberts, J.; Brown, R.H.; Baines, K.H.; Clark, R.N.

2009-01-01

Images from instruments on Cassini as well as from telescopes on the ground reveal the presence of sporadic small-scale cloud activity in the cold late-winter north polar region of Saturn's large moon Titan. These clouds lie underneath the previously discovered uniform polar cloud attributed to a quiescent ethane cloud at ???40 km and appear confined to the same latitudes as those of the largest known hydrocarbon lakes at the north pole of Titan. The physical properties of these clouds suggest that they are due to methane convection and condensation. Such convection could be caused by a process in some ways analogous to terrestrial lake-effect clouds. The lakes on Titan could be a key connection between the surface and the meteorological cycle. ?? 2009 by the American Geophysical Union.

Polarization of seven MBM clouds at high Galactic latitude

NASA Astrophysics Data System (ADS)

Neha, S.; Maheswar, G.; Soam, A.; Lee, C. W.

2018-06-01

We made R-band polarization measurements of 234 stars towards the direction of the MBM 33-39 cloud complex. The distance of the MBM 33-39 complex was determined as 120 ± 10 pc using polarization results and near-infrared photometry from the 2MASS survey. The magnetic field geometry of the individual clouds inferred from our polarimetric results reveals that the field lines are in general consistent with the global magnetic field geometry of the region obtained from previous studies. This implies that the clouds in the complex are permeated by the interstellar magnetic field. Multi-wavelength polarization measurements of a few stars projected on to the complex suggest that the size of the dust grains in these clouds is similar to those found in the normal interstellar medium of the Milky Way. We studied a possible formation scenario of the MBM 33-39 complex by combining the polarization results from our study with those from the literature and by identifying the distribution of ionized, atomic and molecular (dust) components of material in the region.

Evolved massive stars in W33 and in GMC 23.3-0.3

NASA Astrophysics Data System (ADS)

Messineo, Maria; Clark, J. Simon; Figer, Donald F.; Menten, Karl M.; Kudritzki, Rolf-Peter; Najarro, Francisco; Rich, Michael; Ivanov, Valentin D.; Valenti, Elena; Trombley, Christine; Chen, Rosie; Davies, Ben; MacKenty, John W.

2015-08-01

We have conducted an infrared spectroscopic survey for massive evolved stars and/or clusters in the Galactic giant molecular clouds G23.3-0.3 and W33. A large number of extraordinary sub-clumps/clusters of massive stars were detected. The spatial and temporal distribution of these massive stars yields information on the star formation history of the clouds.In G23.3-0.3, we discovered a dozen massive O-type stars, one candidate luminous blue variable, and several red supergiants. The O-type stars have masses from 25 to 50 Msun and ages of 5-8 Myr, while the RSGs belong to a burst that occurred 20-30 Myr ago. Therefore, GMC G23.3-0.3 has had one of the longest known histories of star formation (20-30 Myr). GMC G23.3-0.3 is rich in HII regions and supernova remnants; we detected massive stars in the cores of SNR W41 and of SNR G22.7-0.2.In W33, we detected a few evolved O-type stars and one Wolf-Rayet star, but none of the late-type objects has the luminosity of a red supergiant. W33 is characterized by discrete sources and has had at least 3-5 Myr of star formation history, which is now propagating from west to east. While our detections of massive evolved stars in W33 are made on the west side of the cloud, several dense molecular cores that may harbor proto clusters have recently been detected on the east side of the cloud by Immer et al. (2014).Messineo, Maria; Menten, Karl M.; Figer, Donald F.; Davies, Ben; Clark, J. Simon; Ivanov, Valentin D.Kudritzki, Rolf-Peter; Rich, R. Michael; MacKenty, John W.; Trombley, Christine 2014A&A...569A..20MMessineo, Maria; Clark, J. Simon; Figer, Donald F.; Kudritzki, Rolf-Peter; Francisco, Najarro; Rich, R. Michael; Menten, Karl M.; Ivanov, Valentin D.; Valenti, Elena; Trombley, Christine; Chen, C.H. Rosie; Davies, Ben; submitted to ApJ.

Interaction of a supernova shock with two interstellar clouds

NASA Astrophysics Data System (ADS)

Hansen, J. F.; McKee, C. F.

2005-10-01

The interaction of supernova shocks and interstellar clouds is an important astrophysical phenomenon since it can result in stellar and planetary formation. Our experiments attempt to simulate this mass-loading as it occurs when a shock passes through interstellar clouds. We drive a strong shock using a 5 kJ laser into a foam-filled cylinder with embedded Al spheres (diameter D=120 μm) simulating interstellar clouds. The density ratio between Al and foam is ˜9. We have previously reported on the interaction between shock and a single cloud, and the ensuing Kelvin-Helmholtz and Widnall instabilities. We now report on experiments under way in which two clouds are placed side by side. Cloud separation (center to center) is either 1.2xD or 1.5xD. Initial results for 1.2xD show that cloud material merges and travels further downstream than in the single cloud case. For 1.5xD, material does not merge, but the clouds tilt toward each other. Work performed under the auspices of the Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.

Hole-boring through clouds for laser power beaming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipinski, R.J.; Walter, R.F.

Power beaming to satellites with a ground-based laser can be limited by clouds. Hole-boring through the clouds with a laser has been proposed as a way to overcome this obstacle. This paper reviews the past work on laser hole-boring and concludes that hole-boring for direct beaming to satellites is likely to require 10--100 MW. However, it may be possible to use an airborne relay mirror at 10--25 km altitude for some applications in order to extend the range of the laser (e.g., for beaming to satellites near the horizon). In these cases, use of the relay mirror also would allowmore » a narrow beam between the laser and the relay, as well as the possibility of reducing the crosswind if the plane matched speed with the cloud temporarily. Under these conditions, the power requirement to bore a hole through most cirrus and cirrostratus clouds might be only 500-kW if the hole is less than 1 m in diameter and if the crosswind speed is less than 10 m/s. Overcoming cirrus and cirrostratus clouds would reduce the downtime due to weather by a factor of 2. However, 500 kW is a large laser, and it may be more effective instead to establish a second power beaming site in a separate weather zone. An assessment of optimum wavelengths for hole boring also was made, and the best options were found to be 3.0--3.4 {mu}m and above 10 {mu}m.« less

Scanning ARM Cloud Radar Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Widener, K; Bharadwaj, N; Johnson, K

2012-06-18

The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and Northmore » Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.« less

Life and Death in a Star-Forming Cloud

NASA Image and Video Library

2012-11-14

W44 is located around 10,000 light-years away, within a forest of dense star-forming clouds in the constellation of Aquila, the Eagle. This image combines data from ESA Herschel and XXM-Newton space observatories.

Global epidemiology of capsular group W meningococcal disease (1970-2015): Multifocal emergence and persistence of hypervirulent sequence type (ST)-11 clonal complex.

PubMed

Mustapha, Mustapha M; Marsh, Jane W; Harrison, Lee H

2016-03-18

Following an outbreak in Mecca Saudi Arabia in 2000, meningococcal strains expressing capsular group W (W) emerged as a major cause of invasive meningococcal disease (IMD) worldwide. The Saudi Arabian outbreak strain (Hajj clone) belonging to the ST-11 clonal complex (cc11) is similar to W cc11 causing occasional sporadic disease before 2000. Since 2000, W cc11 has caused large meningococcal disease epidemics in the African meningitis belt and endemic disease in South America, Europe and China. Traditional molecular epidemiologic typing suggested that a majority of current W cc11 burden represented global spread of the Hajj clone. However, recent whole genome sequencing (WGS) analyses revealed significant genetic heterogeneity among global W cc11 strains. While continued spread of the Hajj clone occurs in the Middle East, the meningitis belt and South Africa have co-circulation of the Hajj clone and other unrelated W cc11 strains. Notably, South America, the UK, and France share a genetically distinct W cc11 strain. Other W lineages persist in low numbers in Europe, North America and the meningitis belt. In summary, WGS is helping to unravel the complex genomic epidemiology of group W meningococcal strains. Wider application of WGS and strengthening of global IMD surveillance is necessary to monitor the continued evolution of group W lineages. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impacts of cloud immersion on microclimate, photosynthesis and water relations of fraser fir in a temperate mountain cloud forest

Treesearch

Keith Reinhardt; William K. Smith

2010-01-01

The red spruce-Fraser fir ecosystem (Picea rubens Sarg.-Abies fraseri [Pursh] Poir.) of the southern Appalachian mountains is a temperate zone cloud forest immersed in clouds for 30 to 40 percent of a typical summer day, and experiencing immersion on about 65 percent of all days annually. We compared the microclimate,...

Equatorial cloud level convection on Venus

NASA Astrophysics Data System (ADS)

Lee, Yeon Joo; Imamura, Takeshi; Sugiyama, Koichiro; Sato, Takao M.; Maejima, Yasumitsu

2016-10-01

In the equatorial region on Venus, a clear cloud top morphology difference depending on solar local time has been observed through UV images. Laminar flow shaped clouds are shown on the morning side, and convective-like cells on the afternoon side (Titov et al. 2012). Baker et al. (1998) suggested that deep convective motions in the low-to-middle cloud layers at the 40-60 km range can explain cellular shapes. Imamura et al. (2014), however argued that this cannot be a reason, as convection in the low-to-middle cloud layers can be suppressed near sub solar regions due to a stabilizing effect by strong solar heating. We suggest that the observed feature may be related to strong solar heating at local noon time (Lee et al. 2015). Horizontal uneven distribution of an unknown UV absorber and/or cloud top structure may trigger horizontal convection (Toigo et al. 1994). In order to examine these possibilities, we processed 1-D radiative transfer model calculations from surface to 100 km altitude (SHDOM, Evans 1998), which includes clouds at 48-71 km altitudes (Crisp et al. 1986). The results on the equatorial thermal cooling and solar heating profiles were employed in a 2D fluid dynamic model calculation (CReSS, Tsuboki and Sakakibara 2007). The calculation covered an altitude range of 40-80 km and a 100-km horizontal distance. We compared three conditions; an 'effective' global circulation condition that cancels out unbalanced net radiative energy at equator, a condition without such global circulation effect, and the last condition assumed horizontally inhomogeneous unknown UV absorber distribution. Our results show that the local time dependence of lower level cloud convection is consistent with Imamura et al.'s result, and suggest a possible cloud top level convection caused by locally unbalanced net energy and/or horizontally uneven solar heating. This may be related to the observed cloud morphology in UV images. The effective global circulation condition, however

A novel organic-inorganic hybrid based on a dinuclear copper (II)-oxalate complex, a α-metatungstate cluster [H 2W 12O 40] 6- with catalytic activity in H 2O 2 decomposition

NASA Astrophysics Data System (ADS)

Sun, Ping; Liu, Shuxia; Feng, Dan; Ma, Fengji; Zhang, Wei; Ren, Yuanhang; Cao, Jianfang

2010-04-01

A novel organic-inorganic hybrid compound H 2[Cu 2(bpy) 2(H 2O) 2(μ-ox)] 2[H 2W 12O 40]·9H 2O ( 1) (2,2 '-bipyrine and ox = oxalate) has been successfully synthesized under open-air mild reaction condition and characterized by elemental analysis, IR spectrum, thermal stability analysis, single-crystal X-ray diffraction and magnetic susceptibility measurement. The main structural feature of compound 1 is the presence of α-metatungstate cluster [H 2W 12O 40] 6- as inorganic building blocks, on which the bridged-oxalate dinuclear copper metalorganic units are supported. Magnetic susceptibility studies reveal that the compound 1 shows paramagnetic property with a magnetic moment about the Cu 2+ ion, indicating antiferromagnetic coupling between the neighboring Cu 2+ ions in the structure. The compound 1 also displays a good catalytic activity with the conversion 42.4% for H 2O 2 decomposition.

West Antarctic Ice Sheet cloud cover and surface radiation budget from NASA A-Train satellites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, Ryan C.; Lubin, Dan; Vogelmann, Andrew M.

Clouds are an essential parameter of the surface energy budget influencing the West Antarctic Ice Sheet (WAIS) response to atmospheric warming and net contribution to global sea-level rise. A four-year record of NASA A-Train cloud observations is combined with surface radiation measurements to quantify the WAIS radiation budget and constrain the three-dimensional occurrence frequency, thermodynamic phase partitioning, and surface radiative effect of clouds over West Antarctica (WA). The skill of satellite-modeled radiative fluxes is confirmed through evaluation against measurements at four Antarctic sites (WAIS Divide Ice Camp, Neumayer, Syowa, and Concordia Stations). And due to perennial high-albedo snow and icemore » cover, cloud infrared emission dominates over cloud solar reflection/absorption leading to a positive net all-wave cloud radiative effect (CRE) at the surface, with all monthly means and 99.15% of instantaneous CRE values exceeding zero. The annual-mean CRE at theWAIS surface is 34 W m -2, representing a significant cloud-induced warming of the ice sheet. Low-level liquid-containing clouds, including thin liquid water clouds implicated in radiative contributions to surface melting, are widespread and most frequent in WA during the austral summer. Clouds warm the WAIS by 26 W m -2, in summer, on average, despite maximum offsetting shortwave CRE. Glaciated cloud systems are strongly linked to orographic forcing, with maximum incidence on the WAIS continuing downstream along the Transantarctic Mountains.« less

West Antarctic Ice Sheet cloud cover and surface radiation budget from NASA A-Train satellites

DOE PAGES

Scott, Ryan C.; Lubin, Dan; Vogelmann, Andrew M.; ...

2017-04-26

Clouds are an essential parameter of the surface energy budget influencing the West Antarctic Ice Sheet (WAIS) response to atmospheric warming and net contribution to global sea-level rise. A four-year record of NASA A-Train cloud observations is combined with surface radiation measurements to quantify the WAIS radiation budget and constrain the three-dimensional occurrence frequency, thermodynamic phase partitioning, and surface radiative effect of clouds over West Antarctica (WA). The skill of satellite-modeled radiative fluxes is confirmed through evaluation against measurements at four Antarctic sites (WAIS Divide Ice Camp, Neumayer, Syowa, and Concordia Stations). And due to perennial high-albedo snow and icemore » cover, cloud infrared emission dominates over cloud solar reflection/absorption leading to a positive net all-wave cloud radiative effect (CRE) at the surface, with all monthly means and 99.15% of instantaneous CRE values exceeding zero. The annual-mean CRE at theWAIS surface is 34 W m -2, representing a significant cloud-induced warming of the ice sheet. Low-level liquid-containing clouds, including thin liquid water clouds implicated in radiative contributions to surface melting, are widespread and most frequent in WA during the austral summer. Clouds warm the WAIS by 26 W m -2, in summer, on average, despite maximum offsetting shortwave CRE. Glaciated cloud systems are strongly linked to orographic forcing, with maximum incidence on the WAIS continuing downstream along the Transantarctic Mountains.« less

Molecular clouds in the extreme outer galaxy

NASA Technical Reports Server (NTRS)

Digel, S.; De Geus, E.; Thaddeus, P.

1994-01-01

We present observation of 11 molecular clouds with kinematic Galactocentric distances of 18-28 kpc. The most distant is approximately 10 kpc farther from the Galactic center than any previously known and apparently lies beyond the edge of the optical disk. All are associated with much larger H I concentrations, with typical offsets of approximately 40 pc from the H I peaks. CO observations with the CfA 1.2 m and National Radio Astronomy Observatory (NRAO) 12 m telescopes indicate typical sizes of 20-40 pc, velocity widths of 1-3 km/s, and kinetic temperatures of 10-25 K. They apparently have lower CO luminosities than clouds near the solar circle with similar properties. Some may have associated infrared sources, but owing to the great distances of the clouds, the only general conclusion that can be made about star formation is that stars earlier than B1 are absent. The apparent scarcity of clouds like these indicates that their contribution to the mass of the ISM beyond R = 18 kpc is not significant.

CO observations of dark clouds in Lupus

NASA Technical Reports Server (NTRS)

Murphy, D. C.; Cohen, R.; May, J.

1986-01-01

C-12O observations covering 170 square degrees toward the southern T Association Lupus have revealed the presence of an extended physically related complex of dark clouds which have recently formed low mass stars. The estimated mass of the clouds (about 30,000 solar masses) is comparable to that of the nearby Ophiuchus dust clouds. The Lupus clouds are projected onto a gap between two subgroups of the Scorpio-Centaurus OB association suggesting that this long accepted subgrouping may require reinterpretation.

40-Gb/s PDM-QPSK signal transmission over 160-m wireless distance at W-band.

PubMed

Xiao, Jiangnan; Yu, Jianjun; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long

2015-03-15

We experimentally demonstrate a W-band optical-wireless transmission system over 160-m wireless distance with a bit rate up to 40 Gb/s. The optical-wireless transmission system adopts optical polarization-division-multiplexing (PDM), multiple-input multiple-output (MIMO) reception and antenna polarization diversity. Using this system, we experimentally demonstrate the 2×2 MIMO wireless delivery of 20- and 40-Gb/s PDM quadrature-phase-shift-keying (PDM-QPSK) signals over 640- and 160-m wireless links, respectively. The bit-error ratios (BERs) of these transmission systems are both less than the forward-error-correction (FEC) threshold of 3.8×10^-3.

Does a Relationship Between Arctic Low Clouds and Sea Ice Matter?

NASA Technical Reports Server (NTRS)

Taylor, Patrick C.

2016-01-01

Arctic low clouds strongly affect the Arctic surface energy budget. Through this impact Arctic low clouds influence important aspects of the Arctic climate system, namely surface and atmospheric temperature, sea ice extent and thickness, and atmospheric circulation. Arctic clouds are in turn influenced by these elements of the Arctic climate system, and these interactions create the potential for Arctic cloud-climate feedbacks. To further our understanding of potential Arctic cloudclimate feedbacks, the goal of this paper is to quantify the influence of atmospheric state on the surface cloud radiative effect (CRE) and its covariation with sea ice concentration (SIC). We build on previous research using instantaneous, active remote sensing satellite footprint data from the NASA A-Train. First, the results indicate significant differences in the surface CRE when stratified by atmospheric state. Second, there is a weak covariation between CRE and SIC for most atmospheric conditions. Third, the results show statistically significant differences in the average surface CRE under different SIC values in fall indicating a 3-5 W m(exp -2) larger LW CRE in 0% versus 100% SIC footprints. Because systematic changes on the order of 1 W m(exp -2) are sufficient to explain the observed long-term reductions in sea ice extent, our results indicate a potentially significant amplifying sea ice-cloud feedback, under certain meteorological conditions, that could delay the fall freeze-up and influence the variability in sea ice extent and volume. Lastly, a small change in the frequency of occurrence of atmosphere states may yield a larger Arctic cloud feedback than any cloud response to sea ice.

Thin ice clouds in the Arctic: cloud optical depth and particle size retrieved from ground-based thermal infrared radiometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blanchard, Yann; Royer, Alain; O'Neill, Norman T.

Multiband downwelling thermal measurements of zenith sky radiance, along with cloud boundary heights, were used in a retrieval algorithm to estimate cloud optical depth and effective particle diameter of thin ice clouds in the Canadian High Arctic. Ground-based thermal infrared (IR) radiances for 150 semitransparent ice clouds cases were acquired at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada (80° N, 86° W). We analyzed and quantified the sensitivity of downwelling thermal radiance to several cloud parameters including optical depth, effective particle diameter and shape, water vapor content, cloud geometric thickness and cloud base altitude. A lookupmore » table retrieval method was used to successfully extract, through an optimal estimation method, cloud optical depth up to a maximum value of 2.6 and to separate thin ice clouds into two classes: (1) TIC1 clouds characterized by small crystals (effective particle diameter ≤ 30 µm), and (2) TIC2 clouds characterized by large ice crystals (effective particle diameter > 30 µm). The retrieval technique was validated using data from the Arctic High Spectral Resolution Lidar (AHSRL) and Millimeter Wave Cloud Radar (MMCR). Inversions were performed over three polar winters and results showed a significant correlation ( R 2 = 0.95) for cloud optical depth retrievals and an overall accuracy of 83 % for the classification of TIC1 and TIC2 clouds. A partial validation relative to an algorithm based on high spectral resolution downwelling IR radiance measurements between 8 and 21µm was also performed. It confirms the robustness of the optical depth retrieval and the fact that the broadband thermal radiometer retrieval was sensitive to small particle (TIC1) sizes.« less

Thin ice clouds in the Arctic: cloud optical depth and particle size retrieved from ground-based thermal infrared radiometry

DOE PAGES

Blanchard, Yann; Royer, Alain; O'Neill, Norman T.; ...

2017-06-09

Multiband downwelling thermal measurements of zenith sky radiance, along with cloud boundary heights, were used in a retrieval algorithm to estimate cloud optical depth and effective particle diameter of thin ice clouds in the Canadian High Arctic. Ground-based thermal infrared (IR) radiances for 150 semitransparent ice clouds cases were acquired at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada (80° N, 86° W). We analyzed and quantified the sensitivity of downwelling thermal radiance to several cloud parameters including optical depth, effective particle diameter and shape, water vapor content, cloud geometric thickness and cloud base altitude. A lookupmore » table retrieval method was used to successfully extract, through an optimal estimation method, cloud optical depth up to a maximum value of 2.6 and to separate thin ice clouds into two classes: (1) TIC1 clouds characterized by small crystals (effective particle diameter ≤ 30 µm), and (2) TIC2 clouds characterized by large ice crystals (effective particle diameter > 30 µm). The retrieval technique was validated using data from the Arctic High Spectral Resolution Lidar (AHSRL) and Millimeter Wave Cloud Radar (MMCR). Inversions were performed over three polar winters and results showed a significant correlation ( R 2 = 0.95) for cloud optical depth retrievals and an overall accuracy of 83 % for the classification of TIC1 and TIC2 clouds. A partial validation relative to an algorithm based on high spectral resolution downwelling IR radiance measurements between 8 and 21µm was also performed. It confirms the robustness of the optical depth retrieval and the fact that the broadband thermal radiometer retrieval was sensitive to small particle (TIC1) sizes.« less

Aerosol nucleation and its role for clouds and Earth's radiative forcing in the aerosol-climate model ECHAM5-HAM

NASA Astrophysics Data System (ADS)

Kazil, J.; Stier, P.; Zhang, K.; Quaas, J.; Kinne, S.; O'Donnell, D.; Rast, S.; Esch, M.; Ferrachat, S.; Lohmann, U.; Feichter, J.

2010-05-01

Nucleation from the gas phase is an important source of aerosol particles in the Earth's atmosphere, contributing to the number of cloud condensation nuclei, which form cloud droplets. We have implemented in the aerosol-climate model ECHAM5-HAM a new scheme for neutral and charged nucleation of sulfuric acid and water based on laboratory data, and nucleation of an organic compound and sulfuric acid using a parametrization of cluster activation based on field measurements. We give details of the implementation, compare results with observations, and investigate the role of the individual aerosol nucleation mechanisms for clouds and the Earth's radiative budget. The results of our simulations are most consistent with observations when neutral and charged nucleation of sulfuric acid proceed throughout the troposphere and nucleation due to cluster activation is limited to the forested boundary layer. The globally averaged annual mean contributions of the individual nucleation processes to total absorbed solar short-wave radiation via the direct, semi-direct, indirect cloud-albedo and cloud-lifetime effects in our simulations are -1.15 W/m2 for charged H2SO4/H2O nucleation, -0.235 W/m2 for cluster activation, and -0.05 W/m2 for neutral H2SO4/H2O nucleation. The overall effect of nucleation is -2.55 W/m2, which exceeds the sum of the individual terms due to feedbacks and interactions in the model. Aerosol nucleation contributes over the oceans with -2.18 W/m2 to total absorbed solar short-wave radiation, compared to -0.37 W/m2 over land. We explain the higher effect of aerosol nucleation on Earth's radiative budget over the oceans with the larger area covered by ocean clouds, due to the larger contrast in albedo between clouds and the ocean surface compared to continents, and the larger susceptibility of pristine clouds owing to the saturation of effects. The large effect of charged nucleation in our simulations is not in contradiction with small effects seen in local

Aerosol nucleation and its role for clouds and Earth's radiative forcing in the aerosol-climate model ECHAM5-HAM

NASA Astrophysics Data System (ADS)

Kazil, J.; Stier, P.; Zhang, K.; Quaas, J.; Kinne, S.; O'Donnell, D.; Rast, S.; Esch, M.; Ferrachat, S.; Lohmann, U.; Feichter, J.

2010-11-01

Nucleation from the gas phase is an important source of aerosol particles in the Earth's atmosphere, contributing to the number of cloud condensation nuclei, which form cloud droplets. We have implemented in the aerosol-climate model ECHAM5-HAM a new scheme for neutral and charged nucleation of sulfuric acid and water based on laboratory data, and nucleation of an organic compound and sulfuric acid using a parametrization of cluster activation based on field measurements. We give details of the implementation, compare results with observations, and investigate the role of the individual aerosol nucleation mechanisms for clouds and the Earth's radiative forcing. The results of our simulations are most consistent with observations when neutral and charged nucleation of sulfuric acid proceed throughout the troposphere and nucleation due to cluster activation is limited to the forested boundary layer. The globally averaged annual mean contributions of the individual nucleation processes to total absorbed solar short-wave radiation via the direct, semi-direct, indirect cloud-albedo and cloud-lifetime effects in our simulations are -1.15 W/m2 for charged H2SO4/H2O nucleation, -0.235 W/m2 for cluster activation, and -0.05 W/m2 for neutral H2SO4/H2O nucleation. The overall effect of nucleation is -2.55 W/m2, which exceeds the sum of the individual terms due to feedbacks and interactions in the model. Aerosol nucleation contributes over the oceans with -2.18 W/m2 to total absorbed solar short-wave radiation, compared to -0.37 W/m2 over land. We explain the higher effect of aerosol nucleation on Earth's radiative forcing over the oceans with the larger area covered by ocean clouds, due to the larger contrast in albedo between clouds and the ocean surface compared to continents, and the larger susceptibility of pristine clouds owing to the saturation of effects. The large effect of charged nucleation in our simulations is not in contradiction with small effects seen in local

Na/K-ATPase/src complex mediates regulation of CD40 in renal parenchyma.

PubMed

Xie, Jeffrey X; Zhang, Shungang; Cui, Xiaoyu; Zhang, Jue; Yu, Hui; Khalaf, Fatimah K; Malhotra, Deepak; Kennedy, David J; Shapiro, Joseph I; Tian, Jiang; Haller, Steven T

2017-12-22

Recent studies have highlighted a critical role for CD40 in the pathogenesis of renal injury and fibrosis. However, little is currently understood about the regulation of CD40 in this setting. We use novel Na/K-ATPase cell lines and inhibitors in order to demonstrate the regulatory function of Na/K-ATPase with regards to CD40 expression and function. We utilize 5/6 partial nephrectomy as well as direct infusion of a Na/K-ATPase ligand to demonstrate this mechanism exists in vivo. We demonstrate that knockdown of the α1 isoform of Na/K-ATPase causes a reduction in CD40 while rescue of the α1 but not the α2 isoform restores CD40 expression in renal epithelial cells. Second, because the major functional difference between α1 and α2 is the ability of α1 to form a functional signaling complex with Src, we examined whether the Na/K-ATPase/Src complex is important for CD40 expression. We show that a gain-of-Src binding α2 mutant restores CD40 expression while loss-of-Src binding α1 reduces CD40 expression. Furthermore, loss of a functional Na/K-ATPase/Src complex also disrupts CD40 signaling. Importantly, we show that use of a specific Na/K-ATPase/Src complex antagonist, pNaKtide, can attenuate cardiotonic steroid (CTS)-induced induction of CD40 expression in vitro. Because the Na/K-ATPase/Src complex is also a key player in the pathogenesis of renal injury and fibrosis, our new findings suggest that Na/K-ATPase and CD40 may comprise a pro-fibrotic feed-forward loop in the kidney and that pharmacological inhibition of this loop may be useful in the treatment of renal fibrosis. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Joiner, J.; Vasilkov, A. P.; Gupta, Pawan; Bhartia, P. K.; Veefkind, Pepijn; Sneep, Maarten; deHaan, Johan; Polonsky, Igor; Spurr, Robert

2011-01-01

We have developed a relatively simple scheme for simulating retrieved cloud optical centroid pressures (OCP) from satellite solar backscatter observations. We have compared simulator results with those from more detailed retrieval simulators that more fully account for the complex radiative transfer in a cloudy atmosphere. We used this fast simulator to conduct a comprehensive evaluation of cloud OCPs from the two OMI algorithms using collocated data from CloudSat and Aqua MODIS, a unique situation afforded by the A-train formation of satellites. We find that both OMI algorithms perform reasonably well and that the two algorithms agree better with each other than either does with the collocated CloudSat data. This indicates that patchy snow/ice, cloud 3D, and aerosol effects not simulated with the CloudSat data are affecting both algorithms similarly. We note that the collocation with CloudSat occurs mainly on the East side of OMI's swath. Therefore, we are not able to address cross-track biases in OMI cloud OCP retrievals. Our fast simulator may also be used to simulate cloud OCP from output generated by general circulation models (GCM) with appropriate account of cloud overlap. We have implemented such a scheme and plan to compare OMI data with GCM output in the near future.

Antarctica Cloud Cover for October 2003 from GLAS Satellite Lidar Profiling

NASA Technical Reports Server (NTRS)

Spinhirne, J. D.; Palm, S. P.; Hart, W. D.

2005-01-01

Seeing clouds in polar regions has been a problem for the imagers used on satellites. Both clouds and snow and ice are white, which makes clouds over snow hard to see. And for thermal infrared imaging both the surface and the clouds cold. The Geoscience Laser Altimeter System (GLAS) launched in 2003 gives an entirely new way to see clouds from space. Pulses of laser light scatter from clouds giving a signal that is separated in time from the signal from the surface. The scattering from clouds is thus a sensitive and direct measure of the presence and height of clouds. The GLAS instrument orbits over Antarctica 16 times a day. All of the cloud observations for October 2003 were summarized and compared to the results from the MODIS imager for the same month. There are two basic cloud types that are observed, low stratus with tops below 3 km and high cirrus form clouds with cloud top altitude and thickness tending at 12 km and 1.3 km respectively. The average cloud cover varies from over 93 % for ocean and coastal regions to an average of 40% over the East Antarctic plateau and 60-90% over West Antarctica. When the GLAS monthly average cloud fractions are compared to the MODIS cloud fraction data product, differences in the amount of cloud cover are as much as 40% over the continent. The results will be used to improve the way clouds are detected from the imager observations. These measurements give a much improved understanding of distribution of clouds over Antarctica and may show how they are changing as a result of global warming.

Cloud microphysics and aerosol indirect effects in the global climate model ECHAM5-HAM

NASA Astrophysics Data System (ADS)

Lohmann, U.; Stier, P.; Hoose, C.; Ferrachat, S.; Kloster, S.; Roeckner, E.; Zhang, J.

2007-07-01

The double-moment cloud microphysics scheme from ECHAM4 that predicts both the mass mixing ratios and number concentrations of cloud droplets and ice crystals has been coupled to the size-resolved aerosol scheme ECHAM5-HAM. ECHAM5-HAM predicts the aerosol mass, number concentrations and mixing state. The simulated liquid, ice and total water content and the cloud droplet and ice crystal number concentrations as a function of temperature in stratiform mixed-phase clouds between 0 and -35° C agree much better with aircraft observations in the ECHAM5 simulations. ECHAM5 performs better because more realistic aerosol concentrations are available for cloud droplet nucleation and because the Bergeron-Findeisen process is parameterized as being more efficient. The total anthropogenic aerosol effect includes the direct, semi-direct and indirect effects and is defined as the difference in the top-of-the-atmosphere net radiation between present-day and pre-industrial times. It amounts to -1.9 W m-2 in ECHAM5, when a relative humidity dependent cloud cover scheme and aerosol emissions representative for the years 1750 and 2000 from the AeroCom emission inventory are used. The contribution of the cloud albedo effect amounts to -0.7 W m-2. The total anthropogenic aerosol effect is larger when either a statistical cloud cover scheme or a different aerosol emission inventory are employed because the cloud lifetime effect increases.

Cloud level winds from UV and IR images obtained by VMC onboard Venus Express

NASA Astrophysics Data System (ADS)

Khatuntsev, Igor; Patsaeva, Marina; Titov, Dmitri; Ignatiev, Nikolay; Turin, Alexander; Bertaux, Jean-Loup

2017-04-01

During eight years Venus Monitoring Camera (VMC) [1] onboard the Venus Express orbiter has observed the upper cloud layer of Venus. The largest set of images was obtained in the UV (365 nm), visible (513 nm) and two infrared channels - 965 nm and 1010 nm. The UV dayside images were used to study the atmospheric circulation at the Venus cloud tops [2], [3]. Mean zonal and meridional profiles of winds and their variability were derived from cloud tracking of UV images. In low latitudes the mean retrograde zonal wind at the cloud top (67±2 km) is about 95 m/s with a maximum of about 102 m/s at 40-50°S. Poleward from 50°S the zonal wind quickly fades out with latitude. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S. Poleward from this latitude, the absolute value of the meridional component monotonically decreases to zero at the pole. The VMC observations suggest clear diurnal signature in the wind field. They also indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the middle of 2012. The trend was explained by influence of the surface topography on the zonal flow [4]. Cloud features tracking in the IR images provided information about winds in the middle cloud deck (55±4 km). In the low and middle latitudes (5-65°S) the IR mean retrograde zonal velocity is about 68-70 m/s. In contrast to poleward flow at the cloud tops, equatorward motions dominate in the middle cloud with maximum speed of 5.8±1.2 m/s at latitude 15°S. The meridional speed slowly decreases to 0 at 65-70°S. At low latitudes the zonal and meridional speed demonstrate long term variations. Following [4] we explain the observed long term trend of zonal and meridional components by the influence of surface topography of highland region Aphrodite Terra on dynamic processes in the middle cloud deck through gravity waves. Acknowledgements: I.V. Khatuntsev

Star formation in evolving molecular clouds

NASA Astrophysics Data System (ADS)

Völschow, M.; Banerjee, R.; Körtgen, B.

2017-09-01

Molecular clouds are the principle stellar nurseries of our universe; they thus remain a focus of both observational and theoretical studies. From observations, some of the key properties of molecular clouds are well known but many questions regarding their evolution and star formation activity remain open. While numerical simulations feature a large number and complexity of involved physical processes, this plethora of effects may hide the fundamentals that determine the evolution of molecular clouds and enable the formation of stars. Purely analytical models, on the other hand, tend to suffer from rough approximations or a lack of completeness, limiting their predictive power. In this paper, we present a model that incorporates central concepts of astrophysics as well as reliable results from recent simulations of molecular clouds and their evolutionary paths. Based on that, we construct a self-consistent semi-analytical framework that describes the formation, evolution, and star formation activity of molecular clouds, including a number of feedback effects to account for the complex processes inside those objects. The final equation system is solved numerically but at much lower computational expense than, for example, hydrodynamical descriptions of comparable systems. The model presented in this paper agrees well with a broad range of observational results, showing that molecular cloud evolution can be understood as an interplay between accretion, global collapse, star formation, and stellar feedback.

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

NASA Technical Reports Server (NTRS)

Dong, Xiquan; Xi, Baike; Minnis, Patrick

2006-01-01

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

The Magnetic Field Structure of W3(OH)

NASA Astrophysics Data System (ADS)

El-Batal, Adham M.; Clemens, Dan P.; Montgomery, Jordan

2018-06-01

Situated in the Perseus arm of the Galaxy, the W3 molecular cloud is a high-mass star-forming region with low foreground optical extinction. Near-infrared H- and K-band polarimetric observations of a 10' × 10' field of view of W3 were obtained using the Mimir instrument on the 1.8 m Perkins Telescope. This field of view encompasses W3(OH), a region of OH and H2O masers as well as an HII region. The H-band data were used in conjunction with Spitzer M-band data to map extinction via H-M color excess. In total, 2654 stellar objects were found in the Mimir field of view, of which 1013 had H and M magnitudes with low errors. Using the extinction map and the individual stellar H-M color excess values, 429 stars with polarized signals were found to be background to the molecular cloud. These were useful for mapping the magnetic field structure and estimating the magnetic field strength of the cloud. Mid- to far-infrared (70 - 870 μm) archival Herschel and Planck data were used to map dust extinction at 850 µm and create an H2 column density map. Combined, maps of magnetic field strength and hydrogen column density can be used to infer the ratio of gravitational potential to magnetic potential ( M/Φ ). Findings are discussed in the context of M/Φ ratio in models and the stability of high-mass star-forming regions.This work has been supported by NSF AST14-12269 and NASA NNX15AE51G grants.

Does Cloud Computing in the Atmospheric Sciences Make Sense? A case study of hybrid cloud computing at NASA Langley Research Center

NASA Astrophysics Data System (ADS)

Nguyen, L.; Chee, T.; Minnis, P.; Spangenberg, D.; Ayers, J. K.; Palikonda, R.; Vakhnin, A.; Dubois, R.; Murphy, P. R.

2014-12-01

The processing, storage and dissemination of satellite cloud and radiation products produced at NASA Langley Research Center are key activities for the Climate Science Branch. A constellation of systems operates in sync to accomplish these goals. Because of the complexity involved with operating such intricate systems, there are both high failure rates and high costs for hardware and system maintenance. Cloud computing has the potential to ameliorate cost and complexity issues. Over time, the cloud computing model has evolved and hybrid systems comprising off-site as well as on-site resources are now common. Towards our mission of providing the highest quality research products to the widest audience, we have explored the use of the Amazon Web Services (AWS) Cloud and Storage and present a case study of our results and efforts. This project builds upon NASA Langley Cloud and Radiation Group's experience with operating large and complex computing infrastructures in a reliable and cost effective manner to explore novel ways to leverage cloud computing resources in the atmospheric science environment. Our case study presents the project requirements and then examines the fit of AWS with the LaRC computing model. We also discuss the evaluation metrics, feasibility, and outcomes and close the case study with the lessons we learned that would apply to others interested in exploring the implementation of the AWS system in their own atmospheric science computing environments.

Lidar cirrus cloud retrieval - methodology and applications

NASA Astrophysics Data System (ADS)

Larroza, Eliane; Keckhut, Philippe; Nakaema, Walter; Brogniez, Gérard; Dubuisson, Philippe; Pelon, Jacques; Duflot, Valentin; Marquestaut, Nicolas; Payen, Guillaume

2016-04-01

In the last decades numerical modeling has experimented sensitive improvements on accuracy and capability for climate predictions. In the same time it has demanded the reduction of uncertainties related with the respective input parameters. In this context, high altitude clouds (cirrus) have attracted special attention for their role as radiative forcing. Also such clouds are associated with the vertical transport of water vapor from the surface to upper troposphere/lower stratosphere (URLS) in form of ice crystals with variability of concentration and morphology. Still cirrus formation can occur spatially and temporally in great part of the globe due to horizontal motion of air masses and circulations. Determining accurately the physical properties of cirrus clouds still represents a challenge. Especially the so-called subvisible cirrus clouds (optical depth inferior to 0.03) are invisible for space-based passive observations. On the other hand, ground based active remote sensing as lidar can be used to suppress such deficiency. Lidar signal can provide spatial and temporal high resolution to characterize physically (height, geometric thickness, mean temperature) and optically (optical depth, extinction-to-scattering ratio or lidar ratio, depolarization ratio) the cirrus clouds. This report describes the evolution of the methodology initially adopted to retrieval systematically the lidar ratio and the subsequent application on case studies and climatology on the tropical sites of the globe - São Paulo, Brazil (23.33 S, 46.44 W) and OPAR observatory at Ille de La Réunion (21.07 S, 55.38 W). Also is attempting a synergy between different instrumentations and lidar measurements: a infrared radiometer to estimate the kind of ice crystals compounding the clouds; CALIPSO satellite observations and trajectory model (HYSPLIT) for tracking air masses potentially responsible for the horizontal displacement of cirrus. This last approach is particularly interesting to

Age, altitude, and workload effects on complex performance.

DOT National Transportation Integrated Search

1983-09-01

Fifteen healthy men in each of three age groups, 20-29 yrs, 40-49 yrs, and 60-69 yrs, were evaluated regarding complex performance in two altitude conditions (ground level vs. 3,810 m) which were administered during performance testing. Performance w...

The clouds of Venus. [physical and chemical properties

NASA Technical Reports Server (NTRS)

Young, A. T.

1975-01-01

The physical and chemical properties of the clouds of Venus are reviewed, with special emphasis on data that are related to cloud dynamics. None of the currently-popular interpretations of cloud phenomena on Venus is consistent with all the data. Either a considerable fraction of the observational evidence is faulty or has been misinterpreted, or the clouds of Venus are much more complex than the current simplistic models. Several lines of attack are suggested to resolve some of the contradictions. A sound understanding of the clouds appears to be several years in the future.

Identity-Based Authentication for Cloud Computing

NASA Astrophysics Data System (ADS)

Li, Hongwei; Dai, Yuanshun; Tian, Ling; Yang, Haomiao

Cloud computing is a recently developed new technology for complex systems with massive-scale services sharing among numerous users. Therefore, authentication of both users and services is a significant issue for the trust and security of the cloud computing. SSL Authentication Protocol (SAP), once applied in cloud computing, will become so complicated that users will undergo a heavily loaded point both in computation and communication. This paper, based on the identity-based hierarchical model for cloud computing (IBHMCC) and its corresponding encryption and signature schemes, presented a new identity-based authentication protocol for cloud computing and services. Through simulation testing, it is shown that the authentication protocol is more lightweight and efficient than SAP, specially the more lightweight user side. Such merit of our model with great scalability is very suited to the massive-scale cloud.

Assessment of NASA GISS CMIP5 ModelE simulated clouds and TOA radiation budgets using satellite observations over the southern mid-latitudes

NASA Astrophysics Data System (ADS)

Stanfield, Ryan Evan

Past, current, and future climates have been simulated by the National Aeronautics and Space Administration (NASA) Goddard Institute for Space Studies (GISS) ModelE Global Circulation Model (GCM) and summarized by the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC, AR4). New simulations from the updated CMIP5 version of the NASA GISS ModelE GCM were recently released to the public community during the summer of 2011 and will be included in the upcoming IPCC AR5 ensemble of simulations. Due to the recent nature of these simulations, they have not yet been extensively validated against observations. To assess the NASA GISS-E2-R GCM, model simulated clouds and cloud properties are compared to observational cloud properties derived from the Clouds and Earth's Radiant Energy System (CERES) project using MODerate Resolution Imaging Spectroradiometer (MODIS) data for the period of March 2000 through December 2005. Over the 6-year period, the global average modeled cloud fractions are within 1% of observations. However, further study however shows large regional biases between the GCM simulations and CERES-MODIS observations. The southern mid-latitudes (SML) were chosen as a focus region due to model errors across multiple GCMs within the recent phase 5 of the Coupled Model Intercomparison Project (CMIP5). Over the SML, the GISS GCM undersimulates total cloud fraction over 20%, but oversimulates total water path by 2 g m-2. Simulated vertical cloud distributions over the SML when compared to both CERES-MODIS and CloudSat/CALIPSO observations show a drastic undersimulation of low level clouds by the GISS GCM, but higher fractions of thicker clouds. To assess the impact of GISS simulated clouds on the TOA radiation budgets, the modeled TOA radiation budgets are compared to CERES EBAF observations. Because modeled low-level cloud fraction is much lower than observed over the SML, modeled reflected shortwave (SW) flux at the TOA is 13 W m -2 lower and

EMBEDDED CLUSTERS IN THE LARGE MAGELLANIC CLOUD USING THE VISTA MAGELLANIC CLOUDS SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romita, Krista; Lada, Elizabeth; Cioni, Maria-Rosa, E-mail: k.a.romita@ufl.edu, E-mail: elada@ufl.edu, E-mail: mcioni@aip.de

We present initial results of the first large-scale survey of embedded star clusters in molecular clouds in the Large Magellanic Cloud (LMC) using near-infrared imaging from the Visible and Infrared Survey Telescope for Astronomy Magellanic Clouds Survey. We explored a ∼1.65 deg{sup 2} area of the LMC, which contains the well-known star-forming region 30 Doradus as well as ∼14% of the galaxy’s CO clouds, and identified 67 embedded cluster candidates, 45 of which are newly discovered as clusters. We have determined the sizes, luminosities, and masses for these embedded clusters, examined the star formation rates (SFRs) of their corresponding molecularmore » clouds, and made a comparison between the LMC and the Milky Way. Our preliminary results indicate that embedded clusters in the LMC are generally larger, more luminous, and more massive than those in the local Milky Way. We also find that the surface densities of both embedded clusters and molecular clouds is ∼3 times higher than in our local environment, the embedded cluster mass surface density is ∼40 times higher, the SFR is ∼20 times higher, and the star formation efficiency is ∼10 times higher. Despite these differences, the SFRs of the LMC molecular clouds are consistent with the SFR scaling law presented in Lada et al. This consistency indicates that while the conditions of embedded cluster formation may vary between environments, the overall process within molecular clouds may be universal.« less

Biological aerosol effects on clouds and precipitation

NASA Astrophysics Data System (ADS)

Hallar, A. Gannet; Huffman, J. Alex; Fridlind, Ann

2012-12-01

Bioaerosol Effects on Clouds Workshop;Steamboat Springs, Colorado, 5-6August 2012 Bioaerosols such as bacteria have been proposed as significant contributors to cloud ice nucleation, but too little is known about the properties and impacts of bioaerosol and other ice nuclei to make reliable conclusions about their wide-scale impact on clouds and precipitation. During late summer an international group of 40 participants met at a Steamboat Springs ski resort to share perspectives on bioaerosol sources, activity, and influence on clouds. Participants who were invited collectively spanned a broad range of expertise, including atmospheric chemistry, microbiology, micrometeorology, and cloud physics, as well as a broad range of research approaches, including laboratory measurement, field measurement, and modeling. Tours of Storm Peak Laboratory (http://www.stormpeak.dri.edu) were offered before and after the workshop.

Cloud types and the tropical Earth radiation budget, revised

NASA Technical Reports Server (NTRS)

Dhuria, Harbans L.; Kyle, H. Lee

1989-01-01

Nimbus-7 cloud and Earth radiation budget data are compared in a study of the effects of clouds on the tropical radiation budget. The data consist of daily averages over fixed 500 sq km target areas, and the months of July 1979 and January 1980 were chosen to show the effect of seasonal changes. Six climate regions, consisting of 14 to 24 target areas each, were picked for intensive analysis because they exemplified the range in the tropical cloud/net radiation interactions. The normal analysis was to consider net radiation as the independent variable and examine how cloud cover, cloud type, albedo and emitted radiation varied with the net radiation. Two recurring themes keep repeating on a local, regional, and zonal basis: the net radiation is strongly influenced by the average cloud type and amount present, but most net radiation values could be produced by several combinations of cloud types and amount. The regions of highest net radiation (greater than 125 W/sq m) tend to have medium to heavy cloud cover. In these cases, thin medium altitude clouds predominate. Their cloud tops are normally too warm to be classified as cirrus by the Nimbus cloud algorithm. A common feature in the tropical oceans are large regions where the total regional cloud cover varies from 20 to 90 percent, but with little regional difference in the net radiation. The monsoon and rain areas are high net radiation regions.

Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images

NASA Technical Reports Server (NTRS)

Ramirez, Daniel Perez; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

2012-01-01

This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

Global Software Development with Cloud Platforms

NASA Astrophysics Data System (ADS)

Yara, Pavan; Ramachandran, Ramaseshan; Balasubramanian, Gayathri; Muthuswamy, Karthik; Chandrasekar, Divya

Offshore and outsourced distributed software development models and processes are facing challenges, previously unknown, with respect to computing capacity, bandwidth, storage, security, complexity, reliability, and business uncertainty. Clouds promise to address these challenges by adopting recent advances in virtualization, parallel and distributed systems, utility computing, and software services. In this paper, we envision a cloud-based platform that addresses some of these core problems. We outline a generic cloud architecture, its design and our first implementation results for three cloud forms - a compute cloud, a storage cloud and a cloud-based software service- in the context of global distributed software development (GSD). Our ”compute cloud” provides computational services such as continuous code integration and a compile server farm, ”storage cloud” offers storage (block or file-based) services with an on-line virtual storage service, whereas the on-line virtual labs represent a useful cloud service. We note some of the use cases for clouds in GSD, the lessons learned with our prototypes and identify challenges that must be conquered before realizing the full business benefits. We believe that in the future, software practitioners will focus more on these cloud computing platforms and see clouds as a means to supporting a ecosystem of clients, developers and other key stakeholders.

Interstellar molecules and dense clouds.

NASA Technical Reports Server (NTRS)

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

1971-01-01

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

Cloud Statistics for NASA Climate Change Studies

NASA Technical Reports Server (NTRS)

Wylie, Donald P.

1999-01-01

the International Satellite Cloud Climatology Program (ISCCP) and the Stratospheric Aerosol and Gas Experiment (SAGE). A summary of eight years of HIRS data will be published in late 1998. Important information from this study are: 1) cirrus clouds cover most of the earth, 2) they are found about 40% of the time globally, 3) in the tropics cirrus cloud frequencies are even higher, from 80-100%, 4) there is slight evidence that cirnis cloud cover is increasing in the northern hemisphere at about 0.5% per year, and 5) cirrus clouds have an average infrared transmittance of about 40% of the terrestrial radiation. (5) Global Cloud Frequency Statistics published on the Principal Investigator's web page have been used in the planning of the future CRYSTAL experiment and have been used for refinements of a global numerical model operated at the Colorado State University.

10-Year Observations of Cloud and Surface Longwave Radiation at Ny-Ålesund, Svalbard

NASA Astrophysics Data System (ADS)

Yeo, H.; Kim, S. W.; Kim, B. M.; Kim, J. H.; Shiobara, M.; Choi, T. J.; Son, S. W.; Kim, M. H.; Jeong, J. H.; Kim, S. J.

2015-12-01

Arctic clouds play a key role in surface radiation budget and may influence sea ice and snow melting. In this study, 10-year (2004-2013) observations of cloud from Micro-Pulse Lidar (MPL) and surface longwave (LW) radiation at Ny-Ålesund, Svalbard are analyzed to investigate cloud radiative effect. The cloud fraction (CF) derived from MPL shows distinct monthly variation, having higher CF (0.90) in summer and lower CF (0.79) in winter. Downward longwave radiation (DLW) during wintertime (Nov., Dec., Jan., and Feb.) decreases as cloud base height (CBH) increases. The DLW for CBH < 1km (264.7±35.4 W m-2) is approximately 1.46 times larger than that for cloud-free (181.8±25.8 W m-2) conditions. The temperature difference (ΔT) and DLW difference (ΔDLW), which are calculated as the difference of monthly mean temperature and DLW between all-sky and cloud-free conditions, are positively correlated (R2 = 0.83). This implies that an increase of DLW may influence surface warming, which can result in snow and sea ice melting. However, dramatic changes in surface temperature, cloud and DLW are observed with a time scale of a few days. The averaged surface temperature on the presence of low-level clouds (CBH < 2km) and under cloud-free conditions are estimated to be -6.9±6.1°C and -14.5±5.7°C, respectively. The duration of low-level clouds, showing relatively high DLW and high surface temperature, is about 2.5 days. This suggests that DLW induced by low-level clouds may not have a critical effect on surface temperature rising and sea ice melting.

The influence of mixed and phase clouds on surface shortwave irradiance during the Arctic spring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lubin D.; Vogelmann A.

2011-10-13

The influence of mixed-phase stratiform clouds on the surface shortwave irradiance is examined using unique spectral shortwave irradiance measurements made during the Indirect and Semi-Direct Aerosol Campaign (ISDAC), supported by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. An Analytical Spectral Devices (ASD, Inc.) spectroradiometer measured downwelling spectral irradiance from 350 to 2200 nm in one-minute averages throughout April-May 2008 from the ARM Climate Research Facility's North Slope of Alaska (NSA) site at Barrow. This study examines spectral irradiance measurements made under single-layer, overcast cloud decks having geometric thickness < 3000 m. Cloud optical depth is retrieved frommore » irradiance in the interval 1022-1033 nm. The contrasting surface radiative influences of mixed-phase clouds and liquid-water clouds are discerned using irradiances in the 1.6-{micro}m window. Compared with liquid-water clouds, mixed-phase clouds during the Arctic spring cause a greater reduction of shortwave irradiance at the surface. At fixed conservative-scattering optical depth (constant optical depth for wavelengths {lambda} < 1100 nm), the presence of ice water in cloud reduces the near-IR surface irradiance by an additional several watts-per-meter-squared. This additional reduction, or supplemental ice absorption, is typically {approx}5 W m{sup -2} near solar noon over Barrow, and decreases with increasing solar zenith angle. However, for some cloud decks this additional absorption can be as large as 8-10 W m{sup -2}.« less

Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud. I. N159W

NASA Astrophysics Data System (ADS)

Lee, M.-Y.; Madden, S. C.; Lebouteiller, V.; Gusdorf, A.; Godard, B.; Wu, R.; Galametz, M.; Cormier, D.; Le Petit, F.; Roueff, E.; Bron, E.; Carlson, L.; Chevance, M.; Fukui, Y.; Galliano, F.; Hony, S.; Hughes, A.; Indebetouw, R.; Israel, F. P.; Kawamura, A.; Le Bourlot, J.; Lesaffre, P.; Meixner, M.; Muller, E.; Nayak, O.; Onishi, T.; Roman-Duval, J.; Sewiło, M.

2016-12-01

We present Herschel SPIRE Fourier Transform Spectrometer (FTS) observations of N159W, an active star-forming region in the Large Magellanic Cloud (LMC). In our observations, a number of far-infrared cooling lines, including carbon monoxide (CO) J = 4 → 3 to J = 12 → 11, [CI] 609 μm and 370 μm, and [NII] 205 μm, are clearly detected. With an aim of investigating the physical conditions and excitation processes of molecular gas, we first construct CO spectral line energy distributions (SLEDs) on 10 pc scales by combining the FTS CO transitions with ground-based low-J CO data and analyze the observed CO SLEDs using non-LTE (local thermodynamic equilibrium) radiative transfer models. We find that the CO-traced molecular gas in N159W is warm (kinetic temperature of 153-754 K) and moderately dense (H2 number density of (1.1-4.5) × 103 cm-3). To assess the impact of the energetic processes in the interstellar medium on the physical conditions of the CO-emitting gas, we then compare the observed CO line intensities with the models of photodissociation regions (PDRs) and shocks. We first constrain the properties of PDRs by modeling Herschel observations of [OI] 145 μm, [CII] 158 μm, and [CI] 370 μm fine-structure lines and find that the constrained PDR components emit very weak CO emission. X-rays and cosmic-rays are also found to provide a negligible contribution to theCO emission, essentially ruling out ionizing sources (ultraviolet photons, X-rays, and cosmic-rays) as the dominant heating source for CO in N159W. On the other hand, mechanical heating by low-velocity C-type shocks with 10 km s-1 appears sufficient enough to reproduce the observed warm CO. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.The final reduced Herschel data (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or

40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is subject...

40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is subject...

40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is subject...

40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is subject...

Pratt & Whitney Advanced Ducted Propulsor (ADP) Engine Test in 40x80ft w.t.: Engineers Peter

NASA Technical Reports Server (NTRS)

1993-01-01

Pratt & Whitney Advanced Ducted Propulsor (ADP) Engine Test in 40x80ft w.t.: Engineers Peter Zell (left) and Dr Clifton Horne (right) are shown preparing a laser light sheet for a flow visualization test. Shown standing in the nacelle of the ADP is John Girvin, senior test engineer for Pratt & Whitney.

40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under this...

40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under this...

Effects of cloud condensate vertical alignment on radiative transfer calculations in deep convective regions

NASA Astrophysics Data System (ADS)

Wang, Xiaocong

2017-04-01

Effects of cloud condensate vertical alignment on radiative transfer process were investigated using cloud resolving model explicit simulations, which provide a surrogate for subgrid cloud geometry. Diagnostic results showed that the decorrelation length Lcw varies in the vertical dimension, with larger Lcw occurring in convective clouds and smaller Lcw in cirrus clouds. A new parameterization of Lcw is proposed that takes into account such varying features and gives rise to improvements in simulations of cloud radiative forcing (CRF) and radiative heating, i.e., the peak of bias is respectively reduced by 8 W m- 2 for SWCF and 2 W m- 2 for LWCF in comparison with Lcw = 1 km. The role of Lcw in modulating CRFs is twofold. On the one hand, larger Lcw tends to increase the standard deviation of optical depth στ, as dense and tenuous parts of the clouds would be increasingly aligned in the vertical dimension, thereby broadening the probability distribution. On the other hand, larger στ causes a decrease in the solar albedo and thermal emissivity, as implied in their convex functions on τ. As a result, increasing (decreasing) Lcwleads to decreased (increased) CRFs, as revealed by comparisons among Lcw = 0, Lcw = 1 km andLcw = ∞. It also affects the vertical structure of radiative flux and thus influences the radiative heating. A better representation of στ in the vertical dimension yields an improved simulation of radiative heating. Although the importance of vertical alignment of cloud condensate is found to be less than that of cloud cover in regards to their impacts on CRFs, it still has enough of an effect on modulating the cloud radiative transfer process.

Modification of cirrus clouds to reduce global warming

NASA Astrophysics Data System (ADS)

Mitchell, David L.; Finnegan, William

2009-10-01

Greenhouse gases and cirrus clouds regulate outgoing longwave radiation (OLR) and cirrus cloud coverage is predicted to be sensitive to the ice fall speed which depends on ice crystal size. The higher the cirrus, the greater their impact is on OLR. Thus by changing ice crystal size in the coldest cirrus, OLR and climate might be modified. Fortunately the coldest cirrus have the highest ice supersaturation due to the dominance of homogeneous freezing nucleation. Seeding such cirrus with very efficient heterogeneous ice nuclei should produce larger ice crystals due to vapor competition effects, thus increasing OLR and surface cooling. Preliminary estimates of this global net cloud forcing are more negative than -2.8 W m-2 and could neutralize the radiative forcing due to a CO2 doubling (3.7 W m-2). A potential delivery mechanism for the seeding material is already in place: the airline industry. Since seeding aerosol residence times in the troposphere are relatively short, the climate might return to its normal state within months after stopping the geoengineering experiment. The main known drawback to this approach is that it would not stop ocean acidification. It does not have many of the drawbacks that stratospheric injection of sulfur species has.

Aircraft-Induced Hole Punch and Canal Clouds

NASA Astrophysics Data System (ADS)

Heymsfield, A. J.; Kennedy, P.; Massie, S. T.; Schmitt, C. G.; Wang, Z.; Haimov, S.; Rangno, A.

2009-12-01

The production of holes and channels in altocumulus clouds by two commercial turboprop aircraft is documented for the first time. An unprecedented data set combining in situ measurements from microphysical probes with remote sensing measurements from cloud radar and lidar, all operating from the NSF/NCAR C130 aircraft, as well as ground-based NOAA and CSU radars, is used to describe the radar/lidar properties of a hole punch cloud and channel and the ensuing ice microphysical properties and structure of the ice column that subsequently developed. Ice particle production by commercial turboprop aircraft climbing through clouds much warmer than the regions where contrails are produced has the potential to modify significantly the cloud microphysical properties and effectively seed them under some conditions. Jet aircraft may also be producing hole punch clouds when flying through altocumulus with supercooled droplets at heights lower than their normal cruise altitudes where contrails can form. Commercial aircraft therefore can generate ice and affect the clouds at temperatures as much as 30°C warmer than the -40°C contrail formation threshold temperature.

Multi-layer Clouds Over the South Indian Ocean

NASA Image and Video Library

2003-05-07

The complex structure and beauty of polar clouds are highlighted by these images acquired by NASA Terra spacecraft on April 23, 2003. These clouds occur at multiple altitudes and exhibit a noticeable cyclonic circulation over the Southern Indian Ocean,

Abstracting application deployment on Cloud infrastructures

NASA Astrophysics Data System (ADS)

Aiftimiei, D. C.; Fattibene, E.; Gargana, R.; Panella, M.; Salomoni, D.

2017-10-01

Deploying a complex application on a Cloud-based infrastructure can be a challenging task. In this contribution we present an approach for Cloud-based deployment of applications and its present or future implementation in the framework of several projects, such as “!CHAOS: a cloud of controls” [1], a project funded by MIUR (Italian Ministry of Research and Education) to create a Cloud-based deployment of a control system and data acquisition framework, “INDIGO-DataCloud” [2], an EC H2020 project targeting among other things high-level deployment of applications on hybrid Clouds, and “Open City Platform”[3], an Italian project aiming to provide open Cloud solutions for Italian Public Administrations. We considered to use an orchestration service to hide the complex deployment of the application components, and to build an abstraction layer on top of the orchestration one. Through Heat [4] orchestration service, we prototyped a dynamic, on-demand, scalable platform of software components, based on OpenStack infrastructures. On top of the orchestration service we developed a prototype of a web interface exploiting the Heat APIs. The user can start an instance of the application without having knowledge about the underlying Cloud infrastructure and services. Moreover, the platform instance can be customized by choosing parameters related to the application such as the size of a File System or the number of instances of a NoSQL DB cluster. As soon as the desired platform is running, the web interface offers the possibility to scale some infrastructure components. In this contribution we describe the solution design and implementation, based on the application requirements, the details of the development of both the Heat templates and of the web interface, together with possible exploitation strategies of this work in Cloud data centers.

Gamma-Ray Observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.;

Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Ajello, M.; Allafort, A.

We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between ~100 MeV and ~100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to ~10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. Wemore » present here such distributions for Orion A and B, and correlate them with those of the velocity-integrated CO intensity (W CO) at a 1° × 1° pixel level. The correlation is found to be linear over a W CO range of ~10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W CO-to-mass conversion factor, X CO, is found to be ~2.3 × 10 20 cm -2(K km s –1) –1 for the high-longitude part of Orion A (l > 212°), ~1.7 times higher than ~1.3 × 10 20 found for the rest of Orion A and B. We interpret the apparent high X CO in the high-longitude region of Orion A in the light of recent works proposing a nonlinear relation between H2 and CO densities in the diffuse molecular gas. W CO decreases faster than the H 2 column density in the region making the gas "darker" to W CO.« less

Pratt & Whitney Advanced Ducted Propulsor (ADP) Engine Test in 40x80ft w.t.: Engineers Peter

NASA Technical Reports Server (NTRS)

1993-01-01

Pratt & Whitney Advanced Ducted Propulsor (ADP) Engine Test in 40x80ft w.t.: Engineers Peter Zell (left) and Dr Clifton Horne (right) are shown preparing for a laser light sheet for a flow visualization test. Shown standing in the nacelle of the ADP is John Girvin, senior test engineer for Pratt & Whitney.

Observational constraints on Arctic boundary-layer clouds, surface moisture and sensible heat fluxes

NASA Astrophysics Data System (ADS)

Wu, D. L.; Boisvert, L.; Klaus, D.; Dethloff, K.; Ganeshan, M.

2016-12-01

The dry, cold environment and dynamic surface variations make the Arctic a unique but difficult region for observations, especially in the atmospheric boundary layer (ABL). Spaceborne platforms have been the key vantage point to capture basin-scale changes during the recent Arctic warming. Using the AIRS temperature, moisture and surface data, we found that the Arctic surface moisture flux (SMF) had increased by 7% during 2003-2013 (18 W/m2 equivalent in latent heat), mostly in spring and fall near the Arctic coastal seas where large sea ice reduction and sea surface temperature (SST) increase were observed. The increase in Arctic SMF correlated well with the increases in total atmospheric column water vapor and low-level clouds, when compared to CALIPSO cloud observations. It has been challenging for climate models to reliably determine Arctic cloud radiative forcing (CRF). Using the regional climate model HIRHAM5 and assuming a more efficient Bergeron-Findeisen process with generalized subgrid-scale variability for total water content, we were able to produce a cloud distribution that is more consistent with the CloudSat/CALIPSO observations. More importantly, the modified schemes decrease (increase) the cloud water (ice) content in mixed-phase clouds, which help to improve the modeled CRF and energy budget at the surface, because of the dominant role of the liquid water in CRF. Yet, the coupling between Arctic low clouds and the surface is complex and has strong impacts on ABL. Studying GPS/COSMIC radio occultation (RO) refractivity profiles in the Arctic coldest and driest months, we successfully derived ABL inversion height and surface-based inversion (SBI) frequency, and they were anti-correlated over the Arctic Ocean. For the late summer and early fall season, we further analyzed Japanese R/V Mirai ship measurements and found that the open-ocean surface sensible heat flux (SSHF) can explain 10 % of the ABL height variability, whereas mechanisms such as cloud

Airborne measurements of cloud-forming nuclei and aerosol particles in stabilized ground clouds produced by solid rocket booster firings

NASA Technical Reports Server (NTRS)

Hindman, E. E., II; Ala, G. G.; Parungo, F. P.; Willis, P. T.; Bendura, R. J.; Woods, D.

1978-01-01

Airborne measurements of cloud volumes, ice nuclei and cloud condensation nuclei, liquid particles, and aerosol particles were obtained from stabilized ground clouds (SGCs) produced by Titan 3 launches at Kennedy Space Center, 20 August and 5 September 1977. The SGCs were bright, white, cumulus clouds early in their life and contained up to 3.5 g/m3 of liquid in micron to millimeter size droplets. The measured cloud volumes were 40 to 60 cu km five hours after launch. The SGCs contained high concentrations of cloud condensation nuclei active at 0.2%, 0.5%, and 1.0% supersaturation for periods of three to five hours. The SGCs also contained high concentrations of submicron particles. Three modes existed in the particle population: a 0.05 to 0.1 micron mode composed of aluminum-containing particles, a 0.2 to 0.8 micron mode, and a 2.0 to 10 micron mode composed of particles that contained primarily aluminum.

Evaluation of rheological behavior of 10W40 lubricant containing hybrid nano-material by measuring dynamic viscosity

NASA Astrophysics Data System (ADS)

Ahmadi Nadooshan, Afshin; Hemmat Esfe, Mohammad; Afrand, Masoud

2017-08-01

In the present paper, the dynamic viscosity of 10W40 lubricant containing hybrid nano-materials has been examined. Hybrid nano-materials were composed of 90% of silica (SiO2) with 20-30 nm mean particle size and 10% of multi-walled carbon nanotubes (MWCNTs) with inner diameter of 2-6 nm and outer diameter of 5-20 nm. Nano-lubricant samples were prepared by two-step method with solid volume fractions of 0.05%, 0.1%, 0.25%, 0.5%, 0.75% and 1%. Dynamic viscosity of the samples was measured at temperatures between 5 and 55 °C and at shear rates of 666.5 s-1 up to 11,997 s-1. Experimental results indicated that the nano-lubricant had non-Newtonian behavior at all temperatures, while 10w40 oil was non-Newtonian only at high temperatures. With the use of the curve fitting technique of experimental data, power law and consistency indexes were obtained; furthermore, these coefficients were assessed by shear stress and viscosity diagram.

The Surprising Complexity of Diffuse and Translucent Clouds Toward SGR B2: Diatomics and COMs from 4 GHz to 1.2 THz

NASA Astrophysics Data System (ADS)

McGuire, Brett A.; Corby, Joanna F.; Martin-Drumel, Marie-Aline; Schilke, P.; McCarthy, Michael C.; Remijan, Anthony

2017-06-01

Many diffuse and translucent clouds lie along the line of sight between Earth and the Galactic Center that can be probed through molecular absorption at characteristic velocities. We highlight results of a study of diffuse and translucent clouds along the line of sight to Sgr B2, including SOFIA observations of SH near 1.4 THz and GBT PRIMOS observations from 4 to 50 GHz. We find significant variation in the chemical conditions within these clouds, and the abundances do not appear to correlate with the total optical depth. Additionally, from the GBT observations, we report the first detections of multiple complex organic molecules (COMs) in diffuse and translucent clouds, including CH_3CN, HC_3N, CH_3CHO, and NH_2CHO. We compare the GBT results to complementary observations of SH, H_2S, and others at mm, sub-mm, and THz frequencies from the NRAO 12m, Herschel HIFI, and SOFIA facilities, and comment on the insights into interstellar sulfur chemistry which is currently not well constrained.

On the potential influence of ice nuclei on surface-forced marine stratocumulus cloud dynamics

NASA Astrophysics Data System (ADS)

Harrington, Jerry Y.; Olsson, Peter Q.

2001-11-01

The mixed phase cloudy boundary layer that occurs during off-ice flow in the marine Arctic was simulated in an environment with a strong surface heat flux (nearly 800 W m-2). A two-dimensional, eddy-resolving model coupled to a detailed cloud microphysical model was used to study both liquid phase and mixed phase stratocumulus clouds and boundary layer (BL) dynamics in this environment. Since ice precipitation may be important to BL dynamics, and ice nuclei (IN) concentrations modulate ice precipitation rates, the role of IN in cloud and BL development was explored. The results of several simulations illustrate how mixed phase microphysical processes affect the evolution of the cloudy BL in this environment. In agreement with past studies, BLs with mixed phase clouds had weaker convection, shallower BL depths, and smaller cloud fractions than BLs with clouds restricted to the liquid phase only. It is shown that the weaker BL convection is due to strong ice precipitation. Ice precipitation reduces convective strength directly by stabilizing downdrafts and more indirectly by sensibly heating the BL and inhibiting vertical mixing of momentum thereby reducing surface heat fluxes by as much as 80 W m-2. This feedback between precipitation and surface fluxes was found to have a significant impact on cloud/BL morphology, producing oscillations in convective strength and cloud fraction that did not occur if surface fluxes were fixed at constant values. Increases in IN concentrations in mixed phase clouds caused a more rapid Bergeron-Findeisen process leading to larger precipitation fluxes, reduced convection and lower cloud fraction. When IN were removed from the BL through precipitation, fewer crystals were nucleated at later simulation times leading to progressively weaker precipitation rates, greater cloud fraction, and stronger convective BL eddies.

Marine Cloud Brightening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Latham, John; Bower, Keith; Choularton, Tom

2012-09-07

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

Marine cloud brightening.

PubMed

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

2012-09-13

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

ALMA Observations of a Quiescent Molecular Cloud in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Wong, Tony; Hughes, Annie; Tokuda, Kazuki; Indebetouw, Rémy; Bernard, Jean-Philippe; Onishi, Toshikazu; Wojciechowski, Evan; Bandurski, Jeffrey B.; Kawamura, Akiko; Roman-Duval, Julia; Cao, Yixian; Chen, C.-H. Rosie; Chu, You-hua; Cui, Chaoyue; Fukui, Yasuo; Montier, Ludovic; Muller, Erik; Ott, Juergen; Paradis, Deborah; Pineda, Jorge L.; Rosolowsky, Erik; Sewiło, Marta

2017-12-01

We present high-resolution (subparsec) observations of a giant molecular cloud in the nearest star-forming galaxy, the Large Magellanic Cloud. ALMA Band 6 observations trace the bulk of the molecular gas in 12CO(2-1) and the high column density regions in 13CO(2-1). Our target is a quiescent cloud (PGCC G282.98-32.40, which we refer to as the “Planck cold cloud” or PCC) in the southern outskirts of the galaxy where star formation activity is very low and largely confined to one location. We decompose the cloud into structures using a dendrogram and apply an identical analysis to matched-resolution cubes of the 30 Doradus molecular cloud (located near intense star formation) for comparison. Structures in the PCC exhibit roughly 10 times lower surface density and five times lower velocity dispersion than comparably sized structures in 30 Dor, underscoring the non-universality of molecular cloud properties. In both clouds, structures with relatively higher surface density lie closer to simple virial equilibrium, whereas lower surface-density structures tend to exhibit supervirial line widths. In the PCC, relatively high line widths are found in the vicinity of an infrared source whose properties are consistent with a luminous young stellar object. More generally, we find that the smallest resolved structures (“leaves”) of the dendrogram span close to the full range of line widths observed across all scales. As a result, while the bulk of the kinetic energy is found on the largest scales, the small-scale energetics tend to be dominated by only a few structures, leading to substantial scatter in observed size-line-width relationships.

Modification of cirrus clouds to reduce global warming

NASA Astrophysics Data System (ADS)

Mitchell, D. L.

2009-12-01

Since both greenhouse gases and cirrus clouds strongly affect outgoing longwave radiation (OLR) with no affect or less affect on solar radiation, respectively, an attempt to delay global warming to buy time for emission reduction strategies to work might naturally target cirrus clouds. Cirrus having optical depths < 3.6 cover 13% of the globe and have a net warming effect on climate, with the coldest cirrus having the strongest warming effect. Roughly 2/3 of predicted global warming is due to the feedback effect of water vapor and clouds from an initial greenhouse gas forcing, and a recent study indicates water vapor and clouds in the upper troposphere (UT) have the greatest impact on climate sensitivity (the equilibrium response of global-mean surface temperature to a CO2 doubling). Thus altering UT water vapor and cirrus may be a good strategy for climate engineering. Cirrus cloud coverage is predicted to be sensitive to the ice fall speed which depends on ice crystal size. The higher the cirrus, the greater their impact is on OLR. Thus by changing ice crystal size in the coldest cirrus, OLR and climate might be modified. Fortunately the coldest cirrus have the highest ice supersaturation due to the dominance of homogeneous freezing nucleation. Seeding such cirrus with very efficient heterogeneous ice nuclei should produce larger ice crystals due to vapor competition effects, thus increasing OLR and surface cooling. Preliminary estimates of this global net cloud forcing via GCM simulations are more negative than -2.8 W m-2 and could neutralize the radiative forcing due to a CO2 doubling (3.7 W m-2). This cirrus engineered net forcing is due to (1) reduced cirrus coverage and (2) reduced upper tropospheric water vapor, due to enhanced ice sedimentation. The implementation of this climate engineering could use the airline industry to disperse the seeding material. Commercial airliners typically fly at temperatures between -40 and -60 deg. C (where homogeneous

Evaluating stratiform cloud base charge remotely

NASA Astrophysics Data System (ADS)

Harrison, R. Giles; Nicoll, Keri A.; Aplin, Karen L.

2017-06-01

Stratiform clouds acquire charge at their upper and lower horizontal boundaries due to vertical current flow in the global electric circuit. Cloud charge is expected to influence microphysical processes, but understanding is restricted by the infrequent in situ measurements available. For stratiform cloud bases below 1 km in altitude, the cloud base charge modifies the surface electric field beneath, allowing a new method of remote determination. Combining continuous cloud height data during 2015-2016 from a laser ceilometer with electric field mill data, cloud base charge is derived using a horizontal charged disk model. The median daily cloud base charge density found was -0.86 nC m-2 from 43 days' data. This is consistent with a uniformly charged region 40 m thick at the cloud base, now confirming that negative cloud base charge is a common feature of terrestrial layer clouds. This technique can also be applied to planetary atmospheres and volcanic plumes.