WorldWideScience

Sample records for atmospheric layers

  1. the Martian atmospheric boundary layer

    DEFF Research Database (Denmark)

    Petrosyan, A.; Galperin, B.; Larsen, Søren Ejling

    2011-01-01

    The planetary boundary layer (PBL) represents the part of the atmosphere that is strongly influenced by the presence of the underlying surface and mediates the key interactions between the atmosphere and the surface. On Mars, this represents the lowest 10 km of the atmosphere during the daytime...

  2. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar

  3. Inhomogeneities in Molecular Layers of Mira Atmospheres

    Science.gov (United States)

    2011-01-01

    Wood10, and A. A. Zijlstra11 1 ESO, Karl- Schwarzschild -Str. 2, 85748 Garching bei München, Germany e-mail: mwittkow@eso.org 2 US Naval Observatory, 3450...with the predictions of the latest dynamic model atmosphere series based on self-excited pulsation models. The wavelength-dependent radius variations...based on self-excited pulsation models. The wavelength-dependent radius variations are interpreted as the effect of molecular layers lying above the

  4. Acoustic tomography in the atmospheric surface layer

    Directory of Open Access Journals (Sweden)

    A. Ziemann

    Full Text Available Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

    Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques.

  5. Exploring Isothermal Layers in the Stable Atmospheric Boundary Layer

    Science.gov (United States)

    Wilkins, Joseph

    2011-03-01

    Simulating the stable atmospheric boundary-layer presents a significant challenge to numerical models due to the interactions of several processes with widely varying scales. The goal of this project is to more clearly define the cause of isothermal layers observed during the Meteorological Experiment in Arizona's Meteor Crater and to test the National Taiwan University/Purdue University (NTU/P) model in stable environments with complex terrain. The NTU/P model is able to utilize the actual terrain data with minimal smoothing for stability. We have found that isothermal profiles can be generated by the standing wave that develops due to weak wind flowing over the crater. However, the horizontal heterogeneity is greater than observed. Continued effort will explore enhancing horizontal mixing due to turbulence and radiative transfer. Louis Stokes Alliances for Minority Participation Program, Summer Research Opportunities Program.

  6. Helicity in the atmospheric boundary layer

    Science.gov (United States)

    Kurgansky, Michael; Koprov, Boris; Koprov, Victor; Chkhetiani, Otto

    2017-04-01

    An overview is presented of recent direct field measurements at the Tsimlyansk Scientific Station of A.M. Obukhov Institute of Atmospheric Physics in Moscow of turbulent helicity (and potential vorticity) using four acoustic anemometers positioned, within the atmospheric surface-adjacent boundary layer, in the vertices of a rectangular tetrahedron, with an approximate 5 m distance between the anemometers and a 5.5 m elevation of the tetrahedron base above the ground surface (Koprov, Koprov, Kurgansky and Chkhetiani. Izvestiya, Atmospheric and Oceanic Physics, 2015, Vol.51, 565-575). The same ideology was applied in a later field experiment in Tsimlyansk with the tetrahedron's size of 0.7 m and variable elevation over the ground from 3.5 to 25 m. It is illustrated with examples of the statistical distribution of instantaneous (both positive and negative) turbulent helicity values. A theory is proposed that explains the measured mean turbulent helicity sign, including the sign of contribution to helicity from the horizontal and vertical velocity & vorticity components, respectively, and the sign of helicity buoyant production term. By considering a superposition of the classic Ekman spiral solution and a jet-like wind profile that mimics a shallow breeze circulation over a non-uniformly heated Earth surface, a possible explanation is provided, why the measured mean turbulent helicity sign is negative. The pronounced breeze circulation over the Tsimlyansk polygon which is located nearby the Tsimlyansk Reservoir was, indeed, observed during the measurements period. Whereas, essentially positive helicity is injected into the boundary layer from the free atmosphere in the Northern Hemisphere.

  7. Turbulent transport in the atmospheric surface layer

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern [Dept. of Physical Geography and Ecosystem Science, Lund Univ., Lund (Sweden)

    2012-04-15

    In the modelling of transport and accumulation of the radioactive isotope carbon-14 (C-14) in the case of a potential release from a future repository of radioactive waste, it is important to describe the transport of the isotope in the atmosphere. This report aims to describe the turbulent transport within the lower part of the atmosphere; the inertial surface layer and the roughness sublayer. Transport in the inertial surface layer is dependent on several factors, whereof some can be neglected under certain circumstances. Under steady state conditions, fully developed turbulent conditions, in flat and horizontal homogeneous areas, it is possible to apply an eddy diffusivity approach for estimating vertical transport of C. The eddy diffusivity model assumes that there is proportionality between the vertical gradient and the transport of C. The eddy diffusivity is depending on the atmospheric turbulence, which is affected by the interaction between mean wind and friction of the ground surface and of the sensible heat flux in the atmosphere. In this report, it is described how eddy diffusivity of the inertial surface layer can be estimated from 3-d wind measurements and measurements of sensible heat fluxes. It is also described how to estimate the eddy diffusivity in the inertial surface layer from profile measurements of temperature and wind speed. Close to the canopy, wind and C profiles are influenced by effects of the surface roughness; this section of the atmosphere is called the roughness sublayer. Its height is up to {approx}3 times the height of the plant canopy. When the mean wind interacts with the canopy, turbulence is not only produced by shear stress and buoyancy, it is additionally created by wakes, which are formed behind the plants. Turbulence is higher than it would be over a flat surface, and the turbulent transport is hereby more efficient. Above the plant canopy, but still within the roughness sublayer, a function that compensates for the effect

  8. The Atmospheric boundary layer over Arctic fjords

    Energy Technology Data Exchange (ETDEWEB)

    Kilpelaeinen, Tiina

    2011-07-01

    Arctic fjords represent one of the most challenging environments in the world for weather prediction and climate models. This is due to complex interactions between the large-scale weather conditions, land, sea, sea ice and surrounding topography consisting of mountains, valleys and glaciers. This thesis describes some special characteristics of the lowest part of the atmosphere over fjords in Svalbard. The main research topics are 1) the exchange of energy between the atmosphere and sea, 2) vertical structure of temperature, humidity and wind, 3) spatial variability of the meteorological variables and 4) identifying the main challenges for the weather prediction models. Kilpelaeinen has collected data using weather masts and tethered balloons at the coasts of fjords in Svalbard. In addition, she has made high-resolution simulations of the meteorological conditions over Svalbard fjords with a weather prediction model. Kilpelaeinens investigations show that the vertical profiles of temperature, humidity and wind over Arctic fjords are complex and therefore challenging for the weather prediction models to capture. Layers with a temperature and humidity increase with height are commonly found over Svalbard fjords, often even on multiple levels. A weather prediction model does not realistically capture these layers, which leads to fairly large errors in the modeled surface variables. Further, she found that a wind maximum at a low altitude is also a typical feature over Arctic fjords. The height of this wind maximum depends on the sea-ice conditions, being highest when sea ice is present. The thesis points out that due to the complex topography and the surface types (sea ice and water), spatial variability of meteorological variables within a fjord is very large and can reach levels comparable to the temporal variability. Hence, a high horizontal resolution in the order of 1 km is needed in the weather prediction models to realistically simulate all the significant

  9. Exploring Scintillometry in the Stable Atmospheric Surface Layer

    NARCIS (Netherlands)

    Hartogensis, O.K.

    2006-01-01

    The main objective of this thesis is to investigate observation methods of heat and momentum exchange and key variables that characterise turbulence in the atmospheric stable surface layer (SSL), a layer defined as the lower part of the stable boundary layer (SBL) where surface fluxes do not change

  10. The turning of the wind in the atmospheric boundary layer

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Gryning, Sven-Erik; Floors, Rogier Ralph

    2014-01-01

    Here we use accurate observations of the wind speed vector to analyze the behavior with height of the wind direction. The observations are a combination of tall meteorological mast and long-range wind lidar measurements covering the entire atmospheric boundary layer. The observations were performed...... winds underpredict the turning of the wind and the boundary-layer winds in general....

  11. Aspects of the atmospheric surface layers on Mars and Earth

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling; Ejsing Jørgensen, Hans; Landberg, L.

    2002-01-01

    and mean flow on Mars is found to obey the same scaling laws as on Earth. The largest micrometeorological differences between the two atmospheres are associated with the low air density of the Martian atmosphere. Together with the virtual absence of water vapour, it reduces the importance......The structures of mean flow and turbulence in the atmospheric surface boundary layer have been extensively studied on Earth, and to a far less extent on Mars, where only the Viking missions and the Pathfinder mission have delivered in-situ data. Largely the behaviour of surface-layer turbulence...

  12. Lower Atmospheric Boundary Layer Experiment (LABLE) Final Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Klein, P [University of Oklahoma - School of Meteorology; Bonin, TA; Newman, JF [National Renewable Energy Laboratory; Turner, DD [National Oceanic and Atmospheric Administration; Chilson, P [University of Oklahoma; Blumberg, WG [University of Oklahoma; Mishra, S; Wainwright, CE; Carney, M [University of Oklahoma - School of Meteorology; Jacobsen, EP [University of Oklahoma; Wharton, S [Lawrence Livermore National Laboratory

    2015-11-01

    The Lower Atmospheric Boundary Layer Experiment (LABLE) included two measurement campaigns conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site in Oklahoma during 2012 and 2013. LABLE was designed as a multi-phase, low-cost collaboration among the University of Oklahoma, the National Severe Storms Laboratory, Lawrence Livermore National Laboratory, and the ARM program. A unique aspect was the role of graduate students in LABLE. They served as principal investigators and took the lead in designing and conducting experiments using different sampling strategies to best resolve boundary-layer phenomena.

  13. Simulation of Wind turbines in the atmospheric boundary layer

    DEFF Research Database (Denmark)

    Chivaee, Hamid Sarlak; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    Large eddy simulation of an arbitrary wind farm is studied in the neutral and thermally stratified atmospheric boundary Layer. Large eddy simulations of industrial flows usually requires full resolution of the flow near the wall and this is believed to be one of the main deficiencies of LES because...... layer. In the current study, another approach has been implemented to simulate the flow in a fully developed wind farm boundary layer. The approach is based on Immersed Boundary Method and involves implementation of an arbitrary prescribed initial boundary layer. An initial boundary layer is enforced...... through the whole domain, without wind turbines included, while the body forces that are required to maintain that flow field is calculated. The body forces are then stored and applied on the domain through the simulation of wind turbine and the boundary layer shape will be modified based on the turbine...

  14. Understanding and prediction of stable atmospheric boundary layers over land

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2007-01-01

    The main objective of this thesis is to contribute to further understanding of the stable boundary layer (SBL) over land, and its representation in atmospheric models. A SBL develops during night due to radiative surface cooling. Observations in the SBL are difficult since many different physical

  15. The determination of turbulent structures in the atmospheric surface layer

    NARCIS (Netherlands)

    Schols, J.L.J.

    1984-01-01

    The turbulent flow in the atmospheric surface layer (ASL) contains turbulent structures, which are defined as spatially coherent, organized flow motions. 'Organized' means that characteristic patterns, observed at a point in space, occur almost simultaneously in more than one turbulence signal and

  16. On the marine atmospheric boundary layer characteristics over Bay ...

    Indian Academy of Sciences (India)

    Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made ...

  17. Atmospheric boundary layer evening transitions over West Texas

    Science.gov (United States)

    A systemic analysis of the atmospheric boundary layer behavior during some evening transitions over West Texas was done using the data from an extensive array of instruments which included small and large aperture scintillometers, net radiometers, and meteorological stations. The analysis also comp...

  18. Characterization of the atmospheric boundary layer from radiosonde ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, a comparison of two methods for the calculation of the height of atmospheric boundary layer (ABL), using balloon-borne GPS radiosonde data is presented. ABL has been characterized using vertical profiles of meteorological parameter. The gradient of virtual potential temperature (v) profile for the ...

  19. Whirlwinds and hairpins in the atmospheric surface layer

    NARCIS (Netherlands)

    Oncley, Steven P.; Hartogensis, O.K.; Tong, Chenning

    2016-01-01

    Vortices in the atmospheric surface layer are characterized using observations at unprecedented resolution from a fixed array of 31 turbulence sensors. During the day, these vortices likely are dust devils, though no visual observations are available for confirmation. At night, hairpin vortices

  20. Spatial atmospheric atomic layer deposition of alxzn1-xo

    NARCIS (Netherlands)

    Illiberi, A.; Scherpenborg, R.; Wu, Y.; Roozeboom, F.; Poodt, P.

    2013-01-01

    The possibility of growing multicomponent oxides by spatial atmospheric atomic layer deposition has been investigated. To this end, Al xZn1-xO films have been deposited using diethyl zinc (DEZ), trimethyl aluminum (TMA), and water as Zn, Al, and O precursors, respectively. When the metal precursors

  1. Observations of the atmospheric surface layer parameters over a ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    1999-08-11

    Aug 11, 1999 ... ciated cloud cover softened the expected dramatic changes in the ASL. In the present paper we are reporting the eclipse-induced changes observed in the mean, turbulence parameters and spectra in the atmospheric surface layer during the sudden diminution of solar energy associated with the solar.

  2. The Temporal Behavior of the Atmospheric Boundary Layer in Israel.

    Science.gov (United States)

    Dayan, Uri; Rodnizki, Jacob

    1999-06-01

    Upper-air measurements collected for three consecutive years (1987-89) from the Israel Meteorological Service permanent sounding site, in Beit-Dagan, Israel, enabled the temporal behavior of the atmospheric boundary layer over Israel to be characterized. Data analyzed consisted of the layer depth, the thermal gradient within the layer, and occurrence frequency of radiative and elevated inversions. To adequately represent the multiyear seasonal and diurnal behavior, the 3-yr databases were merged based on the tested hypothesis that the month sample in each individual year comes from the same population. The analysis shows that the depth of the radiative ground-based inversion, its frequency, as well as its thermal profile are maximal during spring and early summer. The upper-inversion layer is well defined during the summer, its lowest base (0.5-1 km MSL) indicating a sharp interface layer formed between the marine turbulent boundary layer at the shallow layer of the atmosphere and the subsiding downward motion caused by the subtropical high pressure system. During the other three seasons a significant temporal variation of the upper-inversion base is observed as a result of the frequent larger-scale synoptic weather systems. The diurnal variation of the mixed-layer depth is most evident during the summer because it is mainly governed by heat fluxes and the daily sea-breeze cycle that are most intensive then. Henceforth, the layer minimal depth, along the coast, usually occurs during late afternoon hours when the wind speed of the cool sea breeze reaches its minimal rate and heat fluxes dissipate rapidly, leading to a decrease of the marine turbulent boundary layer.

  3. Enhancement of atmospheric radiation by an aerosol layer

    Science.gov (United States)

    Michelangeli, Diane V.; Yung, Yuk L.; Shia, Run-Lie; Eluszkiewicz, Janusz; Allen, Mark; Crisp, David

    1992-01-01

    The presence of a stratospheric haze layer may produce increases in both the actinic flux and the irradiance below this layer. Such haze layers result from the injection of aerosol-forming material into the stratosphere by volcanic eruptions. Simple heuristic arguments show that the increase in flux below the haze layer, relative to a clear sky case, is a consequence of 'photon trapping'. The magnitude of these flux perturbations, as a function of aerosol properties and illumination conditions, is explored with a new radiative transfer model that can accurately compute fluxes in an inhomogeneous atmosphere with nonconservative scatterers having arbitrary phase function. One calculated consequence of the El Chichon volcanic eruption is an increase in the midday surface actinic flux at 20 deg N latitude, summer, by as much as 45 percent at 2900 A. This increase in flux in the UV-B wavelength range was caused entirely by aerosol scattering, without any reduction in the overhead ozone column.

  4. Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

    Science.gov (United States)

    Sarlak, H.; Sørensen, J. N.; Mikkelsen, R.

    2012-09-01

    Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically required for such problems.

  5. Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

    DEFF Research Database (Denmark)

    Chivaee, Hamid Sarlak; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    2012-01-01

    Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM......) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation...... and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically...

  6. Measurement Science of the Intermittent Atmospheric Boundary Layer

    Science.gov (United States)

    2014-01-01

    investigate intermittency fluxes of clear-air radar reflectivity inthe atmospheric boundary layer, 2013 IEEE International Symposium on Antennas and...meridionally by 40 m), eight ultrasonic anemometers, two low-response thermometers, two low-response hygrometers, three quartz-crystal barometers, and...vertically spaced sonics can be used for post-facto calibration (Muschinski and Ayvazian, 2014) of relative biases in a pair of ultrasonic

  7. Turbulence Scales Simulations in Atmospheric Boundary Layer Wind Tunnels

    OpenAIRE

    Teleman, Elena-Carmen; Silion, Radu; Axinte, Elena; Pescaru, Radu

    2008-01-01

    The simulation of the air flow over models in atmospheric boundary layer tunnels is a research domain based on advanced scientific technologies imposed by the necessity of studying the turbulent fluid movements in the proximity of the Earth’s surface. The experiment presented herein is developed in the wind tunnel from the Laboratory of Structural Aerodynamics of the Faculty of Civil Engineering and Building Services in Iassy. Measurements necessary for the determination of the turbulence sca...

  8. The collapse of turbulence in the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Van de Wiel, B J H; Clercx, H J H [Department of Physics, Eindhoven University of Technology (Netherlands); Moene, A F [Department of Meteorology and Air Quality, Wageningen University and Research Centre (Netherlands); Jonker, H J J, E-mail: b.j.h.v.d.wiel@tue.nl [Department of Multi-scale Pysics, Delft University of Technology (Netherlands)

    2011-12-22

    A well-known phenomenon in the atmospheric boundary layer is the fact that winds may become very weak in the evening after a clear sunny day. In these quiet conditions usually hardly any turbulence is present. Consequently this type of boundary layer is referred to as the quasi-laminar boundary layer. In spite of its relevance, the appearance of laminar boundary layers is poorly understood and forms a long standing problem in meteorological research. Here we investigate an analogue problem in the form of a stably stratified channel flow. The flow is studied with a simplified atmospheric model as well as with Direct Numerical Simulations. Both models show remarkably similar behaviour with respect to the mean variables such as temperature and wind speed. The similarity between both models opens new way for understanding and predicting the laminarization process. Mathematical analysis on the simplified model shows that relaminarization can be understood from the existence of a definite limit in the maximum sustainable heat flux under stably stratified conditions. This fascinating aspect will be elaborated in future work.

  9. Atmospheric boundary layers in storms: advanced theory and modelling applications

    Directory of Open Access Journals (Sweden)

    S. S. Zilitinkevich

    2005-01-01

    Full Text Available Turbulent planetary boundary layers (PBLs control the exchange processes between the atmosphere and the ocean/land. The key problems of PBL physics are to determine the PBL height, the momentum, energy and matter fluxes at the surface and the mean wind and scalar profiles throughout the layer in a range of regimes from stable and neutral to convective. Until present, the PBLs typical of stormy weather were always considered as neutrally stratified. Recent works have disclosed that such PBLs are in fact very strongly affected by the static stability of the free atmosphere and must be treated as factually stable (we call this type of the PBL "conventionally neutral" in contract to the "truly neutral" PBLs developed against the neutrally stratified free flow. It is common knowledge that basic features of PBLs exhibit a noticeable dependence on the free-flow static stability and baroclinicity. However, the concern of the traditional theory of neural and stable PBLs was almost without exception the barotropic nocturnal PBL, which develops at mid latitudes during a few hours in the night, on the background of a neutral or slightly stable residual layer. The latter separates this type of the PBL from the free atmosphere. It is not surprising that the nature of turbulence in such regimes is basically local and does not depend on the properties of the free atmosphere. Alternatively, long-lived neutral (in fact only conditionally neutral or stable PBLs, which have much more time to grow up, are placed immediately below the stably stratified free flow. Under these conditions, the turbulent transports of momentum and scalars even in the surface layer - far away from the PBL outer boundary - depend on the free-flow Brunt-Väisälä frequency, N. Furthermore, integral measures of the long-lived PBLs (their depths and the resistance law functions depend on N and also on the baroclinic shear, S. In the traditional PBL models both non-local parameters N and S

  10. Coherence of simulated atmospheric boundary-layer turbulence

    Science.gov (United States)

    Jiadong, Zeng; Zhiguo, Li; Mingshui, Li

    2017-12-01

    The coherences in a plane perpendicular to incoming flow are measured in wind tunnel simulations of atmospheric turbulent flow. The measured coherences are compared with analytical expressions tailored to field measurements and with theoretical coherence models which assume homogeneous turbulence and the von Kármán’s spectrum. The comparison indicates that the simulated atmospheric boundary layer flow is approximately horizontally homogeneous turbulence. Based on the above assumption and the systematic analysis of lateral coherence, it can be concluded that the lateral coherences of simulated atmospheric boundary turbulence can be determined accurately using the von Kármán spectrum and the turbulence parameters measured by a few measurement points. The measured results also show that the spatial characteristics of vertical coherences are closely related to the dimensionless parameter {{Δ }}z/({\\bar{z}}0.3{L}ux 0.7). The vertical coherence at two heights can be roughly estimated by the ratio to {{Δ }}z/({\\bar{z}}0.3{L}ux 0.7). The relationship between the phase angles of u-, v- and w-components and the vertical separation distance and the height from the ground is further analyzed. Finally, the roles of the type of land surface roughness, the height from the ground, the turbulence intensity and the integral length scale in lateral and vertical coherences are also discussed in this study.

  11. Turbulence Scales Simulations in Atmospheric Boundary Layer Wind Tunnels

    Directory of Open Access Journals (Sweden)

    Elena-Carmen Teleman

    2008-01-01

    Full Text Available The simulation of the air flow over models in atmospheric boundary layer tunnels is a research domain based on advanced scientific technologies imposed by the necessity of studying the turbulent fluid movements in the proximity of the Earth’s surface. The experiment presented herein is developed in the wind tunnel from the Laboratory of Structural Aerodynamics of the Faculty of Civil Engineering and Building Services in Iassy. Measurements necessary for the determination of the turbulence scales of the wind action in urban environment were conducted. The data obtained were processed and analyzed and interpreted with specific software. The results are used for a synthesis regarding the scales of turbulence of the model of flow and the actual accuracy of measurements. The paper presents some of the important elements of this synthesis.

  12. Characteristics of turbulent structures in the unstable atmospheric surface layer

    Science.gov (United States)

    Schols, J. L. J.; Jansen, A. E.; Krom, J. G.

    1985-10-01

    An atmospheric surface-layer (ASL) experiment conducted at a meteorological site in the Oostelijk-Flevoland polder of the Netherlands is described. Turbulent fluctuations of wind velocity, air temperature and static pressure were measured, using three 10 m towers. Simultaneous turbulent signals at several heights on the towers were used to investigate the properties of the turbulent structures which contribute most significantly to the turbulent vertical transports in the unstable ASL. These turbulent structures produce between 30 and 50% of the mean turbulent vertical transport of horizontal alongwind momentum and they contribute to between 40 and 50% of the mean turbulent vertical heat transport; in both cases this occurs during 15 to 20% of the total observation time. The translation speed of the turbulent structures equals the wind speed averaged over the depth of the ASL, which scales on the surface friction velocity. The inclination angle of the temperature interface at the upstream edge of the turbulent structures to the surface is significantly smaller than that of the internal shear layer, which is associated with the temperature interface. The turbulent structures in the unstable ASL are determined by a large-scale temperature field: Convective motions, which encompass the whole depth of the planetary boundary layer (PBL), penetrate into the ASL. The curvature of the vertical profile of mean horizontal alongwind velocity forces the alignment of the convective cells in the flow direction (Kuettner, 1971), which have an average length of several hundreds of metres and an average width of a few tens of metres. This mechanism leads to the formation of turbulent structures, which extend throughout the depth of the ASL.

  13. NOAA Climate Data Record (CDR) of Atmospheric Layer Temperatures, Version 3.3

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Atmospheric Layer Temperature Climate Data Record (CDR) dataset is a monthly analysis of the tropospheric and stratospheric data using temperature sounding...

  14. Shallow marine cloud topped boundary layer in atmospheric models

    Science.gov (United States)

    Janjic, Zavisa

    2017-04-01

    A common problem in many atmospheric models is excessive expansion over cold water of shallow marine planetary boundary layer (PBL) topped by a thin cloud layer. This phenomenon is often accompanied by spurious light precipitation. The "Cloud Top Entrainment Instability" (CTEI) was proposed as an explanation of the mechanism controlling this process in reality thereby preventing spurious enlargement of the cloudy area and widely spread light precipitation observed in the models. A key element of this hypothesis is evaporative cooling at the PBL top. However, the CTEI hypothesis remains controversial. For example, a recent direct simulation experiment indicated that the evaporative cooling couldn't explain the break-up of the cloudiness as hypothesized by the CTEI. Here, it is shown that the cloud break-up can be achieved in numerical models by a further modification of the nonsingular implementation of the Mellor-Yamada Level 2.5 turbulence closure model (MYJ) developed at the National Centers for Environmental Prediction (NCEP) Washington. Namely, the impact of moist convective instability is included into the turbulent energy production/dissipation equation if (a) the stratification is stable, (b) the lifting condensation level (LCL) for a particle starting at a model level is below the next upper model level, and (c) there is enough turbulent kinetic energy so that, due to random vertical turbulent motions, a particle starting from a model level can reach its LCL. The criterion (c) should be sufficiently restrictive because otherwise the cloud cover can be completely removed. A real data example will be shown demonstrating the ability of the method to break the spurious cloud cover during the day, but also to allow its recovery over night.

  15. Rocket dust storms and detached layers in the Martian atmosphere

    Science.gov (United States)

    Spiga, A.; Faure, J.; Madeleine, J.; Maattanen, A. E.; Forget, F.

    2012-12-01

    Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling with radiatively-active transported dust to predict the evolution of a local dust storm monitored by OMEGA onboard Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, in lieu of latent heating in moist convection on Earth. We propose to use the terminology "rocket dust storm", or conio-cumulonimbus, to describe those storms in which rapid and efficient vertical transport takes place, injecting dust particles at high altitudes in the Martian troposphere (30 to 50 km). Combined to horizontal transport by large-scale winds, rocket dust storms form detached layers of dust reminiscent of those observed with instruments onboard Mars Global Surveyor and Mars Reconnaissance Orbiter. Detached layers are stable over several days owing to nighttime sedimentation being unable to counteract daytime convective transport, and to the resupply of convective energy at sunrise. The peak activity of rocket dust storms is expected in low-latitude regions at clear season, which accounts for the high-altitude tropical dust maximum unveiled by Mars Climate Sounder. Our findings on dust-driven deep convection have strong implications for the Martian dust cycle, thermal structure, atmospheric dynamics, cloud microphysics, chemistry, and robotic and human exploration.ensity-scaled dust optical depth at local times 1400 1600 and 1800 (lat 2.5°S, Ls 135°) hortwave heating rate at local time 1500 and latitude 2.5°S.

  16. CFD simulation of neutral ABL flows; Atmospheric Boundary Layer

    Energy Technology Data Exchange (ETDEWEB)

    Xiaodong Zhang

    2009-04-15

    This work is to evaluate the CFD prediction of Atmospheric Boundary Layer flow field over different terrains employing Fluent 6.3 software. How accurate the simulation could achieve depend on following aspects: viscous model, wall functions, agreement of CFD model with inlet wind velocity profile and top boundary condition. Fluent employ wall function roughness modifications based on data from experiments with sand grain roughened pipes and channels, describe wall adjacent zone with Roughness Height (Ks) instead of Roughness Length (z{sub 0}). In a CFD simulation of ABL flow, the mean wind velocity profile is generally described with either a logarithmic equation by the presence of aerodynamic roughness length z{sub 0} or an exponential equation by the presence of exponent. As indicated by some former researchers, the disagreement between wall function model and ABL velocity profile description will result in some undesirable gradient along flow direction. There are some methods to improve the simulation model in literatures, some of them are discussed in this report, but none of those remedial methods are perfect to eliminate the streamwise gradients in mean wind speed and turbulence, as EllipSys3D could do. In this paper, a new near wall treatment function is designed, which, in some degree, can correct the horizontal gradients problem. Based on the corrected model constants and near wall treatment function, a simulation of Askervein Hill is carried out. The wind condition is neutrally stratified ABL and the measurements are best documented until now. Comparison with measured data shows that the CFD model can well predict the velocity field and relative turbulence kinetic energy field. Furthermore, a series of artificial complex terrains are designed, and some of the main simulation results are reported. (au)

  17. Analytical solution for the convectively-mixed atmospheric boundary layer

    NARCIS (Netherlands)

    Ouwersloot, H.G.; Vilà-Guerau de Arellano, J.

    2013-01-01

    Based on the prognostic equations of mixed-layer theory assuming a zeroth order jump at the entrainment zone, analytical solutions for the boundary-layer height evolution are derived with different degrees of accuracy. First, an exact implicit expression for the boundary-layer height for a situation

  18. Introduction to the Third GEWEX Atmospheric Boundary Layer Study (GABLS3)

    NARCIS (Netherlands)

    Holtslag, A.A.M.

    2014-01-01

    The atmospheric boundary layer (ABL) plays a dominant role in the exchange of energy, water vapour, trace gases and momentum between the earth’s surface and the overlying atmosphere. Consequently, the ABL is an important part of any numerical model in use for atmospheric and climate research, for

  19. Characterization of the atmospheric boundary layer from radiosonde ...

    Indian Academy of Sciences (India)

    moisture) or substances originating from the sur- face. It is usually flatter than the boundary layer, but fills the whole ABL in the deep convective boundary layers ..... Wea. Rev. 92 235–242. Holzworth G C 1967 Mixing depths, wind speeds and air pollution potential for selected locations in the United. States; J. Appl. Meteorol.

  20. Significant Atmospheric Boundary Layer Change Observed above an Agulhas Current Warm Cored Eddy

    Directory of Open Access Journals (Sweden)

    C. Messager

    2016-01-01

    Full Text Available The air-sea impact of a warm cored eddy ejected from the Agulhas Retroflection region south of Africa was assessed through both ocean and atmospheric profiling measurements during the austral summer. The presence of the eddy causes dramatic atmospheric boundary layer deepening, exceeding what was measured previously over such a feature in the region. This deepening seems mainly due to the turbulent heat flux anomaly above the warm eddy inducing extensive deep and persistent changes in the atmospheric boundary layer thermodynamics. The loss of heat by turbulent processes suggests that this kind of oceanic feature is an important and persistent source of heat for the atmosphere.

  1. Laboratory simulations of the atmospheric mixed-layer in flow ...

    Science.gov (United States)

    A laboratory study of the influence of complex terrain on the interface between a well-mixed boundary layer and an elevated stratified layer was conducted in the towing-tank facility of the U.S. Environmental Protection Agency. The height of the mixed layer in the daytime boundary layer can have a strong influence on the concentration of pollutants within this layer. Deflections of streamlines at the height of the interface are primarily a function of hill Froude number (Fr), the ratio of mixed-layer height (zi) to terrain height (h), and the crosswind dimension of the terrain. The magnitude of the deflections increases as Fr increases and zi / h decreases. For mixing-height streamlines that are initially below the terrain top, the response is linear with Fr; for those initially above the terrain feature the response to Fr is more complex. Once Fr exceeds about 2, the terrain related response of the mixed layer interface decreases somewhat with increasing Fr (toward more neutral flow). Deflections are also shown to increase as the crosswind dimensions of the terrain increases. Comparisons with numerical modeling, limited field data and other laboratory measurements reported in the literature are favorable. Additionally, visual observations of dye streamers suggests that the flow structure exhibited for our elevated inversions passing over three dimensional hills is similar to that reported in the literature for continuously stratified flow over two-dimensional h

  2. Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

    National Research Council Canada - National Science Library

    Sullivan, Peter P; McWilliams, James C; Melville, W. K

    2008-01-01

    .... Our long term scientific objective was to explore the nature of intermittence, coherent structures, and turbulent fluxes and their coupling in the surface layers of the marine atmospheric and oceanic...

  3. Surface layer conditions of the atmosphere over western Bay of Bengal during Monex

    Digital Repository Service at National Institute of Oceanography (India)

    Anto, A.F.; Rao, L.V.G.; Somayajulu, Y.K.

    Based on surface meteorological data and wave data collected from 2 stations in the western Bay of Bengal in July 1979, surface layer (SL) conditions of the atmosphere for different situations of surface circulations and the associated sea surface...

  4. [Characteristics of Winter Atmospheric Mixing Layer Height in Beijing-Tianjin-Hebei Region and Their Relationship with the Atmospheric Pollution].

    Science.gov (United States)

    Li, Meng; Tang, Gui-qian; Huang, Jun; Liu, Zi-rui; An, Jun-lin; Wang, Yue-si

    2015-06-01

    Atmospheric mixing layer height (MLH) is one of the main factors affecting the atmospheric diffusion and plays an important role in air quality assessment and distribution of the pollutants. Based on the ceilometers data, this paper has made synchronous observation on MLH in Beijing-Tianjin-Hebei region (Beijing, Tianjin, Shijiazhuang and Qinhuangdao) in heavy polluted February 2014 and analyzed the respective overall change and its regional features. Results show that in February 2014,the average of mixing layer height in Qinhuangdao is the highest, up to 865 +/- 268 m, and in Shijiazhuang is the lowest (568 +/- 207 m), Beijing's and Tianjin's are in between, 818 +/- 319 m and 834 +/- 334 m respectively; Combined with the meteorological data, we find that radiation and wind speed are main factors of the mixing layer height; The relationship between the particle concentration and mixing layer height in four sites suggests that mixing layer is less than 800 m, concentration of fine particulate matter in four sites will exceed the national standard (GB 3095-2012, 75 microg x m(-3)). During the period of observation, the proportion of days that mixing layer is less than 800 m in Beijing, Tianjin, Shijiazhuang and Qinhuangdao are 50%, 43%, 80% and 50% respectively. Shijiazhuang though nearly formation contaminant concentration is high, within the atmospheric mixed layer pollutant load is not high. Unfavorable atmospheric diffusion conditions are the main causes of heavy pollution in Shijiazhuang for a long time. The results of the study are of great significance for cognitive Beijing-Tianjin-Hebei area pollution distribution, and can provide a scientific reference for reasonable distribution of regional pollution sources.

  5. Study of stable atmospheric boundary layer characterization over highveld region of South Africa

    CSIR Research Space (South Africa)

    Luhunga, P

    2011-09-01

    Full Text Available ATMOSPHERIC BOUNDARY LAYER CHARACTERIZATION OVER HIGHVELD REGION OF SOUTH AFRICA Philbert Luhunga1, 2, 3, George Djolov1, Venkataraman Sivakumar1,4,5 1 University of Pretoria, Department of Geography Geoinformatics and Meterology, Lynnwood road, 0001.... INTRODUCTION The stable atmospheric boundary layer (SBL) study over the Highveld South Africa has a special relevance, since it has the majority of the electric power generating plants located in this region. SBL is characterized by a steady wind near...

  6. Directional Shear in the Nocturnal Atmospheric Surface Layer

    Science.gov (United States)

    Mahrt, L.

    2017-10-01

    We examine the potential importance of wind-directional shear in the surface layer of the stable nocturnal boundary layer by analyzing two tower datasets with eddy-correlation measurements at multiple levels. Directional shear is a major contributor to the total vector shear for weak winds due primarily to frequent shallow drainage flows at one site and due primarily to non-stationary modes at the second site. For weak winds, the turbulence intensity is more related to the wind-directional shear than to the wind speed or stratification, at least for these two datasets.

  7. Behavior of self-confined spherical layer of light radiation in the air atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Torchigin, V.P.; Torchigin, A.V

    2004-07-26

    Behavior of thin spherical layer of intensive light in an inhomogeneous atmosphere is considered. It is shown that the behavior is similar to puzzling and mysterious behavior of ball lightnings. Under assumption that ball lightning moves along the gradient of atmosphere air density process of ball lightning penetration in a salon of a flying airplane is analyzed.

  8. Turbulent exchange of energy, momentum, and reactive gases between high vegetation and the atmospheric boundary layer

    NARCIS (Netherlands)

    Shapkalijevski, M.M.

    2017-01-01

    This thesis deals with the representation of the exchange of energy, momentum and chemically reactive compounds between the land, covered by high vegetation, and the lowest part of the atmosphere, named as atmospheric boundary layer (ABL). The study presented in this thesis introduces the roughness

  9. Computational Fluid Dynamics model of stratified atmospheric boundary-layer flow

    DEFF Research Database (Denmark)

    Koblitz, Tilman; Bechmann, Andreas; Sogachev, Andrey

    2015-01-01

    transport, are mostly ignored. In order to decrease the uncertainty of wind resource assessment, the present work focuses on atmospheric flows that include stability and Coriolis effects. The influence of these effects on the whole atmospheric boundary-layer are examined using a Reynolds-averaged Navier–Stokes...

  10. The groundwater-land-surface-atmosphere connection: soil moisture effects on the atmospheric boundary layer in fully-coupled simulations

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R M; Chow, F K; Kollet, S J

    2007-02-02

    This study combines a variably-saturated groundwater flow model and a mesoscale atmospheric model to examine the effects of soil moisture heterogeneity on atmospheric boundary layer processes. This parallel, integrated model can represent spatial variations in land-surface forcing driven by three-dimensional (3D) atmospheric and subsurface components. The development of atmospheric flow is studied in a series of idealized test cases with different initial soil moisture distributions generated by an offline spin-up procedure or interpolated from a coarse-resolution dataset. These test cases are performed with both the fully-coupled model (which includes 3D groundwater flow and surface water routing) and the uncoupled atmospheric model. The effects of the different soil moisture initializations and lateral subsurface and surface water flow are seen in the differences in atmospheric evolution over a 36-hour period. The fully-coupled model maintains a realistic topographically-driven soil moisture distribution, while the uncoupled atmospheric model does not. Furthermore, the coupled model shows spatial and temporal correlations between surface and lower atmospheric variables and water table depth. These correlations are particularly strong during times when the land surface temperatures trigger shifts in wind behavior, such as during early morning surface heating.

  11. On the Nature, Theory, and Modeling of Atmospheric Planetary Boundary Layers

    DEFF Research Database (Denmark)

    Baklanov, Alexander A.; Grisogono, Branko; Bornstein, Robert

    2011-01-01

    The gap between our modern understanding of planetary boundary layer physics and its decades-old representations in current operational atmospheric models is widening, which has stimulated this review of the current state of the art and an analysis of the immediate needs in boundary layer theory......, measurements, and modeling....

  12. Formulation of a Prototype Coupled Atmospheric and Oceanic Boundary Layer Model.

    Science.gov (United States)

    1982-12-01

    layers. The approach will be to compare observed evolutions in the oceanic and atmospheric boundary layers with predictions from bulk modelo wherein...a very complex subject and is beyond the scope of this paper. An excellent review of this sub- ject has beer. published by Fairall (1981). An

  13. Monitoring of the atmospheric ozone layer and natural ultraviolet radiation: Annual report 2011

    Energy Technology Data Exchange (ETDEWEB)

    Svendby, T.M.; Myhre, C.L.; Stebel, K.; Edvardsen, K; Orsolini, Y.; Dahlback, A.

    2012-07-01

    This is an annual report describing the activities and main results of the monitoring programme: Monitoring of the atmospheric ozone layer and natural ultraviolet radiation for 2011. 2011 was a year with generally low ozone values above Norway. A clear decrease in the ozone layer above Norway during the period 1979-1997 stopped after 1998 and the ozone layer above Norway seems now to have stabilized.(Author)

  14. Some aspects of atmospheric dispersion in the stratified atmospheric boundary layer over homogeneous terrain

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik

    1999-01-01

    The ability to simulate atmospheric dispersion with models developed for applied use under stable atmospheric stability conditions is discussed. The paper is based on model simulations of three experimental data sets reported in the literature. The Hanford data set covered weakly stable conditions......, the Prairie Grass experiments covered both weakly stable and very stable atmospheric conditions, and the Lillestrom experiment was carried out during very stable conditions. Simulations of these experiments reported in the literature for eight different models are discussed. Applied models based...

  15. Heat and Moisture Transport in the Atmospheric Boundary Layer.

    Science.gov (United States)

    1987-01-05

    upwind profile is linea , then it follows from (4. 1Oa) that, if the variation of wind speed over the hill height is small, i.e. (4.23a) HdU,’dz /U(0) o 1...Foldvick (1962), S -S (2.6a) or algebraically : S - SO (h m/Z) where N0 and U are the values at the height hm of the mid- dle layer, and hi is the vertical...systern does not present problems either by hand or by mac hine or b\\ ., n. -hic algebra program, such as MAKCYMA. Our first goal following the Interim I

  16. Interaction of Atmospheric Turbulence with Blade Boundary Layer Dynamics on a 5MW Wind Turbine using Blade-Boundary-Layer-Resolved CFD with hybrid URANS-LES.

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, Ganesh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pennsylvania State Univ., University Park, PA (United States); Brasseur, James [Pennsylvania State Univ., University Park, PA (United States); Univ. of Colorado, Boulder, CO (United States); Lavely, Adam; Jayaraman, Balaji; Craven, Brent

    2016-01-04

    We describe the response of the NREL 5 MW wind turbine blade boundary layer to the passage of atmospheric turbulence using blade-boundary-layer-resolved computational fluid dynamics with hybrid URANS-LES modeling.

  17. Multi-parameter detection of atmospheric metal layers by Beijing Na-K lidar

    Science.gov (United States)

    Wang, Jihong; Jiao, Jing; Yang, Guotao

    2017-04-01

    Beijing Na-K lidar has been started running in 2010. This lidar has two laser beams: one dye laser emits a 589-nm laser beam for Na layer detection; the other dye laser emits a 770-nm laser beam for K layer detection. Under similar conditions, the echo signal of K layer is only about 2 orders of magnitude smaller than that of Na layer. This lidar has a sufficient Signal Noise Ratio (SNR). The structure and details of potassium layer can be effectively distinguished from a single original echo. Several examples of co-observation of density of Na and K layer showed some different results with previous studies. This lidar not only can supplement the lack of Na and K layer observation at this latitude region, but also provide evidence for the atmospheric sciences and space environment monitoring.

  18. Initial multi-parameter detection of atmospheric metal layers by Beijing Na-K lidar

    Science.gov (United States)

    Jiao, Jing; Yang, Guotao; Wang, Jihong; Cheng, Xuewu; Du, Lifang; Wang, Zelong; Gong, Wei

    2017-02-01

    Beijing Na-K lidar has been started running in 2010. This lidar has two laser beams: one dye laser emits a 589-nm laser beam for Na layer detection; the other dye laser emits a 770-nm laser beam for K layer detection. Under similar conditions, the echo signal of K layer is only about 2 orders of magnitude smaller than that of Na layer. This lidar has a sufficient Signal Noise Ratio (SNR). The structure and details of potassium layer can be effectively distinguished from a single original echo. Several examples of co-observation of density of Na and K layer showed some different results with previous studies. This lidar not only can supplement the lack of Na and K layer observation at this latitude region, but also provide evidence for the atmospheric sciences and space environment monitoring.

  19. Temporal Dynamics of Bacterial and Fungal Community Composition in the Atmospheric Boundary Layer

    Science.gov (United States)

    Emerson, J. B.; Perring, A. E.; Schwarz, J. P.; Fahey, D. W.; Fierer, N.

    2014-12-01

    There is increasing evidence for significant microbial influences on atmospheric chemistry, cloud condensation, and ice nuclei concentrations, with known health impacts, yet we have a limited understanding of the types, abundances, and spatiotemporal dynamics of bacteria and fungi in the atmosphere. Here we use culture-independent molecular approaches, including targeted gene sequencing and quantitative PCR, to characterize bacterial and fungal community composition and abundance in the atmospheric boundary layer. We present results from 32 air samples, collected via vacuum filtration at 10 m and 250 m on the Boulder Atmospheric Observatory tower (Erie, CO) between November 2013 and April 2014. Samples were collected at night, and each sample was integrated over consecutive nights for approximately two weeks. Significant temporal shifts in bacterial and fungal community composition were observed over the course of the study, corresponding to changing bacterial and fungal concentrations. Within the same sampling time periods, bacterial and fungal communities from the near-surface atmosphere (10 m) were generally similar to those aloft (250 m), although coupled temporal and altitudinal effects were observed in some cases, particularly for fungi. Overall, our results indicate that bacterial and fungal communities exhibit minimal vertical stratification throughout the nocturnal atmospheric boundary layer but show a high degree of variability on two-week timescales. This study paves the way for further research into the connections between boundary layer microbiology, atmospheric dynamics, emissions, and local meteorology.

  20. Fiber optic distributed temperature sensing for the determination of the nocturnal atmospheric boundary layer height

    Directory of Open Access Journals (Sweden)

    C. A. Keller

    2011-02-01

    Full Text Available A new method for measuring air temperature profiles in the atmospheric boundary layer at high spatial and temporal resolution is presented. The measurements are based on Raman scattering distributed temperature sensing (DTS with a fiber optic cable attached to a tethered balloon. These data were used to estimate the height of the stable nocturnal boundary layer. The experiment was successfully deployed during a two-day campaign in September 2009, providing evidence that DTS is well suited for this atmospheric application. Observed stable temperature profiles exhibit an exponential shape confirming similarity concepts of the temperature inversion close to the surface. The atmospheric mixing height (MH was estimated to vary between 5 m and 50 m as a result of the nocturnal boundary layer evolution. This value is in good agreement with the MH derived from concurrent Radon-222 (222Rn measurements and in previous studies.

  1. A Study of stable Atmospheric Boundary Layer over highveld South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Luhunga, P; Djolov, G [University of Pretoria (South Africa); Esau, I, E-mail: george.djolov@up.ac.z

    2010-08-15

    The study is part of the South African - Norwegian Programme for Research and Co-operation Phase II 'Analysis and Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes'. The research strategy of the project is based on 4 legged approach. 1) Application and further development of contemporary atmospheric boundary layer theory. 2) Use of modeling based on large eddy simulation techniques. 3) Experimental investigation of turbulent fluxes. 4) Training and developing academics capable of dealing with the present and new challenges. The paper presents some preliminary results on the micrometeorological variability of the basic meteorological parameters and turbulent fluxes.

  2. A Study of stable Atmospheric Boundary Layer over highveld South Africa

    Science.gov (United States)

    Luhunga, P.; Esau, I.; Djolov, G.

    2010-08-01

    The study is part of the South African - Norwegian Programme for Research and Co-operation Phase II "Analysis and Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes". The research strategy of the project is based on 4 legged approach. 1) Application and further development of contemporary atmospheric boundary layer theory. 2) Use of modeling based on large eddy simulation techniques. 3) Experimental investigation of turbulent fluxes. 4) Training and developing academics capable of dealing with the present and new challenges. The paper presents some preliminary results on the micrometeorological variability of the basic meteorological parameters and turbulent fluxes.

  3. A model study of mixing and entrainment in the horizontally evolving atmospheric convective boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Fedorovich, E.; Kaiser, R. [Univ. Karlsruhe, Inst. fuer Hydrologie und Wasserwirtschaft (Germany)

    1997-10-01

    We present results from a parallel wind-tunnel/large-eddy simulation (LES) model study of mixing and entrainment in the atmospheric convective boundary layer (CBL) longitudinally developing over a heated surface. The advection-type entrainment of warmer air from upper turbulence-free layers into the growing CBL has been investigated. Most of numerical and laboratory model studies of the CBL carried out so far dealt with another type of entrainment, namely the non-steady one, regarding the CBL growth as a non-stationary process. In the atmosphere, both types of the CBL development can take place, often being superimposed. (au)

  4. Layer-by-layer assembly of thin organic films on PTFE activated by cold atmospheric plasma

    Directory of Open Access Journals (Sweden)

    Tóth András

    2014-12-01

    Full Text Available An air diffuse coplanar surface barrier discharge is used to activate the surface of polytetrafluoroethylene (PTFE samples, which are subsequently coated with polyvinylpyrrolidone (PVP and tannic acid (TAN single, bi- and multilayers, respectively, using the dip-coating method. The surfaces are characterized by X-ray Photoelectron Spectroscopy (XPS, Attenuated Total Reflection – Fourier Transform Infrared Spectroscopy (ATR-FTIR and Atomic Force Microscopy (AFM. The XPS measurements show that with plasma treatment the F/C atomic ratio in the PTFE surface decreases, due to the diminution of the concentration of CF2 moieties, and also oxygen incorporation through formation of new C–O, C=O and O=C–O bonds can be observed. In the case of coated samples, the new bonds indicated by XPS show the bonding between the organic layer and the surface, and thus the stability of layers, while the gradual decrease of the concentration of F atoms with the number of deposited layers proves the creation of PVP/TAN bi- and multi-layers. According to the ATR-FTIR spectra, in the case of PVP/TAN multilayer hydrogen bonding develops between the PVP and TAN, which assures the stability of the multilayer. The AFM lateral friction measurements show that the macromolecular layers homogeneously coat the plasma treated PTFE surface.

  5. Preface: GEWEX Atmospheric Boundary-layer Study (GABLS) on Stable Boundary Layers

    NARCIS (Netherlands)

    Holtslag, A.A.M.

    2006-01-01

    The Global Energy and Water Cycle Experiment (GEWEX) is a program initiated by the World Climate Research Programme (WCRP) to observe, understand and model the hydrological cycle and the related energy fluxes in the atmosphere, at the land surface and in the upper oceans. Consequently the

  6. LOLAS: an optical turbulence profiler in the atmospheric boundary layer with extreme altitude-resolution

    OpenAIRE

    Avila, R.; Aviles, J. L.; Wilson, R. W.; Chun, M.; Butterley, T.; Carrasco, E.

    2008-01-01

    We report the development and first results of an instrument called Low Layer Scidar (LOLAS) which is aimed at the measurement of optical-turbulence profiles in the atmospheric boundary layer with high altitude-resolution. The method is based on the Generalized Scidar (GS) concept, but unlike the GS instruments which need a 1- m or larger telescope, LOLAS is implemented on a dedicated 40-cm telescope, making it an independent instrument. The system is designed for widely separated double-star...

  7. Towards grid-converged wall-modeled LES of atmospheric boundary layer flows

    Science.gov (United States)

    Yellapantula, Shashank; Vijayakumar, Ganesh; Henry de Frahan, Marc; Churchfield, Matthew; Sprague, Michael

    2017-11-01

    Accurate characterization of incoming atmospheric boundary layer (ABL) turbulence is a critical factor in improving accuracy and predictive nature of simulation of wind farm flows. Modern commercial wind turbines operate in the log layer of the ABL that are typically simulated using wall-modeled large-eddy simulation (WMLES). One of the long-standing issues associated with wall modeling for LES and hybrid RANS-LES for atmospheric boundary layers is the over-prediction of the mean-velocity gradient, commonly referred to as log-layer mismatch. Kawai and Larsson in 2012, identified under-resolution of the near-wall region and the incorrect information received by the wall model as potential causes for the log-layer mismatch in WMLES of smooth-wall boundary-layer flows. To solve the log layer mismatch issue, they proposed linking the wall model to the LES solution at a physical of height of ym, instead of the first grid point. In this study, we extend their wall modeling approach to LES of the rough-wall ABL to investigate issues of log-layer mismatch and grid convergence. This work was funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Wind Energy Technologies Office, under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory.

  8. An Estimation of Turbulent Kinetic Energy and Energy Dissipation Rate Based on Atmospheric Boundary Layer Similarity Theory

    Science.gov (United States)

    Han, Jongil; Arya, S. Pal; Shaohua, Shen; Lin, Yuh-Lang; Proctor, Fred H. (Technical Monitor)

    2000-01-01

    Algorithms are developed to extract atmospheric boundary layer profiles for turbulence kinetic energy (TKE) and energy dissipation rate (EDR), with data from a meteorological tower as input. The profiles are based on similarity theory and scalings for the atmospheric boundary layer. The calculated profiles of EDR and TKE are required to match the observed values at 5 and 40 m. The algorithms are coded for operational use and yield plausible profiles over the diurnal variation of the atmospheric boundary layer.

  9. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.

    2013-04-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  10. Atmospheric spatial atomic layer deposition of in-doped ZnO

    NARCIS (Netherlands)

    Illiberi, A.; Scherpenborg, R.; Roozeboom, F.; Poodt, P.

    2014-01-01

    Indium-doped zinc oxide (ZnO:In) has been grown by spatial atomic layer deposition at atmospheric pressure (spatial-ALD). Trimethyl indium (TMIn), diethyl zinc (DEZ) and deionized water have been used as In, Zn and O precursor, respectively. The metal content of the films is controlled in the range

  11. Single Column Modeling of Atmospheric Boundary Layers and the Complex Interactions with the Land Surface

    NARCIS (Netherlands)

    Holtslag, A.A.M.; Steeneveld, G.J.

    2009-01-01

    In this paper a summary is given of the basic approaches for the modeling and parameterization of turbulence in the atmospheric boundary layer. The treated approaches are in current use in regional and global-scale models for the forecasting and study of weather, climate and air quality. Here we

  12. Impact of aerosol heat radiation absorption on the dynamics of an atmospheric boundary layer in equilibrium

    NARCIS (Netherlands)

    Barbaro, E.W.; Vilà-Guerau de Arellano, J.; Krol, M.C.; Holtslag, A.A.M.

    2012-01-01

    The objective of this work is to investigate the influence of the shortwave radiation (SW) absorption by aerosols on the dynamics and heat budget of the atmospheric boundary layer (ABL). This study is relevant for areas characterized by large concentrations of light-absorbing aerosol, which are

  13. Impacts of Aerosol Shortwave Radiation Absorption on the Dynamics of an Idealized Convective Atmospheric Boundary Layer

    NARCIS (Netherlands)

    Wilde Barbaro, E.; Vilà-Guerau de Arellano, J.; Krol, M.C.; Holtslag, A.A.M.

    2013-01-01

    We investigated the impact of aerosol heat absorption on convective atmospheric boundary-layer (CBL) dynamics. Numerical experiments using a large-eddy simulation model enabled us to study the changes in the structure of a dry and shearless CBL in depthequilibrium for different vertical profiles of

  14. Wind Energy-Related Atmospheric Boundary Layer Large-Eddy Simulation Using OpenFOAM: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Churchfield, M.J.; Vijayakumar, G.; Brasseur, J.G.; Moriarty, P.J.

    2010-08-01

    This paper develops and evaluates the performance of a large-eddy simulation (LES) solver in computing the atmospheric boundary layer (ABL) over flat terrain under a variety of stability conditions, ranging from shear driven (neutral stratification) to moderately convective (unstable stratification).

  15. Numerical model of a non-steady atmospheric planetary boundary layer, based on similarity theory

    DEFF Research Database (Denmark)

    Zilitinkevich, S.S.; Fedorovich, E.E.; Shabalova, M.V.

    1992-01-01

    A numerical model of a non-stationary atmospheric planetary boundary layer (PBL) over a horizontally homogeneous flat surface is derived on the basis of similarity theory. The two most typical turbulence regimes are reproduced: one corresponding to a convectively growing PBL and another correspon...

  16. Approximate analytical solution to diurnal atmospheric boundary-layer growth under well-watered conditions

    Science.gov (United States)

    The system of governing equations of a simplified slab model of the uniformly-mixed, purely convective, diurnal atmospheric boundary layer (ABL) is shown to allow immediate solutions for the potential temperature and specific humidity as functions of the ABL height and net radiation when expressed i...

  17. Application of a commercial lidar-ceilometer to studies of aerosols in the atmospheric boundary layer

    CSIR Research Space (South Africa)

    Ramkilowan, A

    2015-09-01

    Full Text Available has therefore become of great interest. CSIR/DPSS has acquired and deployed a Vaisala CL51 ceilometer chiefly for the purpose of investigating the vertical distribution of aerosols in the Atmospheric Boundary Layer (ABL) and cloud base height...

  18. Spatial atmospheric atomic layer deposition of InxGayZnzO for thin film transistors

    NARCIS (Netherlands)

    Illiberi, A.; Cobb, B.; Sharma, A.; Grehl, T.; Brongersma, H.; Roozeboom, F.; Gelinck, G.; Poodt, P.

    2015-01-01

    We have investigated the nucleation and growth of InGaZnO thin films by spatial atmospheric atomic layer deposition. Diethyl zinc (DEZ), trimethyl indium (TMIn), triethyl gallium (TEGa), and water were used as Zn, In, Ga and oxygen precursors, respectively. The vaporized metal precursors have been

  19. Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98) : a report

    NARCIS (Netherlands)

    Cuxart, J.; Yague, C.; Morales, G.; Terradelles, E.; Orbe, J.; Calvo, J.; Vilu-Guerau, de J.; Soler, M.R.; Infante, C.; Buenestado, P.; Espinalt, A.; Jorgensem, H.E.

    2000-01-01

    This paper describes the Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98), which took place over the northern Spanish plateau comprising relatively flat grassland, in September 1998. The main objectives of the campaign were to study the properties of the mid-latitude stable boundary

  20. Dynamics of the atmospheric boundary layer response to ocean mesoscale sea surface temperatures

    Science.gov (United States)

    Schneider, Niklas; Taguchi, Bunmei; Nonaka, Masami; Kuwano-Yoshida, Akira; Nakamura, Hisashi

    2017-04-01

    A recent theory for the mid-latitude atmospheric response to ocean mesoscale sea surface temperature (SST) variations is tested in the Southern Ocean using an extended integration of an atmospheric general circulation model. The theory is based on a linearization of the steady state, atmospheric boundary-layer dynamics, and yields the atmospheric response as classical Ekman dynamics extended to include advection, and sea surface temperature induced changes of atmospheric mixing and hydrostatic pressure. The theory predicts the response at each horizontal wave number to be governed by spectral transfer function between sea surface temperature and boundary layer variables, that are dependent on large-scale winds and the formulation of boundary layer mixing. The general circulation model, AFES, is shown to reproduce observed regressions between surface wind stress and sea surface temperatures. These 'coupling coefficients' are explained by SST induced changes of the surface stability, that directly impact surface stress, and changes of the surface winds. Estimates of the spectral transfer function between the latter and surface temperature are consistent with the theory, and suggest that it faithfully captures the underlying physics.

  1. Laser beam propagation through an atmospheric transitional and turbulent boundary layer

    Science.gov (United States)

    Katz, Richard A.; Manzur, Tariq

    2015-05-01

    This study investigates laser beam propagation through an atmospheric boundary layer near the ocean surface. Objectives of this research are to ascertain feasibility limits for achieving maximum energy efficiency at extended ranges in the face of atmospheric and other distortions as the laser beam penetrates through transitional (anisotropic) and turbulent (isotropic) boundary layer regimes. Various aspects of turbulence modeling of laser beam propagation near the ocean surface are discussed including: Kolmogorov's model of atmospheric turbulence, parameterized structure functions (e.g., velocity and temperature gradients, gradients in refractive index) and other important factors affecting near surface propagation such as humidity, aerosols, and wave slap. Various preliminary modeled propagation results are shown, and a new methodology is proposed for improving existing model estimates with new time domain measurement procedures.

  2. An observational study of the evolution of the atmospheric boundary-layer over Cabo Frio, Brazil

    Directory of Open Access Journals (Sweden)

    S. H. Franchito

    2007-08-01

    Full Text Available The effect of coastal upwelling on the evolution of the atmospheric boundary layer (ABL in Cabo Frio (Brazil is investigated. For this purpose, radiosounding data collected in two experiments made during the austral summer (upwelling case and austral winter (no upwelling case are analysed. The results show that during the austral summer, cold waters that crop up near the Cabo Frio coast favour the formation of an atmospheric stable layer, which persists during the upwelling episode. Due to the low SSTs, the descending branch of the sea-breeze circulation is located close to the coast, inhibiting the development of a mixed layer mainly during the day. At night, with the reduction of the land-sea thermal contrast the descending motion is weaker, allowing a vertical mixing. The stable ABL favours the formation of a low level jet, which may also contribute to the development of a nocturnal atmospheric mixed layer. During the austral winter, due to the higher SSTs observed near the coast, the ABL is less stable compared with that in the austral summer. Due to warming, a mixed layer is observed during the day. The observed vertical profiles of the zonal winds show that the easterlies at low levels are stronger in the austral summer, indicating that the upwelling modulates the sea-breeze signal, thus confirming model simulations.

  3. Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon boundary layer

    Science.gov (United States)

    Zimmerman, P. R.; Greenberg, J. P.; Westberg, C. E.

    1988-01-01

    Tropospheric mixing ratios of methane, C2-C10 hydrocarbons, and carbon monoxide were measured over the Amazon tropical forest near Manaus, Amazonas, Brazil, in July and August 1985. The measurements, consisting mostly of altitude profiles of these gases, were all made within the atmospheric boundary layer up to an altitude of 1000 m above ground level. Data characterize the diurnal hydrocarbon composition of the boundary layer. Biogenic emissions of isoprene control hydroxyl radical concentrations over the forest. Biogenic emission fluxes of isoprene and terpenes are estimated to be 25,000 micrograms/sq m per day and 5600 micrograms/sq m per day, respectively. This isoprene emission is equivalent to 2 percent of the net primary productivity of the tropical forest. Atmospheric oxidation of biogenic isoprene and terpenes emissions from the Amazon forest may account for daily increases of 8-13 ppb for carbon monoxide in the planetary boundary layer.

  4. Lidar-Observed Stress Vectors and Veer in the Atmospheric Boundary Layer

    DEFF Research Database (Denmark)

    Berg, Jacob; Mann, Jakob; Patton, Edward G.

    2013-01-01

    This study demonstrates that a pulsed wind lidar is a reliable instrument for measuring angles between horizontal vectors of significance in the atmospheric boundary layer. Three different angles are considered: the wind turning, the angle between the stress vector and the mean wind direction......, and the angle between the stress vector and the vertical gradient of the mean velocity vector. The latter is assumed to be zero by the often applied turbulent-viscosity hypothesis, so that the stress vector can be described through the vertical gradient of velocity. In the atmospheric surface layer, where...... the Coriolis force is negligible, this is supposedly a good approximation. High-resolution large-eddy simulation data show that this is indeed the case even beyond the surface layer. In contrast, through analysis of WindCube lidar measurements supported by sonic measurements, the study shows that it is only...

  5. A Diagnostic Diagram to Understand the Marine Atmospheric Boundary Layer at High Wind Speeds

    Science.gov (United States)

    Kettle, Anthony

    2014-05-01

    Long time series of offshore meteorological measurements in the lower marine atmospheric boundary layer show dynamical regimes and variability that are forced partly by interaction with the underlying sea surface and partly by the passage of cloud systems overhead. At low wind speeds, the dynamics and stability structure of the surface layer depend mainly on the air-sea temperature difference and the measured wind speed at a standard height. The physical processes are mostly understood and the quantified through Monin-Obukhov (MO) similarity theory. At high wind speeds different dynamical regimes become dominant. Breaking waves contribute to the atmospheric loading of sea spray and water vapor and modify the character of air-sea interaction. Downdrafts and boundary layer rolls associated with clouds at the top of the boundary layer impact vertical heat and momentum fluxes. Data from offshore meteorological monitoring sites will typically show different behavior and the regime shifts depending on the local winds and synoptic conditions. However, the regular methods to interpret time series through spectral analysis give only a partial view of dynamics in the atmospheric boundary layer. Also, the spectral methods have limited use for boundary layer and mesoscale modellers whose geophysical diagnostics are mostly anchored in directly measurable quantities: wind speed, temperature, precipitation, pressure, and radiation. Of these, wind speed and the air-sea temperature difference are the most important factors that characterize the dynamics of the lower atmospheric boundary layer and they provide a dynamical and thermodynamic constraint to frame observed processes, especially at high wind speeds. This was recognized in the early interpretation of the Froya database of gale force coastal winds from mid-Norway (Andersen, O.J. and J. Lovseth, Gale force maritime wind. The Froya data base. Part 1: Sites and instrumentation. Review of the data base, Journal of Wind

  6. Tracking atmospheric boundary layer dynamics with water vapor D-excess observations

    KAUST Repository

    Parkes, Stephen

    2015-04-01

    Stable isotope water vapor observations present a history of hydrological processes that have impacted on an air mass. Consequently, there is scope to improve our knowledge of how different processes impact on humidity budgets by determining the isotopic end members of these processes and combining them with in-situ water vapor measurements. These in-situ datasets are still rare and cover a limited geographical expanse, so expanding the available data can improve our ability to define isotopic end members and knowledge about atmospheric humidity dynamics. Using data collected from an intensive field campaign across a semi-arid grassland site in eastern Australia, we combine multiple methods including in-situ stable isotope observations to study humidity dynamics associated with the growth and decay of the atmospheric boundary layer and the stable nocturnal boundary layer. The deuterium-excess (D-excess) in water vapor is traditionally thought to reflect the sea surface temperature and relative humidity at the point of evaporation over the oceans. However, a number of recent studies suggest that land-atmosphere interactions are also important in setting the D-excess of water vapor. These studies have shown a highly robust diurnal cycle for the D-excess over a range of sites that could be exploited to better understand variations in atmospheric humidity associated with boundary layer dynamics. In this study we use surface radon concentrations as a tracer of surface layer dynamics and combine these with the D-excess observations. The radon concentrations showed an overall trend that was inversely proportional to the D-excess, with early morning entrainment of air from the residual layer of the previous day both diluting the radon concentration and increasing the D-excess, followed by accumulation of radon at the surface and a decrease in the D-excess as the stable nocturnal layer developed in the late afternoon and early evening. The stable nocturnal boundary layer

  7. CURIE: A low power X-band, low atmospheric boundary layer doppler radar

    Energy Technology Data Exchange (ETDEWEB)

    Al-Sakka, Hassan; Weill, Alain; Le Gac, Christophe; Ney, Richard; Chardenal, Laurent; Vinson, Jean Paul; Barthes, Laurent [Lab. Atmospheres, Milieux, Observations Spatiales, LATMOS/IPSL, Velizy (France); Dupont, Eric [EDF, R and D, CEREA, Chatou (France)

    2009-06-15

    A new X-band Doppler miniradar, the CURIE radar (Canopy Urban Research on Interactions and Exchanges), mainly adapted to low Atmospheric Boundary Layer ABL sounding has been developed at LATMOS (Laboratoire Atmospheres, Milieux, Observations Spatiales) formerly CETP (Centre d'etude des Environnements Terrestre et Planetaires). After a brief description of the measurement conditions in a turbulent atmosphere, the main characteristics of the new sensor are presented. As an example, we compare CURIE vertical velocity fluctuations with UHF observations to show the vertical velocity measurement validity. As a prospective area of application in clear air, we focus on a first observation of vertical velocity variance which is supposed to be related to entrainment across the inversion layer. As our objective is to study low boundary layers during different atmospheric conditions and since the radar works in the presence of precipitation (as all X-band radar do), we also show vertical rain soundings in the lower part of the ABL and illustrate our findings with results demonstrating comparable reflectivity and precipitation rates as estimated with a disdrometer and with a rain gauge. (orig.)

  8. Buoyancy effect on atmospheric surface layer: measurements from the East Coast of Malaysia

    Science.gov (United States)

    Harun, Z.; Reda, E.; Zulkifli, Rozli

    2017-04-01

    The nature and evolution of the atmospheric surface layer is still unresolved completely. Many questions regarding the existence of the z-less layer and trend of the cross correlations still remain open. This research analyzes some of the surface layer ambiguities. In this research temperature, velocity and turbulence data were collected from a weather station facility located in the Marine Ecosystem Research Centre (EKOMAR) Mersing on the East Coast of Malaysia. Two high resolution hotwires were utilized at 3 m and 12 m heights above ground. Both gradient Richardson number and Obukhov stability parameter were calculated. Turbulence spectra were plotted at different stability conditions. The results does not show the existence of the z-less layer at deep stable condition. The buoyancy force, under unstable condition, was found responsible for the increase of vertical correlation factor. The fingerprint of the buoyancy force was detected in the spectra at low frequencies.

  9. Sulfur processing in the marine atmospheric boundary layer: A review and critical assessment of modeling uncertainties

    Science.gov (United States)

    Faloona, Ian

    Sulfur is an extremely motile and vital element in the Earth's biogeochemical environment, one whose active redox chemistry maintains small reservoirs in the atmosphere and biosphere yet large fluxes through both. Essential for life, intimately linked to the climate state, and an important component of air quality, sulfur and its transport and processing in the atmosphere have been the subject of active research for several decades. This review article describes the current state of our understanding of the atmospheric sulfur cycle, focusing on the marine atmospheric boundary layer, with the aim of identifying the largest roots of uncertainty that most inhibit accurate simulation of sulfur cycling in the atmosphere. An overview of the emissions by phytoplankton and shipping, dispersion and entrainment in the marine boundary layer, and chemical processing by aerosols, clouds, and dry deposition is presented. Analysis of 20 contemporary modeling studies suggests that the greatest ambiguity in global sulfur cycling derives from (in descending order) wet deposition of aerosol sulfate, dry deposition of sulfur dioxide to the Earth's surface, and the heterogeneous oxidation of SO 2 in aerosols and clouds.

  10. Manufacturing of Electrolyte and Cathode Layers SOFC Using Atmospheric Spraying Method and Its Characterization

    Directory of Open Access Journals (Sweden)

    S. Sulistyo

    2012-12-01

    Full Text Available The use of Solid Oxide Fuel Cell (SOFC has created various interest in many parties, due to its capability to convert gases into electricity. The main requirement of SOFC cell components is to be produced as thin as possible to minimize the losses of electrical resistance, as well as able to support internal and external loads. This paper discusses the procedure of making a thin electrolyte layer, as well as a porous thin layer cathode using atmospheric spraying technique. The procedure of spraying was in room temperature with the process of sintering at temperature of 13500 C held for 3 hours. The SOFC characterization of electrolyte and cathode microstructure was determined by using the SEM, FESEM, XRD and impedance spectroscopy, to measure the impedance of SOFC cells. The results show that the thickness of thin layer electrolyte and porous cathode obtained of about 20 µm and 4 µm, respectively. Also the SOFC cell impedance was measured of 2.3726 x 106 Ω at room temperature. The finding also demonstrated that although the materials (anode, cathode and electrolyte possess different coefficient thermal expansion, there was no evidence of flaking layers which seen the materials remain intact. Thus, the atmospheric spraying method can offer an alternative method to manufacturing of SOFC thin layer electrolyte and cathode. [Key words: SOFC; spraying method; electrolyte; cathode

  11. Physical modeling of the atmospheric boundary layer in the UNH Flow Physics Facility

    Science.gov (United States)

    Taylor-Power, Gregory; Gilooly, Stephanie; Wosnik, Martin; Klewicki, Joe; Turner, John

    2016-11-01

    The Flow Physics Facility (FPF) at UNH has test section dimensions W =6.0m, H =2.7m, L =72m. It can achieve high Reynolds number boundary layers, enabling turbulent boundary layer, wind energy and wind engineering research with exceptional spatial and temporal instrument resolution. We examined the FPF's ability to experimentally simulate different types of the atmospheric boundary layer (ABL) using upstream roughness arrays. The American Society for Civil Engineers defines standards for simulating ABLs for different terrain types, from open sea to dense city areas (ASCE 49-12). The standards require the boundary layer to match a power law shape, roughness height, and power spectral density criteria. Each boundary layer type has a corresponding power law exponent and roughness height. The exponent and roughness height both increase with increasing roughness. A suburban boundary layer was chosen for simulation and a roughness element fetch was created. Several fetch lengths were experimented with and the resulting boundary layers were measured and compared to standards in ASCE 49-12: Wind Tunnel Testing for Buildings and Other Structures. Pitot tube and hot wire anemometers were used to measure average and fluctuating flow characteristics. Velocity profiles, turbulence intensity and velocity spectra were found to compare favorably.

  12. Characteristics of aerosol at a lower atmospheric layer in DRAGON field campaign

    Science.gov (United States)

    KUJI, M.; Azuma, Y.; Kitakoga, S.; Sano, I.; Holben, B. N.

    2013-12-01

    Air pollution arises severely over East Asia with the rapid economic development nowadays. Monitoring the atmospheric environment, as one of the purposes, an intensive field campaign, Distributed Regional Aerosol Gridded Observation Networks (DRAGON), was carried out in the spring of year 2012, led by National Aeronautics and Space Administration (NASA). At that time, atmospheric phenomena such as Yellow sand and haze events were observed at Nara in the western part of Japan, as one of the DRAGON observation sites. The atmospheric events were characterized with the AErosol RObotic NETwork (AERONET) data. As a result of the data analysis, it was found that more light-absorbing and smaller particles dominated at the lower than upper atmospheric layer for the Kosa event in particular. A backward trajectory analysis suggested that the Yellow sand event traveled over the East Asian industrial cities, which could lead to a mixture of sand and air pollutants with moderate particle size and light-absorptivity. In addition, visibility observation was evaluated quantitatively with AERONET data in the DRAGON campaign since eye observation was inherently semi-quantitative. The extinction coefficient estimated from visibility was compared to that from AERONET. As a result, it was found that the extinction coefficients were generally consistent to each other. But there were some discrepancies, which could be caused with the atmospheric phenomena or aerosol types. It is confirmed that visibility is strongly influenced with aerosols in the case of severe atmospheric phenomena in particular.

  13. Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer.

    Science.gov (United States)

    Wilcox, Eric M; Thomas, Rick M; Praveen, Puppala S; Pistone, Kristina; Bender, Frida A-M; Ramanathan, Veerabhadran

    2016-10-18

    The introduction of cloud condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low clouds, yielding significant radiative forcing of climate. The magnitude and sign of changes in cloud coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (Cloud Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed layer at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed layer because of aerosol radiative heating and reduced turbulence. The polluted surface mixed layer was also observed to be more humid with higher relative humidity. Greater humidity enhances cloud development, as evidenced by polluted clouds that penetrate higher above the top of the surface mixed layer. Reduced entrainment of dry air into the surface layer from above the inversion capping the surface mixed layer, due to weaker turbulence, may contribute to higher relative humidity in the surface layer during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on clouds. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events.

  14. Reply to comment by Igor Esau on “Do stable atmospheric layers exist?”

    Science.gov (United States)

    Lovejoy, S.; Tuck, A. F.; Schertzer, D.; Hovde, S. J.

    2009-06-01

    We would like to thank Esau (2009) for attempting to save the classical notion of stable layers; his argument is very close to one raised up by an anonymous reviewer of Lovejoy et al. (2008b). Since a similar argument is often invoked to justify atmospheric applications of linear gravity wave theories, it appears to be widespread in the community. We therefore hope this debate will clarify the issue.

  15. Key features of the atmospheric boundary layer measurement by small unmanned aerial vehicles

    Science.gov (United States)

    Polivanov, P. A.; Sidorenko, A. A.

    2017-10-01

    A review of the current state of the methods for measuring the atmospheric boundary layer is carried out. It is shown that the use of small unmanned vehicles can improve the quality of measurements. The paper discusses the problems associated with the data processing of air speed sensors of small aircraft. To restore data on wind speed and its pulsations, the use of algorithms using accelerometers and GPS sensors was suggested.

  16. Design of Meteorological Element Detection Platform for Atmospheric Boundary Layer Based on UAV

    Directory of Open Access Journals (Sweden)

    Yonghong Zhang

    2017-01-01

    Full Text Available Among current detection methods of the atmospheric boundary layer, sounding balloon has disadvantages such as low recovery and low reuse rate, anemometer tower has disadvantages such as fixed location and high cost, and remote sensing detection has disadvantages such as low data accuracy. In this paper, a meteorological element sensor was carried on a six-rotor UAV platform to achieve detection of meteorological elements of the atmospheric boundary layer, and the influence of different installation positions of the meteorological element sensor on the detection accuracy of the meteorological element sensor was analyzed through many experiments. Firstly, a six-rotor UAV platform was built through mechanical structure design and control system design. Secondly, data such as temperature, relative humidity, pressure, elevation, and latitude and longitude were collected by designing a meteorological element detection system. Thirdly, data management of the collected data was conducted, including local storage and real-time display on ground host computer. Finally, combined with the comprehensive analysis of the data of automatic weather station, the validity of the data was verified. This six-rotor UAV platform carrying a meteorological element sensor can effectively realize the direct measurement of the atmospheric boundary layer and in some cases can make up for the deficiency of sounding balloon, anemometer tower, and remote sensing detection.

  17. Intercomparison of Martian Lower Atmosphere Simulated Using Different Planetary Boundary Layer Parameterization Schemes

    Science.gov (United States)

    Natarajan, Murali; Fairlie, T. Duncan; Dwyer Cianciolo, Alicia; Smith, Michael D.

    2015-01-01

    We use the mesoscale modeling capability of Mars Weather Research and Forecasting (MarsWRF) model to study the sensitivity of the simulated Martian lower atmosphere to differences in the parameterization of the planetary boundary layer (PBL). Characterization of the Martian atmosphere and realistic representation of processes such as mixing of tracers like dust depend on how well the model reproduces the evolution of the PBL structure. MarsWRF is based on the NCAR WRF model and it retains some of the PBL schemes available in the earth version. Published studies have examined the performance of different PBL schemes in NCAR WRF with the help of observations. Currently such assessments are not feasible for Martian atmospheric models due to lack of observations. It is of interest though to study the sensitivity of the model to PBL parameterization. Typically, for standard Martian atmospheric simulations, we have used the Medium Range Forecast (MRF) PBL scheme, which considers a correction term to the vertical gradients to incorporate nonlocal effects. For this study, we have also used two other parameterizations, a non-local closure scheme called Yonsei University (YSU) PBL scheme and a turbulent kinetic energy closure scheme called Mellor- Yamada-Janjic (MYJ) PBL scheme. We will present intercomparisons of the near surface temperature profiles, boundary layer heights, and wind obtained from the different simulations. We plan to use available temperature observations from Mini TES instrument onboard the rovers Spirit and Opportunity in evaluating the model results.

  18. Vertical Sampling Scales for Atmospheric Boundary Layer Measurements from Small Unmanned Aircraft Systems (sUAS

    Directory of Open Access Journals (Sweden)

    Benjamin L. Hemingway

    2017-09-01

    Full Text Available The lowest portion of the Earth’s atmosphere, known as the atmospheric boundary layer (ABL, plays an important role in the formation of weather events. Simple meteorological measurements collected from within the ABL, such as temperature, pressure, humidity, and wind velocity, are key to understanding the exchange of energy within this region, but conventional surveillance techniques such as towers, radar, weather balloons, and satellites do not provide adequate spatial and/or temporal coverage for monitoring weather events. Small unmanned aircraft, or aerial, systems (sUAS provide a versatile, dynamic platform for atmospheric sensing that can provide higher spatio-temporal sampling frequencies than available through most satellite sensing methods. They are also able to sense portions of the atmosphere that cannot be measured from ground-based radar, weather stations, or weather balloons and have the potential to fill gaps in atmospheric sampling. However, research on the vertical sampling scales for collecting atmospheric measurements from sUAS and the variabilities of these scales across atmospheric phenomena (e.g., temperature and humidity is needed. The objective of this study is to use variogram analysis, a common geostatistical technique, to determine optimal spatial sampling scales for two atmospheric variables (temperature and relative humidity captured from sUAS. Results show that vertical sampling scales of approximately 3 m for temperature and 1.5–2 m for relative humidity were sufficient to capture the spatial structure of these phenomena under the conditions tested. Future work is needed to model these scales across the entire ABL as well as under variable conditions.

  19. On the parametrization of the planetary boundary layer of the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Yordanov, D. [Bulgarian Academy of Sciences, Geophysical Inst., Sofia (Bulgaria); Syrakov, D.; Kolarova, M. [Bulgarian Academy of Sciences, National Inst. of Meteorology and Hydrology, Sofia (United Kingdom)

    1997-10-01

    The investigation of the dynamic processes in the planetary boundary layer presents a definite theoretical challenge and plays a growing role for the solution of a number of practical tasks. The improvement of large-scale atmospheric weather forecast depends, to a certain degree, on the proper inclusion of the planetary boundary layer dynamics in the numerical models. The modeling of the transport and the diffusion of air pollutants is connected with estimation of the different processes in the Planetary Boundary Layer (PBL) and needs also a proper PBL parametrization. For the solution of these practical tasks the following PBL models;(i) a baroclinic PBL model with its barotropic version, and (ii) a convective PBL model were developed. Both models are one dimensional and are based on the similarity theory and the resistance lows extended for the whole PBL. Two different PBL parametrizations under stable and under convective conditions are proposed, on the basis of which the turbulent surface heat and momentum fluxes are estimated using generalized similarity theory. By the proposed parametrizations the internal parameters are calculated from the synoptic scale parameters as geostrophyc wind, potential temperature and humidity given at two levels (ground level and at 850 hPa) and from them - the PBL profiles. The models consists of two layers: a surface layer (SL) with a variable height and a second (Ekman layer) over it with a constant with height turbulent exchange coefficient. (au) 14 refs.

  20. Development and evaluation of airborne microwave refractometer for studies on atmospheric tropical boundary layer radiorefractive index

    Directory of Open Access Journals (Sweden)

    S. B. S. S. Sarma

    Full Text Available Observations of high-resolution data on radio refractivity were obtained by the airborne microwave refractometer over the Indian sub-continent (a tropical country from 1971 to 1988. Detailed vertical and horizontal distributions of radio refractivity on a near-real-time basis in the atmospheric boundary layer were determined . Radiosonde observations cannot detect the thin refractivity gradients which characterize the propagation environment in this low-altitude region. This knowledge is required to design reliable and efficient communication systems for strategic, tactical and operational needs. However, the results demonstrate the layer structures and the variability of the boundary layer in time and space. The radio refractive effects on electromagnetic propagation and the future direction of radio refractivity fine-structure measurements are discussed.

  1. Scaling Characteristics of Mesoscale Wind Fields in the Lower Atmospheric Boundary Layer: Implications for Wind Energy

    Science.gov (United States)

    Kiliyanpilakkil, Velayudhan Praju

    Atmospheric motions take place in spatial scales of sub-millimeters to few thousands of kilometers with temporal changes in the atmospheric variables occur in fractions of seconds to several years. Consequently, the variations in atmospheric kinetic energy associated with these atmospheric motions span over a broad spectrum of space and time. The mesoscale region acts as an energy transferring regime between the energy generating synoptic scale and the energy dissipating microscale. Therefore, the scaling characterizations of mesoscale wind fields are significant in the accurate estimation of the atmospheric energy budget. Moreover, the precise knowledge of the scaling characteristics of atmospheric mesoscale wind fields is important for the validation of the numerical models those focus on wind forecasting, dispersion, diffusion, horizontal transport, and optical turbulence. For these reasons, extensive studies have been conducted in the past to characterize the mesoscale wind fields. Nevertheless, the majority of these studies focused on near-surface and upper atmosphere mesoscale regimes. The present study attempt to identify the existence and to quantify the scaling of mesoscale wind fields in the lower atmospheric boundary layer (ABL; in the wind turbine layer) using wind observations from various research-grade instruments (e.g., sodars, anemometers). The scaling characteristics of the mesoscale wind speeds over diverse homogeneous flat terrains, conducted using structure function based analysis, revealed an altitudinal dependence of the scaling exponents. This altitudinal dependence of the wind speed scaling may be attributed to the buoyancy forcing. Subsequently, we use the framework of extended self-similarity (ESS) to characterize the observed scaling behavior. In the ESS framework, the relative scaling exponents of the mesoscale atmospheric boundary layer wind speed exhibit quasi-universal behavior; even far beyond the inertial range of turbulence (Delta

  2. Ground-based satellite-type images of the upper-atmosphere emissive layer

    Science.gov (United States)

    Pautet, Dominique; Moreels, Guy

    2002-02-01

    With the introduction of infrared (IR) retina sensors used as focal-plane arrays in large telescopes, astronomical observations are now frequently located in the near-IR part of the spectrum. In this region the upper atmosphere introduces in the 0.7-3-μm range an additional component due to the OH vibrational band emission that should be subtracted from the astronomical data. Observations of this upper-atmosphere emission performed at the Pic de Cha‸teaurenard (altitude of 2989 m) are presented here. A panoramic image of the emission is constructed by use of a set of 48 images obtained with a CCD camera mounted on an alt-azimuthal platform. After a numerical filter is used to suppress the star images, the atmospheric emission shows two distinct sets of arches vanishing at two opposite points in the WNW and ESE azimuths. The emissive layer, caused by the ozone-hydrogen reaction, is thin and located at the altitude of 85 km. By use of these data, the perspective effect that produces the panoramic arches is inverted in introducing the concept of a virtual camera. The Van Rhijn effect and the refraction correction are taken into account. The three punctual transformations that use matrix algorithms are analyzed. The result is a satellite-type view of the emissive layer that appears as a disk having a radius of ~1100 km. This disk is limited by the summit line of the Alps surrounding the Pic de Cha‸teaurenard. The field of view covers a large part of Europe, the Mediterranean Sea, and North Africa. It shows an extended wave system. The images presented show that the upper-atmospheric layer is an efficient tracer of the dynamic processes at that level. Satellite-type views can be calculated without the drawback of looking downward from a satellite and measuring the numerous emissions from cities, oil fields, and other luminous sources.

  3. Towards fully predictive large-eddy simulation of the atmospheric boundary layer

    Science.gov (United States)

    Matheou, G.; Chung, D.; Teixeira, J.

    2012-12-01

    The atmospheric boundary layer is host to a plethora of physical processes that strongly affect the energy balance of Earth, and consequently weather and climate. Large-eddy Simulation (LES) is an invaluable technique in the study and prediction of the boundary layer mainly because it can capture detailed flow structure including clouds. In spite of the widespread use of LES, predictions of atmospheric flows lack fidelity. We discuss the development of a novel state-of-the-art LES framework suitable for the simulation of atmospheric flows and focus on the effects of turbulent transport, including stable stratification and multi-phase/latent heat exchange physics. The main components of the LES framework are a high-order fully conservative finite difference discretization and the buoyancy-adjusted stretched-vortex subgrid-scale (SGS) model. The new stability correction of the SGS model accounts of the increasing anisotropy of turbulence motions as stratification increases in a way that is consistent with the physics of stratified turbulence. Moreover, the SGS model employs no flow adjustable parameters. Our aim is twofold: (i) using identical LES setup (e.g. advection scheme and SGS-model parameters), perform simulations of diverse boundary layers, including stable, convectively unstable, cumulus and stratocumulus convection; and (ii) investigate grid convergence of flow statistics. We show that the new LES framework accurately predicts a diverse set of atmospheric conditions and in all cases the statistics exhibit good grid resolution independence, even for resolutions that are typically considered coarse. Grid convergence criteria are also discussed.

  4. Model Simulations of the Arctic Atmospheric Boundary Layer from the SHEBA Year

    Energy Technology Data Exchange (ETDEWEB)

    Tjernstroem, Michael; Zagar, Mark; Svensson, Gunilla [Stockholm Univ. (Sweden). Dept. of Meteorology

    2004-06-01

    We present Arctic atmospheric boundary-layer modeling with a regional model COAMPSTM, for the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment. Model results are compared to soundings, near-surface measurements and forecasts from the ECMWF model. The near-surface temperature is often too high in winter, except in shorter periods when the boundary layer was cloud-capped and well-mixed due to cloud-top cooling. Temperatures are slightly too high also during the summer melt season. Effects are too high boundary-layer moisture and formation of too dense stratocumulus, generating a too deep well-mixed boundary layer with a cold bias at the simulated boundary-layer top. Errors in temperature and therefore moisture are responsible for large errors in heat flux, in particular in solar radiation, by forming these clouds. We conclude that the main problems lie in the surface energy balance and the treatment of the heat conduction through the ice and snow and in how low-level clouds are treated.

  5. Controlled meteorological (CMET) balloon profiling of the Arctic atmospheric boundary layer

    Science.gov (United States)

    Roberts, Tjarda; Hole, Lars; Voss, Paul

    2017-04-01

    We demonstrate profiling of the atmospheric boundary layer over Arctic ice-free and sea-ice covered regions by free-floating controllable CMET balloons. The CMET observations (temperature, humidity, wind-speed, pressure) provide in-situ meteorological datasets in very remote regions for comparison to atmospheric models. Controlled Meteorological (CMET) balloons are small airborne platforms that use reversible lift-gas compression to regulate altitude. These balloons have approximately the same payload mass as standard weather balloons but can float for many days, change altitude on command, and transmit meteorological and system data in near-real time via satellite. Five Controlled Meteorological (CMET) balloons were launched from Ny-Ålesund in Svalbard (Spitsbergen) over 5-12 May 2011 and measured vertical atmospheric profiles (temperature, humidity, wind) over coastal and remote areas to both the east and west. One notable CMET flight achieved a suite of 18 continuous soundings that probed the Arctic atmospheric boundary layer (ABL) over a period of more than 10 h. Profiles from two CMET flights are compared to model output from ECMWF Era-Interim reanalysis (ERA-I) and to a high-resolution (15 km) Arctic System Reanalysis (ASR) product. To the east of Svalbard over sea-ice, the CMET observed a stable ABL profile with a temperature inversion that was reproduced by ASR but not captured by ERA-I. In a coastal ice-free region to the west of Svalbard, the CMET observed a stable ABL with strong wind-shear. The CMET profiles document increases in ABL temperature and humidity that are broadly reproduced by both ASR and ERA-I. The ASR finds a more stably stratified ABL than observed but captured the wind shear in contrast to ERA-I. Detailed analysis of the coastal CMET-automated soundings identifies small-scale temperature and humidity variations with a low-level flow and provides an estimate of local wind fields. We show that CMET balloons are a valuable approach for

  6. The atmospheric boundary layer during wintertime persistent inversions in the Grenoble valleys

    Directory of Open Access Journals (Sweden)

    Yann Largeron

    2016-07-01

    Full Text Available This study addresses the atmospheric boundary layer dynamics in the Grenoble valleys during persistent inversions, for 5 months during the 2006-2007 winter. During a persistent inversion, the boundary layer contains a layer with a positive vertical temperature gradient over a few days. Temperature data recorded on the valley sidewalls are first used. A bulk measure of the boundary layer stability, based upon the temperature difference between the valley top and the valley bottom, is introduced and a criterion is proposed to detect persistent inversions. We show that this criterion is equivalently expressed in terms of the heat deficit inside the boundary layer. Nine episodes are detected and coincide with the PM10-polluted periods of the 2006-2007 winter.Secondly, the five strongest and longest persistent inversions are simulated using the MesoNH model. Focus is made on the stagnation stage of the episode, during which the inversion exhibits a diurnal cycle that does not significantly evolve from day to day. Whatever the episode, the inversion develops from the ground over a height of about 1200 m, with a nighttime temperature strength of about 20 K.The boundary-layer dynamics within the inversion layer are fully decoupled from the (anticyclonic, weak synoptic flow, independent from the synoptic-wind direction and similar whatever the episode. This implies that these dynamics are controlled by thermal winds and solely depends upon the geometry of the topography and upon the radiative cooling of the ground.Finally, a two-day high-resolution simulation is made for the strongest case, representative of any persistent inversion. The flow pattern displays a well-defined spatial structure, with a vertical layering resulting from the superposition of the down-valley winds flowing from the different valleys surrounding Grenoble. This pattern persists all day long over a shallow convective layer of about 50 m forming above the ground during the reduced

  7. Investigation of the atmospheric boundary layer dynamics during the ESCOMPTE campaign

    Directory of Open Access Journals (Sweden)

    F. Saïd

    2007-03-01

    Full Text Available This paper presents some results about the behavior of the atmospheric boundary layer observed during the ESCOMPTE experiment. This campaign, which took place in south-eastern France during summer 2001, was aimed at improving our understanding of pollution episodes in relation to the dynamics of the lower troposphere. Using a large data set, as well as a simulation from the mesoscale non-hydrostatic model Meso-NH, we describe and analyze the atmospheric boundary layer (ABL development during two specific meteorological conditions of the second Intensive Observation Period (IOP. The first situation (IOP2a, from 22 June to 23 June corresponds to moderate, dry and cold northerly winds (end of Mistral event, coupled with a sea-breeze in the lower layer, whereas sea-breeze events with weak southerly winds occurred during the second part of the period (IOP2b, from 24 June to 26 June. In this study, we first focus on the validation of the model outputs with a thorough comparison of the Meso-NH simulations with fields measurements on three days of the IOP: 22 June, 23 June and 25 June. We also investigate the structure of the boundary layer on IOP2a when the Mistral is superimposed on a sea breeze. Then, we describe the spatial and diurnal variability of the ABL depths over the ESCOMPTE domain during the whole IOP. This step is essential if one wants to know the depth of the layer where the pollutants can be diluted or accumulated. Eventually, this study intends to describe the ABL variability in relation to local or mesoscale dynamics and/or induced topographic effects, in order to explain pollution transport processes in the low troposphere.

  8. Investigation of the atmospheric boundary layer dynamics during the ESCOMPTE campaign

    Energy Technology Data Exchange (ETDEWEB)

    Said, F.; Campistron, B. [Centre de Recherches Atmospheriques, UMR CNRS 5560, Campistrous (France); Brut, A. [Centre d' Etudes Spatiales de la BIOsphere UMR 5126, Toulouse (France); Cousin, F. [Lab. d' Aerologie, UMR CNRS 5560, Toulouse (France)

    2007-07-01

    This paper presents some results about the behavior of the atmospheric boundary layer observed during the ESCOMPTE experiment. This campaign, which took place in south-eastern France during summer 2001, was aimed at improving our understanding of pollution episodes in relation to the dynamics of the lower troposphere. Using a large data set, as well as a simulation from the mesoscale non-hydrostatic model Meso-NH, we describe and analyze the atmosphere boundary layer (ABL) development during two specific meteorological conditions of the second Intensive Observation Period (IOP). The first situation (IOP2a, from 22 June to 23 June) corresponds to moderate, dry and cold northerly winds (end of Mistral event), coupled with a sea-breeze in the lower layer, whereas sea-breeze events with weak southerly winds occurred during the second part of the period (IOP2b, from 24 June to 26 June). In this study, we first focus on the validation of the model outputs with a thorough comparison of the Meso-NH simulations with fields measurements on three days of the IOP: 22 June, 23 June and 25 June. We also investigate the structure of the boundary layer on IOP2a when the Mistral is superimposed on a sea breeze. Then, we describe the spatial and diurnal variability of the ABL depths over the ESCOMPTE domain during the whole IOP. This step is essential if one wants to know the depth of the layer where the pollutants can be diluted or accumulated. Eventually, this study intends to describe the ABL variability in relation to local or mesoscale dynamics and/or induced topographic effects, in order to explain pollution transport processes in the low troposphere. (orig.)

  9. Investigation of the atmospheric boundary layer dynamics during the ESCOMPTE campaign

    Directory of Open Access Journals (Sweden)

    F. Saïd

    2007-03-01

    Full Text Available This paper presents some results about the behavior of the atmospheric boundary layer observed during the ESCOMPTE experiment. This campaign, which took place in south-eastern France during summer 2001, was aimed at improving our understanding of pollution episodes in relation to the dynamics of the lower troposphere. Using a large data set, as well as a simulation from the mesoscale non-hydrostatic model Meso-NH, we describe and analyze the atmospheric boundary layer (ABL development during two specific meteorological conditions of the second Intensive Observation Period (IOP. The first situation (IOP2a, from 22 June to 23 June corresponds to moderate, dry and cold northerly winds (end of Mistral event, coupled with a sea-breeze in the lower layer, whereas sea-breeze events with weak southerly winds occurred during the second part of the period (IOP2b, from 24 June to 26 June.

    In this study, we first focus on the validation of the model outputs with a thorough comparison of the Meso-NH simulations with fields measurements on three days of the IOP: 22 June, 23 June and 25 June. We also investigate the structure of the boundary layer on IOP2a when the Mistral is superimposed on a sea breeze. Then, we describe the spatial and diurnal variability of the ABL depths over the ESCOMPTE domain during the whole IOP. This step is essential if one wants to know the depth of the layer where the pollutants can be diluted or accumulated. Eventually, this study intends to describe the ABL variability in relation to local or mesoscale dynamics and/or induced topographic effects, in order to explain pollution transport processes in the low troposphere.

  10. Atmospheric surface layer responses to the extreme lightning day in plateau region in India

    Science.gov (United States)

    Dwivedi, Arun K.; Chandra, Sagarika; Kumar, Manoj; Kumar, Sanjay; Kiran Kumar, N. V. P.

    2014-12-01

    This paper discusses the observations of the atmospheric surface layer (ASL) parameters during the lightning event. During this event behaviour of surface layer parameters has been observed. Other derived parameters like Monin-Obukhov stability parameter (z/L), turbulent kinetic energy (TKE), momentum flux (MF) and sensible heat flux (SHF) have also been considered during this stochastic phenomenon. Characteristics of these surface layer parameters have been analysed during lightning period and compared with the clear weather day. During the peak period of the lightning, the incoming solar irradiance was reduced by one third of its normal value, resulting in an air-temperature decrement near the surface in the range of 4 °C to 6 °C. In addition to that a significant reduction in energy exchanges between surface and lower lying atmosphere (viz. TKE, MF and SHF), has also been observed. The rate of instantaneous decay in solar irradiance and SHF from the first strike to its peak strike time was larger than that seen during clear day hours. The normalized standard deviations of wind components during clear day were studied using Monin-Obukhov similarity theory (MOST) and the results have been compared with earlier studies reported in the literature.

  11. Airborne Measurement of Insolation Impact on the Atmospheric Surface Boundary Layer

    Science.gov (United States)

    Jacob, Jamey; Chilson, Phil; Houston, Adam; Detweiler, Carrick; Bailey, Sean; Cloud-Map Team

    2017-11-01

    Atmospheric surface boundary layer measurements of wind and thermodynamic parameters are conducted during variable insolation conditions, including the 2017 eclipse, using an unmanned aircraft system. It is well known that the air temperatures can drop significantly during a total solar eclipse as has been previously observed. In past eclipses, these observations have primarily been made on the ground. We present results from airborne measurements of the near surface boundary layer using a small unmanned aircraft with high temporal resolution wind and thermodynamic observations. Questions that motivate the study include: How does the temperature within the lower atmospheric boundary vary during an eclipse? What impact does the immediate removal of radiative heating on the ground have on the lower ABL? Do local wind patterns change during an eclipse event and if so why? Will there be a manifestation of the nocturnal boundary layer wind maximum? Comparisons are made with the DOE ARM SGP site that experiences a lower but still significant insolation. Supported by the National Science Foundation under Award Number 1539070.

  12. The atmospheric boundary layer response to the dynamic new Arctic Ocean

    Science.gov (United States)

    Wu, D. L.; Ganeshan, M.

    2016-12-01

    The increasing ice-free area in the Arctic Ocean has transformed its climate system to one with more dynamic boundary layer clouds and seasonal sea ice. During the fall freeze season, the surface sensible heat flux (SSHF) is a crucial mechanism for the loss of excessive ocean heat to the atmosphere, and it has been speculated to play an important role in the recent cloud cover increase and boundary layer (BL) instability observed in the Beaufort and Chukchi seas. Based on multi-year Japanese cruise ship observations from the ice-strengthened R/V Mirai, we are able to characterize the late summer and early fall ocean-BL interactions in this region. Although the BL is found to be well-mixed more than 90% of the time, the SSHF can explain only 10% of the mixed layer height variability. It is the cloud-generated convective turbulence that apparently dominates BL mixing in this ice-free region, which is similar to previous in-situ observations (SHEBA, ASCOS) over sea ice. The SSHF, however, may contribute to BL instability during conditions of uplift (low-pressure), and the presence of the highly stable stratus cloud regime. The efficiency of sensible heat exchange is low during cold air advection (associated with the stratocumulus cloud regime) despite an enhanced ocean-atmosphere temperature difference (ΔT). In general, surface-generated mixing is favored during episodes of high surface wind speeds as opposed to pronounced ΔT. Our analysis suggests a weak local response of the boundary layer stability to the loss of sea ice cover during late summer, which is masked by the strong influence of the large-scale circulation (and clouds). Apart from the fall season, we also studied the Arctic Ocean BL properties during the cold months (Nov-Apr) using multi-year satellite measurements (COSMIC RO). As the boundary layer is typically stable at this time, one might expect major differences in the nature of surface-atmosphere coupling compared to that observed during late

  13. Deposition rates of viruses and bacteria above the atmospheric boundary layer.

    Science.gov (United States)

    Reche, Isabel; D'Orta, Gaetano; Mladenov, Natalie; Winget, Danielle M; Suttle, Curtis A

    2018-01-29

    Aerosolization of soil-dust and organic aggregates in sea spray facilitates the long-range transport of bacteria, and likely viruses across the free atmosphere. Although long-distance transport occurs, there are many uncertainties associated with their deposition rates. Here, we demonstrate that even in pristine environments, above the atmospheric boundary layer, the downward flux of viruses ranged from 0.26 × 10 9 to >7 × 10 9  m -2 per day. These deposition rates were 9-461 times greater than the rates for bacteria, which ranged from 0.3 × 10 7 to >8 × 10 7  m -2 per day. The highest relative deposition rates for viruses were associated with atmospheric transport from marine rather than terrestrial sources. Deposition rates of bacteria were significantly higher during rain events and Saharan dust intrusions, whereas, rainfall did not significantly influence virus deposition. Virus deposition rates were positively correlated with organic aerosols 0.7 μm, implying that viruses could have longer residence times in the atmosphere and, consequently, will be dispersed further. These results provide an explanation for enigmatic observations that viruses with very high genetic identity can be found in very distant and different environments.

  14. A consistent turbulence formulation for the dynamic wake meandering model in the atmospheric boundary layer

    DEFF Research Database (Denmark)

    Keck, Rolf-Erik; Veldkamp, Dick; Wedel-Heinen, Jens Jakob

    evolution 4. atmospheric stability effects on wake deficit evolution and meandering The conducted research is to a large extent based on detailed wake investigations and reference data generated through computational fluid dynamics simulations, where the wind turbine rotor has been represented...... as a standalone flow-solver for the velocity and turbulence distribution, and power production in a wind farm. The performance of the standalone implementation is validated against field data, higher-order computational fluid dynamics models, as well as the most common engineering wake models in the wind industry....... 2. The EllipSys3D actuator line model, including the synthetic methods used to model atmospheric boundary layer shear and turbulence, is verified for modelling the evolution of wind turbine wake turbulence by comparison to field data and wind tunnel experiments. 3. A two-dimensional eddy viscosity...

  15. Impact of the atmospheric boundary layer profile on the ventilation of a cubic building with two large opposite openings

    OpenAIRE

    Bastide, Alain; Lucas, Franck; Boyer, Harry

    2014-01-01

    International audience; The aim of this paper is to show the influence of the atmospheric boundary layer profile on the distribution of velocity in a building having two large openings. The knowledge of the flow form inside a building is useful to define a thermal environment favourable with thermal comfort and good air quality. In computational fluid dynamics, several profiles of atmospheric boundary layer can be used like logarithmic profiles or power profiles. This paper shows the impact o...

  16. The effect of the Asian Monsoon to the atmospheric boundary layer over the Tibetan Plateau

    Science.gov (United States)

    Li, Maoshan; Su, Zhongbo; Chen, Xuelong; Zheng, Donghai; Sun, Fanglin; Ma, Yaoming; Hu, Zeyong

    2016-04-01

    Modulation of the diurnal variations in the convective activities associated with day-by-day changes of surface flux and soil moisture was observed in the beginning of the monsoon season on the central Tibetan plateau (Sugimoto et al., 2008) which indicates the importance of land-atmosphere interactions in determining convective activities over the Tibetan plateau. Detailed interaction processes need to be studied by experiments designed to evaluate a set of hypotheses on mechanisms and linkages of these interactions. A possible function of vegetation to increase precipitation in cases of Tibetan High type was suggested by Yamada and Uyeda (2006). Use of satellite derived plateau scale soil moisture (Wen et al., 2003) enables the verification of these hypotheses (e.g. Trier et al. 2004). To evaluate these feedbacks, the mesoscale WRF model will be used because several numerical experiments are being conducted to improve the soil physical parameterization in the Noah land surface scheme in WRF so that the extreme conditions on the Tibetan plateau could be adequately represented (Van der Velde et al., 2009) such that the impacts on the structure of the atmospheric boundary layer can be assessed and improved. The Tibetan Observational Research Platform (TORP) operated by the Institute of Tibetan Plateau (Ma et al., 2008) will be fully utilized to study the characteristics of the plateau climate and different aspects of the WRF model will be evaluated using this extensive observation platform (e.g. Su et al., 2012). Recently, advanced studies on energy budget have been done by combining field and satellite measurements over the Tibetan Plateau (e.g. Ma et al., 2005). Such studies, however, were based on a single satellite observation and for a few days over an annual cycle, which are insufficient to reveal the relation between the land surface energy budget and the Asian monsoon over the Tibetan plateau. Time series analysis of satellite observations will provide the

  17. CONCENTRATION OF HARMFUL SUBSTANCES REDUCING IN SURFACE LAYER OF ATMOSPHERE AT RHEOSTAT LOCOMOTIVE TESTS

    Directory of Open Access Journals (Sweden)

    E. A. Bondar

    2010-06-01

    Full Text Available It is shown that at present an acceptable way of reducing the concentration of harmful substances in the surface layer of the atmosphere at rheostat tests of locomotives is their dispersion in a large volume of air. Channels, installed above an exhaust pipe of diesel locomotive with a break at the gas flow, work as ejectors. We have solved jointly the equation of aerodynamic characteristics of the ejector device and the equation of diffusion of gases; as a result the calculated dependence for determining the necessary height of ejector device has been obtained.

  18. Wind instability of a foam layer sandwiched between the atmosphere and the ocean

    CERN Document Server

    Shtemler, Yuri M; Mond, Michael

    2007-01-01

    Kelvin-Helmholtz instability of short gravity waves is examined in order to explain the recent findings of the decrease in momentum transfer from hurricane winds to sea waves. A three-fluid configuration of a foam layer between the atmosphere and the ocean is suggested to provide signifficant stabilization of the system and shifting the marginal critical wavelength to the shortwave part of the spectrum. It is conjectured that such stabilization leads to the observed drag reduction. The high contrasts in three fluid densities provide a universal mechanism for stabilizing surface perturbations.

  19. Two-dimensional modeling of thermal inversion layers in the middle atmosphere of Mars

    Science.gov (United States)

    Theodore, B.; Chassefiere, E.

    1993-01-01

    There is some evidence that the thermal structure of the martian middle atmosphere may be altered in a significant way by the general circulation motions. Indeed, while it is well known that the circulation in the meridional plane is responsible for the reversal of the latitudinal thermal gradient at the solstice through the adiabatic heating due to sinking motions above the winter pole, here we want to emphasize that a likely by-product effect could be the formation of warm layers, mainly located in the winter hemisphere, and exhibiting an inversion of the vertical thermal gradient.

  20. Experimental investigation of turbulent transport of momentum and heat in the atmospheric surface layer

    Science.gov (United States)

    Han, Guowen; Zheng, X. J.; Bo, Tianli

    2017-11-01

    In our study, turbulent transport of momentum and heat is investigated in the neutral and unstable atmospheric surface layer (ASL) over the edge of a desert. Our results reveal that with the increase of wind speed the transport efficiencies for momentum and heat increased, furthermore, transport efficiency of momentum increases faster than that of heat. In addition, the method of quadrant analysis and turbulent events were used to analyze the moment flux and heat flux. Experimental results show that the influence of wind speed on moment flux and heat flux can be quite different, which maybe has a great impact on the turbulent transport of momentum and heat in ASL.

  1. Atmospheric boundary layer measurements during summer MONEX 79 at Digha, India

    Energy Technology Data Exchange (ETDEWEB)

    SethuRaman, S.; Michael, P.; Tuthill, W.A.; McNeil, J.

    1979-11-01

    Marine boundary layer experiments conducted over the Bay of Bengal at Digha Beach, West Bengal, India, as part of the International Monsoon Experiments (MONEX 79) are described. The experiments consisted of measurements of atmospheric turbulence and fluxes of momentum, heat, and water vapor from a 10-m-high coastal meteorological tower. Mean meteorological parameters were measured with an automated electronic weather station. Wind speed and direction profiles were obtained with pilot balloon soundings. Some typical tropical meteorological features photographed during the experiment are also presented.

  2. Differences in the efficacy of climate forcings explained by variations in atmospheric boundary layer depth.

    Science.gov (United States)

    Davy, Richard; Esau, Igor

    2016-05-25

    The Earth has warmed in the last century and a large component of that warming has been attributed to increased anthropogenic greenhouse gases. There are also numerous processes that introduce strong, regionalized variations to the overall warming trend. However, the ability of a forcing to change the surface air temperature depends on its spatial and temporal distribution. Here we show that the efficacy of a forcing is determined by the effective heat capacity of the atmosphere, which in cold and dry climates is defined by the depth of the planetary boundary layer. This can vary by an order of magnitude on different temporal and spatial scales, and so we get a strongly amplified temperature response in shallow boundary layers. This must be accounted for to assess the efficacy of a climate forcing, and also implies that multiple climate forcings cannot be linearly combined to determine the temperature response.

  3. Atmospheric Plasma Deposition of SiO2 Films for Adhesion Promoting Layers on Titanium

    Directory of Open Access Journals (Sweden)

    Liliana Kotte

    2014-12-01

    Full Text Available This paper evaluates the deposition of silica layers at atmospheric pressure as a pretreatment for the structural bonding of titanium (Ti6Al4V, Ti15V3Cr3Sn3Al in comparison to an anodizing process (NaTESi process. The SiO2 film was deposited using the LARGE plasma source, a linearly extended DC arc plasma source and applying hexamethyldisiloxane (HMDSO as a precursor. The morphology of the surface was analyzed by means of SEM, while the characterization of the chemical composition of deposited plasma layers was done by XPS and FTIR. The long-term durability of bonded samples was evaluated by means of a wedge test in hot/wet condition. The almost stoichiometric SiO2 film features a good long-term stability and a high bonding strength compared to the films produced with the wet-chemical NaTESi process.

  4. Application of Atmospheric Plasma-Sprayed Ferrite Layers for Particle Accelerators

    CERN Document Server

    Caspers, F; Federmann, S; Taborelli, M; Schulz, C; Bobzin, K; Wu, J

    2013-01-01

    A common problem in all kinds of cavity-like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures as diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However, the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 μm to about 300 μm can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented.

  5. Statistical-mechanical approach to study the hydrodynamic stability of the stably stratified atmospheric boundary layer

    Science.gov (United States)

    Nevo, G.; Vercauteren, N.; Kaiser, A.; Dubrulle, B.; Faranda, D.

    2017-08-01

    We study the hydrodynamic equilibrium properties of the stably stratified atmospheric boundary layer from measurements obtained in the Snow-Horizontal Array Turbulence Study campaign at the Plaine Morte Glacier in the Swiss Alps. Our approach is based on a combination of dynamical systems techniques and statistical analysis. The main idea is to measure the deviations from the behavior expected by a turbulent observable when it is close to a transition between different metastable states. We first assess the performance of our method on the Lorenz attractor, then on a turbulent flow. The results show that the method recognizes subtle differences among different stable boundary layer turbulence regimes and may be used to help characterize their transitions.

  6. How can a dusty cold pool change the diurnal evolution of the Saharan Atmospheric Boundary Layer ?

    Science.gov (United States)

    Kocha, Cécile; Flamant, Cyrille; Berckmans, Julie; Fink, Andreas; Garcia-Carreras, Luis; Knippertz, Peter; Lafore, Jean-Philippe; Marnas, Fabien; Marsham, John; Parker, Doug; Rosenberg, Philip; Ryder, Claire; Tulet, Pierre; Washington, Richard

    2013-04-01

    In the framework of the Fennec 2011 Special Observing period, a large and dusty density current (known as a haboob) was observed on the 21 June to cover half of the western part of the Sahara. Thanks to the AROME high resolution model used to forecast this event in real time, two research aircraft (the SAFIRE Falcon and the FAAM BAe 146) operated over Mauritania and Mali on that day, and we are able to document its characteristics in detail. Particularly large dust particles were observed in this haboob. These particles are known to absorb and scatter solar and thermal radiation. The comparison of AROME simulations with and without coupling with dust shows that the radiative impact of the dust induced a decrease of sensible heat fluxes by 200W/m²/AOD and an increase of the temperature in the atmospheric boundary layer by 1°C. Surface fluxes are one of the principal parameters controlling the growth of the boundary layer. However, during the day, the simulation coupled with dust shows a deeper boundary layer (reaching ~5km high) than the simulation without dust. Here, we explore the competition between surface heating and elevated heating in the boundary-layer development.

  7. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  8. Characteristics of the atmospheric boundary layer over a scots pine forest

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, D.

    2004-06-01

    The atmospheric boundary layer is structured vertically into several conceptual sublayers because the main airflow characteristics, e.g. the velocity field, air temperature, and air moisture, show different height dependent features. To investigate mean airflow characteristics over a Scots pine forest up to several stand heights, remote sensing and in situ measurements (profile and eddy covariance method) were conducted at the forest meteorological experimental site Hartheim in the Upper Rhine Valley. This methodological combination enables the continuous measurement of the main airflow characteristics exceeding the measuring range of tower-based measurements. Up to now airflow characteristics of the atmospheric boundary layer over forests exceeding the range of tower-based instrumentation are little experimentally studied because - remote sensing devices for operational use are available only for a short time, - of the extensive infrastructure and the problematic experimental setup. Therefore, airflow characteristics above and within forests were often studied based on selected time series and in a narrow range of atmospheric stability conditions when air-flow characteristics were most pronounced (Lu and Fitzjarrald, 1994; Brunet and Irvine, 2000). Furthermore, most of the knowledge of turbulent airflow characteristics and air mass exchange processes between tall plant canopies and the atmosphere has been gained of studies in relatively dense plant canopies (Green et al., 1995; Poggi et al., 2004). Few studies investigated turbulence characteristics in thinly stocked plant canopies such as the Hartheim Scots pine forest. Starting from these deficits the aim of this study is to examine airflow characteristics above and within the Hartheim Scots pine forest the under more general conditions as a function of - atmospheric stability conditions, - seasonal dynamics, up to a height of 200 m a.g.l. Target quantities are variables, which are suitable to describe the

  9. On the Structure and Adjustment of Inversion-Capped Neutral Atmospheric Boundary-Layer Flows: Large-Eddy Simulation Study

    DEFF Research Database (Denmark)

    Pedersen, Jesper Grønnegaard; Gryning, Sven-Erik; Kelly, Mark C.

    2014-01-01

    A range of large-eddy simulations, with differing free atmosphere stratification and zero or slightly positive surface heat flux, is investigated to improve understanding of the neutral and near-neutral, inversion-capped, horizontally homogeneous, barotropic atmospheric boundary layer with emphas...

  10. Retrieving 4-dimensional atmospheric boundary layer structure from surface observations and profiles over a single station

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zhaoxia [Univ. of Utah, Salt Lake City, UT (United States)

    2015-10-06

    Most routine measurements from climate study facilities, such as the Department of Energy’s ARM SGP site, come from individual sites over a long period of time. While single-station data are very useful for many studies, it is challenging to obtain 3-dimensional spatial structures of atmospheric boundary layers that include prominent signatures of deep convection from these data. The principal objective of this project is to create realistic estimates of high-resolution (~ 1km × 1km horizontal grids) atmospheric boundary layer structure and the characteristics of precipitating convection. These characteristics include updraft and downdraft cumulus mass fluxes and cold pool properties over a region the size of a GCM grid column from analyses that assimilate surface mesonet observations of wind, temperature, and water vapor mixing ratio and available profiling data from single or multiple surface stations. The ultimate goal of the project is to enhance our understanding of the properties of mesoscale convective systems and also to improve their representation in analysis and numerical simulations. During the proposed period (09/15/2011–09/14/2014) and the no-cost extension period (09/15/2014–09/14/2015), significant accomplishments have been achieved relating to the stated goals. Efforts have been extended to various research and applications. Results have been published in professional journals and presented in related science team meetings and conferences. These are summarized in the report.

  11. New Setup of the UAS ALADINA for Measuring Boundary Layer Properties, Atmospheric Particles and Solar Radiation

    Directory of Open Access Journals (Sweden)

    Konrad Bärfuss

    2018-01-01

    Full Text Available The unmanned research aircraft ALADINA (Application of Light-weight Aircraft for Detecting in situ Aerosols has been established as an important tool for boundary layer research. For simplified integration of additional sensor payload, a flexible and reliable data acquisition system was developed at the Institute of Flight Guidance, Technische Universität (TU Braunschweig. The instrumentation consists of sensors for temperature, humidity, three-dimensional wind vector, position, black carbon, irradiance and atmospheric particles in the diameter range of ultra-fine particles up to the accumulation mode. The modular concept allows for straightforward integration and exchange of sensors. So far, more than 200 measurement flights have been performed with the robustly-engineered system ALADINA at different locations. The obtained datasets are unique in the field of atmospheric boundary layer research. In this study, a new data processing method for deriving parameters with fast resolution and to provide reliable accuracies is presented. Based on tests in the field and in the laboratory, the limitations and verifiability of integrated sensors are discussed.

  12. Wind Turbine Performance in an Atmospheric Boundary Layer: Betz Analysis Revisited

    Science.gov (United States)

    West, Jacob; Lele, Sanjiva

    2017-11-01

    Using large eddy simulation of an infinite (periodic in x and y) wind farm, we compute momentum and mean mechanical energy budgets. We focus on the control volume defined by a streamtube of the mean flow that intersects with a turbine actuator disk, in a similar way as traditional Betz analysis is done for a streamtube in inviscid, irrotational flow through an actuator disk. This analysis reveals that many of the same phenomena from Betz analysis are found in the atmospheric boundary layer case. The streamtube expands as the fluid decelerates through the turbine, and the pressure increases and then drops sharply across the actuator disk. However, away from the turbine, the downstream streamtube shrinks and fluid accelerates due to turbulent mixing. In this way, turbulence alters the idealization of the Betz streamtube. We anticipate that the Betz analysis can be applied most effectively to a wind turbine in the atmospheric boundary layer by focusing on the immediate vicinity around the turbine, where inviscid, potential flow effects dominate. Adjustments can be made to account for the vertical energy flux in wind farms, as well as the energy contained in velocity fluctuations.

  13. Aerosols in the Convective Boundary Layer: Radiation Effects on the Coupled Land-Atmosphere System

    Science.gov (United States)

    Barbaro, E.; Vila-Guerau Arellano, J.; Ouwersloot, H. G.; Schroter, J.; Donovan, D. P.; Krol, M. C.

    2013-12-01

    We investigate the responses of the surface energy budget and the convective boundary-layer (CBL) dynamics to the presence of aerosols using a combination of observations and numerical simulations. A detailed observational dataset containing (thermo)dynamic variables observed at CESAR (Cabauw Experimental Site for Atmospheric Research) and aerosol information from the European Integrated Project on Aerosol, Cloud, Climate, and Air Quality Interactions (IMPACT/EUCAARI) campaign is employed to design numerical experiments reproducing two prototype clear-sky days characterized by: (i) a well-mixed residual layer above a ground inversion and (ii) a continuously growing CBL. A large-eddy simulation (LES) model and a mixed-layer (MXL) model, both coupled to a broadband radiative transfer code and a land-surface model, are used to study the impacts of aerosol scattering and absorption of shortwave radiation on the land-atmosphere system. We successfully validate our model results using the measurements of (thermo)dynamic variables and aerosol properties for the two different CBL prototypes studied here. Our findings indicate that in order to reproduce the observed surface energy budget and CBL dynamics, information of the vertical structure and temporal evolution of the aerosols is necessary. Given the good agreement between the LES and the MXL model results, we use the MXL model to explore the aerosol effect on the land-atmosphere system for a wide range of optical depths and single scattering albedos. Our results show that higher loads of aerosols decrease irradiance, imposing an energy restriction at the surface. Over the studied well-watered grassland, aerosols reduce the sensible heat flux more than the latent heat flux. As a result, aerosols increase the evaporative fraction. Moreover, aerosols also delay the CBL morning onset and anticipate its afternoon collapse. If also present above the CBL during the morning transition, aerosols maintain a persistent near

  14. Modulation mechanisms of marine atmospheric boundary layer at the Brazil-Malvinas Confluence region

    Science.gov (United States)

    de Camargo, Ricardo; Todesco, Enzo; Pezzi, Luciano Ponzi; de Souza, Ronald Buss

    2013-06-01

    The influence of the Brazil-Malvinas Confluence (BMC) region on the marine atmospheric boundary layer (MABL) is investigated through in situ data analysis of five different cruises (2004 to 2008) and numerical experiments with a regional atmospheric model. Two different groups of numerical experiments were performed in order to evaluate the relevance of static stability and hydrostatic balance physical mechanisms for the MABL instability. The first group used monthly climatological sea surface temperature (SST) as bottom boundary condition while the second used daily updated Advanced Microwave Scanning Radiometer-EOS SST data together with radiosondes and surface data assimilation. A reasonable agreement between numerical results and QuikSCAT wind data was observed through correlation coefficients and mean square error values. In terms of the horizontal structure of the MABL, stronger winds were found over the warm side of the BMC region as well as over the thermal front itself, which supports the coexistence of both modulation mechanisms. The analyzed patterns of surface atmospheric thermal advection showed a clear interaction between the synoptic and regional scales. The signature of the oceanic thermal front (almost meridionally oriented) on the air temperature at 2 m makes the temperature advection strongly determined by the zonal component of the wind. The analysis of momentum budget terms did not show a clear and reasonable explanation of the existence or predominance of the modulation mechanisms, and it also suggested the relevance of other effects, such as the idea based on unbalanced Coriolis force and turbulence/friction effects.

  15. LOLAS: an optical turbulence profiler in the atmospheric boundary layer with extreme altitude resolution

    Science.gov (United States)

    Avila, R.; Avilés, J. L.; Wilson, R. W.; Chun, M.; Butterley, T.; Carrasco, E.

    2008-07-01

    We report the development and first results of an instrument called Low Layer SCIDAR (Scintillation Detection and Ranging) (LOLAS) which is aimed at the measurement of optical-turbulence profiles in the atmospheric boundary layer with high altitude resolution. The method is based on the Generalized SCIDAR (GS) concept, but unlike the GS instruments which need a 1-m or larger telescope, LOLAS is implemented on a dedicated 40-cm telescope, making it an independent instrument. The system is designed for widely separated double-star targets, which enables the high altitude resolution. Using a 200-arcsec-separation double star, we have obtained turbulence profiles with unprecedented 12-m resolution. The system incorporates necessary novel algorithms for autoguiding, autofocus and image stabilization. The results presented here were obtained at Mauna Kea Observatory. They show LOLAS capabilities but cannot be considered as representative of the site. A forthcoming paper will be devoted to the site characterization. The instrument was built as part of the Ground Layer Turbulence Monitoring Campaign on Mauna Kea for Gemini Observatory.

  16. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    Science.gov (United States)

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation.

  17. Aerosol model development for environmental monitoring in the coastal atmosphere surface layer

    Science.gov (United States)

    Kaloshin, Gennady A.; Matvienko, Gennady G.

    2007-06-01

    Extinction of radiation in the marine boundary layer is dominated by scattering and absorption due to atmospheric aerosol. It is known, that the extinction of optical radiation visible and near IR spectra in the marine surface layer is determined mainly by scattering and absorption atmospheric aerosol. It influences on a dependence of spectral transmission and extinction both natural, and artificial light that is of interest for a wide range of problems, in particular for radiating problems at studying laws of climate formation, and for lines of the applications connected to the forecast of a signal power in coastal conditions at an estimation of EO systems characteristics. This is important to optical retrievals from satellite, remote sensing at environmental monitoring, backscatter of light to space (including climate forcing), cloud properties etc. In unpolluted regions the greatest effects on near shore scattering extinction will be a result of sea-salt from breaking waves and variations in relative humidity. The role of breaking waves appears to be modulated by wind, tide, swell, wave spectra and coastal conditions. These influences will be superimposed upon aerosol generated by open ocean sea-salt aerosol that varies with wind speed. The focus of our study is the extinction and optical effects due to aerosol in a specific coastal region. This involves linking coastal physical properties to oceanic and meteorological parameters in order to develop predictive algorithms that describe 3-D aerosol structure and variability. The aerosol microphysical model of the marine and coastal atmosphere surface layer is considered. The model distinctive feature is parameterization of amplitude and width of the modes as functions of fetch and wind speed. In the paper the dN/dr behavior depending at change meteorological parameters, heights above sea level, fetch, wind speed and RH is show. On the basis of the developed model with usage of Mie theory for spheres the

  18. On the influence of atmospheric super-saturation layer on China's heavy haze-fog events

    Science.gov (United States)

    Wang, Jizhi; Yang, Yuanqin; Zhang, Xiaoye; Liu, Hua; Che, Huizheng; Shen, Xiaojing; Wang, Yaqiang

    2017-12-01

    With the background of global change, the air quality in Earth's atmosphere has significantly decreased. The North China Plain (NCP), Yangtze River Delta (YRD), Pearl River Delta (PRD) and Si-Chuan Basin (SCB) are the major areas suffering the decreasing air quality and frequent pollution events in recent years. Studying the effect of meteorological conditions on the concentration of pollution aerosols in these pollution sensitive regions is a hot focus now. This paper analyses the characteristics of atmospheric super-saturation and the corresponding H_PMLs (height of supersaturated pollution mixing layer), investigating their contribution to the frequently-seen heavy haze-fog weather. The results suggest that: (1) in the above-mentioned pollution sensitive regions in China, super-saturated layers repeatedly appear in the low altitude and the peak value of supersaturation S can reach 6-10%, which makes pollution particles into the wet adiabatic uplift process in the stable-static atmosphere. After low-level atmosphere reaches the super-saturation state below the H_PMLs, meteorological condition contributes to humidification and condensation of pollution particles. (2) Caculation of condensation function Fc, one of PLAM sensetive parameter, indicates that super-saturation state helps promote condensation, beneficial to the formation of Condensational Kink (CK) in the pollution sensitive areas. This favors the formation of new aerosol particles and intensities the cumulative growth of aerosol concentration. (3) By calculating the convective inhibition energy on average │CIN│ > 1.0 × 104 J kg-1, we found the value is about 100 times higher than the stable critical value. The uplifting diffusion of the particles is inhibited by the ambient airflow. So, this is the important reason for the aggravation and persistence of aerosol pollutants in local areas. (4) H_PMLs is negatively correlated to the pollution meteorological condition index PLAM which can describe the

  19. Impact of the Diurnal Cycle of the Atmospheric Boundary Layer on Wind-Turbine Wakes: A Numerical Modelling Study

    Science.gov (United States)

    Englberger, Antonia; Dörnbrack, Andreas

    2017-10-01

    The wake characteristics of a wind turbine for different regimes occurring throughout the diurnal cycle are investigated systematically by means of large-eddy simulation. Idealized diurnal cycle simulations of the atmospheric boundary layer are performed with the geophysical flow solver EULAG over both homogeneous and heterogeneous terrain. Under homogeneous conditions, the diurnal cycle significantly affects the low-level wind shear and atmospheric turbulence. A strong vertical wind shear and veering with height occur in the nocturnal stable boundary layer and in the morning boundary layer, whereas atmospheric turbulence is much larger in the convective boundary layer and in the evening boundary layer. The increased shear under heterogeneous conditions changes these wind characteristics, counteracting the formation of the night-time Ekman spiral. The convective, stable, evening, and morning regimes of the atmospheric boundary layer over a homogeneous surface as well as the convective and stable regimes over a heterogeneous surface are used to study the flow in a wind-turbine wake. Synchronized turbulent inflow data from the idealized atmospheric boundary-layer simulations with periodic horizontal boundary conditions are applied to the wind-turbine simulations with open streamwise boundary conditions. The resulting wake is strongly influenced by the stability of the atmosphere. In both cases, the flow in the wake recovers more rapidly under convective conditions during the day than under stable conditions at night. The simulated wakes produced for the night-time situation completely differ between heterogeneous and homogeneous surface conditions. The wake characteristics of the transitional periods are influenced by the flow regime prior to the transition. Furthermore, there are different wake deflections over the height of the rotor, which reflect the incoming wind direction.

  20. Laboratory modelling of the transfer processes between the ocean and atmosphere in the boundary layers

    Science.gov (United States)

    Sergeev, Daniil; Kandaurov, Alexander; Troitskaya, Yuliya; Vdovin, Maxim

    The processes of momentum and heat transfer between ocean and atmosphere in the boundary layer were investigated within laboratory modeling for a wide range of wind speed and surface wave including hurricane conditions. Experiments were carried out on the Wind-Wave Flume of the Large Thermostratified Tank of IAP RAS. A special net located under the surface at different depths allows to vary parameters of surface waves independently on wind parameters. Theory of self-similarity of air flow parameters in the flume was used to calculate values aerodynamic and heat transfer coefficients from the measured velocity and temperature profiles by Pito and hotfilm gauges respectively. Simultaneous measurements of surface elevation with system wire allow to obtain spectra and integral parameters of waves. It was demonstrated that in contrast to the drag coefficient, heat transfer coefficient is virtually independent of wind speed and wave parameters to the moment of the beginning of spray generation and then increases rapidly.

  1. Climate change and atmospheric chemistry: how will the stratospheric ozone layer develop?

    Science.gov (United States)

    Dameris, Martin

    2010-10-25

    The discovery of the ozone hole over Antarctica in 1985 was a surprise for science. For a few years the reasons of the ozone hole was speculated about. Soon it was obvious that predominant meteorological conditions led to a specific situation developing in this part of the atmosphere: Very low temperatures initiate chemical processes that at the end cause extreme ozone depletion at altitudes of between about 15 and 30 km. So-called polar stratospheric clouds play a key role. Such clouds develop at temperatures below about 195 K. Heterogeneous chemical reactions on cloud particles initiate the destruction of ozone molecules. The future evolution of the ozone layer will not only depend on the further development of concentrations of ozone-depleting substances, but also significantly on climate change.

  2. Laboratory modelling of the transfer processes between the ocean and atmosphere in the boundary layers

    Directory of Open Access Journals (Sweden)

    Sergeev Daniil

    2017-01-01

    Full Text Available The processes of momentum and heat transfer between ocean and atmosphere in the boundary layer were investigated within laboratory modeling for a wide range of wind speed and surface wave including hurricane conditions. Experiments were carried out on the Wind-Wave Flume of the Large Thermostratified Tank of IAP RAS. A special net located under the surface at different depths allows to vary parameters of surface waves independently on wind parameters. Theory of self-similarity of air flow parameters in the flume was used to calculate values aerodynamic and heat transfer coefficients from the measured velocity and temperature profiles by Pito and hotfilm gauges respectively. Simultaneous measurements of surface elevation with system wire allow to obtain spectra and integral parameters of waves. It was demonstrated that in contrast to the drag coefficient, heat transfer coefficient is virtually independent of wind speed and wave parameters to the moment of the beginning of spray generation and then increases rapidly.

  3. Spatial atmospheric atomic layer deposition of InxGayZnzO for thin film transistors.

    Science.gov (United States)

    Illiberi, A; Cobb, B; Sharma, A; Grehl, T; Brongersma, H; Roozeboom, F; Gelinck, G; Poodt, P

    2015-02-18

    We have investigated the nucleation and growth of InGaZnO thin films by spatial atmospheric atomic layer deposition. Diethyl zinc (DEZ), trimethyl indium (TMIn), triethyl gallium (TEGa), and water were used as Zn, In, Ga and oxygen precursors, respectively. The vaporized metal precursors have been coinjected in the reactor. The metal composition of InGaZnO has been controlled by varying the TMIn or TEGa flow to the reactor, for a given DEZ flow and exposure time. The morphology of the films changes from polycrystalline, for ZnO and In-doped ZnO, to amorphous for In-rich IZO and InGaZnO. The use of these films as the active channel in TFTs has been demonstrated and the influence of In and Ga cations on the electrical characteristics of the TFTs has been studied.

  4. Acid-base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer.

    Science.gov (United States)

    Chen, Modi; Titcombe, Mari; Jiang, Jingkun; Jen, Coty; Kuang, Chongai; Fischer, Marc L; Eisele, Fred L; Siepmann, J Ilja; Hanson, David R; Zhao, Jun; McMurry, Peter H

    2012-11-13

    Climate models show that particles formed by nucleation can affect cloud cover and, therefore, the earth's radiation budget. Measurements worldwide show that nucleation rates in the atmospheric boundary layer are positively correlated with concentrations of sulfuric acid vapor. However, current nucleation theories do not correctly predict either the observed nucleation rates or their functional dependence on sulfuric acid concentrations. This paper develops an alternative approach for modeling nucleation rates, based on a sequence of acid-base reactions. The model uses empirical estimates of sulfuric acid evaporation rates obtained from new measurements of neutral molecular clusters. The model predicts that nucleation rates equal the sulfuric acid vapor collision rate times a prefactor that is less than unity and that depends on the concentrations of basic gaseous compounds and preexisting particles. Predicted nucleation rates and their dependence on sulfuric acid vapor concentrations are in reasonable agreement with measurements from Mexico City and Atlanta.

  5. Investigation of chemical properties and transport phenomena associated with pollutants in the atmospheric boundary layer

    Science.gov (United States)

    Holmes, Heather A.

    Under the Clean Air Act, the U.S. Environmental Protection Agency is required to determine which air pollutants are harmful to human health, then regulate, monitor and establish criteria levels for these pollutants. To accomplish this and for scientific advancement, integration of knowledge from several disciplines is required including: engineering, atmospheric science, chemistry and public health. Recently, a shift has been made to establish interdisciplinary research groups to better understand the atmospheric processes that govern the transport of pollutants and chemical reactions of species in the atmospheric boundary layer (ABL). The primary reason for interdisciplinary collaboration is the need for atmospheric processes to be treated as a coupled system, and to design experiments that measure meteorological, chemical and physical variables simultaneously so forecasting models can be improved (i.e., meteorological and chemical process models). This dissertation focuses on integrating research disciplines to provide a more complete framework to study pollutants in the ABL. For example, chemical characterization of particulate matter (PM) and the physical processes governing PM distribution and mixing are combined to provide more comprehensive data for source apportionment. Data from three field experiments were utilized to study turbulence, meteorological and chemical parameters in the ABL. Two air quality field studies were conducted on the U.S./Mexico border. The first was located in Yuma, AZ to investigate the spatial and temporal variability of PM in an urban environment and relate chemical properties of ambient aerosols to physical findings. The second border air quality study was conducted in Nogales, Sonora, Mexico to investigate the relationship between indoor and outdoor air quality in order to better correlate cooking fuel types and home activities to elevated indoor PM concentrations. The final study was executed in southern Idaho and focused on

  6. Acoustic pulse propagation through a fluctuating stably stratified atmospheric boundary layer

    Science.gov (United States)

    Chunchuzov, Igor; Kulichkov, Sergey; Otrezov, Alexander; Perepelkin, Vitaly

    2005-04-01

    Mesoscale wind speed and temperature fluctuations with periods from 1 min to a few hours significantly affect temporal variability and turbulent regime of the stable atmospheric boundary layer (ABL). Their statistical characteristics are still poorly understood, although the knowledge of such statistics is required when modeling sound propagation through the stable ABL. Several field experiments have been conducted to study the influence of mesoscale wind speed fluctuations on acoustic pulse propagation through the stable ABL. Some results of these experiments are described in this paper. A special acoustic source was used to generate acoustic pulses by the detonation of an air-propane mixture with a repetition period 30 s. The mean wind speed and temperature profiles were continuously measured by Doppler sodar and temperature profiler, whereas mesoscale wind fluctuations were measured by anemometers placed on a 56-m mast. From the measurements of the pulse travel time fluctuations at different distances from the source, the statistical characteristics of the mesoscale wind fluctuations, such as frequency spectra, coherences, horizontal phase speeds and scales, have been obtained. Some of the obtained results are interpreted with the use of a recently developed model for the internal wave spectrum in a stably stratified atmosphere. .

  7. Acoustic pulse propagation through stable atmospheric boundary layer: Theory and experiment

    Science.gov (United States)

    Chunchuzov, Igor; Kulichkov, Sergey; Otrezov, Alexander; Perepelkin, Vitaly

    2004-05-01

    Mesoscale wind speed and temperature fluctuations with periods from 1 min to a few hours significantly affect a variability and turbulent regime of stable atmospheric boundary layer (ABL). Their statistical characteristics are still poorly understood, although the knowledge of such statistics is required when modeling sound propagation through stable ABL. Several field experiments have been conducted to study the influence of mesoscale wind speed fluctuations on acoustic pulse propagation in stable ABL. The results of these experiments are presented in this work. A special acoustic source was used to generate acoustic pulses due to a detonation of air-propane mixture with a repetition period of 1 min or 30 s. The mean wind speed profiles and mesoscale wind fluctuations were measured by Doppler sodar up to a height of 300 m, and by anemometers placed on a 56-mast. From the measurements of the pulse travel time fluctuations at different distances from the source the statistical characteristics of the mesoscale wind fluctuations such as frequency spectra, coherences, horizontal phase speeds and scales have been obtained. Some of the obtained results are interpreted with a recently developed model of internal wave spectrum in a stably stratified atmosphere.

  8. Stability and turbulence in the atmospheric boundary layer: A comparison of remote sensing and tower observations

    Science.gov (United States)

    Friedrich, Katja; Lundquist, Julie K.; Aitken, Matthew; Kalina, Evan A.; Marshall, Robert F.

    2012-02-01

    When monitoring winds and atmospheric stability for wind energy applications, remote sensing instruments present some advantages to in-situ instrumentation such as larger vertical extent, in some cases easy installation and maintenance, measurements of vertical humidity profiles throughout the boundary layer, and no restrictions on prevailing wind directions. In this study, we compare remote sensing devices, Windcube lidar and microwave radiometer, to meteorological in-situ tower measurements to demonstrate the accuracy of these measurements and to assess the utility of the remote sensing instruments in overcoming tower limitations. We compare temperature and wind observations, as well as calculations of Brunt-Väisälä frequency and Richardson numbers for the instrument deployment period in May-June 2011 at the U.S. Department of Energy National Renewable Energy Laboratory's National Wind Technology Center near Boulder, Colorado. The study reveals that a lidar and radiometer measure wind and temperature with the same accuracy as tower instruments, while also providing advantages for monitoring stability and turbulence. We demonstrate that the atmospheric stability is determined more accurately when the liquid-water mixing ratio derived from the vertical humidity profile is considered under moist-adiabatic conditions.

  9. Profiles of Wind and Turbulence in the Coastal Atmospheric Boundary Layer of Lake Erie

    KAUST Repository

    Wang, H

    2014-06-16

    Prediction of wind resource in coastal zones is difficult due to the complexity of flow in the coastal atmospheric boundary layer (CABL). A three week campaign was conducted over Lake Erie in May 2013 to investigate wind characteristics and improve model parameterizations in the CABL. Vertical profiles of wind speed up to 200 m were measured onshore and offshore by lidar wind profilers, and horizontal gradients of wind speed by a 3-D scanning lidar. Turbulence data were collected from sonic anemometers deployed onshore and offshore. Numerical simulations were conducted with the Weather Research Forecasting (WRF) model with 2 nested domains down to a resolution of 1-km over the lake. Initial data analyses presented in this paper investigate complex flow patterns across the coast. Acceleration was observed up to 200 m above the surface for flow coming from the land to the water. However, by 7 km off the coast the wind field had not yet reached equilibrium with the new surface (water) conditions. The surface turbulence parameters over the water derived from the sonic data could not predict wind profiles observed by the ZephlR lidar located offshore. Horizontal wind speed gradients near the coast show the influence of atmospheric stability on flow dynamics. Wind profiles retrieved from the 3-D scanning lidar show evidence of nocturnal low level jets (LLJs). The WRF model was able to capture the occurrence of LLJ events, but its performance varied in predicting their intensity, duration, and the location of the jet core.

  10. Spatial structures in the heat budget of the Antarctic atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    W. J. van de Berg

    2008-01-01

    Full Text Available Output from the regional climate model RACMO2/ANT is used to calculate the heat budget of the Antarctic atmospheric boundary layer (ABL. The main feature of the wintertime Antarctic ABL is a persistent temperature deficit compared to the free atmosphere. The magnitude of this deficit is controlled by the heat budget. During winter, transport of heat towards the surface by turbulence and net longwave emission are the primary ABL cooling terms. These processes show horizontal spatial variability only on continental scales. Vertical and horizontal, i.e. along-slope, advection of heat are the main warming terms. Over regions with convex ice sheet topography, i.e. domes and ridges, warming by downward vertical advection is enhanced due to divergence of the ABL wind field. Horizontal advection balances excess warming caused by vertical advection, hence the temperature deficit in the ABL weakens over domes and ridges along the prevailing katabatic wind. Conversely, vertical advection is reduced in regions with concave topography, i.e. valleys, where the ABL temperature deficit enlarges along the katabatic wind. Along the coast, horizontal and vertical advection is governed by the inability of the large-scale circulation to adapt to small scale topographic features. Meso-scale topographic structures have thus a strong impact on the ABL winter temperature, besides latitude and surface elevation. During summer, this mechanism is much weaker, and the horizontal variability of ABL temperatures is smaller.

  11. The Influence of High Aerosol Concentration on Atmospheric Boundary Layer Temperature Stratification

    Energy Technology Data Exchange (ETDEWEB)

    Khaykin, M.N.; Kadygrove, E.N.; Golitsyn, G.S.

    2005-03-18

    Investigations of the changing in the atmospheric boundary layer (ABL) radiation balance as cased by natural and anthropogenic reasons is an important topic of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program. The influence of aerosol on temperature stratification of ABL while its concentration was extremely high within a long period of time was studied experimentally. The case was observed in Moscow region (Russia) with the transport of combustion products from peat-bog and forest fires in July-September, 2002. At this time the visibility was some times at about 100-300 m. Aerosol concentration measured by Moscow University Observatory and A.M. Obukhov Institute of Atmospheric Physics field station in Zvenigorod (55.7 N; 36.6 E) for several days was in 50-100 times more than background one (Gorchakov at al 2003). The high aerosol concentration can change the radiation balance at ABL, and so to change thermal stratification in ABL above the mega lopolis. For the analysis the data were used of synchronous measurements by MTP-5 (Microwave Temperature Profiler operating at wavelength 5 mm) in two locations, namely: downtown Moscow and country-side which is 50 km apart to the West (Zvenigorod station). (Kadygrov and Pick 1998; Westwater at al 1999; Kadygrov at al 2002). Zvenigorod station is located in strongly continental climate zone which is in between of the climates of ARM sites (NSANorth Slope of Alaska and SGP-Southern Great Plains). The town of Zvenigorod has little industry, small traffic volume and topography conductive to a good air ventilation of the town. For these reasons Zvenigorod can be considered as an undisturbed rural site. For the analysis some days were chosen with close meteorological parameters (average temperature, humidity, wind, pressure and cloud form) but strongly differing in aerosol concentration level.

  12. Influence of Evaporating Droplets in the Turbulent Marine Atmospheric Boundary Layer

    Science.gov (United States)

    Peng, Tianze; Richter, David

    2017-08-01

    Sea-spray droplets ejected into the marine atmospheric boundary layer take part in a series of complex transport processes. By capturing the air-droplet coupling and feedback, we focus on how droplets modify the total heat transfer across a turbulent boundary layer. We implement a high-resolution Eulerian-Lagrangian algorithm with varied droplet size and mass loading in a turbulent open-channel flow, revealing that the influence from evaporating droplets varies for different dynamic and thermodynamic characteristics of droplets. Droplets that both respond rapidly to the ambient environment and have long suspension times are able to modify the latent and sensible heat fluxes individually, however the competing signs of this modification lead to an overall weak effect on the total heat flux. On the other hand, droplets with a slower thermodynamic response to the environment are less subjected to this compensating effect. This indicates a potential to enhance the total heat flux, but the enhancement is highly dependent on the concentration and suspension time.

  13. Atmospheric Feedback of Urban Boundary Layer with Implications for Climate Adaptation.

    Science.gov (United States)

    Liang, Marissa S; Keener, Timothy C

    2015-09-01

    Atmospheric structure changes in response to the urban form, land use, and the type of land cover (LULC). This interaction controls thermal and air pollutant transport and distribution. The interrelationships among LULC, ambient temperature, and air quality were analyzed and found to be significant in a case study in Cincinnati, Ohio, U.S.A. Within the urban canopy layer (UCL), traffic-origin PM2.5 and black carbon followed Gaussian dispersion in the near road area in the daytime, while higher concentrations, over 1 order of magnitude, were correlated to the lapse rate under nocturnal inversions. In the overlying urban boundary layer (UBL), ambient temperature and PM2.5 variations were correlated among urban-wide locations indicating effective thermal and mass communications. Beyond the spatial correlation, LULC-related local urban heat island effects are noteworthy. The high-density urbanized zone along a narrow highway-following corridor is marked by higher nighttime temperature by ∼1.6 °C with a long-term increase by 2.0 °C/decade, and by a higher PM2.5 concentration, than in the low-density residential LULC. These results indicate that the urban LULC may have contributed to the nocturnal thermal inversion affecting urban air circulation and air quality in UCL and UBL. Such relationships point to the potentials of climate adaptation through urban planning.

  14. Mechanistic modeling study on process optimization and precursor utilization with atmospheric spatial atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Zhang; He, Wenjie; Duan, Chenlong [State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Chen, Rong, E-mail: rongchen@mail.hust.edu.cn [State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Shan, Bin [State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2016-01-15

    Spatial atomic layer deposition (SALD) is a promising technology with the aim of combining the advantages of excellent uniformity and conformity of temporal atomic layer deposition (ALD), and an industrial scalable and continuous process. In this manuscript, an experimental and numerical combined model of atmospheric SALD system is presented. To establish the connection between the process parameters and the growth efficiency, a quantitative model on reactant isolation, throughput, and precursor utilization is performed based on the separation gas flow rate, carrier gas flow rate, and precursor mass fraction. The simulation results based on this model show an inverse relation between the precursor usage and the carrier gas flow rate. With the constant carrier gas flow, the relationship of precursor usage and precursor mass fraction follows monotonic function. The precursor concentration, regardless of gas velocity, is the determinant factor of the minimal residual time. The narrow gap between precursor injecting heads and the substrate surface in general SALD system leads to a low Péclet number. In this situation, the gas diffusion act as a leading role in the precursor transport in the small gap rather than the convection. Fluid kinetics from the numerical model is independent of the specific structure, which is instructive for the SALD geometry design as well as its process optimization.

  15. Analytical Reduced Models for the Non-stationary Diabatic Atmospheric Boundary Layer

    Science.gov (United States)

    Momen, Mostafa; Bou-Zeid, Elie

    2017-09-01

    Geophysical boundary-layer flows feature complex dynamics that often evolve with time; however, most current knowledge centres on the steady-state problem. In these atmospheric and oceanic boundary layers, the pressure gradient, buoyancy, Coriolis, and frictional forces interact to determine the statistical moments of the flow. The resulting equations for the non-stationary mean variables, even when succinctly closed, remain challenging to handle mathematically. Here, we derive a simpler physical model that reduces these governing unsteady Reynolds-averaged Navier-Stokes partial differential equations into a single first-order ordinary differential equation with non-constant coefficients. The reduced model is straightforward to solve under arbitrary forcing, even when the statistical moments are non-stationary and the viscosity varies in time and space. The model is successfully validated against large-eddy simulation for, (1) time-variable pressure gradients, and (2) linearly time-variable buoyancy. The new model is shown to have a superior performance compared to the classic Blackadar solutions (and later improvements on these solutions), and it covers a much wider range of conditions.

  16. Variability in the summertime coastal marine atmospheric boundary-layer off California, USA

    Science.gov (United States)

    Ström, Linda; Tjernström, Michael

    2004-01-01

    An analysis of boundary-layer structure and surface-layer turbulence from measurements off the California coast is presented from data collected by research aircraft during two field experiments: the Coastal Waves 1996 (CW96) and the Monterey Area Ship Track (MAST) experiments. CW96 covers the near-coast region, in particular in the vicinity of major headlands, whereas MAST extends offshore. Along the US west coast, coastal modification of the along-coast flow occurs on two main horizontal scales. Firstly, a large-scale variability is due to the interplay between the shallow near-coast marine atmospheric boundary-layer (MABL) and the coastal terrain, typically higher than the MABL depth. The MABL depth decreases smoothly towards the coast while the wind speed increases to a coastal jet in response to the sloping MABL inversion. Secondly, the flow is affected by supercritical flow dynamics. As the wind speed increases and the MABL depth decreases towards the coast, the MABL flow becomes supercritical in a shallow-water sense. As supercritical shallow-water flow interacts with major headlands, expansion fans form, affecting both the wind speed and the MABL depth. The combination of CW96 and MAST data reveals significant differences between the flow along the coast and that far offshore. MABL winds are stronger near the coast whereas aloft the winds are weaker than offshore. The near-coast MABL is also better mixed. Turbulence increases towards the coast while the sensible-heat flux decreases and often changes sign, leading to stable stratification near the coast. A length-scale determining the across-coast influence of the expansion fans is defined from simple inviscid and irrotational shallow-water theory. Data from four days of the CW96 experiment show that this simple theory describes the low-level wind speed adequately. Surface-layer turbulence also scales with this simple length-scale, but the results are complicated by upwelling of cold water, giving rise to

  17. Rocket dust storms and detached dust layers in the Martian atmosphere

    Science.gov (United States)

    Spiga, Aymeric; Faure, Julien; Madeleine, Jean-Baptiste; Määttänen, Anni; Forget, François

    2013-04-01

    Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling that includes the transport of radiatively active dust to predict the evolution of a local dust storm monitored by OMEGA on board Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, rather than by latent heating as in moist convection on Earth. We propose to use the terminology "rocket dust storm," or conio-cumulonimbus, to describe those storms in which rapid and efficient vertical transport takes place, injecting dust particles at high altitudes in the Martian troposphere (30-50 km). Combined to horizontal transport by large-scale winds, rocket dust storms produce detached layers of dust reminiscent of those observed with Mars Global Surveyor and Mars Reconnaissance Orbiter. Since nighttime sedimentation is less efficient than daytime convective transport, and the detached dust layers can convect during the daytime, these layers can be stable for several days. The peak activity of rocket dust storms is expected in low-latitude regions at clear seasons (late northern winter to late northern summer), which accounts for the high-altitude tropical dust maxima unveiled by Mars Climate Sounder. Dust-driven deep convection has strong implications for the Martian dust cycle, thermal structure, atmospheric dynamics, cloud microphysics, chemistry, and robotic and human exploration.

  18. Applications of the Remotely Piloted Aircraft (RPA) 'MASC' in Atmospheric Boundary Layer Research

    Science.gov (United States)

    Wildmann, Norman; Platis, Andreas; Tupman, David-James; Bange, Jens

    2015-04-01

    The remotely piloted aircraft (RPA) MASC (Multipurpose Airborne Sensor Carrier) was developed at the University of Tübingen in cooperation with the University of Stuttgart, University of Applied Sciences Ostwestfalen-Lippe and 'ROKE-Modelle'. Its purpose is the investigation of thermodynamic processes in the atmospheric boundary layer (ABL), including observations of temperature, humidity and wind profiles, as well as the measurement of turbulent heat, moisture and momentum fluxes. The aircraft is electrically powered, has a maximum wingspan of 3.40~m and a total weight of 5-8~kg, depending on the battery- and payload. The standard meteorological payload consists of two temperature sensors, a humidity sensor, a flow probe, an inertial measurement unit and a GNSS. The sensors were optimized for the resolution of small-scale turbulence down to length scales in the sub-meter range. In normal operation, the aircraft is automatically controlled by the ROCS (Research Onboard Computer System) autopilot to be able to fly predefined paths at constant altitude and airspeed. Only take-off and landing are carried out by a human RC pilot. Since 2012, the system is operational and has since then been deployed in more than ten measurement campaigns, with more than 100 measurement flights. The fields of research that were tackled in these campaigns include sensor validation, fundamental boundary-layer research and wind-energy research. In 2014, for the first time, two MASC have been operated at the same time within a distance of a few kilometres, in order to investigate the wind field over an escarpment in the Swabian Alb. Furthermore, MASC was first deployed off-shore in October 2014, starting from the German island Heligoland in the North Sea, for the purpose of characterization of the marine boundary layer for offshore wind parks. Detailed descriptions of the experimental setup and first preliminary results will be presented.

  19. Application of the Remotely Piloted Aircraft (RPA) 'MASC' in Atmospheric Boundary Layer Research

    Science.gov (United States)

    Wildmann, Norman; Bange, Jens

    2014-05-01

    The remotely piloted aircraft (RPA) MASC (Multipurpose Airborne Sensor Carrier) was developed at the University of Tübingen in cooperation with the University of Stuttgart, University of Applied Sciences Ostwestfalen-Lippe and 'ROKE-Modelle'. Its purpose is the investigation of thermodynamic processes in the atmospheric boundary layer (ABL), including observations of temperature, humidity and wind profiles, as well as the measurement of turbulent heat, moisture and momentum fluxes. The aircraft is electrically powered, has a maximum wingspan of 3.40 m and a total weight of 5-8 kg, depending on battery- and payload. The standard meteorological payload consists of temperature sensors, a humidity sensor, a flow probe, an inertial measurement unit and a GNSS. In normal operation, the aircraft is automatically controlled by the ROCS (Research Onboard Computer System) autopilot to be able to fly predefined paths at constant altitude and airspeed. Since 2010 the system has been tested and improved intensively. In September 2012 first comparative tests could successfully be performed at the Lindenberg observatory of Germany's National Meteorological Service (DWD). In 2013, several campaigns were done with the system, including fundamental boundary layer research, wind energy meteorology and assistive measurements to aerosol investigations. The results of a series of morning transition experiments in summer 2013 will be presented to demonstrate the capabilities of the measurement system. On several convective days between May and September, vertical soundings were done to record the evolution of the ABL in the early morning, from about one hour after sunrise, until noon. In between the soundings, flight legs of up to 1 km length were performed to measure turbulent statistics and fluxes at a constant altitude. With the help of surface flux measurements of a sonic anemometer, methods of similarity theory could be applied to the RPA flux measurements to compare them to

  20. A methodology for the design and testing of atmospheric boundary layer models for wind energy applications

    Directory of Open Access Journals (Sweden)

    J. Sanz Rodrigo

    2017-02-01

    Full Text Available The GEWEX Atmospheric Boundary Layer Studies (GABLS 1, 2 and 3 are used to develop a methodology for the design and testing of Reynolds-averaged Navier–Stokes (RANS atmospheric boundary layer (ABL models for wind energy applications. The first two GABLS cases are based on idealized boundary conditions and are suitable for verification purposes by comparing with results from higher-fidelity models based on large-eddy simulation. Results from three single-column RANS models, of 1st, 1.5th and 2nd turbulence closure order, show high consistency in predicting the mean flow. The third GABLS case is suitable for the study of these ABL models under realistic forcing such that validation versus observations from the Cabauw meteorological tower are possible. The case consists on a diurnal cycle that leads to a nocturnal low-level jet and addresses fundamental questions related to the definition of the large-scale forcing, the interaction of the ABL with the surface and the evaluation of model results with observations. The simulations are evaluated in terms of surface-layer fluxes and wind energy quantities of interest: rotor equivalent wind speed, hub-height wind direction, wind speed shear and wind direction veer. The characterization of mesoscale forcing is based on spatially and temporally averaged momentum budget terms from Weather Research and Forecasting (WRF simulations. These mesoscale tendencies are used to drive single-column models, which were verified previously in the first two GABLS cases, to first demonstrate that they can produce similar wind profile characteristics to the WRF simulations even though the physics are more simplified. The added value of incorporating different forcing mechanisms into microscale models is quantified by systematically removing forcing terms in the momentum and heat equations. This mesoscale-to-microscale modeling approach is affected, to a large extent, by the input uncertainties of the mesoscale

  1. Massive-scale aircraft observations of giant sea-salt aerosol particle size distributions in atmospheric marine boundary layers

    Science.gov (United States)

    Jensen, J. B.

    2015-12-01

    iant sea-salt aerosol particles (dry radius, rd > 0.5 μm) occur nearly everywhere in the marine boundary layer and frequently above. This study presents observations of atmospheric sea-salt size distributions in the range 0.7 Chile and the 2011 ICE-T in the Caribbean. In each deployment, size distributions using hundreds of slides are used to relate fitted log-normal size distributions parameters to wind speed, altitude and other atmospheric conditions. The size distributions provide a unique observational set for initializing cloud models with coarse-mode aerosol particle observations for marine atmospheres.

  2. Atmospheric boundary layer dynamics in the Grenoble valley during strongly stable episodes

    Science.gov (United States)

    Staquet, C.; Largeron, Y.; Chollet, J.

    2013-12-01

    This paper addresses the dynamics of the atmospheric boundary layer in the Grenoble valley under strongly stable and polluted conditions. Numerical modeling is used for this purpose, along with available ground temperature measurements. Though the Grenoble valley is the most populated area in the Alps and is subjected to serious pollution episodes in winter, no such study had been conducted previously. We first analyzed ground temperature data within the valley at altitudes ranging between 220 m (valley bottom) and 1730 m during 5 months of winter 2006-2007. These data were provided by Meteo-France et by Air Rhône-Alpes, the air quality agency of Région Rhône-Alpes. Our purpose was to detect strongly stable episodes, these being defined by the episode-averaged vertical gradient of the absolute temperature being larger than the winter average during at least three days. Five episodes were selected from this criterion. We also analyzed air quality data recorded by Air Rhône-Alpes during the same winter to detect strongly polluted events for PM10 and found that the five episodes were also strongly polluted ones. To perform a more detailed analysis of these five episodes, we used the numerical code Meso-NH developed by Météo-France and the Laboratory of Aérology in Toulouse and simulated the dynamics of the atmospheric boundary layer during each episode. Four nested domains were used, the horizontal resolution of the innermost (and smallest) domain, containing the Grenoble valley, being 333 m; from comparison with the ground temperature data, we found that the vertical resolution above ground level had to be as low as 4 meters. As expected, the boundary layer dynamics in the numerical simulation for each episode was found to be decoupled from the (anticyclonic, weak) synoptic flow, consistent with the value of the Froude number associated with the inversion layer. These dynamics are controlled by thermal (mostly katabatic) winds flowing from the higher altitude

  3. An observational investigation of transitory turbulence in the atmospheric boundary layer

    Science.gov (United States)

    Jensen, Derek D.

    Within the atmospheric boundary layer (ABL), atmospheric fluid flow is in a constant state of transition in both time and space. Under calm conditions through the mid-daytime hours and over quasi-uniform terrain, the temporal and spatial evolution of the atmosphere is gradual. The structure and governing equations are well understood, allowing for numerical models to accurately forecast the evolution of the ABL. Under nocturnal conditions, the atmospheric processes are more complicated, yet numerical models still perform reasonably well. When changes in the state of the atmosphere occur abruptly, whether in time or space, the fidelity of most numerical weather models diminishes appreciably. This occurs because many of the simplifying assumptions intrinsic in most numerical models are no longer valid. The objective of this dissertation is to use observational data collected within such transitions to gain more insight into the mechanisms responsible for the evolution of the rapidly evolving ABL. First, near-surface turbulence data are used to study countergradient heat fluxes that occur through the evening transition. The countergradient heat flux may be produced by the sign change of the sensible heat flux preceding the sign change of the local temperature gradient and vice versa. The phenomenon is studied by considering the budget equations of both temperature and sensible heat flux. The behaviour of the countergradient heat flux is governed by the surface and subsurface characteristics. The duration of the countergradient flux may be prognosed by considering a ratio of terms in the heat flux budget equation evaluated during the mid- to late afternoon. Next, data collected over an arid shallow slope (2-4°) are used to study the structure and onset of katabatic flow through the evening transition. The katabatic onset, jet velocity and jet height all show a large degree of interdiurnal variability. The slope-aligned budgets of momentum and potential temperature are

  4. Convergence of Extreme Value Statistics in a Two-Layer Quasi-Geostrophic Atmospheric Model

    Directory of Open Access Journals (Sweden)

    Vera Melinda Gálfi

    2017-01-01

    Full Text Available We search for the signature of universal properties of extreme events, theoretically predicted for Axiom A flows, in a chaotic and high-dimensional dynamical system. We study the convergence of GEV (Generalized Extreme Value and GP (Generalized Pareto shape parameter estimates to the theoretical value, which is expressed in terms of the partial information dimensions of the attractor. We consider a two-layer quasi-geostrophic atmospheric model of the mid-latitudes, adopt two levels of forcing, and analyse the extremes of different types of physical observables (local energy, zonally averaged energy, and globally averaged energy. We find good agreement in the shape parameter estimates with the theory only in the case of more intense forcing, corresponding to a strong chaotic behaviour, for some observables (the local energy at every latitude. Due to the limited (though very large data size and to the presence of serial correlations, it is difficult to obtain robust statistics of extremes in the case of the other observables. In the case of weak forcing, which leads to weaker chaotic conditions with regime behaviour, we find, unsurprisingly, worse agreement with the theory developed for Axiom A flows.

  5. The formation of snow streamers in the turbulent atmosphere boundary layer

    Science.gov (United States)

    Huang, Ning; Wang, Zheng-Shi

    2016-12-01

    The drifting snow in the turbulent atmosphere boundary layer is an important type of aeolian multi-phase flow. Current theoretical and numerical studies of drifting snow mostly consider the flow field as steady wind velocity. Whereas, little is known about the effects of turbulent wind structures on saltating snow particles. In this paper, a 3-D drifting snow model based on Large Eddy Simulation is established, in which the trajectory of every snow grain is calculated and the coupling effect between wind field and snow particles is considered. The results indicate that the saltating snow particles are re-organized by the suction effect of high-speed rotating vortexes, which results in the local convergence of particle concentration, known as snow streamers. The turbulent wind leads to the spatial non-uniform of snow particles lifted by aerodynamic entrainment, but this does not affect the formation of snow streamers. Whereas the stochastic grain-bed interactions make a great contribution to the final shapes of snow streamers. Generally, snow streamers display a characteristic length about 0.5 m and a characteristic width of approximately 0.16 m, and their characteristic sizes are not sensitive to the wind speed. Compared to the typical sand streamer, snow streamer is slightly narrower and the occurrence of other complex streamer patterns is later than that of sand streamers due to the better follow performance of snow grains with air flow.

  6. Validation of the simpleFoam (RANS solver for the atmospheric boundary layer in complex terrain

    Directory of Open Access Journals (Sweden)

    Peralta C.

    2014-01-01

    Full Text Available We validate the simpleFoam (RANS solver in OpenFOAM (version 2.1.1 for simulating neutral atmospheric boundary layer flows in complex terrain. Initial and boundary conditions are given using Richards and Hoxey proposal [1]. In order to obtain stable simulation of the ABL, modified wall functions are used to set the near-wall boundary conditions, following Blocken et al remedial measures [2]. A structured grid is generated with the new library terrainBlockMesher [3,4], based on OpenFOAM's blockMesh native mesher. The new tool is capable of adding orographic features and the forest canopy. Additionally, the mesh can be refined in regions with complex orography. We study both the classical benchmark case of Askervein hill [5] and the more recent Bolund island data set [6]. Our purpose is two-folded: to validate the performance of OpenFOAM steady state solvers, and the suitability of the new meshing tool to generate high quality structured meshes, which will be used in the future for performing more computationally intensive LES simulations in complex terrain.

  7. Towards wafer-size graphene layers by atmospheric pressure graphitization of silicon carbide.

    Science.gov (United States)

    Emtsev, Konstantin V; Bostwick, Aaron; Horn, Karsten; Jobst, Johannes; Kellogg, Gary L; Ley, Lothar; McChesney, Jessica L; Ohta, Taisuke; Reshanov, Sergey A; Röhrl, Jonas; Rotenberg, Eli; Schmid, Andreas K; Waldmann, Daniel; Weber, Heiko B; Seyller, Thomas

    2009-03-01

    Graphene, a single monolayer of graphite, has recently attracted considerable interest owing to its novel magneto-transport properties, high carrier mobility and ballistic transport up to room temperature. It has the potential for technological applications as a successor of silicon in the post Moore's law era, as a single-molecule gas sensor, in spintronics, in quantum computing or as a terahertz oscillator. For such applications, uniform ordered growth of graphene on an insulating substrate is necessary. The growth of graphene on insulating silicon carbide (SiC) surfaces by high-temperature annealing in vacuum was previously proposed to open a route for large-scale production of graphene-based devices. However, vacuum decomposition of SiC yields graphene layers with small grains (30-200 nm; refs 14-16). Here, we show that the ex situ graphitization of Si-terminated SiC(0001) in an argon atmosphere of about 1 bar produces monolayer graphene films with much larger domain sizes than previously attainable. Raman spectroscopy and Hall measurements confirm the improved quality of the films thus obtained. High electronic mobilities were found, which reach mu=2,000 cm (2) V(-1) s(-1) at T=27 K. The new growth process introduced here establishes a method for the synthesis of graphene films on a technologically viable basis.

  8. Evaluation of Low-Cost Multi-Hole Probes for Atmospheric Boundary Layer Investigation

    Science.gov (United States)

    Azartash-Namin, Solmoz; Jacob, Jamey; Canter, Caleb; Bailey, Sean; Cloud-Map Team

    2017-11-01

    Low-cost multi-hole probes (MHPs) for atmospheric boundary layer (ABL) studies are investigated. Probes are designed using rapid prototyping methods through FDM, SLA, and other techniques for evaluation through calibration testing and comparison with probes manufactured through more traditional methods. Each probe is tested and validated to develop calibration curves and PIV is used to examine the flow field around the probe during both attached and separated conditions. Standard non-nulling calibration and data reduction methods were used showing performance characteristics of each probe. Impact of probe tip geometry and internal duct arrangements are examined. Multiple geometries, including hemispherical and pyramid, as well as multiple sizes are evaluated for both accuracy and sensitivity. Of the two primary geometric designs evaluated, the hemisphere 5HPs produced the most symmetric calibration curves with linearity between +/-25° . Further issues related to optimized probe designs, manufacturing quality consistency, and sensor development are discussed. A custom weather data sensor package has been developed for flight testing in ABL studies and preliminary results are presented. Supported in part by National Science Foundation Award Numbers 1351411 and 1539070.

  9. Experimental investigation on the wake interference among wind turbines sited in atmospheric boundary layer winds

    Science.gov (United States)

    Tian, W.; Ozbay, A.; Wang, X. D.; Hu, H.

    2017-08-01

    We examined experimentally the effects of incoming surface wind on the turbine wake and the wake interference among upstream and downstream wind turbines sited in atmospheric boundary layer (ABL) winds. The experiment was conducted in a large-scale ABL wind tunnel with scaled wind turbine models mounted in different incoming surface winds simulating the ABL winds over typical offshore/onshore wind farms. Power outputs and dynamic loadings acting on the turbine models and the wake flow characteristics behind the turbine models were quantified. The results revealed that the incoming surface winds significantly affect the turbine wake characteristics and wake interference between the upstream and downstream turbines. The velocity deficits in the turbine wakes recover faster in the incoming surface winds with relatively high turbulence levels. Variations of the power outputs and dynamic wind loadings acting on the downstream turbines sited in the wakes of upstream turbines are correlated well with the turbine wakes characteristics. At the same downstream locations, the downstream turbines have higher power outputs and experience greater static and fatigue loadings in the inflow with relatively high turbulence level, suggesting a smaller effect of wake interference for the turbines sited in onshore wind farms.

  10. Investigation of the atmospheric boundary layer characteristics on gust factor for the calculation of wind load

    Science.gov (United States)

    Ghanadi, Farzin; Emes, Matthew; Yu, Jeremy; Arjomandi, Maziar; Kelso, Richard

    2017-06-01

    Dynamic amplification and gust effects from turbulence can increase wind loads significantly over and above the static wind loads that have been used for heliostat design. This paper presents the results of analyzing the relationship between gust factor and turbulence intensity within the atmospheric boundary layer (ABL) based on the high fidelity measurements of wind velocity at the SLTEST facility in the Utah desert. Results showed that there are distinct characteristics of a low roughness ABL that deviate from semi-empirical relationships derived for open country and urban terrains with larger surface roughness heights. The analysis also indicated that gust factor is increased by 2.4% when lowering the gust period from 3s to 1s in the low roughness field experiment ABL, compared to a 3.6% increase in a suburban terrain at a 10m height. Although 3s gust periods are recommended in AS/NZS 1170.2 [1], comparison of gust factor data with a 1s gust period is recommended particularly in high roughness ABLs such as in urban areas, to ensure that buildings are adequately designed to withstand higher frequency gusts. This research proved the strength of the correlation between gust factor and turbulence intensity is dependent on the surface roughness height of the terrain. It is recommended that the coefficient in the previous semi-empirical equation must be adjusted to be fitted to the low roughness desert terrain in the field experiment ABL.

  11. Simulations of Vertical Axis Wind Turbine Farms in the Atmospheric Boundary Layer

    Science.gov (United States)

    Hezaveh, Seyed Hossein; Bou-Zeid, Elie; Lohry, Mark; Martinelli, Luigi

    2014-11-01

    Wind power is an abundant and clean source of energy that is increasingly being tapped to reduce the environmental footprint of anthropogenic activities. The vertical axis wind turbine (VAWT) technology is now being revisited due to some important advantages over horizontal axis wind turbines (HAWTS) that are particularly important for farms deployed offshore or in complex terrain. In this talk, we will present the implementation and testing of an actuator line model (ALM) for VAWTs in a large eddy simulation (LES) code for the atmospheric boundary layer, with the aim of optimizing large VAWT wind farm configurations. The force coefficients needed for the ALM are here obtained from blade resolving RANS simulations of individual turbines for each configuration. Comparison to various experimental results show that the model can very successfully reproduce observed wake characteristic. The influence of VAWT design parameters such as solidity, height to radius ratio, and tip speed ratio (TSR) on these wake characteristics, particularly the velocity deficit profile, is then investigated.

  12. Transfer of atmospheric matter through the euphotic layer in the northwestern Mediterranean: seasonal pattern and driving forces

    Science.gov (United States)

    Migon, Christophe; Sandroni, Valérie; Marty, Jean-Claude; Gasser, Beat; Miquel, Juan-Carlos

    The transfer of atmospheric particulate matter through the surface marine layer was studied by comparing atmospheric and marine fluxes. Time series were obtained from the coupling of a coastal atmospheric sampling station (Cap Ferrat, French Riviera) and a marine sampling site (DYFAMED site, central Ligurian Sea). Liquid phase traps were used for measuring total atmospheric fluxes and sediment traps deployed at 200 m depth for measuring marine fluxes. Fluxes of mass, aluminium, and soluble anthropogenic metals (Cd, Pb and Zn) were obtained from both these reservoirs. Physical and biological time series data acquired at the DYFAMED site also were used to describe a three-step seasonal transfer scenario: In summer and autumn, during the period of water stratification, marine fluxes are low and do not account for the transfer of lithogenic material, as revealed by low Al to mass flux ratios and high proportions of organic carbon at 200 m depth. Atmospheric material accumulates along the thermocline, while a series of physico-chemical processes lead to the formation of small (⩽150 μm) non-biogenic organic aggregates. In winter, the sinking of dense water that occurs in the Ligurian Sea is responsible for a rapid downward transfer of the lithogenic matter accumulated in the surface layer. The fact that soluble trace metals (e.g., cadmium) accumulated in the surface layer are only partially found in sediment traps may indicate that sorption processes play a minor role in the formation of organic aggregates, compared with coagulation processes. In spring, nutrients brought to surface waters by the winter vertical mixing allow phytoplanktonic blooms, and the transfer of atmospheric matter is then governed by the temporal variations of biological activity. The seasonal variability of the vertical transfer leads to the concept of seasonal variability of elemental residence times in the euphotic layer.

  13. Amendment to "Analytical Solution for the Convectively-Mixed Atmospheric Boundary Layer": Inclusion of Subsidence

    NARCIS (Netherlands)

    Ouwersloot, H.G.; Arellano, de J.V.G.

    2013-01-01

    In Ouwersloot and Vila-Guerau de Arellano (Boundary-Layer Meteorol. doi: 10. 1007/s10546-013-9816-z, 2013, this issue), the analytical solutions for the boundary-layer height and scalar evolutions are derived for the convective boundary layer, based on the prognostic equations of mixed-layer slab

  14. Interactions of the land-surface with the atmospheric boundary layer

    NARCIS (Netherlands)

    Ek, M.B.

    2005-01-01

    We study daytime land-atmosphere interaction using a one-dimensional (column) coupled land-surface - atmospheric boundary-Iayer (ABL) model and data sets gathered at Cabauw (1978, central Netherlands) and during the Hydrological and Atmospheric Pilot Experiment - Modélisation du Bilan Hydrique

  15. Transport and deposition of nitrogen oxides and ozone in the atmospheric surface layer

    Science.gov (United States)

    Li, Yongxian

    Tropospheric ozone is an important photochemical air pollutant, which increases respiratory-related diseases, decreases crop yields, and causes other environmental problems. This research has focused on the measurement of soil biogenic emissions of nitric oxide (NO), one of the precursors for ozone formation, from intensively managed soils in the Southeast US, and examined the transport and deposition of NOx (NO + NO2) and ozone in the atmospheric surface layer, and the effects of NO emissions and its chemical reactions on ozone flux and deposition to the earth's surface. Emissions of nitric oxide were measured from an intensively managed agricultural soil, in the lower coastal plain of North Carolina (near Plymouth, NC), using a dynamic chamber technique. Measurements of soil NO emissions in several crop canopies were conducted at four different sites in North Carolina during late spring and summer of 1994-1996. The turbulent fluxes of NO2 and O3 at 5 m and 10 m above the ground were measured using the eddy-correlation technique near Plymouth, NC during late spring of 1995 and summer of 1996, concurrent with measurements of soil NO emissions using the dynamic chamber system. Soil NO emission from within the corn field was high averaging approximately 35 ng N/m2/s during the measurement period of 1995. In another study, vertical measurements of ozone were made on a 610 m tall tower located 15 km Southeast of Raleigh, NC during the summers of 1993-1997, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. A strong correlation was observed between the nighttime and early morning ozone concentrations in the residual layer (CR) above the NBL and the maximum ground level concentration (C o max) the following afternoon. Based on this correlation, an empirical regression equation (Co max = 27.67*exp(0.016 CR)) was developed for predicting maximum ground level ozone

  16. Meteorological responses in the atmospheric boundary layer over southern England to the deep partial eclipse of 20 March 2015.

    Science.gov (United States)

    Burt, Stephen

    2016-09-28

    A wide range of surface and near-surface meteorological observations were made at the University of Reading's Atmospheric Observatory in central southern England (latitude 51.441° N, longitude 0.938° W, altitude 66 m above mean sea level) during the deep partial eclipse on the morning of 20 March 2015. Observations of temperature, humidity, radiation, wind speed and direction, and atmospheric pressure were made by computerized logging equipment at 1 Hz, supplemented by an automated cloud base recorder sampling at 1 min intervals and a high-resolution (approx. 10 m vertical interval) atmospheric sounding by radiosonde launched from the same location during the eclipse. Sources and details of each instrumental measurement are described briefly, followed by a summary of observed and derived measurements by meteorological parameter. Atmospheric boundary layer responses to the solar eclipse were muted owing to the heavily overcast conditions which prevailed at the observing location, but instrumental records of the event documented a large (approx. 80%) reduction in global solar radiation, a fall in air temperature of around 0.6°C, a decrease in cloud base height, and a slight increase in atmospheric stability during the eclipse. Changes in surface atmospheric moisture content and barometric pressure were largely insignificant during the event.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'. © 2016 The Author(s).

  17. Assessing State-of-the-Art Capabilities for Probing the Atmospheric Boundary Layer: The XPIA Field Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Lundquist, Julie K. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, and National Renewable Energy Laboratory, Golden, Colorado; Wilczak, James M. [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Ashton, Ryan [The University of Texas at Dallas, Dallas, Texas; Bianco, Laura [Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado; Brewer, W. Alan [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Choukulkar, Aditya [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Clifton, Andrew [National Renewable Energy Laboratory, Golden, Colorado; Debnath, Mithu [The University of Texas at Dallas, Dallas, Texas; Delgado, Ruben [University of Maryland, Baltimore County, Baltimore, Maryland; Friedrich, Katja [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Gunter, Scott [Texas Tech University, Lubbock, Texas; Hamidi, Armita [The University of Texas at Dallas, Dallas, Texas; Iungo, Giacomo Valerio [The University of Texas at Dallas, Dallas, Texas; Kaushik, Aleya [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Kosović, Branko [National Center for Atmospheric Research, Boulder, Colorado; Langan, Patrick [University of Maryland, Baltimore County, Baltimore, Maryland; Lass, Adam [University of Maryland, Baltimore County, Baltimore, Maryland; Lavin, Evan [University of Maryland, Baltimore County, Baltimore, Maryland; Lee, Joseph C. -Y. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; McCaffrey, Katherine L. [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Newsom, Rob K. [Pacific Northwest National Laboratory, Richland, Washington; Noone, David C. [College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, Oregon; Oncley, Steven P. [National Center for Atmospheric Research, Boulder, Colorado; Quelet, Paul T. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Sandberg, Scott P. [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Schroeder, John L. [Texas Tech University, Lubbock, Texas; Shaw, William J. [Pacific Northwest National Laboratory, Richland, Washington; Sparling, Lynn [University of Maryland, Baltimore County, Baltimore, Maryland; Martin, Clara St. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Pe, Alexandra St. [University of Maryland, Baltimore County, Baltimore, Maryland; Strobach, Edward [University of Maryland, Baltimore County, Baltimore, Maryland; Tay, Ken [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Vanderwende, Brian J. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado; Weickmann, Ann [National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder, Colorado; Wolfe, Daniel [Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado; Worsnop, Rochelle [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado

    2017-02-01

    The synthesis of new measurement technologies with advances in high performance computing provides an unprecedented opportunity to advance our understanding of the atmosphere, particularly with regard to the complex flows in the atmospheric boundary layer. To assess current measurement capabilities for quantifying features of atmospheric flow within wind farms, the U.S. Dept. of Energy sponsored the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign at the Boulder Atmospheric Observatory (BAO) in spring 2015. Herein, we summarize the XPIA field experiment design, highlight novel approaches to boundary-layer measurements, and quantify measurement uncertainties associated with these experimental methods. Line-of-sight velocities measured by scanning lidars and radars exhibit close agreement with tower measurements, despite differences in measurement volumes. Virtual towers of wind measurements, from multiple lidars or dual radars, also agree well with tower and profiling lidar measurements. Estimates of winds over volumes,conducted with rapid lidar scans, agree with those from scanning radars, enabling assessment of spatial variability. Microwave radiometers provide temperature profiles within and above the boundary layer with approximately the same uncertainty as operational remote sensing measurements. Using a motion platform, we assess motion-compensation algorithms for lidars to be mounted on offshore platforms. Finally, we highlight cases that could be useful for validation of large-eddy simulations or mesoscale numerical weather prediction, providing information on accessing the archived dataset. We conclude that modern remote Lundquist et al. XPIA BAMS Page 4 of 81 sensing systems provide a generational improvement in observational capabilities, enabling resolution of refined processes critical to understanding 61 inhomogeneous boundary-layer flows such as those found in wind farms.

  18. Forecasting of aerosol extinction of the sea and coastal atmosphere surface layer

    Science.gov (United States)

    Kaloshin, G. A.

    2010-04-01

    The focus of our study is the extinction and optical effects due to aerosol in a specific coastal region. The aerosol microphysical model of the marine and coastal atmosphere surface layer is considered. The model is made on the basis of the long-term experimental data received at researches of aerosol sizes distribution function (dN/dr) in the band particles sizes in 0.01 - 100 μk. The model is developed by present time for the band of heights is 0 - 25 m. Bands of wind speed is 3 - 18 km/s, sizes fetch is up to 120 km, RH = 40 - 98 %. Key feature of model is parameterization of amplitude and width of the modes as functions of fetch and wind speed. In the paper the dN/dr behavior depending at change meteorological parameters, heights above sea level, fetch (X), wind speed (U) and RH is show. On the basis of the developed model with usage of Mie theory for spheres the description of last version of developed code MaexPro (Marine Aerosol Extinction Profiles) for spectral profiles of aerosol extinction coefficients α(λ) calculations in the wavelength band, equal λ = 0.2 - 12 μm is presented. The received results are compared models NAN and ANAM. Also α(λ) profiles for various wind modes (combinations X and U) calculated by MaexPro code are given. The calculated spectrums of α(λ) profiles are compared with experimental data of α(λ) received by a transmission method in various geographical areas.

  19. Characterization of wake turbulence in a wind turbine array submerged in atmospheric boundary layer flow

    Science.gov (United States)

    Jha, Pankaj Kumar

    Wind energy is becoming one of the most significant sources of renewable energy. With its growing use, and social and political awareness, efforts are being made to harness it in the most efficient manner. However, a number of challenges preclude efficient and optimum operation of wind farms. Wind resource forecasting over a long operation window of a wind farm, development of wind farms over a complex terrain on-shore, and air/wave interaction off-shore all pose difficulties in materializing the goal of the efficient harnessing of wind energy. These difficulties are further amplified when wind turbine wakes interact directly with turbines located downstream and in adjacent rows in a turbulent atmospheric boundary layer (ABL). In the present study, an ABL solver is used to simulate different atmospheric stability states over a diurnal cycle. The effect of the turbines is modeled by using actuator methods, in particular the state-of-the-art actuator line method (ALM) and an improved ALM are used for the simulation of the turbine arrays. The two ALM approaches are used either with uniform inflow or are coupled with the ABL solver. In the latter case, a precursor simulation is first obtained and data saved at the inflow planes for the duration the turbines are anticipated to be simulated. The coupled ABL-ALM solver is then used to simulate the turbine arrays operating in atmospheric turbulence. A detailed accuracy assessment of the state-of-the-art ALM is performed by applying it to different rotors. A discrepancy regarding over-prediction of tip loads and an artificial tip correction is identified. A new proposed ALM* is developed and validated for the NREL Phase VI rotor. This is also applied to the NREL 5-MW turbine, and guidelines to obtain consistent results with ALM* are developed. Both the ALM approaches are then applied to study a turbine-turbine interaction problem consisting of two NREL 5-MW turbines. The simulations are performed for two ABL stability

  20. Laboratory simulations of the atmospheric mixed layer in flow over complex terrain

    Data.gov (United States)

    U.S. Environmental Protection Agency — A laboratory study of the influence of complex terrain on the interface between a well-mixed boundary layer and an elevated stratified layer was conducted in the...

  1. Variability in the summertime coastal marine atmospheric boundary‐layer off California, USA

    National Research Council Canada - National Science Library

    Ström, Linda; Tjernström, Michael

    2004-01-01

    An analysis of boundary‐layer structure and surface‐layer turbulence from measurements off the California coast is presented from data collected by research aircraft during two field experiments...

  2. Spatial Atmospheric Pressure Atomic Layer Deposition of Tin Oxide as an Impermeable Electron Extraction Layer for Perovskite Solar Cells with Enhanced Thermal Stability.

    Science.gov (United States)

    Hoffmann, Lukas; Brinkmann, Kai O; Malerczyk, Jessica; Rogalla, Detlef; Becker, Tim; Theirich, Detlef; Shutsko, Ivan; Görrn, Patrick; Riedl, Thomas

    2018-02-14

    Despite the notable success of hybrid halide perovskite-based solar cells, their long-term stability is still a key-issue. Aside from optimizing the photoactive perovskite, the cell design states a powerful lever to improve stability under various stress conditions. Dedicated electrically conductive diffusion barriers inside the cell stack, that counteract the ingress of moisture and prevent the migration of corrosive halogen species, can substantially improve ambient and thermal stability. Although atomic layer deposition (ALD) is excellently suited to prepare such functional layers, ALD suffers from the requirement of vacuum and only allows for a very limited throughput. Here, we demonstrate for the first time spatial ALD-grown SnO x at atmospheric pressure as impermeable electron extraction layers for perovskite solar cells. We achieve optical transmittance and electrical conductivity similar to those in SnO x grown by conventional vacuum-based ALD. A low deposition temperature of 80 °C and a high substrate speed of 2.4 m min -1 yield SnO x layers with a low water vapor transmission rate of ∼10 -4 gm -2 day -1 (at 60 °C/60% RH). Thereby, in perovskite solar cells, dense hybrid Al:ZnO/SnO x electron extraction layers are created that are the key for stable cell characteristics beyond 1000 h in ambient air and over 3000 h at 60 °C. Most notably, our work of introducing spatial ALD at atmospheric pressure paves the way to the future roll-to-roll manufacturing of stable perovskite solar cells.

  3. Atmospheric spatial atomic-layer-deposition of Zn(O, S) buffer layer for flexible Cu(In, Ga)Se2 solar cells: From lab-scale to large area roll to roll processing

    NARCIS (Netherlands)

    Frijters, C.H.; Bolt, P.J.; Poodt, P.W.G.; Knaapen, R.; Brink, J. van den; Ruth, M.; Bremaud, D.; Illiberi, A.

    2016-01-01

    In this manuscript we present the first successful application of a spatial atomic-layer-deposition process to thin film solar cells. Zn(O,S) has been grown by spatial atomic layer deposition (S-ALD) at atmospheric pressure and applied as buffer layer in rigid and flexible CIGS cells by a lab-scale

  4. Quantitative estimates of disturbances contributed by a megalopolis to the temperature field of the atmospheric boundary layer

    Science.gov (United States)

    Kadygrov, N. E.; Kruchenitskii, G. M.; Lykov, A. D.

    2007-02-01

    Seasonal and diurnal variations in the temperature of the atmospheric boundary layer (ABL) are analyzed, and the features of spatial and temporal variations in ABL temperature that are caused by the influence of a megalopolis are revealed. The gradients of air temperature for the megalopolis, its vicinity, and background conditions are compared. A multiplicative model of the seasonal diurnal variability of ABL temperature is constructed, and the relative frequencies of unstable ABL-temperature stratification are studied.

  5. Satellite Sounder Observations of Contrasting Tropospheric Moisture Transport Regimes: Saharan Air Layers, Hadley Cells, and Atmospheric Rivers

    Energy Technology Data Exchange (ETDEWEB)

    Nalli, Nicholas R.; Barnet, Christopher D.; Reale, Tony; Liu, Quanhua; Morris, Vernon R.; Spackman, J. Ryan; Joseph, Everette; Tan, Changyi; Sun, Bomin; Tilley, Frank; Leung, L. Ruby; Wolfe, Daniel

    2016-12-01

    This paper examines the performance of satellite sounder atmospheric vertical moisture proles (AVMP) under tropospheric conditions encompassing moisture contrasts driven by convection and advection transport mechanisms, specifically Atlantic Ocean Saharan air layers (SALs) and Pacific Ocean moisture conveyer belts (MCBs) commonly referred to as atmospheric rivers (ARs), both of these being mesoscale to synoptic meteorological phenomena within the vicinity of subtropical Hadley subsidence zones. Operational AVMP environmental data records retrieved from the Suomi National Polar-orbiting Partnership (SNPP) NOAA-Unique Combined Atmospheric Processing System (NUCAPS) are collocated with dedicated radiosonde observations (RAOBs) obtained from ocean-based intensive field campaigns; these RAOBs provide uniquely independent correlative truth data not assimilated into numerical weather prediction models for satellite sounder validation over open ocean. Using these marine-based data, we empirically assess the performance of the operational NUCAPS AVMP product for detecting and resolving these tropospheric moisture features over otherwise RAOB-sparse regions.

  6. Marine Atmospheric Boundary Layer Observations from GPS Occultation and CALIPSO over Subtropical Eastern Oceans

    Science.gov (United States)

    Xie, F.; Wu, D. L.; Wood, R.; Ao, C. O.; Mannucci, A.

    2012-12-01

    The highly reflective low clouds that are generally trapped below the shallow marine atmospheric boundary layer (MABL) inversion produce profound radiative cooling effects in the climate system. The low cloud feedback remains a primary cause of uncertainty in global climate model projections. Understanding how climate sensitivity is controlled by these low clouds remains one of the key challenges partly due to the lack of global observation of the low cloud morphology and MABL thermodynamic structures, such as the cloud height, thickness, cloud fraction and cloud top inversion strength, which are difficult to model and integrate into global climate/forecast simulations. High-resolution, self-calibrated Global Positioning System (GPS) radio occultation (RO) soundings provide a unique capability for MABL sensing in all-weather conditions. The thermal inversion along with a large moisture decrease across the MABL top leads to a large bending angle and a sharp refractivity gradient that can be precisely detected by the GPS RO measurements. On the other hand, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar offers cloud-top-height (CTH) measurements with superior resolution (60 m). In this study, we derive the MABL height climatology from Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) GPS RO observations over five selected regions in subtropical eastern oceans, which include the northeast and southeast Pacific and Atlantic as well as the southeast Indian Ocean off the coast of west Australia. The CTH climatology is also derived from CALIPSO lidar measurements. The CALIPSO CTH shows consistent features with the GPS thermal inversion height over stratocumulus region. However, a large discrepancy is found over the trade-cumulus region. A further comparison of the MABL height observations from GPS/CALIPSO with state-of-the-art global reanalyses, such as the ECMWF-ERA-interim, the NOAA Climate Forecast

  7. A comprehensive investigation on afternoon transition of the atmospheric boundary layer over a tropical rural site

    Science.gov (United States)

    Sandeep, A.; Rao, T. N.; Rao, S. V. B.

    2015-07-01

    The transitory nature of the atmospheric boundary layer (ABL) a few hours before and after the time of sunset has been studied comprehensively over a tropical station, Gadanki (13.45° N, 79.18° E), using a suite of in situ and remote sensing devices. This study addresses the following fundamental and important issues related to the afternoon transition (AT): which state variable first identifies the AT? Which variable best identifies the AT? Does the start time of the AT vary with season and height? If so, which physical mechanism is responsible for the observed height variation in the start time of the transition? At the surface, the transition is first seen in temperature (T) and wind variance (σ2WS), ~ 100 min prior to the time of local sunset, then in the vertical temperature gradient and finally in water vapor mixing ratio variations. Aloft, both signal-to-noise ratio (SNR) and spectral width (σ) show the AT nearly at the same time. The T at the surface and SNR aloft are found to be the best indicators of transition. Their distributions for the start time of the AT with reference to time of sunset are narrow and consistent in both total and seasonal plots. The start time of the transition shows some seasonal variation, with delayed transitions occurring mostly in the rainy and humid season of the northeast monsoon. Interestingly, in contrast to the general perception, the signature of the transition is first seen in the profiler data, then in the sodar data, and finally in the surface data. This suggests that the transition follows a top-to-bottom evolution. It indicates that other processes, like entrainment, could also play a role in altering the structure of the ABL during the AT, when the sensible heat flux decreases progressively. These mechanisms are quantified using a unique high-resolution data set to understand their variation in light of the intriguing height dependency of the start time of the AT.

  8. Dynamics of Atmospheric Boundary Layers: Large-Eddy Simulations and Reduced Analytical Models

    Science.gov (United States)

    Momen, Mostafa

    Real-world atmospheric and oceanic boundary layers (ABL) involve many inherent complexities, the understanding and modeling of which manifestly exceeds our current capabilities. Previous studies largely focused on the "textbook ABL", which is (quasi) steady and barotropic. However, it is evident that the "real-world ABL", even over flat terrain, rarely meets such simplifying assumptions. The present thesis aims to illustrate and model four complicating features of ABLs that have been overlooked thus far despite their ubiquity: 1) unsteady pressure gradients in neutral ABLs (Chapters 2 and 3), 2) interacting effects of unsteady pressure gradients and static stability in diabatic ABLs (Chapter 4), 3) time-variable buoyancy fluxes (Chapter 5) , and 4) impacts of baroclinicity in neutral and diabatic ABLs (Chapter 6). State-of-the-art large-eddy simulations will be used as a tool to explain the underlying physics and to validate analytical models we develop for these features. Chapter 2 focuses on the turbulence equilibrium: when the forcing time scale is comparable to the turbulence time scale, the turbulence is shown to be out of equilibrium, and the velocity profiles depart from the log-law; However, for longer, and surprisingly for shorter forcing times, quasi-equilibrium is maintained. In Chapter 3, a reduced analytical model, based on the Navier-Stokes equations, will be introduced and shown to be analogous to a damped oscillator where inertial, Coriolis, and friction forces mirror the mass, spring, and damper, respectively. When a steady buoyancy (stable or unstable) is superposed on the unsteady pressure gradient, the same model structure can be maintained, but the damping term, corresponding to friction forces and vertical coupling, needs to account for stability. However, for the reverse case with variable buoyancy flux and stability, the model needs to be extended to allow time-variable damper coefficient. These extensions of the analytical model are

  9. Advances and limitations of atmospheric boundary layer observations with GPS occultation over southeast Pacific Ocean

    Directory of Open Access Journals (Sweden)

    F. Xie

    2012-01-01

    Full Text Available The typical atmospheric boundary layer (ABL over the southeast (SE Pacific Ocean is featured with a strong temperature inversion and a sharp moisture gradient across the ABL top. The strong moisture and temperature gradients result in a sharp refractivity gradient that can be precisely detected by the Global Positioning System (GPS radio occultation (RO measurements. In this paper, the Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC GPS RO soundings, radiosondes and the high-resolution ECMWF analysis over the SE Pacific are analyzed. COSMIC RO is able to detect a wide range of ABL height variations (1–2 km as observed from the radiosondes. However, the ECMWF analysis systematically underestimates the ABL heights. The sharp refractivity gradient at the ABL top frequently exceeds the critical refraction (e.g., −157 N-unit km−1 and becomes the so-called ducting condition, which results in a systematic RO refractivity bias (or called N-bias inside the ABL. Simulation study based on radiosonde profiles reveals the magnitudes of the N-biases are vertical resolution dependent. The $N$-bias is also the primary cause of the systematically smaller refractivity gradient (rarely exceeding −110 N-unit km−1 at the ABL top from RO measurement. However, the N-bias seems not affect the ABL height detection. Instead, the very large RO bending angle and the sharp refractivity gradient due to ducting allow reliable detection of the ABL height from GPS RO. The seasonal mean climatology of ABL heights derived from a nine-month composite of COSMIC RO soundings over the SE Pacific reveals significant differences from the ECMWF analysis. Both show an increase of ABL height from the shallow stratocumulus near the coast to a much higher trade wind inversion further off the coast. However, COSMIC RO shows an overall deeper ABL and reveals different locations of the minimum and maximum ABL

  10. Influence of the nucleation layer annealing atmosphere on the resistivity of GaN grown by metalorganic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Weike, E-mail: luowk688@163.com; Li, Liang; Li, Zhonghui; Dong, Xun; Peng, Daqing; Zhang, Dongguo; Xu, Xiaojun

    2015-06-05

    Graphical abstract: LT-PL spectra of GaN samples A, B and C with sheet resistance of 1.1 × 10{sup 4} Ω/sq, 5.5 × 10{sup 4} Ω/sq and 1.0 × 10{sup 8} Ω/sq, respectively. - Highlights: • HR-GaN was fabricated by optimizing the nucleation layer annealing (NL) atmosphere. • The morphology of NLs annealed in different atmosphere has been investigated. • The resistance of GaN increased with density of edge type threading dislocations. • The PL results indicate that the HR-GaN is achieved due to the compensation of acceptor states. - Abstract: High-resistance (HR) GaN with sheet resistance of 1.0 × 10{sup 8} Ω/sq was grown on sapphire substrates using metal organic chemical vapor deposition. Sheet resistance of the GaN film increases 4 orders of magnitude by changing the nucleation layer (NL) annealing atmosphere from H{sub 2} to N{sub 2}. It is observed that the morphology of the NLs strongly depends on the annealing atmosphere. The analysis results based on high-resolution X-ray diffraction (HR-XRD) and etch pit density (EPD) measurements demonstrate that the density of edge-type threading dislocations increases with the proportion of the N{sub 2} in the annealing atmosphere. Photoluminescence (PL) spectra is employed to analyze the optical properties of GaN films. The XRD and PL results indicate the primary compensating mechanism is due to acceptor levels introduced by the increase in edge-type threading dislocations density. It is concluded that the annealing atmosphere of the NL controls sizes and densities of the nucleation islands, which affect electrical properties of GaN epitaxial films through changing the ratio of edge to screw/mixed-type threading dislocations.

  11. Non-steady dynamics of atmospheric turbulence interaction with wind turbine loadings through blade-boundary-layer-resolved CFD

    Science.gov (United States)

    Vijayakumar, Ganesh

    Modern commercial megawatt-scale wind turbines occupy the lower 15-20% of the atmospheric boundary layer (ABL), the atmospheric surface layer (ASL). The current trend of increasing wind turbine diameter and hub height increases the interaction of the wind turbines with the upper ASL which contains spatio-temporal velocity variations over a wide range of length and time scales. Our interest is the interaction of the wind turbine with the energetic integral-scale eddies, since these cause the largest temporal variations in blade loadings. The rotation of a wind turbine blade through the ABL causes fluctuations in the local velocity magnitude and angle of attack at different sections along the blade. The blade boundary layer responds to these fluctuations and in turn causes temporal transients in local sectional loads and integrated blade and shaft bending moments. While the integral scales of the atmospheric boundary layer are ˜ O(10--100m) in the horizontal with advection time scales of order tens of seconds, the viscous surface layer of the blade boundary layer is ˜ O(10 -- 100 mum) with time scales of order milliseconds. Thus, the response of wind turbine blade loadings to atmospheric turbulence is the result of the interaction between two turbulence dynamical systems at extremely disparate ranges of length and time scales. A deeper understanding of this interaction can impact future approaches to improve the reliability of wind turbines in wind farms, and can underlie future improvements. My thesis centers on the development of a computational framework to simulate the interaction between the atmospheric and wind turbine blade turbulence dynamical systems using a two step one-way coupled approach. Pseudo-spectral large eddy simulation (LES) is used to generate a true (equilibrium) atmospheric boundary layer over a flat land with specified surface roughness and heating consistent with the stability state of the daytime lower troposphere. Using the data from the

  12. The Deep Atmospheric Boundary Layer and Its Significance to the Stratosphere and Troposphere Exchange over the Tibetan Plateau

    Science.gov (United States)

    Chen, Xuelong; Añel, Juan A.; Su, Zhongbo; de la Torre, Laura; Kelder, Hennie; van Peet, Jacob; Ma, Yaoming

    2013-01-01

    In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was measured during a regional radiosonde observation campaign in 2008 and found to be deeper than indicated by previously measurements. Results indicate that during fair weather conditions on winter days, the top of the mixed layers can be up to 5 km above the ground (9.4 km above sea level). Measurements also show that the depth of the ABL is quite distinct for three different periods (winter, monsoon-onset, and monsoon seasons). Turbulence at the top of a deep mixing layer can rise up to the upper troposphere. As a consequence, as confirmed by trajectory analysis, interaction occurs between deep ABLs and the low tropopause during winter over the Tibetan Plateau. PMID:23451108

  13. Radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer and its feedback on the haze formation

    Science.gov (United States)

    Wei, Chao; Su, Hang; Cheng, Yafang

    2016-04-01

    Planetary boundary layer (PBL) plays a key role in air pollution dispersion and influences day-to-day air quality. Some studies suggest that high aerosol loadings during severe haze events may modify PBL dynamics by radiative effects and hence enhance the development of haze. This study mainly investigates the radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer by conducting simulations with Weather Research and Forecasting single-column model (WRF-SCM). We find that high aerosol loading in PBL depressed boundary layer height (PBLH). But the magnitude of the changes of PBLH after adding aerosol loadings in our simulations are small and can't explain extreme high aerosol concentrations observed. We also investigate the impacts of the initial temperature and moisture profiles on the evolution of PBL. Our studies show that the impact of the vertical profile of moisture is comparable with aerosol effects.

  14. Rough-to-smooth transition of an equilibrium neutral constant stress layer. [atmospheric flow over rough terrain

    Science.gov (United States)

    Logan, E., Jr.; Fichtl, G. H.

    1975-01-01

    A model is proposed for low-level atmospheric flows over terrains of changing roughness length, such as those found at the windward end of landing strips adjoining rough terrain. The proposed model is used to develop a prediction technique for calculating transition wind and shear-stress profiles in the region following surface roughness discontinuity. The model for the transition region comprises two layers: a logarithmic layer and a buffer layer. The flow is assumed to be steady, two-dimensional, and incompressible, with neutral hydrostatic stability. A diagram is presented for a typical wind profile in the transition region, obtained from the logarithmic and velocity defect profiles using shear stress calculated by relevant equations.

  15. Scaling properties of velocity and temperature spectra above the surface friction layer in a convective atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    K. G. McNaughton

    2007-06-01

    Full Text Available We report velocity and temperature spectra measured at nine levels from 1.42 meters up to 25.7 m over a smooth playa in Western Utah. Data are from highly convective conditions when the magnitude of the Obukhov length (our proxy for the depth of the surface friction layer was less than 2 m. Our results are somewhat similar to the results reported from the Minnesota experiment of Kaimal et al. (1976, but show significant differences in detail. Our velocity spectra show no evidence of buoyant production of kinetic energy at at the scale of the thermal structures. We interpret our velocity spectra to be the result of outer eddies interacting with the ground, not "local free convection".

    We observe that velocity spectra represent the spectral distribution of the kinetic energy of the turbulence, so we use energy scales based on total turbulence energy in the convective boundary layer (CBL to collapse our spectra. For the horizontal velocity spectra this scale is (zi εo2/3, where zi is inversion height and εo is the dissipation rate in the bulk CBL. This scale functionally replaces the Deardorff convective velocity scale. Vertical motions are blocked by the ground, so the outer eddies most effective in creating vertical motions come from the inertial subrange of the outer turbulence. We deduce that the appropriate scale for the peak region of the vertical velocity spectra is (z εo2/3 where z is height above ground. Deviations from perfect spectral collapse under these scalings at large and small wavenumbers are explained in terms of the energy transport and the eddy structures of the flow.

    We find that the peaks of the temperature spectra collapse when wavenumbers are scaled using (z1/2 zi1/2. That is, the lengths of the thermal structures depend on both the lengths of the

  16. Observations of atmospheric trace gases by MAX-DOAS in the coastal boundary layer over Jiaozhou Bay

    Science.gov (United States)

    Li, Xianxin; Wang, Zhangjun; Meng, Xiangqian; Zhou, Haijin; Du, Libin; Qu, Junle; Chen, Chao; An, Quan; Wu, Chengxuan; Wang, Xiufen

    2014-11-01

    Atmospheric trace gases exist in the atmosphere of the earth rarely. But the atmospheric trace gases play an important role in the global atmospheric environment and ecological balance by participating in the global atmospheric cycle. And many environmental problems are caused by the atmospheric trace gases such as photochemical smog, acid rain, greenhouse effect, ozone depletion, etc. So observations of atmospheric trace gases become very important. Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) developed recently is a kind of promising passive remote sensing technology which can utilize scattered sunlight received from multiple viewing directions to derive vertical column density of lower tropospheric trace gases like ozone, sulfur dioxide and nitrogen dioxide. It has advantages of simple structure, stable running, passive remote sensing and real-time online monitoring automatically. A MAX-DOAS has been developed at Shandong Academy of Sciences Institute of Oceanographic Instrumentation (SDIOI) for remote measurements of lower tropospheric trace gases (NO2, SO2, and O3). In this paper, we mainly introduce the stucture of the instrument, calibration and results. Detailed performance analysis and calibration of the instrument were made at Qingdao. We present the results of NO2, SO2 and O3 vertical column density measured in the coastal boundary layer over Jiaozhou Bay. The diurnal variation and the daily average value comparison of vertical column density during a long-trem observation are presented. The vertical column density of NO2 and SO2 measured during Qingdao oil pipeline explosion on November 22, 2013 by MAX-DOAS is also presented. The vertical column density of NO2 reached to a high value after the explosion. Finally, the following job and the outlook for future possible improvements are given. Experimental calibration and results show that the developed MAX-DOAS system is reliable and credible.

  17. Climatological perspectives of air transport from atmospheric boundary layer to tropopause layer over Asian monsoon regions during boreal summer inferred from Lagrangian approach

    Science.gov (United States)

    Chen, B.; Xu, X. D.; Yang, S.; Zhao, T. L.

    2012-07-01

    The Asian Summer Monsoon (ASM) region has been recognized as a key region that plays a vital role in troposphere-to-stratosphere transport (TST), which can significant impact the budget of global atmospheric constituents and climate change. However, the details of transport from the boundary layer (BL) to tropopause layer (TL) over these regions, particularly from a climatological perspective, remain an issue of uncertainty. In this study, we present the climatological properties of BL-to-TL transport over the ASM region during boreal summer season (June-July-August) from 2001 to 2009. A comprehensive tracking analysis is conducted based on a large ensemble of TST-trajectories departing from the atmospheric BL and arriving at TL. Driven by the winds fields from NCEP/NCAR Global Forecast System, all the TST-trajectories are selected from the high resolution datasets generated by the Lagrangian particle transport model FLEXPART using a domain-filling technique. Three key atmospheric boundary layer sources for BL-to-TL transport are identified with their contributions: (i) 38% from the region between tropical Western Pacific region and South China Seas (WP) (ii) 21% from Bay of Bengal and South Asian subcontinent (BOB), and (iii) 12% from the Tibetan Plateau, which includes the South Slope of the Himalayas (TIB). Controlled by the different patterns of atmospheric circulation, the air masses originated from these three source regions are transported along the different tracks into the TL. The spatial distributions of three source regions keep similarly from year to year. The timescales of transport from BL to TL by the large-scale ascents r-range from 1 to 7 weeks contributing up to 60-70% of the overall TST, whereas the transport governed by the deep convection overshooting become faster on a timescales of 1-2 days with the contributions of 20-30%. These results provide clear policy implications for the control of very short lived substances, especially for the

  18. Lidar characterization of the Arctic atmosphere during ASTAR 2007: four cases studies of boundary layer, mixed-phase and multi-layer clouds

    Directory of Open Access Journals (Sweden)

    A. Lampert

    2010-03-01

    Full Text Available During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR, which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar and with an airborne elastic lidar. In the time period of the ASTAR 2007 campaign, an increase in low-level cloud cover (cloud tops below 2.5 km from 51% to 65% was observed above Ny-Ålesund. Four different case studies of lidar cloud observations are analyzed: With the ground-based Raman lidar, a layer of spherical particles was observed at an altitude of 2 km after the dissolution of a cloud. The layer probably consisted of small hydrated aerosol (radius of 280 nm with a high number concentration (around 300 cm−3 at low temperatures (−30 °C. Observations of a boundary layer mixed-phase cloud by airborne lidar and concurrent airborne in situ and spectral solar radiation sensors revealed the localized process of total glaciation at the boundary of different air masses. In the free troposphere, a cloud composed of various ice layers with very different optical properties was detected by the Raman lidar, suggesting large differences of ice crystal size, shape and habit. Further, a mixed-phase double layer cloud was observed by airborne lidar in the free troposphere. Local orography influenced the evolution of this cloud. The four case studies revealed relations of cloud properties and specific atmospheric conditions, which we plan to use as the base for numerical simulations of these clouds.

  19. Laboratory simulations of the atmospheric mixed-layer in flow over complex topography

    Science.gov (United States)

    Perry, Steven G.; Snyder, William H.

    2017-02-01

    A laboratory study of the influence of complex terrain on the interface between a well-mixed boundary layer and an elevated stratified layer was conducted in the towing-tank facility of the U.S. Environmental Protection Agency. The height of the mixed layer in the daytime boundary layer can have a strong influence on the concentration of pollutants within this layer. Deflections of streamlines at the height of the interface are primarily a function of hill Froude number (Fr), the ratio of mixed-layer height (zi) to terrain height (h), and the crosswind dimension of the terrain. The magnitude of the deflections increases as Fr increases and zi/h decreases. For mixing-height streamlines that are initially below the terrain top, the response is linear with Fr; for those initially above the terrain feature the response to Fr is more complex. Once Fr exceeds about 2, the terrain-related response of the mixed layer interface decreases somewhat with increasing Fr (toward more neutral flow). Deflections are also shown to increase as the crosswind dimensions of the terrain increase. Comparisons with numerical modeling, limited field data, and other laboratory measurements reported in the literature are favorable. Additionally, visual observations of dye streamers suggest that the flow structure exhibited for our elevated inversions passing over three dimensional hills is similar to that reported in the literature for continuously stratified flow over two-dimensional hills.

  20. Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

    Directory of Open Access Journals (Sweden)

    L. P. Golobokova

    2016-01-01

    Full Text Available Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE, namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3 and Mirny (0,50 ág / m3. The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1. It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of

  1. ALADINA - an unmanned research aircraft for observing vertical and horizontal distributions of ultrafine particles within the atmospheric boundary layer

    Science.gov (United States)

    Altstädter, B.; Platis, A.; Wehner, B.; Scholtz, A.; Wildmann, N.; Hermann, M.; Käthner, R.; Baars, H.; Bange, J.; Lampert, A.

    2015-04-01

    This paper presents the unmanned research aircraft Carolo P360 "ALADINA" (Application of Light-weight Aircraft for Detecting IN situ Aerosol) for investigating the horizontal and vertical distribution of ultrafine particles in the atmospheric boundary layer (ABL). It has a wingspan of 3.6 m, a maximum take-off weight of 25 kg and is equipped with aerosol instrumentation and meteorological sensors. A first application of the system, together with the unmanned research aircraft MASC (Multi-Purpose Airborne Carrier) of the Eberhard Karls University of Tübingen (EKUT), is described. As small payload for ALADINA, two condensation particle counters (CPC) and one optical particle counter (OPC) were miniaturised by re-arranging the vital parts and composing them in a space-saving way in the front compartment of the airframe. The CPCs are improved concerning the lower detection threshold and the response time to less than 1.3 s. Each system was characterised in the laboratory and calibrated with test aerosols. The CPCs are operated in this study with two different lower detection threshold diameters of 11 and 18 nm. The amount of ultrafine particles, which is an indicator for new particle formation, is derived from the difference in number concentrations of the two CPCs (ΔN). Turbulence and thermodynamic structure of the boundary layer are described by measurements of fast meteorological sensors that are mounted at the aircraft nose. A first demonstration of ALADINA and a feasibility study were conducted in Melpitz near Leipzig, Germany, at the Global Atmosphere Watch (GAW) station of the Leibniz Institute for Tropospheric Research (TROPOS) on 2 days in October 2013. There, various ground-based instruments are installed for long-term atmospheric monitoring. The ground-based infrastructure provides valuable additional background information to embed the flights in the continuous atmospheric context and is used for validation of the airborne results. The development of the

  2. Inner Structure of Atmospheric Inversion Layers over Haifa Bay in the Eastern Mediterranean

    Science.gov (United States)

    Haikin, N.; Galanti, E.; Reisin, T. G.; Mahrer, Y.; Alpert, P.

    2015-09-01

    Capping inversions act as barriers to the vertical diffusion of pollutants, occasionally leading to significant low-level air pollution episodes in the lower troposphere. Here, we conducted two summer campaigns where global positioning system radiosondes were operated in Haifa Bay on the eastern Mediterranean coast, a region of steep terrain with significant pollution. The campaigns provided unique high resolution measurements related to capping inversions. It was found that the classical definition of a capping inversion was insufficient for an explicit identification of a layer; hence additional criteria are required for a complete spatial analysis of inversion evolution. Based on the vertical temperature derivative, an inner fine structure of inversion layers was explored, and was then used to track inversion layers spatially and to investigate their evolution. The exploration of the inner structure of inversion layers revealed five major patterns: symmetric peak, asymmetric peak, double peak, flat peak, and the zig-zag pattern. We found that the symmetric peak is related to the strongest inversions, double peak inversions tended to break apart into two layers, and the zig-zag pattern was related to the weakest inversions. Employing this classification is suggested for assistance in following the evolution of inversion layers.

  3. Thin-layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemica lionization

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikova, Olga S [ORNL; Van Berkel, Gary J [ORNL

    2010-01-01

    An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high-performance thin-layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read-out resolution, detection limits, and surface type are discussed.

  4. Improving Wind Predictions in the Marine Atmospheric Boundary Layer through Parameter Estimation in a Single-Column Model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jared A.; Hacker, Joshua P.; Delle Monache, Luca; Kosović, Branko; Clifton, Andrew; Vandenberghe, Francois; Rodrigo, Javier Sanz

    2016-12-14

    A current barrier to greater deployment of offshore wind turbines is the poor quality of numerical weather prediction model wind and turbulence forecasts over open ocean. The bulk of development for atmospheric boundary layer (ABL) parameterization schemes has focused on land, partly due to a scarcity of observations over ocean. The 100-m FINO1 tower in the North Sea is one of the few sources worldwide of atmospheric profile observations from the sea surface to turbine hub height. These observations are crucial to developing a better understanding and modeling of physical processes in the marine ABL. In this study, we use the WRF single column model (SCM), coupled with an ensemble Kalman filter from the Data Assimilation Research Testbed (DART), to create 100-member ensembles at the FINO1 location. The goal of this study is to determine the extent to which model parameter estimation can improve offshore wind forecasts.

  5. A bulk similarity approach in the atmospheric boundary layer using radiometric skin temperature to determine regional surface fluxes

    Science.gov (United States)

    Brutsaert, Wilfried; Sugita, Michiaki

    1991-01-01

    Profiles of wind velocity and temperature in the outer region of the atmospheric boundary layer (ABL) were used together with surface temperature measurements, to determine regional shear stress and sensible heat flux by means of transfer parameterizations on the basis of bulk similarity. The profiles were measured by means of radiosondes and the surface temperatures by infrared radiation thermometry over hilly prairie terrain in northeastern Kansas during the First ISLSCP Field Experiment (FIFE). In the analysis, the needed similarity functions were determined and tested.

  6. The impact of dynamic processes on chemistry in atmospheric boundary layers over tropical and boreal forest

    NARCIS (Netherlands)

    Ouwersloot, H.G.

    2013-01-01

    Improving our knowledge of the atmospheric processes that drive climate and air quality is very relevant for society. The application of this knowledge enables us to predict and mitigate the effects of human induced perturbations to our environment. Key factors in the current and future climate

  7. The structure of the atmospheric surface layer subject to local advection

    NARCIS (Netherlands)

    Bink, N.J.

    1996-01-01


    For many applications in agriculture, hydrology and meteorology simple methods are needed to determine the surface-atmosphere exchange of momentum, heat and water vapour, i.e to determine the fluxes of momentum, heat and water vapour. Most methods to calculate these

  8. SIMULATION OF SUMMER-TIME DIURNAL BACTERIAL DYNAMICS IN THE ATMOSPHERIC SURFACE LAYER

    Science.gov (United States)

    A model was prepared to simulate the observed concentration dynamics of culturable bacteria in the diurnal summer atmosphere at a Willamette River Valley, Oregon location. The meteorological and bacterial mechanisms included in a dynamic null-dimensional model with one-second tim...

  9. Modeling the Effects of Aircraft Emissions on Atmospheric Photochemistry Using Layered Plume Dynamics

    Science.gov (United States)

    Cameron, M. A.; Jacobson, M. Z.; Naiman, A. D.; Lele, S. K.

    2012-12-01

    Aviation is an expanding industry, experiencing continued growth and playing an increasingly noticed role in upper tropospheric/lower stratospheric composition. Nitrogen oxides and other gas-phase emissions from aircraft react to affect ozone photochemistry. This research investigates the effects of treating aircraft gas-phase chemistry within an expanding layered plume versus at the grid scale. SMVGEAR II, a sparse-matrix, vectorized Gear-type solver for ordinary differential equations, is used to solve chemical equations at both the grid scale and subgrid scale. A Subgrid Plume Model (SPM) is used to advance the expanding plume, accounting for wind shear and diffusion. Simulations suggest that using a layered plume approach results in noticeably different final NOx concentrations, demonstrating the importance of these plume dynamics in predicting the effects of aircraft on ozone concentrations. Results showing the effects of a layered plume, single plume, and no plume on ozone after several hours will be presented.

  10. Modelization of a large wind farm, considering the modification of the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, A.; Gomez-Elvira, R. [Univ. Politecnica de Madrid, Mecanica de Fluidos, E.T.S.I. Industriales, Madrid (Spain); Frandsen, S.; Larsen, S.E. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    A method is presented to adapt existing models of wind farms to very large ones that may affect the whole planetary boundary layer. An internal boundary layer is considered that starts developing at the leading edge of the farm until it reaches, sufficiently far downstream, the top of the planetary boundary layer, and a new equilibrium region is reached. The wind farm is simulated by an artificial roughness that is function of the turbine spacing, drag and height. From this model the flow conditions are calculated at a certain reference height and then are used as boundary conditions for a numerical code used to model a wind farm. Three-dimensional effects are considered by applying appropriate conditions at the sides of the farm. Calculations are carried out to estimate the energy production in large wind farms, and it is found that additional losses due to modification of the planetary boundary layer may be of importance for wind farms of size larger than about 100 km. (au)

  11. Stable atmospheric boundary-layer experiment in Spain (SABLES 98): A report

    DEFF Research Database (Denmark)

    Cuxart, J.; Yague, C.; Morales, G.

    2000-01-01

    boundary layer (SBL). Instrumentation deployed on two meteorological masts (of heights 10 m and 100 m) included five sonic anemometers, 15 thermocouples, five cup anemometers and three propeller anemometers, humidity sensors and radiometers. A Sensitron mini-sodar and a tethered balloon were also operated...

  12. A multi - layer land surface energy budget model for implicit coupling with global atmospheric simulations

    NARCIS (Netherlands)

    Ryder, J.; Polcher, J.; Peylin, P.; Ottlé, C.; Chen, Y; van Gorsel, E.; Haverd, V.; McGrath, M.J.; Naudts, K.; Otto, J.; Valade, A; Luyssaert, S

    2014-01-01

    See, stats, and : https : / / www . researchgate . net / publication / 276534648 A - layer for simulations Article DOI : 10 . 5194 / gmdd - 7 - 8649 - 2014 CITATIONS 9 READS 155 12 , including : Some : land Master Jan French 193 , 481 SEE Eva Australian 98 , 225 SEE Vanessa The 85 SEE Juliane

  13. A Simple Model for the Vertical Transport of Reactive Species in the Convective Atmospheric Boundary Layer

    DEFF Research Database (Denmark)

    Kristensen, Leif; Lenschow, Donald H.; Gurarie, David

    2010-01-01

    We have developed a simple, steady-state, one-dimensional second-order closure model to obtain continuous profiles of turbulent fluxes and mean concentrations of non-conserved scalars in a convective boundary layer without shear. As a basic tool we first set up a model for conserved species with ...

  14. Atomic layer deposition of platinum clusters on titania nanoparticles at atmospheric pressure

    NARCIS (Netherlands)

    Goulas, A.; Van Ommen, J.R.

    2013-01-01

    We report the fabrication of platinum nanoclusters with a narrow size distribution on TiO2 nanoparticles using atomic layer deposition. With MeCpPtMe3 and ozone as reactants, the deposition can be carried out at a relatively low temperature of 250 degrees C. Our approach of working with suspended

  15. The atmospheric boundary layer over land and sea: Focus on the off-shore Southern Baltic and Southern North Sea region

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling

    Lecture notes for a short course on the ideal atmospheric boundary layer and its characteristics for different types of real boundary layers, aiming at a discussion of the coastal conditions at the Southern Baltic and North Sea region. The notes are aimed at young scientists (e.g. PhD students...

  16. Towards the fourth GEWEX atmospheric boundary layer model intercomparison study (GABLS4): exploration of very stable conditions over an Antarctic ice shelf

    NARCIS (Netherlands)

    Vihma, T.; Kilpeläinen, T.; Rontu, L.; Anderson, P.S.; Orr, A.; Phillips, T.; Finkele, K.; Rodrigo, I.; Holtslag, A.A.M.; Svensson, G.

    2012-01-01

    Numerical weather prediction and climate models continue to have large errors for stable boundary layers (SBL). To understand and to improve on this, so far three atmospheric boundary layer model inter-comparison studies have been organised within the Global Energy and Water Cycle Experiment (GEWEX)

  17. Unmanned aircraft system measurements of the atmospheric boundary layer over Terra Nova Bay, Antarctica

    Directory of Open Access Journals (Sweden)

    S. L. Knuth

    2013-02-01

    Full Text Available In September 2009, a series of long-range unmanned aircraft system (UAS flights collected basic atmospheric data over the Terra Nova Bay polynya in Antarctica. Air temperature, wind, pressure, relative humidity, radiation, skin temperature, GPS, and operational aircraft data were collected and quality controlled for scientific use. The data have been submitted to the United States Antarctic Program Data Coordination Center (USAP-DCC for free access (doi:10.1594/USAP/0739464.

  18. SUMO: A small unmanned meteorological observer for atmospheric boundary layer research

    Energy Technology Data Exchange (ETDEWEB)

    Reuder, J; Jonassen, M; Mayer, S [Geophysical Institute, University of Bergen, Allegaten 70, 5009 Bergen (Norway); Brisset, P [Ecole Nationale de l' Aviation Civile (ENAC), 7 avenue Edouard Belin, 31055 Toulouse (France); Mueller, M [Orleansstrasse 26a, 31135 Hildesheim (Germany)], E-mail: joachim.reuder@gfi.uib.no, E-mail: pascal.brisset@enac.fr, E-mail: marius.jonassen@gfi.uib.no, E-mail: martin@pfump.org, E-mail: stephanie.mayer@gfi.uib.no

    2008-05-01

    A new system for atmospheric measurements in the lower troposphere has been developed and successfully tested. The presented Small Unmanned Meteorological Observer (SUMO) is based on a light-weighted commercially available model airplane, equipped with an autopilot and meteorological sensors for temperature, humidity and pressure. During the 5 week field campaign FLOHOF (Flow over and around HofsjoUkull) in Central Iceland the system has been successfully tested in July/August 2007. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground. In addition the applicability of SUMO for horizontal surveys up to 4 km away from the launch site has been approved. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under harsh polar conditions, reaching altitudes above 1500 m at ground temperatures of -20 deg. C and wind speeds up to 15 m s{sup -1}. With its wingspan of 80 cm, its length of 75 cm and its weight of below 600 g, SUMO is easy to transport and operate even in remote areas. The direct material costs for one SUMO unit, including airplane, autopilot and sensors are below 1200 Euro. Assuming at least several tenths of flights for each airframe, SUMO provides a cost-efficient measurement system with a large potential to close the existing observational gap of reasonable atmospheric measurement systems in between meteorological masts/towers and radiosondes.

  19. On the predominance of unstable atmospheric conditions in the marine boundary layer offshore of the U.S. northeastern coast

    Science.gov (United States)

    Archer, Cristina L.; Colle, Brian A.; Veron, Dana L.; Veron, Fabrice; Sienkiewicz, Matthew J.

    2016-08-01

    The marine boundary layer of the northeastern U.S. is studied with focus on wind speed, atmospheric stability, and turbulent kinetic energy (TKE), the three most relevant properties in the context of offshore wind power development. Two long-term observational data sets are analyzed. The first one consists of multilevel meteorological variables measured up to 60 m during 2003-2011 at the offshore Cape Wind tower, located near the center of the Nantucket Sound. The second data set comes from the 2013-2014 IMPOWR campaign (Improving the Modeling and Prediction of Offshore Wind Resources), in which wind and wave data were collected with new instruments on the Cape Wind platform, in addition to meteorological data measured during 19 flight missions offshore of New York, Connecticut, Rhode Island, and Massachusetts. It is found that, in this region: (1) the offshore wind resource is remarkable, with monthly average wind speeds at 60 m exceeding 7 m s-1 all year round, highest winds in winter (10.1 m s-1) and lowest in summer (7.1 m s-1), and a distinct diurnal modulation, especially in summer; (2) the marine boundary layer is predominantly unstable (61% unstable vs. 21% neutral vs. 18% stable), meaning that mixing is strong, heat fluxes are positive, and the wind speed profile is often nonlogarithmic (~40% of the time); and (3) the shape of the wind speed profile (log versus nonlog) is an effective qualitative proxy for atmospheric stability, whereas TKE alone is not.

  20. Some Observational and Modeling Studies of the Atmospheric Boundary Layer at Mississippi Gulf Coast for Air Pollution Dispersion Assessment

    Directory of Open Access Journals (Sweden)

    Anjaneyulu Yerramilli

    2008-12-01

    Full Text Available Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25-29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28-30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO2 from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region.

  1. The WELSONS experiment: overview and presentation of first results on the surface atmospheric boundary-layer in semiarid Spain

    Directory of Open Access Journals (Sweden)

    J.-P. Frangi

    Full Text Available This study presents the preliminary results of the local energy budget and dynamic characteristics of the surface atmospheric boundary-layer (SBL during the WELSONS (wind erosion and losses of soil nutrients in semiarid Spain experiment. Some Mediterranean regions suffer land degradation by wind erosion as a consequence of their particular soil and climate conditions and inappropriate agricultural practice. In Spain, where land degradation by water erosion is well known, the lack of field studies to quantify soils losses by wind erosion resulted in the European Community organizing a scientific program for this specific issue. The European programme known as WELSONS was devoted to study the wind erosion process in central Aragon (NE Spain. This multidisciplinary experiment, which began in 1996 and finished in 1998, was carried out over an agricultural soil which was left fallow. Within the experimental field, two plots were delimited where two tillage treatments were applied, a mould-board ploughing (or conventional tillage denoted CT and chisel ploughing (reduced tillage denoted RT. This was to study on bare soil the influence of tillage method on surface conditions, saltation flux, vertical dust flux, erosion rates, dynamics characteristics such as friction velocity, roughness length, etc., and energy budget. The partitioning of the available energy, resulting from the dynamics of the SBL, are quite different over the two plots because of their own peculiar soil and surface properties. The first results show that the RT treatment seems to provide a wind erosion protection. Because of the long data recording time and particular phenomena (formation of a crust at the soil surface, very dry conditions, high wind speed for instance, these microclimatological data acquired during the WELSONS programmes may be helpful to test atmospheric boundary-layer models coupled with soil models.

    Key words: Hydrology (desertification - Meterology and

  2. Differences of atmospheric boundary layer characteristics between pre-monsoon and monsoon period over the Erhai Lake

    Science.gov (United States)

    Xu, Lujun; Liu, Huizhi; Du, Qun; Wang, Lei; Yang, Liu; Sun, Jihua

    2018-01-01

    The differences in planetary boundary layer characteristics, in particular atmospheric boundary layer height (ABLH), humidity, and local circulations in pre-monsoon and monsoon period over the Erhai Lake, were simulated by the lake-atmosphere coupled model WRF v3.7.1. No lake simulations were also conducted to investigate lake effects over complex topography. During pre-monsoon period, local circulation was fully developed under weak synoptic system. The ABLH ran up to 2300 m or so. During monsoon period, temperature difference between land and lake became smaller, resulting in weaker local circulations. The height of circulation reduced by 500 m, and ABLH ran up to 1100 m during the day. Enhanced soil moisture and low surface temperature due to monsoon rainfalls in July could be the main reason for the slightly lower ABLH over the Erhai Lake area. Specific humidity of the boundary layer increased 8.8 g kg-1 or so during monsoon period. The Erhai Lake enlarged thermal contrast between valley and mountain slope in the Dali Basin. The lake reduced air temperature by 2 3 °C during daytime and increased air temperature by nearly 2 °C in the evening. Due to its small roughness length and large thermal capacity, the Erhai Lake enlarged lake-land temperature difference and local wind speed. A cyclonic circulation was maintained by the combination of mountain breeze and land breeze in the south of the lake. The lake decreased air temperature, increased specific humidity, and reduced ABLH during daytime, whereas the opposite effect is presented at night.

  3. The effect of unsteady and baroclinic forcing on predicted wind profiles in Large Eddy Simulations: Two case studies of the daytime atmospheric boundary layer

    DEFF Research Database (Denmark)

    Pedersen, Jesper Grønnegaard; Kelly, Mark C.; Gryning, Sven-Erik

    2013-01-01

    . The applied domain-scale pressure gradient and its height- and time-dependence are estimated from LIDAR measurements of the wind speed above the atmospheric boundary layer in the Høvsøre case, and from radio soundings and a network of ground-based pressure sensors in the Hamburg case. In the two case studies......Due to its fine-resolution requirement and subsequent computational demand, Large Eddy Simulation of the atmospheric boundary layer is limited in most cases to computational domains extending only a few kilometers in both the vertical and horizontal directions. Variations in the flow...... and in relevant atmospheric fields (e.g. temperature) that occur at larger scales must be imposed through boundary conditions or as external forcing. In this work we study the influence of such variations on the wind profile in Large Eddy Simulations of daytime atmospheric boundary layers, by comparing...

  4. Investigation of Turbulence Parametrization Schemes with Reference to the Atmospheric Boundary Layer Over the Aegean Sea During Etesian Winds

    Science.gov (United States)

    Dandou, A.; Tombrou, M.; Kalogiros, J.; Bossioli, E.; Biskos, G.; Mihalopoulos, N.; Coe, H.

    2017-08-01

    The spatial structure of the marine atmospheric boundary layer (MABL) over the Aegean Sea is investigated using the Weather Research and Forecasting (WRF) mesoscale model. Two `first-order' non-local and five `1.5-order' local planetary boundary-layer (PBL) parametrization schemes are used. The predictions from the WRF model are evaluated against airborne observations obtained by the UK Facility for Airborne Atmospheric Measurements BAe-14 research aircraft during the Aegean-GAME field campaign. Statistical analysis shows good agreement between measurements and simulations especially at low altitude. Despite the differences between the predicted and measured wind speeds, they reach an agreement index of 0.76. The simulated wind-speed fields close to the surface differ substantially among the schemes (maximum values range from 13 to 18 m s^{-1} at 150-m height), but the differences become marginal at higher levels. In contrast, all schemes show similar spatial variation patterns in potential temperature fields. A warmer (1-2 K) and drier (2-3 g kg^{-1}) layer than is observed, is predicted by almost all schemes under stable conditions (eastern Aegean Sea), whereas a cooler (up to 2 K) and moister (1-2 g kg^{-1}) layer is simulated under near-neutral to nearly unstable conditions (western Aegean Sea). Almost all schemes reproduce the vertical structure of the PBL and the shallow MABL (up to 300 m) well, including the low-level jet in the eastern Aegean Sea, with non-local schemes being closer to observations. The simulated PBL depths diverge (up to 500 m) due to the different criteria applied by the schemes for their calculation. Under stable conditions, the observed MABL depth corresponds to the height above the sea surface where the simulated eddy viscosity reaches a minimum; under neutral to slightly unstable conditions this is close to the top of the simulated entrainment layer. The observed sensible heat fluxes vary from -40 to 25 W m^{-2}, while the simulated

  5. Investigating sources of measured forest-atmosphere ammonia fluxes using two-layer bi-directional modelling

    DEFF Research Database (Denmark)

    Hansen, K.; Personne, E.; Skjøth, C.A.

    2017-01-01

    of the forest ecosystems, a period with full developed canopy (MMSF) and a senescent period for the DK-Sor site, with leaf fall and leaf litter build-up. Both datasets indicate emissions of NH3 from the forest to the atmosphere. The two-layer NH3 compensation point model SURFATM-NH3 was used in combination...... layer NH3 emission potential (Гg) was successfully applied using the plant area index (PAI) to represent the build-up of a litter layer in the leaf fall period. For a closed green forest canopy (MMSF), unaffected by agricultural NH3 sources, NH3 was emitted with daytime fluxes up to 50ng NH3-N m−2s−1...... and nighttime fluxes up to 30ng NH3-N m−2s−1. For a senescing forest (DK-Sor), located in an agricultural region, deposition rates of 250ng NH3-N m−2s−1 were measured prior to leaf fall, and emission rates up to 670ng NH3-N m−2s−1 were measured following leaf fall. For MMSF, simulated stomatal NH3 emissions...

  6. Deposition of silica protected luminescent layers of Eu:GdVO{sub 4} nanoparticles assisted by atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Moretti, Elisa, E-mail: elisa.moretti@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Pizzol, Giorgia [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Fantin, Marina; Enrichi, Francesco; Scopece, Paolo [Nanofab-Veneto Nanotech, Via delle Industrie 5, 30175 Marghera, Venezia (Italy); Nuñez, Nuria O.; Ocaña, Manuel [Instituto de Ciencia de Materiales de Sevilla, CSIC-US, Americo Vespucio 49, 41092, Isla de la Cartuja, Sevilla (Spain); Benedetti, Alvise [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Polizzi, Stefano [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, INSTM Venice Research Unit, Via Torino 155/B, 30172 Mestre, Venezia (Italy); Centro di Microscopia Elettronica “Giovanni Stevanato”, Università Ca' Foscari Venezia, Via Torino 155/B, 30172 Mestre, Venezia (Italy)

    2016-01-01

    Eu:GdVO{sub 4} nanophosphors with an average size of 60 nm, synthesized by a facile solvothermal method, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesion was estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source. - Highlights: • Luminescent films were obtained by spray deposition of Eu:GdVO{sub 4} nanophosphors. • Plasma jet deposition of SiO{sub 2} fixed the nanophosphors on the substrate. • Optical properties of nanophosphors were preserved after deposition-fixing process. • Films well-adhered to the substrate, even after a scotch tape peeling test and a scratch test.

  7. Large off-shore wind farms: linking wake models with atmospheric boundary layer models

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, Gerard [Energy Research Centre, Wind Energy Dept., Petten (Netherlands); Barthelmie, Rebecca [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Rados, Kostas [Robert Gordon Univ., School of Mechanical and Offshore Engineering, Aberdeen (United Kingdom); Lange, Bernhard [Oldenburg Univ., Dept. of Energy and Semiconductor Research EHF, Oldenburg (Germany); Schlez, Wolfgang [Garrad Hassan and Partners Ltd., Bristol (United Kingdom)

    2001-07-01

    Within the ENDOW project various candidate atmospheric and wake models are available to be incorporated into the design tool. In order to gain insight into the suitability of the various models and in the way how they can be linked, a questionnaire has been distributed between the various modelling partners. Using the response on the questionnaire an inventory of the different models has been made with emphasis on the items which determine the compatibility of the different models. Aspects, which are of importance for this compatibility are consistency from a physical point of view, but also consistency from an informatic point of view (i.e. input/output, platform, compiler etc.). In the paper the first results from the questionnaire are summarised. Thereto Section 2 gives a brief description of the questionnaire. This is followed by section 3 and 4, in which the response on the wake- and the atmospheric models is summarised respectively. In section 5 some first ideas on the interfacing are proposed. It must be noted that the present inventory is very preliminary: Many answers on the questionnaire are still lacking and the paper is mainly intended to encourage further research and as a template for similar studies. (Author)

  8. The Small Unmanned Meteorological Observer SUMO. A new tool for atmospheric boundary layer research

    Energy Technology Data Exchange (ETDEWEB)

    Reuder, Joachim; Jonassen, Marius; Mayer, Stephanie [Bergen Univ. (Norway). Geophysical Inst.; Brisset, Pascal [Ecole Nationale de l' Aviation Civile (ENAC), Toulouse (France); Mueller, Martin [Martin Mueller Engineering, Hildesheim (Germany)

    2009-04-15

    The Small Unmanned Meteorological Observer SUMO has been developed as a cost-efficient measurement system with the aim to close the existing observational gap of atmospheric measurement systems in between meteorological masts/towers and radiosondes. The system is highly flexible and has the capability for in-situ ABL measurements with unique spatial and temporal resolution. SUMO is based on a light-weighted styrofoam model airplane, equipped with an autopilot system for autonomous flight missions and in its recent version with meteorological sensors for temperature, humidity and pressure. With its wingspan of 80 cm, its length of 75 cm and a total lift-off weight of 580 g, SUMO is easy to transport and operate even in remote areas with limited infrastructure. During several field campaigns in 2007 and 2008 the system has been successfully tested and operated. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground during the FLOHOF (FLOw over and around HOFsjoekull) field campaign in Central Iceland in July/August 2007. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under polar conditions, reaching altitudes above 1500 m even at ground temperatures of -20 C and wind speeds up to 15 m s{sup -1}. (orig.)

  9. MPAS Atmospheric Boundary Layer Simulation under Selected Stability Conditions: Evaluation Using the SWIFT Datasen

    Energy Technology Data Exchange (ETDEWEB)

    Kotamarthi, V. Rao [Argonne National Lab. (ANL), Argonne, IL (United States); Feng, Yan [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-10-12

    Modeling the transition from mesoscale to microscale is necessary in order to model different processes that affect a wind farm and to develop forecasting tools that operate at the farm scale. The mesoscale-to-microscale coupling (MMC) project is an A2e (Atmosphere-toelectrons) coordinated activity for developing modeling capabilities at the wind farm scale. By moving the focus of the research from a single wind turbine to the collection of turbines that comprise a wind farm, A2e extends the range of spatial and timescales that need representation in a model from tens of meters to hundreds of kilometers and timescales from a few seconds to days (Bokharaie et al. 2016). In the atmosphere, these scales are represented by mesoscale-tomicroscale models. The modeling available at these scales has differed in its representation of various physical processes. The MMC group is responsible for evaluating existing models at these scales and recommending a set of options for coupling the mesoscale and microscale with the best-performing models. The group was organized in 2015 and will explore options for coupling strategies with real-world test problems in fiscal year (FY) 2017. The model of choice for this exercise is WRF (Weather Research Forecasting) for mesoscale and WRF-LES (Large Eddy Simulation) for microscale simulations. The MPAS (Model Prediction Across Scales) variable mesh model that can be continuously refined; it has dynamic core and physics options adopted from WRF, which offer an alternative platform for modeling the mesoscale.

  10. The Small Unmanned Meteorological Observer SUMO: A new tool for atmospheric boundary layer research

    Directory of Open Access Journals (Sweden)

    Joachim Reuder

    2009-05-01

    Full Text Available The Small Unmanned Meteorological Observer SUMO has been developed as a cost-efficient measurement system with the aim to close the existing observational gap of atmospheric measurement systems in between meteorological masts/towers and radiosondes. The system is highly flexible and has the capability for in-situ ABL measurements with unique spatial and temporal resolution. SUMO is based on a light-weighted styrofoam model airplane, equipped with an autopilot system for autonomous flight missions and in its recent version with meteorological sensors for temperature, humidity and pressure. With its wingspan of 80 cm, its length of 75 cm and a total lift-off weight of 580 g, SUMO is easy to transport and operate even in remote areas with limited infrastructure. During several field campaigns in 2007 and 2008 the system has been successfully tested and operated. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground during the FLOHOF (FLOw over and around HOFsjökull field campaign in Central Iceland in July/August 2007. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under polar conditions, reaching altitudes above 1500 m even at ground temperatures of -20° C and wind speeds up to 15 m s-1.

  11. Gas Hydrates of Coal Layers as a Methane Source in the Atmosphere and Mine Working

    Directory of Open Access Journals (Sweden)

    Dyrdin Valery

    2017-01-01

    Full Text Available Living conditions of gas hydrates of a methane in a coal matrix as one of possible forms of finding of molecules of a methane in coal layers are considered. However, gas hydrates are formed not in all mineral coals even under the thermobaric conditions corresponding to their equilibrium state as the minimum humidity and the corresponding pore width are necessary for each brand of coal for formation of gas hydrate. It is shown that it depends on electric electrical dipole moment of a macromolecule of coal. Coals of brands K, D, Zh were considered. The electric field created by the surface of coal does not allow molecules of water to carry out threedimensional driving, and they keep on an internal surface of a time. By means of theoretical model operation a dipole - dipole interaction of molecules of water with the steam surface of coal values of energy of fiber interaction for various functional groups located in coal “fringe” which size for the first and second layers does not allow molecules of water to participate in formation of gas hydrates are received. For coals of brands K, Zh, D, considering distribution of a time on radiuses, the percent of moisture, which cannot share in education solid coal of gas solutions, is calculated.

  12. Representation of the grey zone of turbulence in the atmospheric boundary layer

    Science.gov (United States)

    Honnert, Rachel

    2016-04-01

    Numerical weather prediction model forecasts at horizontal grid lengths in the range of 100 to 1 km are now possible. This range of scales is the "grey zone of turbulence". Previous studies, based on large-eddy simulation (LES) analysis from the MésoNH model, showed that some assumptions of some turbulence schemes on boundary-layer structures are not valid. Indeed, boundary-layer thermals are now partly resolved, and the subgrid remaining part of the thermals is possibly largely or completely absent from the model columns. First, some modifications of the equations of the shallow convection scheme have been tested in the MésoNH model and in an idealized version of the operational AROME model at resolutions coarser than 500 m. Secondly, although the turbulence is mainly vertical at mesoscale (> 2 km resolution), it is isotropic in LES (AROME, which needs mixing lengths in the formulation. Vertical and horizontal mixing lengths have been calculated from LES of neutral and convective cases at resolutions in the grey zone.

  13. Gas Hydrates of Coal Layers as a Methane Source in the Atmosphere and Mine Working

    Science.gov (United States)

    Dyrdin, Valery; Shepeleva, Sofya; Kim, Tatiana

    2017-11-01

    Living conditions of gas hydrates of a methane in a coal matrix as one of possible forms of finding of molecules of a methane in coal layers are considered. However, gas hydrates are formed not in all mineral coals even under the thermobaric conditions corresponding to their equilibrium state as the minimum humidity and the corresponding pore width are necessary for each brand of coal for formation of gas hydrate. It is shown that it depends on electric electrical dipole moment of a macromolecule of coal. Coals of brands K, D, Zh were considered. The electric field created by the surface of coal does not allow molecules of water to carry out threedimensional driving, and they keep on an internal surface of a time. By means of theoretical model operation a dipole - dipole interaction of molecules of water with the steam surface of coal values of energy of fiber interaction for various functional groups located in coal "fringe" which size for the first and second layers does not allow molecules of water to participate in formation of gas hydrates are received. For coals of brands K, Zh, D, considering distribution of a time on radiuses, the percent of moisture, which cannot share in education solid coal of gas solutions, is calculated.

  14. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.

    2014-05-15

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The Characterization of Atmospheric Boundary Layer Depth and Turbulence in a Mixed Rural and Urban Convective Environment

    Science.gov (United States)

    Hicks, Micheal M.

    A comprehensive analysis of surface-atmosphere flux exchanges over a mixed rural and urban convective environment is conducted at Howard University Beltsville, MD Research Campus. This heterogeneous site consists of rural, suburban and industrial surface covers to its south, east and west, within a 2 km radius of a flux sensor. The eddy covariance method is utilized to estimate surface-atmosphere flux exchanges of momentum, heat and moisture. The attributes of these surface flux exchanges are contrasted to those of classical homogeneous sites and assessed for accuracy, to evaluate the following: (I) their similarity to conventional convective boundary layer (CBL) processes and (II) their representativeness of the surrounding environment's turbulent properties. Both evaluations are performed as a function of upwind surface conditions. In particular, the flux estimates' obedience to spectrum power laws and similarity theory relationships is used for performing the first evaluation, and their ability to close the surface energy balance and accurately model CBL heights is used for the latter. An algorithm that estimates atmospheric boundary layer heights from observed lidar extinction backscatter was developed, tested and applied in this study. The derived lidar based CBL heights compared well with those derived from balloon borne soundings, with an overall Pearson correlation coefficient and standard deviation of 0.85 and 223 m, respectively. This algorithm assisted in the evaluation of the response of CBL processes to surface heterogeneity, by deriving high temporal CBL heights and using them as independent references of the surrounding area averaged sensible heat fluxes. This study found that the heterogeneous site under evaluation was rougher than classical homogeneous sites, with slower dissipation rates of turbulent kinetic energy. Flux measurements downwind of the industrial complexes exhibited enhanced efficiency in surface-atmosphere momentum, heat, and

  16. A discussion on the variations of MST/ST radar echo power with an atmospheric layer resolved by frequency domain interferometry technique

    Science.gov (United States)

    Chen, J. S.; Chu, Y. H.

    2000-11-01

    The relationship between an atmospheric layer and its VHF backscatter resolved by the frequency domain interferometry (FDI) technique is investigated in this article. A theoretical expression connecting the radar echo power with the thickness and position of an atmospheric layer and the range weighting function of a matched filter is derived. It shows that the farther the layer locates from the central height of the radar volume, the weaker the echo power will be. This feature is attributed to the range weighting effect of the radar system. FDI observations also show that the echo power from the atmospheric layer located close to the central height of the radar volume is usually greater than that from the layer located at the edge of the volume, which is in good agreement with the theoretical prediction. Moreover, the correlation between the echo power and layer position is negative (positive) if the layer locates in the upper (lower) part of the radar volume. This behavior is consistent with the theoretical prediction and can also be interpreted by the range weighting effect. It is also suggested that the power-position relation is capable of indicating the system bias causing the systematic error of FDI-estimated layer position. In addition, numerical simulation is performed in this article to examine the difference between the range weighting functions resulting from rectangular and nonrectangular radar pulses for a given receiver impulse response.

  17. A micro-meteorological experiment in the atmospheric boundary layer in Highveld region

    Energy Technology Data Exchange (ETDEWEB)

    Esau, I N; Zilitinkevich, S S [G.C. Rieber Climate Institute of Nansen Environmental and Remote Sensing Center, Thoermohlensgate 47, 5006, Bergen (Norway); Djolov, G; Rautenbach, C J deW, E-mail: igor.ezau@nersc.n [University of Pretoria (South Africa)

    2010-08-15

    Meteorology of the planetary boundary layer (PBL) is to large extent determined by turbulent processes. Those processes and their interaction with surface properties are not well understood. The processes over heterogeneous land surfaces are understood even less. To progress in the understanding simultaneous observations with a network of meteorological stations are needed. A joint project between Norwegian and South African research foundations funded a micrometeorological experiment in the Highveld area of the South Africa (MMEH). The experiment has been organized to collect data from 5 automatic meteorological stations placed at 7 km to 23 km separation distances from each other. The data were collected continuously over 2 years. This paper presents the idea, the theoretical background and the organization of the MMEH.

  18. A micro-meteorological experiment in the atmospheric boundary layer in Highveld region

    Science.gov (United States)

    Esau, I. N.; Zilitinkevich, S. S.; Djolov, G.; deW Rautenbach, C. J.

    2010-08-01

    Meteorology of the planetary boundary layer (PBL) is to large extent determined by turbulent processes. Those processes and their interaction with surface properties are not well understood. The processes over heterogeneous land surfaces are understood even less. To progress in the understanding simultaneous observations with a network of meteorological stations are needed. A joint project between Norwegian and South African research foundations funded a micrometeorological experiment in the Highveld area of the South Africa (MMEH). The experiment has been organized to collect data from 5 automatic meteorological stations placed at 7 km to 23 km separation distances from each other. The data were collected continuously over 2 years. This paper presents the idea, the theoretical background and the organization of the MMEH.

  19. Towards a fundamentally new understanding of the marine atmospheric boundary layer

    DEFF Research Database (Denmark)

    Smedman, Ann-Sofi; Högström, U.; Larsén, Xiaoli Guo

    2004-01-01

    measurements of the wave field, Donelan et al. (1997), Drennan et al. (1999), Rieder and Smith (1998) and our own studies (see below), that effects from waves are of fundamental importance for the turbulent exchange processes in the marine boundary layer and should be included in parameterizations in models....... This contribution summarizes results from measurements during an eight-year period (May, 1995 – present) at the air-sea interaction station Östergarnsholm in the Baltic Sea. It illustrates vividly that the ‘classical’ concept of the sea surface as an analogue to a solid surface with moving roughness elements...... is valid only for the much studied case of growing waves and that understanding the role of relatively long waves, which travel faster than the wind, is crucial for a correct treatment of the air-sea exchange processes....

  20. Ice at the Interface: Atmosphere-Ice-Ocean Boundary Layer Processes and Their Role in Polar Change---Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Hunke, Elizabeth C. [Los Alamos National Laboratory

    2012-07-23

    The atmosphere-ocean boundary layer in which sea ice resides includes many complex processes that require a more realistic treatment in GCMs, particularly as models move toward full earth system descriptions. The primary purpose of the workshop was to define and discuss such coupled processes from observational and modeling points of view, including insight from both the Arctic and Antarctic systems. The workshop met each of its overarching goals, including fostering collaboration among experimentalists, theorists and modelers, proposing modeling strategies, and ascertaining data availability and needs. Several scientific themes emerged from the workshop, such as the importance of episodic or extreme events, precipitation, stratification above and below the ice, and the marginal ice zone, whose seasonal Arctic migrations now traverse more territory than in the past.

  1. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Energy Technology Data Exchange (ETDEWEB)

    Hoye, Robert L. Z., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk; MacManus-Driscoll, Judith L., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Muñoz-Rojas, David [LMGP, University Grenoble-Alpes, CNRS, F-3800 Grenoble (France); Nelson, Shelby F. [Kodak Research Laboratories, Eastman Kodak Company, Rochester, New York 14650 (United States); Illiberi, Andrea; Poodt, Paul [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Roozeboom, Fred [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB (Netherlands)

    2015-04-01

    Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  2. Investigation and validation of wake model combinations for large wind farm modelling in neutral atmospheric boundary layers

    Science.gov (United States)

    Tromeur, E.; Puygrenier, S.; Sanquer, S.

    2016-09-01

    This study is focused on assessing the ability of two refined large wind farm models to describe the disturbance of the neutral atmospheric flow caused by large offshore wind farms. Sensitivity studies of internal boundary layer parameters are carried out. An optimum large wind farm correction is then proposed and combined with two different standard single wake models, the Park and EVM models. The large wind farm wake effect is evaluated and validated against measurements of two offshore wind farms at Horns Rev and Nysted and four standard wake models by computing velocity deficit and normalized power. All large wind farm models proposed were able to capture wake width to some degree and the decrease of power output moving through the wind farm. Despite some uncertainties, this very promising model combinations allows us to take into account the slowdown in large wind farms.

  3. Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2015-04-01

    Full Text Available Atmospheric pressure spatial atomic layer deposition (AP-SALD has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

  4. The Atmospheric Surface Layer in the Polar Regions of the Earth

    Science.gov (United States)

    Kovadlo, P. G.; Shikhovtsev, A. Yu.; Yazev, S. A.

    2017-05-01

    As studies of the Earth history show the energy power and amount of catastrophic events during the planet evolution has been decreasing. Gradually the Earth "was adjusted" under the influence of external factors and internal sources of energy were weakened. The relative stability of climatic characteristics over millions of years indicates this. The modern surface Earth temperature increasing over the past 150 years has been proved by analyzing the series of network instrumental hydrometeorological measurements. The authors of this study proposed a hypothesis to explain the observed warming of the climate. It is supposed that there was a land with enclosed water reservoirs in the past at the Arctic ocean site. Calculations and observations show that there were favorable conditions for the formation and growth of the perennial glaciers` without access of warm ocean waters in the polar region. Further the mass of the Arctic ice sheet increasing led to subsidence of the earth's crust under the influence of its weight. Low-lying plains under the ice were lower than the ocean level. The access of oceanic waters to the ice sheet led to the washing of the base by the waters of the Atlantic and the Pacific oceans. Warm waters largely destroyed the floating part of the ice sheet. Heat which was spent on melting ice in the past warm up the atmosphere and ocean nowadays. Currently, the final stage of this process is observed and the factors discussed are the main cause of the observed warming.

  5. Turbulent characteristics of a semiarid atmospheric surface layer from cup anemometers – effects of soil tillage treatment (Northern Spain

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    2003-10-01

    Full Text Available This paper deals with the characteristics of turbulent flow over two agricultural plots with various tillage treatments in a fallow, semiarid area (Central Aragon, Spain. The main dynamic characteristics of the Atmospheric Surface Layer (ASL measured over the experimental site (friction velocity, roughness length, etc., and energy budget, have been presented previously (Frangi and Richard, 2000. The current study is based on experimental measurements performed with cup anemometers located in the vicinity of the ground at 5 different levels (from 0.25 to 4 m and sampled at 1 Hz. It reveals that the horizontal wind variance, the Eulerian integral scales, the frequency range of turbulence and the turbulent kinetic energy dissipation rate are affected by the surface roughness. In the vicinity of the ground surface, the horizontal wind variance logarithmically increases with height, directly in relation to the friction velocity and the roughness length scale. It was found that the time integral scale (and subsequently the length integral scale increased with the surface roughness and decreased with the anemometer height. These variations imply some shifts in the meteorological spectral gap and some variations of the spectral peak length scale. The turbulent energy dissipation rate, affected by the soil roughness, shows a z-less stratification behaviour under stable conditions. In addition to the characterization of the studied ASL, this paper intends to show which turbulence characteristics, and under what conditions, are accessible through the cup anemometer.Key words. Meteorology and atmospheric dynamics (climatology, turbulence, instruments and techniques

  6. Turbulent characteristics of a semiarid atmospheric surface layer from cup anemometers – effects of soil tillage treatment (Northern Spain

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    Full Text Available This paper deals with the characteristics of turbulent flow over two agricultural plots with various tillage treatments in a fallow, semiarid area (Central Aragon, Spain. The main dynamic characteristics of the Atmospheric Surface Layer (ASL measured over the experimental site (friction velocity, roughness length, etc., and energy budget, have been presented previously (Frangi and Richard, 2000. The current study is based on experimental measurements performed with cup anemometers located in the vicinity of the ground at 5 different levels (from 0.25 to 4 m and sampled at 1 Hz. It reveals that the horizontal wind variance, the Eulerian integral scales, the frequency range of turbulence and the turbulent kinetic energy dissipation rate are affected by the surface roughness. In the vicinity of the ground surface, the horizontal wind variance logarithmically increases with height, directly in relation to the friction velocity and the roughness length scale. It was found that the time integral scale (and subsequently the length integral scale increased with the surface roughness and decreased with the anemometer height. These variations imply some shifts in the meteorological spectral gap and some variations of the spectral peak length scale. The turbulent energy dissipation rate, affected by the soil roughness, shows a z-less stratification behaviour under stable conditions. In addition to the characterization of the studied ASL, this paper intends to show which turbulence characteristics, and under what conditions, are accessible through the cup anemometer.

    Key words. Meteorology and atmospheric dynamics (climatology, turbulence, instruments and techniques

  7. Zeppelin NT - Measurement Platform for the Exploration of Atmospheric Chemistry and Dynamics in the Planetary Boundary Layer

    Science.gov (United States)

    Hofzumahaus, Andreas; Holland, Frank; Oebel, Andreas; Rohrer, Franz; Mentel, Thomas; Kiendler-Scharr, Astrid; Wahner, Andreas; Brauchle, Artur; Steinlein, Klaus; Gritzbach, Robert

    2014-05-01

    The planetary boundary layer (PBL) is the chemically most active and complex part of the atmosphere where freshly emitted reactive trace gases, tropospheric radicals, atmospheric oxidation products and aerosols exhibit a large variability and spatial gradients. In order to investigate the chemical degradation of trace gases and the formation of secondary pollutants in the PBL, a commercial Zeppelin NT was modified to be used as an airborne measurement platform for chemical and physical observations with high spatial resolution. The Zeppelin NT was developed by Zeppelin Luftschifftechnik (ZLT) and is operated by Deutsche Zeppelin Reederei (DZR) in Friedrichshafen, Germany. The modification was performed in cooperation between Forschungszentrum Jülich and ZLT. The airship has a length of 75 m, can lift about 1 ton of scientific payload and can be manoeuvered with high precision by propeller engines. The modified Zeppelin can carry measurement instruments mounted on a platform on top of the Zeppelin, or inside the gondola beneath the airship. Three different instrument packages were developed to investigate a. gas-phase oxidation processes involving free radicals (OH, HO2) b. formation of secondary organic aerosols (SOA) c. new particle formation (nucleation) The presentation will describe the modified airship and provide an overview of its technical performance. Examples of its application during the recent PEGASOS flight campaigns in Europe will be given.

  8. Numerical Study on the Effect of Air–Sea–Land Interaction on the Atmospheric Boundary Layer in Coastal Area

    Directory of Open Access Journals (Sweden)

    Zixuan Yang

    2018-02-01

    Full Text Available We have performed large-eddy simulations (LES to study the effect of complex land topography on the atmospheric boundary layer (ABL in coastal areas. The areas under investigation are located at three beaches in Monterey Bay, CA, USA. The sharp-interface immersed boundary method is employed to resolve the land topography down to grid scale. We have considered real-time and what-if cases. In the real-time cases, measurement data and realistic land topographies are directly incorporated. In the what-if cases, the effects of different scenarios of wind speed, wind direction, and terrain pattern on the momentum flux at the beach are studied. The LES results are compared with simulations using the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS and field measurement data. We find that the land topography imposes a critical influence on the ABL in the coastal area. The momentum fluxes obtained from our LES agree with measurement data. Our results indicate the importance of capturing the effects of land topographies in simulations.

  9. Electrodeposition of ZnO window layer for an all-atmospheric fabrication process of chalcogenide solar cell

    Science.gov (United States)

    Tsin, Fabien; Venerosy, Amélie; Vidal, Julien; Collin, Stéphane; Clatot, Johnny; Lombez, Laurent; Paire, Myriam; Borensztajn, Stephan; Broussillou, Cédric; Grand, Pierre Philippe; Jaime, Salvador; Lincot, Daniel; Rousset, Jean

    2015-01-01

    This paper presents the low cost electrodeposition of a transparent and conductive chlorine doped ZnO layer with performances comparable to that produced by standard vacuum processes. First, an in-depth study of the defect physics by ab-initio calculation shows that chlorine is one of the best candidates to dope the ZnO. This result is experimentally confirmed by a complete optical analysis of the ZnO layer deposited in a chloride rich solution. We demonstrate that high doping levels (>1020 cm−3) and mobilities (up to 20 cm2 V−1 s−1) can be reached by insertion of chlorine in the lattice. The process developed in this study has been applied on a CdS/Cu(In,Ga)(Se,S)2 p-n junction produced in a pilot line by a non vacuum process, to be tested as solar cell front contact deposition method. As a result efficiency of 14.3% has been reached opening the way of atmospheric production of Cu(In,Ga)(Se,S)2 solar cell. PMID:25753657

  10. Characterizing the lower log region of the atmospheric surface layer via large-scale particle tracking velocimetry

    Science.gov (United States)

    Rosi, Giuseppe A.; Sherry, Michael; Kinzel, Matthias; Rival, David E.

    2014-05-01

    As a first step toward characterizing coherent structures within the atmospheric surface layer (ASL), measurements obtained via a large-scale particle tracking velocimetry (LS-PTV) system were validated against wind-measurement station data as well as canonical turbulent boundary layer studies. The LS-PTV system resolves three-dimensional, Lagrangian tracks over a 16 m3 volume. Mean-velocity measurements, as well as vertical and shear Reynolds-stress measurements, generally agreed with wind-measurement station data and Reynolds-stress profiles referenced from literature. The probability distributions for streamwise, spanwise and vertical velocity-fluctuation components appear normally distributed about zero. Furthermore, the probability distributions for all three components of Lagrangian acceleration were exponential and followed the parametrization curve from LaPorta et al. (Lett Nat 409:1017-1019, 2001). Lastly, the vorticity probability distributions were exponential and symmetric about zero, which matches findings from Balint et al. (Fluid Mech 228:53-86, 1991). The vorticity intensity measured by the LS-PTV system was less than values from Priyadarshana et al. (Fluid Mech 570:307-346, 2007), which is attributed to the low spatial resolution. However, the average spacing of 0.5 m between tracer particles is deemed sufficient for the future characterization of vortical structures within the ASL.

  11. Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps

    Science.gov (United States)

    Litt, Maxime; Sicart, Jean-Emmanuel; Six, Delphine; Wagnon, Patrick; Helgason, Warren D.

    2017-04-01

    Over Saint-Sorlin Glacier in the French Alps (45° N, 6.1° E; ˜ 3 km2) in summer, we study the atmospheric surface-layer dynamics, turbulent fluxes, their uncertainties and their impact on surface energy balance (SEB) melt estimates. Results are classified with regard to large-scale forcing. We use high-frequency eddy-covariance data and mean air-temperature and wind-speed vertical profiles, collected in 2006 and 2009 in the glacier's atmospheric surface layer. We evaluate the turbulent fluxes with the eddy-covariance (sonic) and the profile method, and random errors and parametric uncertainties are evaluated by including different stability corrections and assuming different values for surface roughness lengths. For weak synoptic forcing, local thermal effects dominate the wind circulation. On the glacier, weak katabatic flows with a wind-speed maximum at low height (2-3 m) are detected 71 % of the time and are generally associated with small turbulent kinetic energy (TKE) and small net turbulent fluxes. Radiative fluxes dominate the SEB. When the large-scale forcing is strong, the wind in the valley aligns with the glacier flow, intense downslope flows are observed, no wind-speed maximum is visible below 5 m, and TKE and net turbulent fluxes are often intense. The net turbulent fluxes contribute significantly to the SEB. The surface-layer turbulence production is probably not at equilibrium with dissipation because of interactions of large-scale orographic disturbances with the flow when the forcing is strong or low-frequency oscillations of the katabatic flow when the forcing is weak. In weak forcing when TKE is low, all turbulent fluxes calculation methods provide similar fluxes. In strong forcing when TKE is large, the choice of roughness lengths impacts strongly the net turbulent fluxes from the profile method fluxes and their uncertainties. However, the uncertainty on the total SEB remains too high with regard to the net observed melt to be able to

  12. Measurements of mercury in the near-surface layer of the atmosphere of the Russian Arctic.

    Science.gov (United States)

    Golubeva, N; Burtseva, L; Matishov, G

    2003-05-01

    A series of measurements of gaseous elemental mercury concentrations in near-surface air of the Russian Arctic Region were carried out from 1994 to 1997. The measurements were conducted in Murmansk at a stationary site in April-May 1994, on a cruise in Motovsky Bay and Kola Bay during May-June 1996, and along the Russian Northern Sea Route in April-May 1997 on board the nuclear icebreaker 'Soviet Union'. Silver absorption was used for trapping of mercury and the mass of mercury was determined by cold vapour atomic absorption spectrophotometery. Detection limits were approximately 0.3 ng/m(3) (+/- error 46%). Sixty samples were selected and analysed. Sample volumes were 2.2 m(3) ashore, and up to 6.6 m(3) over water. The meteorological conditions, including a wind speed and direction, during the sampling period were typical of the spring-summer period of year, and therefore the concentrations of atmospheric mercury are regarded as representative for this season. The mean concentrations of mercury ranged from 2.2 ng/m(3) for Murmansk city, 1.7 ng/m(3) for Kola Bay, 1.6 ng/m(3) for Motovsky Bay, 1.1 ng/m(3) for the eastern part of the Barents Sea and 0.7 ng/m(3) for the western part of the Kara Sea. The levels of mercury in Murmansk, and over Kola and Motovsky Bays were associated with a primary direction of a near-surface wind from the nearest sources of mercury emission located in the Russian North region. These are the non-ferrous metallurgical plants in Nickel in the case of Motovsky Bay and Murmansk garbage-disposal plant, for sampling points in Murmansk and over Kola Bay. These concentrations of mercury, measured in the spring-summer season, in near-surface air of the Russian North, are more than two-fold lower than the concentrations that are typical of continental background regions in western Russia, and are comparable to the concentrations measured in the Arctic regions of other countries.

  13. Interaction Between the Atmospheric Boundary Layer and Wind Energy: From Continental-Scale to Turbine-Scale

    Science.gov (United States)

    St. Martin, Clara Mae

    Wind turbines and groups of wind turbines, or "wind plants", interact with the complex and heterogeneous boundary layer of the atmosphere. We define the boundary layer as the portion of the atmosphere directly influenced by the surface, and this layer exhibits variability on a range of temporal and spatial scales. While early developments in wind energy could ignore some of this variability, recent work demonstrates that improved understanding of atmosphere-turbine interactions leads to the discovery of new ways to approach turbine technology development as well as processes such as performance validation and turbine operations. This interaction with the atmosphere occurs at several spatial and temporal scales from continental-scale to turbine-scale. Understanding atmospheric variability over continental-scales and across plants can facilitate reliance on wind energy as a baseload energy source on the electrical grid. On turbine scales, understanding the atmosphere's contribution to the variability in power production can improve the accuracy of power production estimates as we continue to implement more wind energy onto the grid. Wind speed and directional variability within a plant will affect wind turbine wakes within the plants and among neighboring plants, and a deeper knowledge of these variations can help mitigate effects of wakes and possibly even allow the manipulation of these wakes for increased production. Herein, I present the extent of my PhD work, in which I studied outstanding questions at these scales at the intersections of wind energy and atmospheric science. My work consists of four distinct projects. At the coarsest scales, I analyze the separation between wind plant sites needed for statistical independence in order to reduce variability for grid-integration of wind. At lower wind speeds, periods of unstable and more turbulent conditions produce more power than periods of stable and less turbulent conditions, while at wind speeds closer to

  14. Periodic bedforms generated by sublimation on terrestrial and martian ice sheets under the influence of the turbulent atmospheric boundary layer

    Science.gov (United States)

    Bordiec, Maï; Carpy, Sabrina; Perret, Laurent; Bourgeois, Olivier; Massé, Marion

    2017-04-01

    The redistribution of surface ice induced the wind flow may lead to the development and migration of periodic bedforms, or "ice ripples", at the surface of ice sheets. In certain cold and dry environments, this redistribution need not involve solid particle transport but may be dominated by sublimation and condensation, inducing mass transfers between the ice surface and the overlying steady boundary layer turbulent flow. These mass transfers diffuse the water vapour sublimated from the ice into the atmosphere and become responsible for the amplification and propagation of ripples in a direction perpendicular to their crests. Such ice ripples, 24 cm in wavelength, have been described in the so-called Blue Ice Areas of Antarctica. In order to understand the mechanisms that generate and develop these periodic bedforms on terrestrial glaciers and to evaluate the plausibility that similar bedforms may develop on Mars, we performed a linear stability analysis applied to a turbulent boundary layer flow perturbed by a wavy ice surface. The model is developed as follow. We first solve the flow dynamics using numerical methods analogous to those used in sand wave models assuming that the airflow is similar in both problems. We then add the transport/diffusion equation of water vapour following the same scheme. We use the Reynolds-averaged description of the equation with a Prandtl-like closure. We insert a damping term in the exponential formula of the Van Driest mixing length, depending on the pressure gradient felt by the flow and related to the thickness of the viscous sublayer at the ice-atmosphere interface. This formulation is an efficient way to properly represent the transitional regime under which the ripples grow. Once the mass flux of water vapour is solved, the phase shift between the ripples crests and the maximum of the flux can be deduced for different environments. The temporal evolution of the ice surface can be expressed from these quantities to infer the

  15. The study of the effects of sea-spray drops on the marine atmospheric boundary layer by direct numerical simulation

    Science.gov (United States)

    Druzhinin, Oleg A.; Troitskaya, Yuliya I.; Zilitinkevich, Sergej S.

    2017-04-01

    Detailed knowledge of the interaction of wind with surface water waves is necessary for correct parameterization of turbulent exchange at the air-sea interface in prognostic models. At sufficiently strong winds, sea-spray-generated droplets interfere with the wind-waves interaction. The results of field experiments and laboratory measurements (Andreas et al., JGR 2010) show that mass fraction of air-borne spume water droplets increases with the wind speed and their impact on the carrier air-flow may become significant. Phenomenological models of droplet-laden marine atmospheric boundary layer (Kudryavtsev & Makin, Bound.-Layer Met. 2011) predict that droplets significantly increase the wind velocity and suppress the turbulent air stress. The results of direct numerical simulation (DNS) of a turbulent particle-laden Couette flow over a flat surface show that inertial particles may significantly reduce the carrier flow vertical momentum flux (Richter & Sullivan, GRL 2013). The results also show that in the range of droplet sizes typically found near the air-sea interface, particle inertial effects are significant and dominate any particle-induced stratification effects. However, so far there has been no attempt to perform DNS of a droplet-laden air-flow over waved water surface. The objective of the present paper is to elucidate possible effects of sea spray on the momentum transfer in marine boundary layer under strong wind-forcing conditions by performing direct numerical simulation (DNS) of turbulent, droplet-laden air-flow over a waved water surface. Three-dimensional, turbulent Couette air-flow is considered in DNS as a model of a constant-flux layer in the atmospheric surface layer. Two-dimensional stationary waves at the water surface are prescribed and assumed to be unaffected by the air-flow and/or droplets. Droplets are considered as non-deformable spheres and tracked in a Lagrangian framework, and their impact on the carrier flow is modeled with the use of

  16. Exploring atmospheric boundary layer characteristics in a severe SO2 episode in the north-eastern Adriatic

    Directory of Open Access Journals (Sweden)

    Z. B. Klaić

    2009-07-01

    Full Text Available Stable atmospheric conditions are often connected with the occurrence of high pollution episodes especially in urban or industrial areas. In this work we investigate a severe SO2 episode observed on 3–5 February 2002 in a coastal industrial town of Rijeka, Croatia, where very high daily mean concentrations (up to 353.5 μg m−3 were measured. The episode occurred under high air pressure conditions, which were accompanied with a fog and low wind speeds. Three air quality models (50-km EMEP model, 10-km EMEP4HR model and 1-km CAMx model were used to simulate SO2 concentrations fields and to evaluate the relative contribution of distant and local pollution sources to observed concentrations. Results suggest that the episode was caused predominately by local sources. Furthermore, using three-dimensional, higher-order turbulence closure mesoscale meteorological model (WRF, the wind regimes and thermo-dynamical structure of the lower troposphere above the greater Rijeka area (GRA were examined in detail. Modelled atmospheric fields suggest several factors whose simultaneous acting was responsible for elevated SO2 concentrations. Established small scale wind directions supported the transport of air from nearby industrial areas with major pollution sources towards Rijeka. This transport was associated with strong, ground-based temperature inversion and correspondingly, very low mixing layer (at most up to about 140 m. Additionally, the surface winds in Rijeka were light or almost calm thus, preventing ventilation of polluted air. Finally, a vertical circulation cell formed between the mainland and a nearby island, supported the air subsidence and the increase of static stability.

  17. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Directory of Open Access Journals (Sweden)

    A. Petzold

    2008-05-01

    Full Text Available Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel−1 by number for non-volatile particles and 174±43 mg (kg fuel−1 by mass for Black Carbon (BC. Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  18. Simulation and modeling of the turbulent katabatic flow along a hyperbolic tangent slope for stably stratified atmospheric boundary layer

    Science.gov (United States)

    Brun, Ch.; Chollet, J. P.

    2009-04-01

    The behaviour of the Atmospheric Boundary layer (ABL) along alpine valleys is strongly dependent on the day-night thermodynamic cycle and might impact meteorology and air pollution prediction. At night, the ABL is stably stratified and the radiative cooling of the surface yields the development of a katabatic flow (Doran and Horst 1983, Monti et al. 2002). This flow consists of a downslope wall-jet which has the structure of both wall turbulence in the inner-layer zone and shear layer turbulence in the outer-layer zone and enhances a relative mixing eventhough stable stratification is considered (Baines 2005). A full 3D description of such flow by mean of Large Eddy Simulation of turbulence (LES) has not yet been achieved, except recently on relatively simple slopes (Skyllingstad 2003, Smith and Skyllingstad 2005) or including geostrophic wind forcing (Cuxart et al. 2006, Cuxart and Jimenez 2006). This is the purpose of the present study to accurately describe the ABL on a hyperbolic tangent slope with stable stratification. The numerical code used, Meso-NH, has been developed in CNRM/Meteo-France and Laboratoire d'Aérologie Toulouse, and consists of an anelastic non-hydrostatic model solving the pseudo-incompressible Navier-Stokes equations with a Boussinesq approximation. About 5 million grid points are necessary to afford a relatively precise description of the flow in the vicinity of the surface, with a special refinement in the vertical direction to capture the wall-jet developing along the slope. The setting of initial and boundary conditions is crucial for the simulation of stable ABL. Initial conditions consist of air at rest following a stable temperature profile with a constant Brunt-Väisälä frequency N=0.013. At the surface two sets of boundary conditions have been considered, first a rough surface condition, second an ideal case with slip conditions. A constant surface cooling q_w=-30 W/m2 is applied on the stably stratified fluid initially at rest

  19. The effect of entrainment through atmospheric boundary layer growth on observed and modeled surface ozone in the Colorado Front Range

    Science.gov (United States)

    Kaser, L.; Patton, E. G.; Pfister, G. G.; Weinheimer, A. J.; Montzka, D. D.; Flocke, F.; Thompson, A. M.; Stauffer, R. M.; Halliday, H. S.

    2017-06-01

    Ozone concentrations at the Earth's surface are controlled by meteorological and chemical processes and are a function of advection, entrainment, deposition, and net chemical production/loss. The relative contributions of these processes vary in time and space. Understanding the relative importance of these processes controlling surface ozone concentrations is an essential component for designing effective regulatory strategies. Here we focus on the diurnal cycle of entrainment through atmospheric boundary layer (ABL) growth in the Colorado Front Range. Aircraft soundings and surface observations collected in July/August 2014 during the DISCOVER-AQ/FRAPPÉ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality/Front Range Air Pollution and Photochemistry Éxperiment) campaigns and equivalent data simulated by a regional chemical transport model are analyzed. Entrainment through ABL growth is most important in the early morning, fumigating the surface at a rate of 5 ppbv/h. The fumigation effect weakens near noon and changes sign to become a small dilution effect in the afternoon on the order of -1 ppbv/h. The chemical transport model WRF-Chem (Weather Research and Forecasting Model with chemistry) underestimates ozone at all altitudes during this study on the order of 10-15 ppbv. The entrainment through ABL growth is overestimated by the model in the order of 0.6-0.8 ppbv/h. This results from differences in boundary layer growth in the morning and ozone concentration jump across the ABL top in the afternoon. This implicates stronger modeled fumigation in the morning and weaker modeled dilution after 11:00 LT.

  20. A study of the atmospheric surface layer and roughness lengths on the high-altitude tropical Zongo glacier, Bolivia

    Science.gov (United States)

    Sicart, Jean Emmanuel; Litt, Maxime; Helgason, Warren; Tahar, Vanessa Ben; Chaperon, Thomas

    2014-04-01

    The atmospheric surface layer of high-altitude tropical glaciers is inadequately understood, particularly concerning turbulent fluxes. Measurements have shown that sublimation reduces melt energy in the dry season, but the errors are large when a katabatic wind maximum occurs at a low height. This study analyzed wind and temperature vertical profiles measured by a 6 m mast in the ablation area of the tropical Zongo glacier (16°S, 5060 m above sea level) in the dry seasons of 2005 and 2007. Surface roughness lengths for momentum and temperature were derived from least squares fits of hourly wind and temperature profile data. Measurement errors were explored, focusing on the poorly defined reference level for sensor heights. A katabatic wind maximum at heights between 2 and 3 m was regularly observed during low wind speed and strong inversion conditions, or about 50%of the time, greatly reducing the surface layer depth. The glacier surface, experiencing melting conditions in the early afternoon and strong cooling at night, remained relatively smooth with z0 1 mm and zT 0.1 mm. Sensible heat flux measured at 1 m was not very sensitive to the zero reference level due to two opposite effects: when measurement heights increase, profile-derived roughness lengths increase but temperature and wind gradients decrease. The relation between zT/z0 and the roughness Reynolds number Re* roughly agrees with the surface renewal model. However, this is mostly due to self-correlation because of the shared variable z0 in zT/z0 and Re*, which prevents a sound experimental validation of the model.

  1. Integrating surface, entrainment and mesoscale in the Atmospheric Boundary Layer dynamics: a 10-year study in Cabauw (The Netherlands)

    Science.gov (United States)

    Ander Arrillaga, Jon; Bosveld, Fred; Jiménez, Pedro A.; Baltink, Henk K.; Yagüe, Carlos; Hensen, Arjan; van Dinther, Danielle; Frumau, Arnoud; Dudhia, Jimy; Zhao, Wanjun; Vilà-Guerau de Arellano, Jordi

    2017-04-01

    The diurnal evolution of the Atmospheric Boundary Layer (ABL) in Cabauw (Netherlands) is investigated by considering the role of local and non-local forcings. By local, we understand, the surface fluxes that drive the growing of the ABL in addition to the non-local entrained fluxes. We study potential disruptions occurring in spring and particularly in summer driven by the formation of sea-breeze flows in the form of density currents, due to the proximity of both The North Sea and the Ijsselmeer closed sea. Moreover, this interactive system of surface, boundary layer and mesoscale may play a role in the transport of carbon dioxide and its diurnal variability. Our method is based on the analysis of a comprehensive 10-yr observational database (2001-2010), which gives the opportunity to understand the ABL dynamics from a robust perspective. To support the analysis, modelling results obtained from the WRF mesoscale model are available during the entire 10-year period. The model is run every 48 h to maintain it close to the synoptic conditions calculated by the ERA-Interim state. A fine horizontal resolution of 2 km is used, and the vertical levels are set to match the observational ones (2, 10, 20, 40, 80, 140 and 200 m). In order to identify the sea-breeze arrival, we apply a sea-breeze criteria selection algorithm. It is developed and adapted after a sea-breeze observational study in the Cantabrian Coast (Spain) to filter the sea-breeze events occurring in Cabauw, and consequently analyse their impact in the ABL and the surface fluxes. Preliminary results show that this criteria is able to distinguish between the two main wind directions related to the sea breeze in Cabauw. Our finding shows that the sea-breeze days are characterized by a sharp increment of the wind speed and a noticeable increase of the specific humidity at around 16-17 UTC.

  2. Atmospheric boundary layer characteristics over the Pearl River Delta, China during summer 2006: measurement and model results

    Science.gov (United States)

    Fan, S. J.; Fan, Q.; Yu, W.; Luo, X. Y.; Wang, B. M.; Song, L. L.; Leong, K. L.

    2011-02-01

    Atmospheric conditions are often connected with the occurrence of high pollution episodes especially in urban areas. As part of the PRIDE-PRD2006 intensive campaign, atmospheric boundary layer (ABL) measurements were carried out at Qingyuan, Panyu and Xinken in the Pearl River Delta (PRD) from 1 July to 30 July of 2006. It was found that in summer, the surface winds in PRD are more controlled by the south, and there usually is vertical wind shear at the height of 800 m or so, therefore, PRD is often influenced by the tropical cyclone/typhoon. The subsidence and precipitation from a tropical cyclone will affect the air quality of PRD. Under the subsidence, the wind speed in ABL and the height of ABL will decrease and result in high level concentrations. When the background wind speed is small or calm, the wind profile at Panyu and Xinken change dramatically with height, which is perhaps caused by the local circulations, such as the sea land breeze. For more understanding about the ABL of PRD, the simulations by the WRF mesoscale model were used to analyse the ABL characteristics in PRD. From three kinds of weather condition simulations (subsidence days, rainy days and sunny days) by WRF model, it was found that the simulated temperature, wind fields in these three cases were moderately consistent with the measurements. The results show that the diurnal variation of ABL in subsidence days and sunny days are obvious, but the diurnal variation of ABL on rainy days is not obvious. The ABL is obviously affected by the local circulation and the features of ABL are different in various stations. A simulation focus on high pollution episode during the subsidence days from 12-15 July 2006, occurred under high pressure conditions, accompanied by a tropical cyclone "Bilis". Comparing the simulated vertical wind fields and temperature structure with the ABL measurements at Xinken, Panyu and Qingyuan station, it was found that, the modelled and measured atmospheric fields reveal

  3. On the role of large-scale forcings on the development of the atmospheric boundary layer during the BLLAST field campaign

    NARCIS (Netherlands)

    Pietersen, H.P.; Vilà-Guerau de Arellano, J.; Coster, de O.; Boer, van de A.; Hartogensis, O.K.; Pino, D.; Gioli, B.; Durand, P.; Lothon, M.; Lohou, F.; Reuder, J.; Jonassen, M.; Faloona, I.

    2012-01-01

    Guided and constrained by a complete data set of surface and upper-air observations taken during the fifth Intensive Observational Period (IOP-05, 25th June 2011) of the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) experiment, we reconstruct the evolution of the atmospheric boundary

  4. Numerical and experimental study of the load of an object due to the effects of a flow field in the atmospheric boundary layer

    Czech Academy of Sciences Publication Activity Database

    Michalcová, V.; Kuznetsov, Sergeii; Pospíšil, S.

    2014-01-01

    Roč. 8, č. 1 (2014), s. 135-140 ISSN 1998-0159 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0060 Institutional support: RVO:68378297 Keywords : atmospheric boundary layer ABL * bluff body * CFD * ELES * SAS * wind tunnel Subject RIV: JM - Building Engineering http://www.naun.org/cms.action?id=7632

  5. Implementation of non-local boundary layer schemes in the Regional Atmospheric Modeling System and its impact on simulated mesoscale circulations

    NARCIS (Netherlands)

    Gómez, I.; Ronda, R.J.; Caselles, V.; Estrela, M.J.

    2016-01-01

    This paper proposes the implementation of different non-local Planetary Boundary Layer schemes within the Regional Atmospheric Modeling System (RAMS) model. The two selected PBL parameterizations are the Medium-Range Forecast (MRF) PBL and its updated version, known as the Yonsei University (YSU)

  6. Measurements of wind turbulence parameters by a conically scanning coherent Doppler lidar in the atmospheric boundary layer

    Science.gov (United States)

    Smalikho, Igor N.; Banakh, Viktor A.

    2017-11-01

    The method and results of lidar studies of spatiotemporal variability of wind turbulence in the atmospheric boundary layer are reported. The measurements were conducted by a Stream Line pulsed coherent Doppler lidar (PCDL) with the use of conical scanning by a probing beam around the vertical axis. Lidar data are used to estimate the kinetic energy of turbulence, turbulent energy dissipation rate, integral scale of turbulence, and momentum fluxes. The dissipation rate was determined from the azimuth structure function of radial velocity within the inertial subrange of turbulence. When estimating the kinetic energy of turbulence from lidar data, we took into account the averaging of radial velocity over the sensing volume. The integral scale of turbulence was determined on the assumption that the structure of random irregularities of the wind field is described by the von Kármán model. The domain of applicability of the used method and the accuracy of the estimation of turbulence parameters were determined. Turbulence parameters estimated from Stream Line lidar measurement data and from data of a sonic anemometer were compared.

  7. CFD modelling of small particle dispersion: The influence of the turbulence kinetic energy in the atmospheric boundary layer

    Science.gov (United States)

    Gorlé, C.; van Beeck, J.; Rambaud, P.; Van Tendeloo, G.

    When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard k- ɛ model, Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the k-ɛ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46-47, 145-153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the k-ɛ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46-47, 145-153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.

  8. Immersed Boundary Methods for High-Resolution Simulation of Atmospheric Boundary-Layer Flow Over Complex Terrain

    Energy Technology Data Exchange (ETDEWEB)

    Lundquist, K A [Univ. of California, Berkeley, CA (United States)

    2010-05-12

    use of flux (non-zero) boundary conditions. This anabatic flow set-up is further coupled to atmospheric physics parameterizations, which calculate surface fluxes, demonstrating that the IBM can be coupled to various land-surface parameterizations in atmospheric models. Additionally, the IB method is extended to three dimensions, using both trilinear and inverse distance weighted interpolations. Results are presented for geostrophic flow over a three-dimensional hill. It is found that while the IB method using trilinear interpolation works well for simple three-dimensional geometries, a more flexible and robust method is needed for extremely complex geometries, as found in three-dimensional urban environments. A second, more flexible, immersed boundary method is devised using inverse distance weighting, and results are compared to the first IBM approach. Additionally, the functionality to nest a domain with resolved complex geometry inside of a parent domain without resolved complex geometry is described. The new IBM approach is used to model urban terrain from Oklahoma City in a one-way nested configuration, where lateral boundary conditions are provided by the parent domain. Finally, the IB method is extended to include wall model parameterizations for rough surfaces. Two possible implementations are presented, one which uses the log law to reconstruct velocities exterior to the solid domain, and one which reconstructs shear stress at the immersed boundary, rather than velocity. These methods are tested on the three-dimensional canonical case of neutral atmospheric boundary layer flow over flat terrain.

  9. Characteristics and sources of tephra layers in the EPICA-Dome C ice record (East Antarctica): Implications for past atmospheric circulation and ice core stratigraphic correlations [rapid communication

    Science.gov (United States)

    Narcisi, B.; Petit, J. R.; Delmonte, B.; Basile-Doelsch, I.; Maggi, V.

    2005-11-01

    Thirteen discrete air-fall tephra layers were identified in the last 200,000-yr section of the EPICA-Dome C ice record drilled in the East Antarctic plateau (75°06'S, 123°21'E). Quantitative grain size, glass particle morphology, and the grain-discrete major element composition of the glass fraction of these layers were investigated. Through comparison with literature data on the rock composition of Quaternary volcanic centres located within and around Antarctica, five tephra layers were attributed to South Sandwich volcanoes in the South Atlantic Ocean, two to South Shetland volcanoes (northern Antarctic Peninsula), two to Andean volcanoes, and four to Antarctic (Marie Byrd Land and Melbourne) provinces. The abundance of layers originating in the southern part of the Atlantic confirms that westerly atmospheric circulation spiralling towards East Antarctica prevailed over the last 200 ka. Moreover, the record of events from Antarctic centres suggests that atmospheric trajectories from West to East Antarctica can also be significant. A few ash layers are geochemically distinct and appear equivalent to levels from Vostok and Dome Fuji deep ice records, located ca. 600 km and ca. 2000 km, respectively, from Dome C on the Antarctic plateau. These layers provide unambiguous markers for future correlation with other Antarctic ice cores and circumpolar marine climatic records. They also provide reliable constraints to get a common timescale by glaciological modelling, and represent a first step towards absolute ice core dating.

  10. Atmospheric boundary layer characteristics over the Pearl River Delta, China, during the summer of 2006: measurement and model results

    Directory of Open Access Journals (Sweden)

    S. J. Fan

    2011-07-01

    Full Text Available As part of the PRIDE-PRD2006 intensive campaign, atmospheric boundary layer (ABL measurements were performed in Qingyuan, Panyu, and Xinken over the Pearl River Delta (PRD on 1–30 July 2006. During the summer, the surface winds over the PRD are generally controlled by the south, usually with vertical wind shear at a height of approximately 800 m. Subsidence and precipitation from a tropical cyclone affects the air quality of the PRD. Under subsidence, wind speed in the ABL and the height of the ABL decrease and result in high-level concentrations. When the background wind speed is small or calm, the wind profile in Panyu and Xinken changes dramatically with height, which is perhaps caused by local circulation, such as sea-land breezes. To better understand the ABL of the PRD, simulations that used the Weather Research and Forecasting (WRF mesoscale model were utilized to analyze the ABL characteristics over the PRD. Based on three types of weather condition simulations (i.e., subsidence days, rainy days, and sunny days, the WRF model revealed that the simulated temperature and wind fields in these three cases were moderately consistent with the measurements. The results showed that diurnal variations of the ABL height on subsidence days and sunny days were obvious, but diurnal variations of the ABL height on rainy days were not apparent. The ABL is obviously affected by local circulation, and the ABL features are different at various stations. A simulation focused on a high pollution episode during the subsidence days on 12–15 July 2006, occurred under high-pressure conditions, accompanied by the tropical cyclone "Bilis". A comparison of the simulated vertical wind fields and temperature structure with the ABL measurements at Xinken, Panyu, and Qingyuan stations found that the modeled and measured atmospheric fields revealed two different types of ABL characteristics over the PRD. When the surface winds over the PRD were light or nearly calm

  11. Contrasting atmospheric boundary layer chemistry of methylhydroperoxide (CH3OOH and hydrogen peroxide (H2O2 above polar snow

    Directory of Open Access Journals (Sweden)

    D. K. Friel

    2009-05-01

    Full Text Available Atmospheric hydroperoxides (ROOH were measured at Summit, Greenland (72.97° N, 38.77° W in summer 2003 (SUM03 and spring 2004 (SUM04 and South Pole in December 2003 (SP03. The two dominant hydroperoxides were H2O2 and CH3OOH (from here on MHP with average (±1σ mixing ratios of 1448 (±688 pptv, 204 (±162 and 278 (±67 for H2O2 and 578 (±377 pptv, 139 (±101 pptv and 138 (±89 pptv for MHP, respectively. In early spring, MHP dominated the ROOH budget and showed night time maxima and daytime minima, out of phase with the diurnal cycle of H2O2, suggesting that the organic peroxide is controlled by photochemistry, while H2O2 is largely influenced by temperature driven exchange between the atmosphere and snow. Highly constrained photochemical box model runs yielded median ratios between modeled and observed MHP of 52%, 148% and 3% for SUM03, SUM04 and SP03, respectively. At Summit firn air measurements and model calculations suggest a daytime sink of MHP in the upper snow pack, which decreases in strength through the spring season into the summer. Up to 50% of the estimated sink rates of 1–5×1011 molecules m−3 s−1 equivalent to 24–96 pptv h−1 can be explained by photolysis and reaction with the OH radical in firn air and in the quasi-liquid layer on snow grains. Rapid processing of MHP in surface snow is expected to contribute significantly to a photochemical snow pack source of formaldehyde (CH2O. Conversely, summer levels of MHP at South Pole are inconsistent with the prevailing high NO concentrations, and cannot be explained currently by known photochemical precursors or transport, thus suggesting a missing source. Simultaneous measurements of H2O2, MHP and CH2O allow to constrain the NO background today and potentially also in the past using ice cores, although it seems less likely that MHP is preserved in firn and ice.

  12. Effect of atmospheric-pressure plasma treatment on the adhesion properties of a thin adhesive layer in a selective transfer process

    Science.gov (United States)

    Yoon, Min-Ah; Kim, Chan; Hur, Min; Kang, Woo Seok; Kim, Jaegu; Kim, Jae-Hyun; Lee, Hak-Joo; Kim, Kwang-Seop

    2018-01-01

    The adhesion between a stamp and thin film devices is crucial for their transfer on a flexible substrate. In this paper, a thin adhesive silicone layer on the stamp was treated by atmospheric pressure plasma to locally control the adhesion strength for the selective transfer. The adhesion strength of the silicone layer was significantly reduced after the plasma treatment, while its surface energy was increased. To understand the inconsistency between the adhesion strength and surface energy changes, the surface properties of the silicone layer were characterized using nanoindentation and X-ray photoelectron spectroscopy. These techniques revealed that a thin, hard, silica-like layer had formed on the surface from plasma-enhanced oxidation. This layer played an important role in decreasing the contact area and increasing the interfacial slippage, resulting in decreased adhesion. As a practical application, the transfer process was demonstrated on GaN LEDs that had been previously delaminated by a laser lift-off (LLO) process. Although the LEDs were not transferred onto the treated adhesive layer due to the reduced adhesion, the untreated adhesive layer could readily pick up the LEDs. It is expected that this simple method of controlling the adhesion of a stamp with a thin adhesive layer would enable a continuous, selective and large-scale roll-to-roll selective transfer process and thereby advance the development of flexible, stretchable and wearable electronics.

  13. RETRACTED ARTICLE: Validation of mean and turbulent parameters measured from the aircraft in the marine atmospheric boundary layer

    Science.gov (United States)

    Kwon, Byung Hyuk; Lee, Gyuwon

    2010-11-01

    The SEMAPHORE (Structure des Echanges Mer-Atmosphère, Propriétés Océaniques/ Recherche Expérimentale) experiment, which took place between 04 Oct. and 17 Nov. 1993, was conducted over the oceanic Azores current located in the Azores basin. The SST (Sea Surface Temperature) field was characterized in the SEMAPHORE area (31°-38°N; 21°-28°W) by a large meander with a SST gradient of about 1°C per 100 km. In order to study the evolution of the MABL (Marine Atmospheric Boundary Layer) over the ocean, the mean and the turbulent data were evaluated by the measurement with two aircraft and a ship in different meteorological conditions. Three cases of low pressure and three cases of high pressure are mainly presented here. For the six cases, the satellite images (NOAA) did not show any relation between the SST field and the cloud cover. At each flight level, the decrease of the SST with the altitude due to the divergence of the infrared radiation flux from the ocean is 0.25°C per 100 m. For the comparison between the two aircraft, the mean thermodynamic and dynamic parameters show a good agreement except for the temperature. The dispersion of the sensible heat flux is larger than that of the latent heat flux due to the weak sensible heat flux over the ocean both in the intercomparison between two aircraft and in the comparison between the aircraft and the ship.

  14. Application of remotely piloted aircraft systems in observing the atmospheric boundary layer over Antarctic sea ice in winter

    Directory of Open Access Journals (Sweden)

    Marius O. Jonassen

    2015-10-01

    Full Text Available The main aim of this paper is to explore the potential of combining measurements from fixed- and rotary-wing remotely piloted aircraft systems (RPAS to complement data sets from radio soundings as well as ship and sea-ice-based instrumentation for atmospheric boundary layer (ABL profiling. This study represents a proof-of-concept of RPAS observations in the Antarctic sea-ice zone. We present first results from the RV Polarstern Antarctic winter expedition in the Weddell Sea in June–August 2013, during which three RPAS were operated to measure temperature, humidity and wind; a fixed-wing small unmanned meteorological observer (SUMO, a fixed-wing meteorological mini-aerial vehicle, and an advanced mission and operation research quadcopter. A total of 86 RPAS flights showed a strongly varying ABL structure ranging from slightly unstable temperature stratification near the surface to conditions with strong surface-based temperature inversions. The RPAS observations supplement the regular upper air soundings and standard meteorological measurements made during the campaign. The SUMO and quadcopter temperature profiles agree very well and, excluding cases with strong temperature inversions, 70% of the variance in the difference between the SUMO and quadcopter temperature profiles can be explained by natural, temporal, temperature fluctuations. Strong temperature inversions cause the largest differences, which are induced by SUMO's high climb rates and slow sensor response. Under such conditions, the quadcopter, with its slower climb rate and faster sensor, is very useful in obtaining accurate temperature profiles in the lowest 100 m above the sea ice.

  15. Influence of the voltage waveform during nanocomposite layer deposition by aerosol-assisted atmospheric pressure Townsend discharge

    Energy Technology Data Exchange (ETDEWEB)

    Profili, J. [LAPLACE, Université de Toulouse, CNRS, INPT, UPS, Toulouse (France); Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada); Levasseur, O.; Stafford, L. [Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada); Naudé, N.; Gherardi, N., E-mail: nicolas.gherardi@laplace.univ-tlse.fr [LAPLACE, Université de Toulouse, CNRS, INPT, UPS, Toulouse (France); Chaneac, C. [Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Collège de France, Laboratoire de Chimie de la Matière Condensée de Paris (CMCP), 4 place Jussieu, F-75005 Paris (France)

    2016-08-07

    This work examines the growth dynamics of TiO{sub 2}-SiO{sub 2} nanocomposite coatings in plane-to-plane Dielectric Barrier Discharges (DBDs) at atmospheric pressure operated in a Townsend regime using nebulized TiO{sub 2} colloidal suspension in hexamethyldisiloxane as the growth precursors. For low-frequency (LF) sinusoidal voltages applied to the DBD cell, with voltage amplitudes lower than the one required for discharge breakdown, Scanning Electron Microscopy of silicon substrates placed on the bottom DBD electrode reveals significant deposition of TiO{sub 2} nanoparticles (NPs) close to the discharge entrance. On the other hand, at higher frequencies (HF), the number of TiO{sub 2} NPs deposited strongly decreases due to their “trapping” in the oscillating voltage and their transport along the gas flow lines. Based on these findings, a combined LF-HF voltage waveform is proposed and used to achieve significant and spatially uniform deposition of TiO{sub 2} NPs across the whole substrate surface. For higher voltage amplitudes, in the presence of hexamethyldisiloxane and nitrous oxide for plasma-enhanced chemical vapor deposition of inorganic layers, it is found that TiO{sub 2} NPs become fully embedded into a silica-like matrix. Similar Raman spectra are obtained for as-prepared TiO{sub 2} NPs and for nanocomposite TiO{sub 2}-SiO{sub 2} coating, suggesting that plasma exposure does not significantly alter the crystalline structure of the TiO{sub 2} NPs injected into the discharge.

  16. An eddy covariance system to characterize the atmospheric surface layer and turbulent latent heat fluxes over a debris-covered Himalayan glacier.

    Science.gov (United States)

    Litt, Maxime; Steiner, Jakob F.; Stigter, Emmy E.; Immerzeel, Walter; Shea, Joseph Michael

    2017-04-01

    Over debris-covered glaciers, water content variations in the debris layer can drive significant changes in its thermal conductivity and significantly impact melt rates. Since sublimation and evaporation are favoured in high-altitude conditions, e.g., low atmospheric pressure and high wind speeds, they are expected to strongly influence the water balance of the debris-layer. Dedicated latent heat fluxes measurements at the debris surface are essential to characterize the debris heat conductivity in order to assess underlying ice melt. Furthermore, the contribution of the turbulent fluxes in the surface energy balance over debris covered glacier remains uncertain since they are generally evaluated through similarity methods which might not be valid in complex terrain. We present the first results of a 15-day eddy-covariance experiment installed at the end of the monsoon (September-October) on a 3-m tower above the debris-covered Lirung glacier in Nepal. The tower also included measurements of the 4 radiation components. The eddy covariance measurements allowed for the characterization of the turbulence in the atmospheric surface layer, as well as the direct measurements of evaporation, sublimation and turbulent sensible heat fluxes. The experiment helps us to evaluate the contribution of turbulent fluxes to the surface energy balance over this debris-covered glacier, through a precise characterization of the overlying turbulent atmospheric surface layer. It also helps to study the role of the debris-layer water content changes through evaporation and sublimation and its feedback on heat conduction in this layer. The large observed turbulent fluxes play a significant role in the energy balance at the debris surface and significantly influence debris moisture, conductivity and subsequently underlying ice melt.

  17. The role of local atmospheric forcing on the modulation of the ocean mixed layer depth in reanalyses and a coupled single column ocean model

    Science.gov (United States)

    Pookkandy, Byju; Dommenget, Dietmar; Klingaman, Nicholas; Wales, Scott; Chung, Christine; Frauen, Claudia; Wolff, Holger

    2016-11-01

    The role of local atmospheric forcing on the ocean mixed layer depth (MLD) over the global oceans is studied using ocean reanalysis data products and a single-column ocean model coupled to an atmospheric general circulation model. The focus of this study is on how the annual mean and the seasonal cycle of the MLD relate to various forcing characteristics in different parts of the world's oceans, and how anomalous variations in the monthly mean MLD relate to anomalous atmospheric forcings. By analysing both ocean reanalysis data and the single-column ocean model, regions with different dominant forcings and different mean and variability characteristics of the MLD can be identified. Many of the global oceans' MLD characteristics appear to be directly linked to the different atmospheric forcing characteristics at different locations. Here, heating and wind-stress are identified as the main drivers; in some, mostly coastal, regions the atmospheric salinity forcing also contributes. The annual mean MLD is more closely related to the annual mean wind-stress and the MLD seasonality is more closely related to the seasonality in heating. The single-column ocean model, however, also points out that the MLD characteristics over most global ocean regions, and in particular in the tropics and subtropics, cannot be maintained by local atmospheric forcings only, but are also a result of ocean dynamics that are not simulated in a single-column ocean model. Thus, lateral ocean dynamics are essential in correctly simulating observed MLD.

  18. Modification of surface layers of copper under the action of the volumetric discharge initiated by an avalanche electron beam in nitrogen and CO2 at atmospheric pressure

    Science.gov (United States)

    Shulepov, M. A.; Akhmadeev, Yu. Kh.; Tarasenko, V. F.; Kolubaeva, Yu. A.; Krysina, O. V.; Kostyrya, I. D.

    2011-05-01

    The results of experimental investigations of the action of the volumetric discharge initiated by an avalanche electron beam on the surface of copper specimens are presented. The volumetric (diffuse) discharge in nitrogen and CO2 at atmospheric pressure was initiated by applying high voltage pulses of nanosecond duration to a tubular foil cathode. It has been found that the treatment of a copper surface by this type of discharge increases the hardness of the surface layer due to oxidation.

  19. Ångström coefficient as an indicator of the atmospheric aerosol type for a well-mixed atmospheric boundary layer : Part 1: Model development

    NARCIS (Netherlands)

    Kuśmierczyk-Michulec, J.T.

    2009-01-01

    The physical and optical properties of an atmospheric aerosol mixture depend on a number of factors. The relative humidity influences the size of hydroscopic particles and the effective radius of an aerosol mixture. In consequence, values of the aerosol extinction, the aerosol optical thickness and

  20. Simulation of the evolution of particle size distributions containing coarse particulate in the atmospheric surface layer with a simple convection-diffusion-sedimentation model

    Science.gov (United States)

    Hubbard, J. A.; Haglund, J. S.; Ezekoye, O. A.

    The Fugitive Dust Model (FDM) and Industrial Source Complex (ISC), widely used coarse particulate dispersion models, have been shown inaccurate due to the neglect of vertical variations in atmospheric wind speed and turbulent diffusivity (Vesovic et al., 2001), omission of the gravitational advection velocity, and an underestimation of the ground deposition velocity (Kim and Larson, 2001). A simple, transient two-dimensional convection-diffusion-sedimentation model is proposed to simulate the evolution in particle size distribution of an aerosol 'puff' containing coarse particulate in the atmospheric surface layer. Monin-Okhubov similarity theory, accompanied by empirical observations made by Businger et al. (1971), is adopted to characterize the surface layer wind speed and turbulent diffusivity profiles over a wide range of atmospheric conditions. A first order analysis of the crossing trajectories effect suggests simulation data presented here are not significantly affected by particle inertia. The model is validated against Suffield experimental data in which coarse particulate deposition was measured out to a distance of 800 m from the source (Walker, 1965). Good agreement is found for the decay in ground deposits with distance from the source for stable atmospheres. Deposition data was also simulated for unstable atmospheric stratification and the current model was determined to modestly underestimate the peak concentration with increasing accuracy further downwind of the release. The current model's effective deposition velocity was compared to that suggested by Kim et al. (2000) and shows improvement with respect to FDM. Lastly, the model was used to simulate the dispersion of nine lognormal aerosol puffs in the lowest 50 m of the atmospheric surface layer for four classes of atmospheric stability. The simulated mass median aerodynamic diameters (MMAD) at multiple downwind sampling locations were calculated and plotted with distance from the source. The

  1. An Investigation on the role of Planetary Boundary Layer Parameterization scheme on the performance of a hydrostatic atmospheric model over a Coastal Region

    Science.gov (United States)

    Anurose, J. T.; Subrahamanyam, Bala D.

    2012-07-01

    As part of the ocean/land-atmosphere interaction, more than half of the total kinetic energy is lost within the lowest part of atmosphere, often referred to as the planetary boundary layer (PBL). A comprehensive understanding of the energetics of this layer and turbulent processes responsible for dissipation of kinetic energy within the PBL require accurate estimation of sensible and latent heat flux and momentum flux. In numerical weather prediction (NWP) models, these quantities are estimated through different surface-layer and PBL parameterization schemes. This research article investigates different factors influencing the accuracy of a surface-layer parameterization scheme used in a hydrostatic high-resolution regional model (HRM) in the estimation of surface-layer turbulent fluxes of heat, moisture and momentum over the coastal regions of the Indian sub-continent. Results obtained from this sensitivity study of a parameterization scheme in HRM revealed the role of surface roughness length (z_{0}) in conjunction with the temperature difference between the underlying ground surface and atmosphere above (ΔT = T_{G} - T_{A}) in the estimated values of fluxes. For grid points over the land surface where z_{0} is treated as a constant throughout the model integration time, ΔT showed relative dominance in the estimation of sensible heat flux. In contrast to this, estimation of sensible and latent heat flux over ocean were found to be equally sensitive on the method adopted for assigning the values of z_{0} and also on the magnitudes of ΔT.

  2. A Large-Eddy Simulation Study of Vertical Axis Wind Turbine Wakes in the Atmospheric Boundary Layer

    Science.gov (United States)

    Shamsoddin, Sina; Porté-Agel, Fernando

    2017-04-01

    In a future sustainable energy vision, in which diversified conversion of renewable energies is essential, vertical axis wind turbines (VAWTs) exhibit some potential as a reliable means of wind energy extraction alongside conventional horizontal axis wind turbines (HAWTs). Nevertheless, there is currently a relative shortage of scientific, academic and technical investigations of VAWTs as compared to HAWTs. Having this in mind, in this work, we aim to, for the first time, study the wake of a single VAWT placed in the atmospheric boundary layer using large-eddy simulation (LES). To do this, we use a previously-validated LES framework in which an actuator line model (ALM) is incorporated. First, for a typical three- and straight-bladed 1-MW VAWT design, the variation of the power coefficient with both the chord length of the blades and the tip-speed ratio is analyzed by performing 117 simulations using LES-ALM. The optimum combination of solidity (defined as Nc/R, where N is the number of blades, c is the chord length and R is the rotor radius) and tip-speed ratio is found to be 0.18 and 4.5, respectively. Subsequently, the wake of a VAWT with these optimum specifications is thoroughly examined by showing different relevant mean and turbulence wake flow statistics. It is found that for this case, the maximum velocity deficit at the equator height of the turbine occurs 2.7 rotor diameters downstream of the center of the turbine, and only after that point, the wake starts to recover. Moreover, it is observed that the maximum turbulence intensity (TI) at the equator height of the turbine occurs at a distance of about 3.8 rotor diameters downstream of the turbine. As we move towards the upper and lower edges of the turbine, the maximum TI (at a certain height) increases, and its location moves relatively closer to the turbine. Furthermore, whereas both TI and turbulent momentum flux fields show clear vertical asymmetries (with larger magnitudes at the upper wake edge

  3. A Large-Eddy Simulation Study of Vertical Axis Wind Turbine Wakes in the Atmospheric Boundary Layer

    Directory of Open Access Journals (Sweden)

    Sina Shamsoddin

    2016-05-01

    Full Text Available In a future sustainable energy vision, in which diversified conversion of renewable energies is essential, vertical axis wind turbines (VAWTs exhibit some potential as a reliable means of wind energy extraction alongside conventional horizontal axis wind turbines (HAWTs. Nevertheless, there is currently a relative shortage of scientific, academic and technical investigations of VAWTs as compared to HAWTs. Having this in mind, in this work, we aim to, for the first time, study the wake of a single VAWT placed in the atmospheric boundary layer using large-eddy simulation (LES. To do this, we use a previously-validated LES framework in which an actuator line model (ALM is incorporated. First, for a typical three- and straight-bladed 1-MW VAWT design, the variation of the power coefficient with both the chord length of the blades and the tip-speed ratio is analyzed by performing 117 simulations using LES-ALM. The optimum combination of solidity (defined as N c / R , where N is the number of blades, c is the chord length and R is the rotor radius and tip-speed ratio is found to be 0.18 and 4.5, respectively. Subsequently, the wake of a VAWT with these optimum specifications is thoroughly examined by showing different relevant mean and turbulence wake flow statistics. It is found that for this case, the maximum velocity deficit at the equator height of the turbine occurs 2.7 rotor diameters downstream of the center of the turbine, and only after that point, the wake starts to recover. Moreover, it is observed that the maximum turbulence intensity (TI at the equator height of the turbine occurs at a distance of about 3.8 rotor diameters downstream of the turbine. As we move towards the upper and lower edges of the turbine, the maximum TI (at a certain height increases, and its location moves relatively closer to the turbine. Furthermore, whereas both TI and turbulent momentum flux fields show clear vertical asymmetries (with larger magnitudes at the

  4. The role of ozone atmosphere-snow gas exchange on polar, boundaru-layer tropospheric ozone - a review sensitivity analysis

    NARCIS (Netherlands)

    Helmig, D.; Ganzeveld, L.N.; Butler, T.; Oltmans, S.

    2007-01-01

    Recent research on snowpack processes and atmosphere-snow gas exchange has demonstrated that chemical and physical interactions between the snowpack and the overlaying atmosphere have a substantial impact on the composition of the lower troposphere. These observations also imply that ozone

  5. NOAA Climate Data Record of Microwave Sounding Unit (MSU) Mean Atmospheric Layer Temperature, Version 1.2 (Superseded)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Please note, this dataset has been superseded by a newer version (see below). Users should not use this version except in rare cases (e.g., when reproducing previous...

  6. Ångström coefficient as an indicator of the atmospheric aerosol type for a well-mixed atmospheric boundary layer: Part 1: Model development

    Directory of Open Access Journals (Sweden)

    Jolanta Kuśmierczyk-Michulec

    2009-03-01

    Full Text Available The physical and optical properties of an atmospheric aerosol mixture depend on a number of factors. The relative humidity influences the size of hydroscopic particles and the effective radius of an aerosol mixture. In consequence, values of the aerosol extinction, the aerosol optical thickness and the Ångström coefficient are modified. A similar effect is observed when the aerosol composition changes. A higher content of small aerosol particles causes the effective radius of an aerosol mixture to decrease and the Ångström coefficient to increase. Both effects are analysed in this paper. The parameters of the size distribution and the type of components used to represent natural atmospheric aerosol mixtures are based on experimental data. The main components are sea-salts (SSA, anthropogenic salts (WS, e.g. NH4HSO4, NH4NO3, (NH42 SO4, organic carbon (OC and black carbon (BC. The aerosol optical thickness is modelled using the external mixing approach. The influence of relative humidity on the optical and physical properties of the following aerosol mixtures is investigated: (SSA & WS, (SSA & OC, (SSA & BC, (SSA, WS & OC and (WS, OC & BC. It is demonstrated that the Ängström coefficient can be used as a rough indicator of the aerosol type.

  7. Parallelisation and application of a multi-layer atmospheric transport model to quantify dispersion and deposition of ammonia over the British Isles.

    Science.gov (United States)

    Fournier, N; Pais, V A; Sutton, M A; Weston, K J; Dragosits, U; Tang, S Y; Aherne, J

    2002-01-01

    An atmospheric transport model, FRAME (Fine Resolution AMmonia Exchange), has been used to model the spatial pattern of ammonia concentrations and deposition over the British Isles for the first time. The model uses a multi-layer approach with diffusion through 33 layers to describe vertical concentration profiles in the atmosphere explicitly. Together with the necessary description of atmospheric reactions with sulphur and oxidised nitrogen, this imposes a major computational requirement, with the model having a run-time of 8.5 days on a mid-range workstation. Improvement in the model run-time was sought by developing a parallel implementation coded in a data-parallel approach using High Performance Fortran. Running the code on a Cray T3E with 128 processors provided a speedup by a factor of 69. The code's portability, its validation with measurements and new maps of its application to the British Isles, are presented. Good agreement is found with measured NH3 concentrations, while wet de-position is underestimated. In addition to model uncertainties, this may be due to an underestimation of the NH3 emissions input data.

  8. Impact of the Loess Plateau on the atmospheric boundary layer structure and air quality in the North China Plain: a case study.

    Science.gov (United States)

    Hu, Xiao-Ming; Ma, ZhiQiang; Lin, Weili; Zhang, Hongliang; Hu, Jianlin; Wang, Ying; Xu, Xiaobin; Fuentes, Jose D; Xue, Ming

    2014-11-15

    The North China Plain (NCP), to the east of the Loess Plateau, experiences severe regional air pollution. During the daytime in the summer, the Loess Plateau acts as an elevated heat source. The impacts of such a thermal effect on meteorological phenomena (e.g., waves, precipitation) in this region have been discussed. However, its impacts on the atmospheric boundary layer structure and air quality have not been reported. It is hypothesized that the thermal effect of the Plateau likely modulates the boundary layer structure and ambient concentrations of pollutants over the NCP under certain meteorological conditions. Thus, this study investigates such effect and its impacts using measurements and three-dimensional model simulations. It is found that in the presence of daytime westerly wind in the lower troposphere (~1 km above the NCP), warmer air above the Loess Plateau was transported over the NCP and imposed a thermal inversion above the mixed boundary layer, which acted as a lid and suppressed the mixed layer growth. As a result, pollutants accumulated in the shallow mixed layer and ozone was efficiently produced. The downward branch of the thermally-induced Mountain-Plains Solenoid circulation over the NCP contributed to enhancing the capping inversion and exacerbating air pollution. Previous studies have reported that low mixed layer, a factor for elevated pollution in the NCP, may be caused by aerosol scattering and absorption of solar radiation, frontal inversion, and large scale subsidence. The present study revealed a different mechanism (i.e., westerly warm advection) for the suppression of the mixed layer in summer NCP, which caused severe O3 pollution. This study has important implications for understanding the essential meteorological factors for pollution episodes in this region and forecasting these severe events. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site

    Energy Technology Data Exchange (ETDEWEB)

    Pal, S., E-mail: sp5hd@Virginia.EDU; Lee, T.R.; Phelps, S.; De Wekker, S.F.J.

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (z{sub i}), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime z{sub i} from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the z{sub i} and the fine fraction (0.3–0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality. - Highlights: • Role of atmospheric boundary layer depth on particle

  10. Atmospheric boundary layer CO2remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

    Science.gov (United States)

    Cadiou, Erwan; Mammez, Dominique; Dherbecourt, Jean-Baptiste; Gorju, Guillaume; Pelon, Jacques; Melkonian, Jean-Michel; Godard, Antoine; Raybaut, Myriam

    2017-10-15

    We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO 2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

  11. Detecting spectrally localized components of lunar tide-frequency in time-series of the electric field vertical component of the earth atmosphere boundary layer

    CERN Document Server

    Isakevich, V V; Isakevich, D V

    2016-01-01

    Using the signal eigenvectors and components analyser (Grunskaya L.V., Isakevich V.V., Isakevich D.V. the RF Utility Model Patent 116242 of 30.09.2011) made it possible to detect non-coherent complex-period components localized at lunar tide frequencies in the time-series of the electric field vertical component of the Earth atmosphere boundary layer. The detected components are unobservable by means of spectral analysis quadrature scheme. The probability of the detected effects being pseudo-estimates is not more than 0.00025

  12. Vertical variations in the turbulent structure of the surface boundary layer over vineyards under unstable atmospheric conditions

    Science.gov (United States)

    Due to their highly-structured canopy, turbulent characteristics within and above vineyards, may not conform to those typically exhibited by other agricultural and natural ecosystems. Using data collected as a part of the Grape Remote sensing and Atmospheric Profiling and Evapotranspiration Experime...

  13. Variability of the Structure Parameters of Temperature and Humidity Observed in the Atmospheric Surface Layer Under Unstable Conditions

    NARCIS (Netherlands)

    Braam, M.; Moene, A.F.; Beyrich, F.

    2014-01-01

    The structure parameters of temperature and humidity are important in scintillometry as they determine the structure parameter of the refractive index of air, the primary atmospheric variable obtained with scintillometers. In this study, we investigate the variability of the logarithm of the

  14. Lifetimes of organic photovoltaics: photochemistry, atmosphere effects and barrier layers in ITO-MEHPPV:PCBM-aluminium devices

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Carlé, Jon Eggert; Cruys-Bagger, N.

    2005-01-01

    Large area polymer photovoltaic cells based on poly[(2-methoxy-5-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) were prepared. The lifetimes of the photovoltaic cells were studied in terms of the atmosphere, handling, electrode treatment, m...

  15. Thermodynamic structure of the Atmospheric Boundary Layer over the Arabian Sea and the Indian Ocean during pre-INDOEX and INDOEX-FFP campaigns

    Directory of Open Access Journals (Sweden)

    M. V. Ramana

    2004-09-01

    Full Text Available Spatial and temporal variability of the Marine Atmospheric Boundary Layer (MABL height for the Indian Ocean Experiment (INDOEX study period are examined using the data collected through Cross-chained LORAN (Long-Range Aid to Navigation Atmospheric Sounding System (CLASS launchings during the Northern Hemispheric winter monsoon period. This paper reports the results of the analyses of the data collected during the pre-INDOEX (1997 and the INDOEX-First Field Phase (FFP; 1998 in the latitude range 14°N to 20°S over the Arabian Sea and the Indian Ocean. Mixed layer heights are derived from thermodynamic profiles and they indicated the variability of heights ranging from 400m to 1100m during daytime depending upon the location. Mixed layer heights over the Indian Ocean are slightly higher during the INDOEX-FFP than the pre-INDOEX due to anomalous conditions prevailing during the INDOEX-FFP. The trade wind inversion height varied from 2.3km to 4.5km during the pre-INDOEX and from 0.4km to 2.5km during the INDOEX-FFP. Elevated plumes of polluted air (lofted aerosol plumes above the marine boundary layer are observed from thermodynamic profiles of the lower troposphere during the INDOEX-FFP. These elevated plumes are examined using 5-day back trajectory analysis and show that one group of air mass travelled a long way from Saudi Arabia and Iran/Iraq through India before reaching the location of measurement, while the other air mass originates from India and the Bay of Bengal.

  16. Modeling coastal aerosol transport and effects of surf-produced aerosols on processes in the marine atmospheric boundary layer

    NARCIS (Netherlands)

    Vignati, E.; Leeuw, G. de; Berkowicz, R.

    2001-01-01

    The Coastal Aerosol Transport (CAT) model was developed to study the evolution of aerosol particle size distributions and composition in the coastal environment. The model simulates such processes as particle production at the sea surface, mixing of particles through the boundary layer by turbulent

  17. Recent Advances in Modeling of the Atmospheric Boundary Layer and Land Surface in the Coupled WRF-CMAQ Model

    Science.gov (United States)

    Advances in the land surface model (LSM) and planetary boundary layer (PBL) components of the WRF-CMAQ coupled meteorology and air quality modeling system are described. The aim of these modifications was primarily to improve the modeling of ground level concentrations of trace c...

  18. Performance of WRF in simulating terrain induced flows and atmospheric boundary layer characteristics over the tropical station Gadanki

    Science.gov (United States)

    Hari Prasad, K. B. R. R.; Srinivas, C. V.; Rao, T. Narayana; Naidu, C. V.; Baskaran, R.

    2017-03-01

    In this study the evolution of the topographic flows and boundary layer features over a tropical hilly station Gadanki in southern India were simulated using Advanced Research WRF (ARW) mesoscale model for fair weather days during southwest monsoon (20-22 July 2011) and winter (18-20 Jan. 2011). Turbulence measurements from an Ultra High Frequency (UHF) Wind Profiler, Ultra Sonic Anemometer, GPS Sonde and meteorological tower were used for comparison. Simulations revealed development of small-scale slope winds in the lower boundary layer (below 800 m) at Gadanki which are more prevalent during nighttime. Stronger slope winds during winter and weaker flows in the monsoon season are simulated indicating the sensitivity of slope winds to the background synoptic flows and radiative heating/cooling. Higher upward surface fluxes (sensible, latent heat) and development of very deep convective boundary layer ( 2500 m) is simulated during summer monsoon relative to the winter season in good agreement with observations. Four PBL parameterizations (YSU, MYJ, MYNN and ACM) were evaluated to simulate the above characteristics. Large differences were noticed in the simulated boundary layer features using different PBL schemes in both the seasons. It is found that the TKE-closures (MYJ, MYNN) produced extremities in daytime PBL depth, surface fluxes, temperature, humidity and winds. The differences in the simulations are attributed to the eddy diffusivities, buoyancy and entrainment fluxes which were simulated differently in the respective schemes. The K-based YSU followed by MYNN best produced the slope winds as well as daytime boundary layer characteristics realistically in both the summer and winter synoptic conditions at Gadanki hilly site though with slight overestimation of nocturnal PBL height.

  19. Double Compressions of Atmospheric Depth by Geopotential Tendency, Vorticity, and Atmospheric Boundary Layer Affected Abrupt High Particulate Matter Concentrations at a Coastal City for a Yellow Dust Period in October

    Directory of Open Access Journals (Sweden)

    Hyo Choi

    2014-01-01

    Full Text Available Using GRIMM-aerosol sampler, NOAA-HYSPLIT model, and 3D-WRF-3.3 model, the transportation of dusts from Gobi Desert toward Gangneung city, Korea was investigated from 09:00 LST October 27 to 04:00 LST October 28, 2003. Maximum PM10 (PM2.5, PM1 concentration was detected with 3.8 (3.4, 14.1 times higher magnitude than one in non-Yellow Dust period. The combination of dusts transported from the desert under westerly wind with particulate matters and gases from vehicles on the road of the city caused high PM concentrations near the ground surface at 09:00 LST and their maxima at 17:00 LST near sunset with further pollutants from heating boilers in the resident area. Positive geopotential tendency at the 500 hPa level of the city (∂Φ/∂t; m day−1 corresponding to negative vorticity of -4×10-5 sec−1 (-2.5×10-5 sec−1 at 0900 LST (21:00 LST; at night was +83 m day−1 (+30 m day−1 and it caused atmospheric depth between 500 hPa level and the ground surface to be vertically expanded. However, its net reduction to −53 m/12 hrs until 21:00 LST indicated synoptic-scale atmospheric layer to be vertical shrunken, resulting in the increase of PM concentrations at 17:00 LST. Simultaneously, much shallower microscale stable nocturnal surface inversion layer (NSIL than daytime thermal internal boundary layer induced particulate matters to be merged inside the NSIL, resulting in maximum PM concentrations at 17:00 LST.

  20. A Lagrangian stochastic model to demonstrate multi-scale interactions between convection and land surface heterogeneity in the atmospheric boundary layer

    Science.gov (United States)

    Parsakhoo, Zahra; Shao, Yaping

    2017-04-01

    Near-surface turbulent mixing has considerable effect on surface fluxes, cloud formation and convection in the atmospheric boundary layer (ABL). Its quantifications is however a modeling and computational challenge since the small eddies are not fully resolved in Eulerian models directly. We have developed a Lagrangian stochastic model to demonstrate multi-scale interactions between convection and land surface heterogeneity in the atmospheric boundary layer based on the Ito Stochastic Differential Equation (SDE) for air parcels (particles). Due to the complexity of the mixing in the ABL, we find that linear Ito SDE cannot represent convections properly. Three strategies have been tested to solve the problem: 1) to make the deterministic term in the Ito equation non-linear; 2) to change the random term in the Ito equation fractional, and 3) to modify the Ito equation by including Levy flights. We focus on the third strategy and interpret mixing as interaction between at least two stochastic processes with different Lagrangian time scales. The model is in progress to include the collisions among the particles with different characteristic and to apply the 3D model for real cases. One application of the model is emphasized: some land surface patterns are generated and then coupled with the Large Eddy Simulation (LES).

  1. Effects of Initial Drivers and Land Use on WRF Modeling for Near-Surface Fields and Atmospheric Boundary Layer over the Northeastern Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Junhua Yang

    2016-01-01

    Full Text Available To improve the simulation performance of mesoscale models in the northeastern Tibetan Plateau, two reanalysis initial datasets (NCEP FNL and ERA-Interim and two MODIS (Moderate-Resolution Imaging Spectroradiometer land-use datasets (from 2001 and 2010 are used in WRF (Weather Research and Forecasting modeling. The model can reproduce the variations of 2 m temperature (T2 and 2 m relative humidity (RH2, but T2 is overestimated and RH2 is underestimated in the control experiment. After using the new initial drive and land use data, the simulation precision in T2 is improved by the correction of overestimated net energy flux at surface and the RH2 is improved due to the lower T2 and larger soil moisture. Due to systematic bias in WRF modeling for wind speed, we design another experiment that includes the Jimenez subgrid-scale orography scheme, which reduces the frequency of low wind speed and increases the frequency of high wind speed and that is more consistent with the observation. Meanwhile, the new drive and land-use data lead to lower boundary layer height and influence the potential temperature and wind speed in both the lower atmosphere and the upper layer, while the impact on water vapor mixing ratio is primarily concentrated in the lower atmosphere.

  2. Effects of Blade Boundary Layer Transition and Daytime Atmospheric Turbulence on Wind Turbine Performance Analyzed with Blade-Resolved Simulation and Field Data

    Science.gov (United States)

    Nandi, Tarak Nath

    Relevant to utility scale wind turbine functioning and reliability, the present work focuses on enhancing our understanding of wind turbine responses from interactions between energy-dominant daytime atmospheric turbulence eddies and rotating blades of a GE 1.5 MW wind turbine using a unique data set from a GE field experiment and computer simulations at two levels of fidelity. Previous studies have shown that the stability state of the lower troposphere has a major impact on the coherent structure of the turbulence eddies, with corresponding differences in wind turbine loading response. In this study, time-resolved aerodynamic data measured locally at the leading edge and trailing edge of three outer blade sections on a GE 1.5 MW wind turbine blade and high-frequency SCADA generator power data from a daytime field campaign are combined with computer simulations that mimic the GE wind turbine within a numerically generated atmospheric boundary layer (ABL) flow field which is a close approximation of the atmospheric turbulence experienced by the wind turbine in the field campaign. By combining the experimental and numerical data sets, this study describes the time-response characteristics of the local loadings on the blade sections in response to nonsteady nonuniform energetic atmospheric turbulence eddies within a daytime ABL which have spatial scale commensurate with that of the turbine blade length. This study is the first of its kind where actuator line and blade boundary layer resolved CFD studies of a wind turbine field campaign are performed with the motivation to validate the numerical predictions with the experimental data set, and emphasis is given on understanding the influence of the laminar to turbulent transition process on the blade loadings. The experimental and actuator line method data sets identify three important response time scales quantified at the blade location: advective passage of energy-dominant eddies (≈25 - 50 s), blade rotation (1P

  3. Conditions for the formation and atmospheric dispersion of a toxic, heavy gas layer during thermal metamorphism of coal and evaporite deposits by sill intrusion

    Science.gov (United States)

    Storey, Michael; Hankin, Robin K. S.

    2010-05-01

    There is compelling evidence for massive discharge of volatiles, including toxic species, into the atmosphere at the end of the Permian. It has been argued that most of the gases were produced during thermal metamorphism of coal and evaporite deposits in the East Siberia Tunguska basin following sill intrusion (Retallack and Jahren, 2008; Svensen et al., 2009). The release of the volatiles has been proposed as a major cause of environmental and extinction events at the end of the Permian, with venting of carbon gases and halocarbons to the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al., 2009) Here we consider the conditions required for the formation and dispersion of toxic, heavier than air, gas plumes, made up of a mixture of CO2, CH4, H2S and SO2 and formed during the thermal metamorphism of C- and S- rich sediments. Dispersion models and density considerations within a range of CO2/CH4 ratios and volatile fluxes and temperatures, for gas discharge by both seepage and from vents, allow the possibility that following sill emplacement much of the vast East Siberia Tunguska basin was - at least intermittently - covered by a heavy, toxic gas layer that was unfavorable for life. Dispersion scenarios for a heavy gas layer beyond the Siberian region during end-Permian times will be presented. REFERENCES G. J. Retallack and A. H. Jahren, Methane release from igneous intrusion of coal during Late Permian extinction events, Journal of Geology, volume 116, 1-20, 2008 H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and Planetary Science Letters, volume 277, 490-500, 2009

  4. Effects of gas temperature in the plasma layer on RONS generation in array-type dielectric barrier discharge at atmospheric pressure

    Science.gov (United States)

    Yoon, Sung-Young; Yi, Changho; Eom, Sangheum; Park, Seungil; Kim, Seong Bong; Ryu, Seungmin; Yoo, Suk Jae

    2017-12-01

    In this work, we studied the control of plasma-produced species under a fixed gas composition (i.e., ambient air) in a 10 kHz-driven array-type dielectric barrier atmospheric-pressure plasma discharge. Instead of the gas composition, only the gas velocity was controlled. Thus, the plasma-maintenance cost was considerably lower than methods such as external N2 or O2 injection. The plasma-produced species were monitored using Fourier transformed infrared spectroscopy. The discharge properties were measured using a voltage probe, current probe, infrared camera, and optical emission spectroscopy. The results showed that the major plasma products largely depend on the gas temperature in the plasma discharge layer. The gas temperature in the plasma discharge layer was significantly different to the temperature of the ceramic adjacent to the plasma discharge layer, even in the small discharge power density of ˜15 W/cm2 or ˜100 W/cm3. Because the vibrational excitation of N2 was suppressed by the higher gas flow, the major plasma-produced species shifted from NOx in low flow to O3 in high flow.

  5. X-rays absorption study on medieval corrosion layers for the understanding of very long-term indoor atmospheric iron corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, J. [SIS2M UMR 3299 CEA-CNRS, Laboratoire Archeomateriaux et Prevision de l' Alteration (LAPA), Gif/Yvette cedex (France); UMR 7182 CNRS and UPEC, Universite Paris-Est, Institut de Chimie et des Materiaux Paris-Est (ICMPE), Thiais (France); Reguer, S.; Vantelon, D. [Synchrotron SOLEIL, Gif-sur-Yvette (France); Dillmann, P. [SIS2M UMR 3299 CEA-CNRS, Laboratoire Archeomateriaux et Prevision de l' Alteration (LAPA), Gif/Yvette cedex (France); IRAMAT UMR 5060 CNRS, Gif sur Yvette (France); Neff, D. [SIS2M UMR 3299 CEA-CNRS, Laboratoire Archeomateriaux et Prevision de l' Alteration (LAPA), Gif/Yvette cedex (France); Guillot, I. [UMR 7182 CNRS and UPEC, Universite Paris-Est, Institut de Chimie et des Materiaux Paris-Est (ICMPE), Thiais (France)

    2010-05-15

    The study and prediction of very long-term atmospheric corrosion behaviour of ferrous alloys is of great importance in different fields. First the conservation of metallic artefacts in museum and the corrosion diagnosis on ferrous reinforcement used in ancient monuments since medieval times needs reliable data to understand the mechanisms. Second, in the frame of the interim storage of nuclear waste in France, it is necessary to model the long-term corrosion of low alloy steel overcontainer. The nature of phases and elements constituting the corrosion layers can greatly influence the corrosion mechanisms. On the one hand, it is crucial to precisely determine the nature of microscopic phases that can be highly reactive. On the other hand, some elements as P and S could modify this reactivity. To clarify this point and complementary to other studies using Raman micro spectroscopy technique, X-rays Absorption Spectroscopy (XAS) under synchrotron radiation plays a crucial role. It allows one to precisely identify the reactive phases in the corrosion layers. Micro-XAS was required in order to refine the spatial variation, at micrometer scale, of the predominant Fe oxidation state and to characterise the corresponding corrosion products. Moreover, the role of minor elements on phase's stability and the chemical form of these elements in the rust layer, especially phosphorus and sulphur, was investigated. (orig.)

  6. Temporal and spatial changes in mixed layer properties and atmospheric net heat flux in the Nordic Seas

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A; Alekseev, G [SI ' Arctic and Antarctic Research Institute' , St. Petersburg (Russian Federation); Korablev, A; Esau, I, E-mail: avsmir@aari.nw.r [Nansen Environmental and Remote Sensing Centre, Bergen (Norway)

    2010-08-15

    The Nordic Seas are an important area of the World Ocean where warm Atlantic waters penetrate far north forming the mild climate of Northern Europe. These waters represent the northern rim of the global thermohaline circulation. Estimates of the relationships between the net heat flux and mixed layer properties in the Nordic Seas are examined. Oceanographic data are derived from the Oceanographic Data Base (ODB) compiled in the Arctic and Antarctic Research Institute. Ocean weather ship 'Mike' (OWS) data are used to calculate radiative and turbulent components of the net heat flux. The net shortwave flux was calculated using a satellite albedo dataset and the EPA model. The net longwave flux was estimated by Southampton Oceanography Centre (SOC) method. Turbulent fluxes at the air-sea interface were calculated using the COARE 3.0 algorithm. The net heat flux was calculated by using oceanographic and meteorological data of the OWS 'Mike'. The mixed layer depth was estimated for the period since 2002 until 2009 by the 'Mike' data as well. A good correlation between these two parameters has been found. Sensible and latent heat fluxes controlled by surface air temperature/sea surface temperature gradient are the main contributors into net heat flux. Significant correlation was found between heat fluxes variations at the OWS 'Mike' location and sea ice export from the Arctic Ocean.

  7. Large-eddy simulation of the diurnal cycle of the atmospheric boundary layer and influence of the radiative forcing during the Wangara experiment.

    Science.gov (United States)

    Dall'Ozzo, Cédric; Carissimo, Bertrand; Milliez, Maya; Musson-Genon, Luc; Dupont, Eric

    2013-04-01

    The ability to simulate the whole diurnal cycle of the atmospheric boundary layer in order to study the complex turbulent structures remains a difficult topic. Consequently large-eddy simulations (LES) are performed with the open source CFD code Code_Saturne [Archambeau et al., 2004]. First the code is validated on an atmospheric convective case [Schmidt and Schumann, 1989] where different subgrid-scale (SGS) models are compared: two non-dynamical SGS models [Smagorinsky, 1963] [Nicoud and Ducros, 1999] and two dynamical SGS models [Germano et al., 1991 ; Lilly, 1992] [Wong and Lilly, 1994]. Then LES are performed to simulate the whole diurnal cycle of the Wangara experiment (Day 33-34). The results are compared to measurements , RANS "k-ɛ" model and other LES performed by [Basu et al., 2008] using a locally averaged scale-dependent dynamic (LASDD) SGS model. Thereafter the influence of the radiative forcing on the atmosphere is studied testing several SGS models. The results are especially discussed on nocturnal low level jet and potential temperature gradient in the stable boundary layer. References: [Archambeau et al., 2004] Archambeau F., Mehitoua N., Sakiz M. (2004). Code_Saturne: a finite volume code for the computation of turbulent incompressible flows. International Journal on Finite Volumes 1(1). [Basu et al., 2008] Basu S., Vinuesa J. F., and Swift A. (2008). Dynamic LES modeling of a diurnal cycle. Journal of Applied Meteorology and Climatology, 47 :1156-1174. [Germano et al., 1991] Germano M., Piomelli U., Moin P., and Cabot W. H. (1991). A dynamic subgrid-scale eddy-viscosity model. Physics of Fluids, A3 :1760-1765. [Lilly, 1992] Lilly D. K. (1992). A proposed modification of the Germano subgrid-scale closure method. Physics of Fluids, A 4 :633-635. [Schmidt and Schumann, 1989] Schmidt H. and Schumann U. (1989). Coherent structure of the convective boundary layer derived from lage-eddy simulation. Journal of Fluid Mechanics, 200 :511-562. [Smagorinsky

  8. Study of the effect of wind speed on evaporation from soil through integrated modeling of atmospheric boundary layer and shallow subsurface

    Science.gov (United States)

    Davarzani, Hossein; Smits, Kathleen; Tolene, Ryan; Illangasekare, Tissa

    2013-04-01

    The study of the interaction between the land and atmosphere is paramount to our understanding of many emerging problems to include climate change, the movement of green house gases such as possible leaking of sequestered CO2 and the accurate detection of buried objects such as landmines. Soil moisture distribution in the shallow subsurface becomes a critical factor in all these problems. The heat and mass flux in the form of soil evaporation across the land surface couples the atmospheric boundary layer to the shallow subsurface. The coupling between land and the atmosphere leads to highly dynamic interactions between the porous media properties, transport processes and boundary conditions, resulting in dynamic evaporative behavior. However, the coupling at the land-atmospheric interface is rarely considered in most current models and their validation for practical applications. This is due to the complexity of the problem in field scenarios and the scarcity of field or laboratory data capable of testing and refining coupled energy and mass transfer theories. In most efforts to compute evaporation from soil, only indirect coupling is provided to characterize the interaction between non-isothermal multiphase flows under realistic atmospheric conditions even though heat and mass flux are controlled by the coupled dynamics of the land and the atmospheric boundary layer. In earlier drying modeling concepts, imposing evaporation flux (kinetic of relative humidity) and temperature as surface boundary condition is often needed. With the goal of improving our understanding of the land/atmospheric coupling, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model consists of the coupled equations of mass conservation for the liquid phase (water) and gas phase (water vapor and air) in porous medium with gas phase (water vapor and air) in free flow domain under non-isothermal, non-equilibrium conditions. The boundary

  9. The Impact of Land-Surface Parameter Properties and Resolution on the Simulated Cloud-Topped Atmospheric Boundary Layer

    Science.gov (United States)

    Gantner, Leonhard; Maurer, Vera; Kalthoff, Norbert; Kiseleva, Olga

    2017-12-01

    Sensitivity tests using the `Consortium for Small Scale Modeling' model in large-eddy simulation mode with a grid spacing of 100 m are performed to investigate the impact of the resolution of soil- and vegetation-related parameters on a cloud-topped boundary layer in a real-data environment. The reference simulation uses the highest land-surface parameter resolution available for operational purposes (300 m). The sensitivity experiments were conducted using spatial averaging of about 2.5 km× 2.5 km and 10 km × 10 km for the land-surface parameters and a completely homogeneous distribution for the whole model domain of about 70 km × 70 km. Additionally, one experiment with a higher mean soil moisture and another with six mesoscale patches of enhanced or reduced soil moisture are performed. Boundary-layer clouds developed in all simulations. To assess the deviations of cloud cover on different scales within the model domain, we calculated the root-mean-square deviation ( RMSD) between the sensitivity experiments and the reference simulation. The RMSD depends strongly on the spatial resolution at which cloud fields are compared. Different spatial resolutions of the cloud fields were generated by applying a low-pass filter. For all sensitivity experiments, large RMSD values occur for cut-off wavelengths {}5 km, the RMSD is still pronounced for the simulation with higher mean soil moisture. Additionally, for cut-off wavelengths between 5 and 30 km, considerable differences can be found for the experiment with mesoscale patches and for that with homogeneous land-surface parameters. Spatial averaging of land-surface parameters for areas of 2.5 km × 2.5 km and 10 km × 10 km results in larger patch sizes but simultaneously in reduced amplitudes of land-surface parameter anomalies and shows the lowest RMSD for all cut-off wavelengths.

  10. Electrochemical Behavior of CoNiCrAlY/ZrO2-Y2O3 Coated Layers with Atmospheric Pressure Plasma Technology in Seawater

    Science.gov (United States)

    Kim, Seong-Jong; Woo, Yong-Bin; Lee, Seung-Jun; Jeong, Jae-Yong

    2013-11-01

    Application of surface treatment has become common for protecting machine parts from oxidation, abrasion and corrosion induced by external environment. In particular, thermal spraying techniques are widely employed to improve wear, corrosion and thermal resistance. And compared to other methods they are simple and cost effective. However, the presence of porosity in the thermal spray coating can be highly detrimental because it provides access to penetration of corrosive matters, lowering corrosion resistance. Therefore, this research evaluate the electrochemical behavior under marine environment for aluminum-bronze alloy coated with MCrAlY and yttria-stabillized zirconia (YSZ) by atmospheric pressure plasma (APP) coating technology. Further application of carbon-based sealer removed voids and defects in the coating. The result reveled that, in case the voids and defects are completely removed, excellent corrosion resistance can be archived by application of good coating material along with formation of compact sealing layer.

  11. Controlled meteorological (CMET free balloon profiling of the Arctic atmospheric boundary layer around Spitsbergen compared to ERA-Interim and Arctic System Reanalyses

    Directory of Open Access Journals (Sweden)

    T. J. Roberts

    2016-09-01

    Full Text Available Observations from CMET (Controlled Meteorological balloons are analysed to provide insights into tropospheric meteorological conditions (temperature, humidity, wind around Svalbard, European High Arctic. Five Controlled Meteorological (CMET balloons were launched from Ny-Ålesund in Svalbard (Spitsbergen over 5–12 May 2011 and measured vertical atmospheric profiles over coastal areas to both the east and west. One notable CMET flight achieved a suite of 18 continuous soundings that probed the Arctic marine boundary layer (ABL over a period of more than 10 h. Profiles from two CMET flights are compared to model output from ECMWF Era-Interim reanalysis (ERA-I and to a high-resolution (15 km Arctic System Reanalysis (ASR product. To the east of Svalbard over sea ice, the CMET observed a stable ABL profile with a temperature inversion that was reproduced by ASR but not captured by ERA-I. In a coastal ice-free region to the west of Svalbard, the CMET observed a stable ABL with strong wind shear. The CMET profiles document increases in ABL temperature and humidity that are broadly reproduced by both ASR and ERA-I. The ASR finds a more stably stratified ABL than observed but captured the wind shear in contrast to ERA-I. Detailed analysis of the coastal CMET-automated soundings identifies small-scale temperature and humidity variations with a low-level flow and provides an estimate of local wind fields. We demonstrate that CMET balloons are a valuable approach for profiling the free atmosphere and boundary layer in remote regions such as the Arctic, where few other in situ observations are available for model validation.

  12. Experimental study on the wind-turbine wake meandering inside a scale model wind farm placed in an atmospheric-boundary-layer wind tunnel

    Science.gov (United States)

    Coudou, N.; Buckingham, S.; van Beeck, J.

    2017-05-01

    Increasing use of wind energy over the years results in more and larger clustered wind farms. It is therefore fundamental to have an in-depth knowledge of wind-turbine wakes, and especially a better understanding of the well-known but less understood wake-meandering phenomenon which causes the wake to move as a whole in both horizontal and vertical directions as it is convected downstream. This oscillatory motion of the wake is crucial for loading on downstream turbines because it increases fatigue loads and in particular yaw loads. In order to address this phenomenon, experimental investigations were carried out in an atmospheric-boundary-layer wind tunnel using a 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models subject to a neutral atmospheric boundary layer (ABL) corresponding to a slightly rough terrain, i.e. to offshore conditions. Particle Image Velocimetry (PIV) measurements were performed in a horizontal plane, at hub height, in the wake of the three wind turbines in the wind-farm centreline. From the PIV velocity fields obtained, the wake-centrelines were determined and a spectral analysis was performed to obtain the characteristics of the wake-meandering phenomenon. In addition, Hot-Wire Anemometry (HWA) measurements were performed in the wakes of the same wind turbines to validate the PIV results. The spectral analysis performed with the spatial and temporal signals obtained from PIV and HWA measurements respectively, led to Strouhal numbers St = fD/Uhub ≃ 0.20 - 0.22.

  13. Two years observations on the diurnal evolution of coastal atmospheric boundary layer features over Thiruvananthapuram (8.5∘ N, 76.9∘ E), India

    Science.gov (United States)

    Anurose, T. J.; Subrahamanyam, D. Bala; Sunilkumar, S. V.

    2018-01-01

    The atmospheric boundary layer (ABL) over a given coastal station is influenced by the presence of mesoscale sea breeze circulation, together with the local and synoptic weather, which directly or indirectly modulate the vertical thickness of ABL ( z ABL). Despite its importance in the characterization of lower tropospheric processes and atmospheric modeling studies, a reliable climatology on the temporal evolution of z ABL is not available over the tropics. Here, we investigate the challenges involved in determination of the ABL heights, and discuss an objective method to define the vertical structure of coastal ABL. The study presents a two year morphology on the diurnal evolution of the vertical thickness of sea breeze flow ( z SBF) and z ABL in association with the altitudes of lifting condensation level ( z LCL) over Thiruvananthapuram (8.5∘ N, 76.9∘ E), a representative coastal station on the western coastline of the Indian sub-continent. We make use of about 516 balloon-borne GPS sonde measurements in the present study, which were carried out as part of the tropical tropopause dynamics field experiment under the climate and weather of the sun-earth system (CAWSES)-India program. Results obtained from the present study reveal major differences in the temporal evolution of the ABL features in relation to the strength of sea breeze circulation and monsoonal wind flow during the winter and summer monsoon respectively. The diurnal evolution in z ABL is very prominent in the winter monsoon as against the summer monsoon, which is attributed to the impact of large-scale monsoonal flow over the surface layer meteorology. For a majority of the database, the z LCL altitudes are found to be higher than that of the z ABL, indicating a possible decoupling of the ABL with the low-level clouds.

  14. Clouds in the atmospheres of extrasolar planets. I. Climatic effects of multi-layered clouds for Earth-like planets and implications for habitable zones

    Science.gov (United States)

    Kitzmann, D.; Patzer, A. B. C.; von Paris, P.; Godolt, M.; Stracke, B.; Gebauer, S.; Grenfell, J. L.; Rauer, H.

    2010-02-01

    Aims: The effects of multi-layered clouds in the atmospheres of Earth-like planets orbiting different types of stars are studied. The radiative effects of cloud particles are directly correlated with their wavelength-dependent optical properties. Therefore the incident stellar spectra may play an important role for the climatic effect of clouds. We discuss the influence of clouds with mean properties measured in the Earth's atmosphere on the surface temperatures and Bond albedos of Earth-like planets orbiting different types of main sequence dwarf stars. The influence of clouds on the position of the habitable zone around these central star types is discussed. Methods: A parametric cloud model has been developed based on observations in the Earth's atmosphere. The corresponding optical properties of the cloud particles are calculated with the Mie theory accounting for shape effects of ice particles by the equivalent sphere method. The parametric cloud model is linked with a one-dimensional radiative-convective climate model to study the effect of clouds on the surface temperature and the Bond albedo of Earth-like planets in dependence of the type of central star. Results: The albedo effect of the low-level clouds depends only weakly on the incident stellar spectra because the optical properties remain almost constant in the wavelength range of the maximum of the incident stellar radiation. The greenhouse effect of the high-level clouds on the other hand depends on the temperature of the lower atmosphere, which is itself an indirect consequence of the different types of central stars. In general the planetary Bond albedo increases with the cloud cover of either cloud type. An anomaly was found for the K and M-type stars however, resulting in a decreasing Bond albedo with increasing cloud cover for certain atmospheric conditions. Depending on the cloud properties, the position of the habitable zone can be located either farther from or closer to the central star. As

  15. Prediction of the (137)Cs activity concentration in the atmospheric surface layer of the Chernobyl exclusion zone.

    Science.gov (United States)

    Garger, E K; Kuzmenko, Yu I; Sickinger, S; Tschiersch, J

    2012-08-01

    The time series of the 10-day average (137)Cs volumetric activity concentration in the lower atmosphere measured from 1987 to 1991 in the town of Pripyat, close to the Chernobyl nuclear power plant, was used to construct a model to predict the airborne activity concentration inside the 30-km exclusion zone. For that purpose, individual components of the observed time series were separated by regression analysis and the Group Method of Data Handling. The measured data in Pripyat were divided in two periods. The long-term prediction by the model established using the measured data of the first period, has been validated with the data in the second period with good agreement. The behaviour of the model parameters depending on the length of the periods was also analysed, and the first period of 4.5 y was shown as sufficient for estimating the parameters. Further increase in the length will not significantly enhance the model parameters and the predictive power. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Bromide and other ions in the snow, firn air, and atmospheric boundary layer at Summit during GSHOX

    Directory of Open Access Journals (Sweden)

    J. E. Dibb

    2010-10-01

    Full Text Available Measurements of gas phase soluble bromide in the boundary layer and in firn air, and Br in aerosol and snow, were made at Summit, Greenland (72.5° N, 38.4° W, 3200 m a.s.l. as part of a larger investigation into the influence of Br chemistry on HOx cycling. The soluble bromide measurements confirm that photochemical activation of Br in the snow causes release of active Br to the overlying air despite trace concentrations of Br in the snow (means 15 and 8 nmol Br kg−1 of snow in 2007 and 2008, respectively. Mixing ratios of soluble bromide above the snow were also found to be very small (mean <1 ppt both years, with maxima of 3 and 4 ppt in 2007 and 2008, respectively, but these levels clearly oxidize and deposit long-lived gaseous elemental mercury and may perturb HOx partitioning. Concentrations of Br in surface snow tended to increase/decrease in parallel with the specific activities of the aerosol-associated radionuclides 7Be and 210Pb. Earlier work has shown that ventilation of the boundary layer causes simultaneous increases in 7Be and 210Pb at Summit, suggesting there is a pool of Br in the free troposphere above Summit in summer time. Speciation and the source of this free tropospheric Br are not well constrained, but we suggest it may be linked to extensive regions of active Br chemistry in the Arctic basin which are known to cause ozone and mercury depletion events shortly after polar sunrise. If this hypothesis is correct, it implies persistence of the free troposphere Br for several months after peak Br activation in March/April. Alternatively, there may be a ubiquitous pool of Br in the free troposphere, sustained by currently unknown sources and processes.

  17. Intercomparison of different subgrid-scale models for the Large Eddy Simulation of the diurnal evolution of the atmospheric boundary layer during the Wangara experiment

    Science.gov (United States)

    Dall'Ozzo, C.; Carissimo, B.; Musson-Genon, L.; Dupont, E.; Milliez, M.

    2012-04-01

    The study of a whole diurnal cycle of the atmospheric boundary layer evolving through unstable, neutral and stable states is essential to test a model applicable to the dispersion of pollutants. Consequently a LES of a diurnal cycle is performed and compared to observations from the Wangara experiment (Day 33-34). All simulations are done with Code_Saturne [1] an open source CFD code. The synthetic eddy method (SEM) [2] is implemented to initialize turbulence at the beginning of the simulation. Two different subgrid-scale (SGS) models are tested: the Smagorinsky model [3],[4] and the dynamical Wong and Lilly model [5]. The first one, the most classical, uses a Smagorinsky constant Cs to parameterize the dynamical turbulent viscosity while the second one relies on a variable C. Cs remains insensitive to the atmospheric stability level in contrary to the parameter C determined by the Wong and Lilly model. It is based on the error minimization of the difference between the tensors of the resolved turbulent stress (Lij) and the difference of the SGS stress tensors at two different filter scales (Mij). Furthermore, the thermal eddy diffusivity, as opposed to the Smagorinsky model, is calculated with a dynamical Prandtl number determination. The results are confronted to previous simulations from Basu et al. (2008) [6], using a locally averaged scale-dependent dynamic (LASDD) SGS model, and to previous RANS simulations. The accuracy in reproducing the experimental atmospheric conditions is discussed, especially regarding the night time low-level jet formation. In addition, the benefit of the utilization of a coupled radiative model is discussed.

  18. Experimental Study on the Wake Meandering Within a Scale Model Wind Farm Subject to a Wind-Tunnel Flow Simulating an Atmospheric Boundary Layer

    Science.gov (United States)

    Coudou, Nicolas; Buckingham, Sophia; Bricteux, Laurent; van Beeck, Jeroen

    2017-12-01

    The phenomenon of meandering of the wind-turbine wake comprises the motion of the wake as a whole in both horizontal and vertical directions as it is advected downstream. The oscillatory motion of the wake is a crucial factor in wind farms, because it increases the fatigue loads, and, in particular, the yaw loads on downstream turbines. To address this phenomenon, experimental investigations are carried out in a wind-tunnel flow simulating an atmospheric boundary layer with the Coriolis effect neglected. A 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models is subject to a neutral boundary layer over a slightly-rough surface, i.e. corresponding to offshore conditions. Particle-image-velocimetry measurements are performed in a horizontal plane at hub height in the wakes of the three wind turbines occupying the wind-farm centreline. These measurements allow determination of the wake centrelines, with spectral analysis indicating the characteristic wavelength of the wake-meandering phenomenon. In addition, measurements with hot-wire anemometry are performed along a vertical line in the wakes of the same wind turbines, with both techniques revealing the presence of wake meandering behind all three turbines. The spectral analysis performed with the spatial and temporal signals obtained from these two measurement techniques indicates a Strouhal number of ≈ 0.20 - 0.22 based on the characteristic wake-meandering frequency, the rotor diameter and the flow speed at hub height.

  19. The Importance and Current Limitations of Planetary Boundary Layer (PBL) Retrieval from Space for Land-Atmosphere Coupling Studies

    Science.gov (United States)

    Santanello, J. A., Jr.; Schaefer, A.

    2016-12-01

    There is an established need for improved PBL remote sounding over land for hydrology, land-atmosphere (L-A), PBL, cloud/convection, pollution/chemistry studies and associated model evaluation and development. Most notably, the connection of surface hydrology (through soil moisture) to clouds and precipitation relies on proper quantification of water's transport through the coupled system, which is modulated strongly by PBL structure, growth, and feedback processes such as entrainment. In-situ (ground-based or radiosonde) measurements will be spatially limited to small field campaigns for the foreseeable future, so satellite data is a must in order to understand these processes globally. The scales of these applications require diurnal resolution (e.g. 3-hourly or finer) at attention or planning (short or long-term) in place for improving lower tropospheric sounding over land, and as a result PBL and L-A interactions have been identified as `gaps' in current programmatic focal areas. It is therefore timely to assess how these technologies can be leveraged, combined, or evolved in order to form a dedicated mission or sub-mission to routinely monitor the PBL on diurnal timescales. In addition, improved PBL monitoring from space needs to be addressed in the next Decadal Survey. In this talk, the importance of PBL information (structure, evolution) for L-A coupling diagnostics and model development will be summarized. The current array of PBL retrieval methods and products from space will then be assessed in terms of meeting the needs of these models, diagnostics, and scales, with a look forward as to how this can and must be improved through future mission and sensor design.

  20. Influence of orographically induced transport process on the structure of the atmospheric boundary layer and on the distribution of trace gases; Einfluss orographisch induzierter Transportprozesse auf die Struktur der atmosphaerischen Grenzschicht und die Verteilung von Spurengasen

    Energy Technology Data Exchange (ETDEWEB)

    Kossmann, M.

    1998-04-01

    The influence of terrain on the structure of the atmospheric boundary-layer and the distribution of trace gases during periods of high atmospheric pressure was studied by means of meteorological and air-chemical data collected in September 1992 during the TRACT experiment in the transition area between the upper Rhine valley and the northern Black Forest. The emphasis was on the investigation of the development of the convective boundary layer, the formation of thermally induced circulation systems, and the orographic exchange between the atmospheric boundary layer and the free troposphere. Thanks to the extensive measurements, phenomena not yet described in literature could be verified by case studies, and processes that had only been established qualitatively could be quantified. (orig.)

  1. Unequivocal detection of ozone recovery in the Antarctic Ozone Hole through significant increases in atmospheric layers with minimum ozone

    Science.gov (United States)

    de Laat, Jos; van Weele, Michiel; van der A, Ronald

    2015-04-01

    An important new landmark in present day ozone research is presented through MLS satellite observations of significant ozone increases during the ozone hole season that are attributed unequivocally to declining ozone depleting substances. For many decades the Antarctic ozone hole has been the prime example of both the detrimental effects of human activities on our environment as well as how to construct effective and successful environmental policies. Nowadays atmospheric concentrations of ozone depleting substances are on the decline and first signs of recovery of stratospheric ozone and ozone in the Antarctic ozone hole have been observed. The claimed detection of significant recovery, however, is still subject of debate. In this talk we will discuss first current uncertainties in the assessment of ozone recovery in the Antarctic ozone hole by using multi-variate regression methods, and, secondly present an alternative approach to identify ozone hole recovery unequivocally. Even though multi-variate regression methods help to reduce uncertainties in estimates of ozone recovery, great care has to be taken in their application due to the existence of uncertainties and degrees of freedom in the choice of independent variables. We show that taking all uncertainties into account in the regressions the formal recovery of ozone in the Antarctic ozone hole cannot be established yet, though is likely before the end of the decade (before 2020). Rather than focusing on time and area averages of total ozone columns or ozone profiles, we argue that the time evolution of the probability distribution of vertically resolved ozone in the Antarctic ozone hole contains a better fingerprint for the detection of ozone recovery in the Antarctic ozone hole. The advantages of this method over more tradition methods of trend analyses based on spatio-temporal average ozone are discussed. The 10-year record of MLS satellite measurements of ozone in the Antarctic ozone hole shows a

  2. Seasonal, synoptic and diurnal variation of atmospheric water-isotopologues in the boundary layer of Southwestern Germany caused by plant transpiration, cold-front passages and dewfall.

    Science.gov (United States)

    Christner, Emanuel; Dyroff, Christoph; Kohler, Martin; Zahn, Andreas; Gonzales, Yenny; Schneider, Matthias

    2013-04-01

    Atmospheric water is an enormously crucial trace gas. It is responsible for ~70 % of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. The isotopic composition of water vapor is an elegant tracer for a better understanding and quantification of the extremely complex and variable hydrological cycle in Earth's atmosphere (evaporation, cloud condensation, rainout, re-evaporation, snow), which in turn is a prerequisite to improve climate modeling and predictions. As H216O, H218O and HDO differ in vapor pressure and mass, isotope fractionation occurs due to condensation, evaporation and diffusion processes. In contrast to that, plants are able to transpire water with almost no isotope fractionation. For that reason the ratio of isotopologue concentrations in the boundary layer (BL) provides, compared to humidity measurements alone, independent and additional constraints for quantifying the strength of evaporation and transpiration. Furthermore the isotope ratios contain information about transport history of an air mass and microphysical processes, that is not accessible by humidity measurements. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) a commercial Picarro Analyzer L2120-i is operated at Karlsruhe in Southwestern Germany, which is continuously measuring the isotopologues H216O, HDO and H218O of atmospheric water vapor since January 2012. A one year record of H216O, HDO and H218O shows clear seasonal, synoptic and diurnal characteristics and reveals the main driving processes affecting the isotopic composition of water vapor in the Middle European BL. Changes in continental plant transpiration and evaporation throughout the year lead to a slow seasonal HDO/H216O-variation, that cannot be explained by pure Rayleigh condensation. Furthermore, cold-front passages from NW lead to fast and pronounced depletion of the HDO/H216O-ratio within

  3. Quantification of urban atmospheric boundary layer greenhouse gas dry mole fraction enhancements in the dormant season: Results from the Indianapolis Flux Experiment (INFLUX

    Directory of Open Access Journals (Sweden)

    Natasha L. Miles

    2017-06-01

    Full Text Available We assess the detectability of city emissions via a tower-based greenhouse gas (GHG network, as part of the Indianapolis Flux (INFLUX experiment. By examining afternoon-averaged results from a network of carbon dioxide (CO2, methane (CH4, and carbon monoxide (CO mole fraction measurements in Indianapolis, Indiana for 2011–2013, we quantify spatial and temporal patterns in urban atmospheric GHG dry mole fractions. The platform for these measurements is twelve communications towers spread across the metropolitan region, ranging in height from 39 to 136 m above ground level, and instrumented with cavity ring-down spectrometers. Nine of the sites were deployed as of January 2013 and data from these sites are the focus of this paper. A background site, chosen such that it is on the predominantly upwind side of the city, is utilized to quantify enhancements caused by urban emissions. Afternoon averaged mole fractions are studied because this is the time of day during which the height of the boundary layer is most steady in time and the area that influences the tower measurements is likely to be largest. Additionally, atmospheric transport models have better performance in simulating the daytime convective boundary layer compared to the nighttime boundary layer. Averaged from January through April of 2013, the mean urban dormant-season enhancements range from 0.3 ppm CO2 at the site 24 km typically downwind of the edge of the city (Site 09 to 1.4 ppm at the site at the downwind edge of the city (Site 02 to 2.9 ppm at the downtown site (Site 03. When the wind is aligned such that the sites are downwind of the urban area, the enhancements are increased, to 1.6 ppm at Site 09, and 3.3 ppm at Site 02. Differences in sampling height affect the reported urban enhancement by up to 50%, but the overall spatial pattern remains similar. The time interval over which the afternoon data are averaged alters the calculated urban enhancement by an average of 0.4 ppm

  4. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site.

    Science.gov (United States)

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (zi), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime zi from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the zi and the fine fraction (0.3-0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. LES of Scalar transport in a turbulent katabatic flow along a curved slope in the context of stably stratified atmospheric boundary layer.

    Science.gov (United States)

    Brun, Christophe; Chollet, Jean Pierre

    2010-05-01

    The behaviour of the Atmospheric Boundary layer (ABL) along alpine valleys is strongly dependent on the day-night thermodynamic cycle and might impact meteorology and air pollution prediction. At night, the ABL is stably stratified and the radiative cooling of the surface yields the development of a katabatic flow. This flow consists of a downslope wall-jet which has the structure of both wall turbulence in the inner-layer zone and shear layer turbulence in the outer-layer zone and enhances a relative mixing eventhough stable stratification is considered. A full 3D description of such flow by mean of Large Eddy Simulation of turbulence (LES) has not yet been achieved, except recently on relatively simple slopes (Skyllingstad 2003, Fedorovith and Shapiro 2009) or including geostrophic wind forcing (Cuxart et al. 2006, Cuxart and Jimenez 2006). This is the purpose of the present study to accurately describe the ABL on a curved slope with stable stratification, including passive scalar transport. The numerical code used, Meso-NH, has been developed in CNRM/Meteo-France and Laboratoire d'Aérologie Toulouse, and consists of an anelastic non-hydrostatic model solving the pseudo-incompressible Navier-Stokes equations. About 5 million grid points are necessary to afford a relatively precise description of the flow in the vicinity of the ground surface, with a special refinement down to 1 m in the vertical direction to capture the wall-jet developing along the slope. The setting of initial and boundary conditions is crucial for the simulation of stable ABL. Initial conditions consist of air at rest following a stable temperature profile with a constant Brunt-Väisälä frequency 0.01

  6. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    Science.gov (United States)

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-06

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry.

  7. A Modulated-Gradient Parametrization for the Large-Eddy Simulation of the Atmospheric Boundary Layer Using the Weather Research and Forecasting Model

    Science.gov (United States)

    Khani, Sina; Porté-Agel, Fernando

    2017-12-01

    The performance of the modulated-gradient subgrid-scale (SGS) model is investigated using large-eddy simulation (LES) of the neutral atmospheric boundary layer within the weather research and forecasting model. Since the model includes a finite-difference scheme for spatial derivatives, the discretization errors may affect the simulation results. We focus here on understanding the effects of finite-difference schemes on the momentum balance and the mean velocity distribution, and the requirement (or not) of the ad hoc canopy model. We find that, unlike the Smagorinsky and turbulent kinetic energy (TKE) models, the calculated mean velocity and vertical shear using the modulated-gradient model, are in good agreement with Monin-Obukhov similarity theory, without the need for an extra near-wall canopy model. The structure of the near-wall turbulent eddies is better resolved using the modulated-gradient model in comparison with the classical Smagorinsky and TKE models, which are too dissipative and yield unrealistic smoothing of the smallest resolved scales. Moreover, the SGS fluxes obtained from the modulated-gradient model are much smaller near the wall in comparison with those obtained from the regular Smagorinsky and TKE models. The apparent inability of the LES model in reproducing the mean streamwise component of the momentum balance using the total (resolved plus SGS) stress near the surface is probably due to the effect of the discretization errors, which can be calculated a posteriori using the Taylor-series expansion of the resolved velocity field. Overall, we demonstrate that the modulated-gradient model is less dissipative and yields more accurate results in comparison with the classical Smagorinsky model, with similar computational costs.

  8. Interpretive Data Layer Showing Distribution of Modern Features Within National Oceanic and Atmospheric Adminitration (NOAA) Survey H11250 (H11250G_MOD, Geographic)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has...

  9. Interpretive Data Layer Showing the Framework Geology of National Oceanic and Atmospheric Administration (NOAA) Survey H11250 (H11250G_GEOL, Geographic)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has...

  10. A model for the estimation of the surface fluxes of momentum, heat and moisture of the cloud topped marine atmospheric boundary layer from satellite measurable parameters. M.S. Thesis

    Science.gov (United States)

    Allison, D. E.

    1984-01-01

    A model is developed for the estimation of the surface fluxes of momentum, heat, and moisture of the cloud topped marine atmospheric boundary layer by use of satellite remotely sensed parameters. The parameters chosen for the problem are the integrated liquid water content, q sub li, the integrated water vapor content, q sub vi, the cloud top temperature, and either a measure of the 10 meter neutral wind speed or the friction velocity at the surface. Under the assumption of a horizontally homogeneous, well-mixed boundary layer, the model calculates the equivalent potential temperature and total water profiles of the boundary layer along with the boundary layer height from inputs of q sub li, q sub vi, and cloud top temperature. These values, along with the 10m neutral wind speed or friction velocity and the sea surface temperature are then used to estimate the surface fluxes. The development of a scheme to parameterize the integrated water vapor outside of the boundary layer for the cases of cold air outbreak and California coastal stratus is presented.

  11. Our Changing Atmosphere.

    Science.gov (United States)

    Clearing, 1988

    1988-01-01

    Summarizes what is known about two major variables involved in certain types of chemical pollution that seem to be changing the structure of the Earth's atmosphere. Discusses the greenhouse effect and the ozone layer. (TW)

  12. Retrieval of atmospheric boundary layer height by CSIR NLC mobile LIDAR, Pretoria (25.5° S; 28.2° E), South Africa

    CSIR Research Space (South Africa)

    Sivakumar, V

    2011-07-01

    Full Text Available In this paper, the authors present the preliminary methods for detection of the boundary layer based on backscattered signals from a mobile LIDAR (LIght Detection And Ranging) developed at Council for Scientific and Industrial Research (CSIR...

  13. Aspects of atmospheric turbulence related to scintillometry

    NARCIS (Netherlands)

    Braam, M.

    2014-01-01

    Aspects of atmospheric turbulence related to scintillometry Atmospheric turbulence is the main vertical transport mechanism in the atmospheric boundary layer. The surface fluxes related to this turbulent transport are the sensible (

  14. Comparison of slant-path scintillometry, sonic anemometry and high-speed videography for vertical profiling of turbulence in the atmospheric surface layer

    CSIR Research Space (South Africa)

    Griffith, DJ

    2013-09-01

    Full Text Available services for the Rietvlei campaign were provided by the Advanced Fire Information System (AFIS8). REFERENCES [1] Weiss-Wrana, K. and Balfour, L. S., “Statistical analysis of measurements of atmospheric turbulence in different climates,” Optics...

  15. TROPOMI on the ESA Sentinel-5 Precursor: A GMES mission for global observations of the atmospheric composition for climate, air quality and ozone layer applications

    NARCIS (Netherlands)

    Veefkind, J.P.; Aben, I.; McMullan, K.; Förster, H.; Vries, J. de; Otter, G.; Claas, J.; Eskes, H.J.; Haan, J.F. de; Kleipool, Q.; Weele, M. van; Hasekamp, O.; Hoogeveen, R.; Landgraf, J.; Snel, R.; Tol, P.; Ingmann, P.; Voors, R.; Kruizinga, B.; Vink, R.; Visser, H.; Levelt, P.F.

    2012-01-01

    The ESA (European Space Agency) Sentinel-5 Precursor (S-5 P) is a low Earth orbit polar satellite to provide information and services on air quality, climate and the ozone layer in the timeframe 2015-2022. The S-5 P mission is part of the Global Monitoring of the Environment and Security (GMES)

  16. dFirst simultaneous space measurements of atmospheric pollutants in the boundary layer from IASI: A case study in the North China Plain

    NARCIS (Netherlands)

    Boynard, A.; Clerbaux, C.; Clarisse, L.; Safieddine, S.; Pommier, M.; van Damme, M.; Bauduin, S.; Oudot, C.; Hadji-Lazaro, J.; Hurtmans, D.; Coheur, P.F.

    2014-01-01

    In this paper we investigate a severe pollution episode that occurred in Beijing, Tianjin, and the Hebei province in January 2013. The episode was caused by the combination of anthropogenic emissions and a high-pressure system that trapped pollutants in the boundary layer. Using IASI (Infrared

  17. Experimental and theoretical study of the atmospheric boundary layer over the paris area; Etude experimentale et theorique de la couche limite atmospherique en agglomeration parisienne

    Energy Technology Data Exchange (ETDEWEB)

    Menut, L

    1997-12-15

    This thesis studied the urban boundary layer dynamic behaviour over the Paris area by comparing urban (Paris) and suburban (Palaiseau) dynamic data such as lidars, sodars, sonic anemometers. All the data were obtained during the ECLAP experiment, specifically performed to characterize the differences between a city and its near environment. (author)

  18. Simulating dynamics of {delta}{sup 13}C of CO{sub 2} in the planetary boundary layer a boreal forest region: covariation between surface fluxes and atmospheric mixing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Baozhang; Chen, Jing M. [Univ. of Toronto, ON (Canada). Dept. of Geography; Tans, Pieter P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Earth System Research Lab.; Huang, Lin [Environment Canada, Toronto, ON (Canada). Atmospheric Science and Technology Directorate

    2006-11-15

    Stable isotopes of CO{sub 2} contain unique information on the biological and physical processes that exchange CO{sub 2} between terrestrial ecosystems and the atmosphere. Ecosystem exchange of carbon isotopes with the atmosphere is correlated diurnally and seasonally with the planetary boundary layer (PBL) dynamics. The strength of this kind of covariation affects the vertical gradient of {delta}{sup 13}C and thus the global {delta}{sup 13}C distribution pattern. We need to understand the various processes involved in transport/diffusion of carbon isotope ratio in the PBL and between the PBL and the biosphere and the troposphere. In this study, we employ a one-dimensional vertical diffusion/transport atmospheric model (VDS), coupled to an ecosystem isotope model (BEPS-EASS) to simulate dynamics of {sup 13}CO{sub 2} in the PBL over a boreal forest region in the vicinity of the Fraserdale (FRD) tower (49 deg 52 min 29.9 sec N, 81 deg 34 min 12.3 sec W) in northern Ontario, Canada. The data from intensive campaigns during the growing season in 1999 at this site are used for model validation in the surface layer. The model performance, overall, is satisfactory in simulating the measured data over the whole course of the growing season. We examine the interaction of the biosphere and the atmosphere through the PBL with respect to {delta}{sup 13}C on diurnal and seasonal scales. The simulated annual mean vertical gradient of {delta}{sup 13}C in the PBL in the vicinity of the FRD tower was about 0.025% in 1999. The {delta}{sup 13}C vertical gradient exhibited strong diurnal (29%) and seasonal (71%) variations that do not exactly mimic those of CO{sub 2}. Most of the vertical gradient (96.5% {+-}) resulted from covariation between ecosystem exchange of carbon isotopes and the PBL dynamics, while the rest (3.5%{+-}) was contributed by isotopic disequilibrium between respiration and photosynthesis. This disequilibrium effect on {delta}{sup 13}C of CO{sub 2} dynamics in PBL

  19. Simulating dynamics of (delta){sup 13}C of CO{sub 2} in the planetary boundary layer a boreal forest region: covariation between surface fluxes and atmospheric mixing

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Baozhang; Chen, Jing M. [Univ. of Toronto, ON (Canada). Dept. of Geography; Tans, Pieter P. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Earth System Research Lab.; Huang, Lin [Environment Canada, Toronto, ON (Canada). Atmospheric Science and Technology Directorate

    2006-11-15

    Stable isotopes of CO{sub 2} contain unique information on the biological and physical processes that exchange CO{sub 2} between terrestrial ecosystems and the atmosphere. Ecosystem exchange of carbon isotopes with the atmosphere is correlated diurnally and seasonally with the planetary boundary layer (PBL) dynamics. The strength of this kind of covariation affects the vertical gradient of (delta){sup 13}C and thus the global (delta){sup 13}C distribution pattern. We need to understand the various processes involved in transport/diffusion of carbon isotope ratio in the PBL and between the PBL and the biosphere and the troposphere. In this study, we employ a one-dimensional vertical diffusion/transport atmospheric model (VDS), coupled to an ecosystem isotope model (BEPS-EASS) to simulate dynamics of {sup 13}CO{sub 2} in the PBL over a boreal forest region in the vicinity of the Fraserdale (FRD) tower (49 deg 52 min 29.9 sec N, 81 deg 34 min 12.3 sec W) in northern Ontario, Canada. The data from intensive campaigns during the growing season in 1999 at this site are used for model validation in the surface layer. The model performance, overall, is satisfactory in simulating the measured data over the whole course of the growing season. We examine the interaction of the biosphere and the atmosphere through the PBL with respect to (delta){sup 13}C on diurnal and seasonal scales. The simulated annual mean vertical gradient of (delta){sup 13}C in the PBL in the vicinity of the FRD tower was about 0.025% in 1999. The (delta){sup 13}C vertical gradient exhibited strong diurnal (29%) and seasonal (71%) variations that do not exactly mimic those of CO{sub 2}. Most of the vertical gradient (96.5% {+-}) resulted from covariation between ecosystem exchange of carbon isotopes and the PBL dynamics, while the rest (3.5%{+-}) was contributed by isotopic disequilibrium between respiration and photosynthesis. This disequilibrium effect on (delta){sup 13}C of CO{sub 2} dynamics in PBL

  20. Investigation of optical turbulence in the atmospheric surface layer using scintillometer measurements along a slant path and comparison to ultrasonic anemometer measurements

    CSIR Research Space (South Africa)

    Sprung, D

    2014-09-01

    Full Text Available and Industrial Research (CSIR) P O Box 395, Pretoria 0001, South Africa dgriffith@csir.co.za ABSTRACT Optical turbulence represented by the structure function parameter of the refractive index Cn 2 is a relevant parameter for the performance... of these time series Cn 2 was derived. Three instruments were mounted at a portable mast in the center of slant path measurements over a horizontal distance of 1000 m using large aperture scintillometers (Boundary layer scintillometer BLS 900). Averaging over...

  1. Turbulent Characterization of atmospheric surface layer over non-homogeneous terrain; Caracterizacion turbulenta de la capa superficial atmosferica en un terreno no homogeneo

    Energy Technology Data Exchange (ETDEWEB)

    Artinano Rodriguez de Torres, B.

    1989-07-01

    About 15000 wind and temperature profiles from a 100 m tower located in CEDER (Soria, Spain) have been analyzed. Using profiles in close neutral conditions, two main parameters of surface layer were obtained. Results show a great dependence of these parameters (Z{sub 0} roughness length and u friction velocity) on flow conditions and terrain (tinctures. Difficulty finding neutral conditions in this type of terrain (gently rolling and scattered bush) and in this latitude , is also remarkable. (Author) 91 refs.

  2. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  3. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...

  4. Comparison of performance and stability of perovskite solar cells with CuInS2 and PH1000 hole transport layers fabricated in a humid atmosphere

    Science.gov (United States)

    Zhai, Yong; Li, Fumin; Guo, Mingxuan; Chen, Chong

    2017-12-01

    The stability of perovskite solar cell has been a problem which prevents the commercialization process. Herein, the perovskite solar cells with CuInS2 and PH1000 films as hole transport materials are fabricated and the device performances are compared with each other in ambient atmosphere with air and 55% relative humidity. The results show that the perovskite solar cell with CuInS2 as hole transport material have better stability and higher energy conversion efficiency compared to the cell with the PH1000, indicating that CuInS2 is a better hole-transporting material which can keep the stability of the perovskite solar cells.

  5. The Høvsøre Tall Wind-Profile Experiment: A Description of Wind Profile Observations in the Atmospheric Boundary Layer

    DEFF Research Database (Denmark)

    Peña, Alfredo; Floors, Rogier Ralph; Gryning, Sven-Erik

    2014-01-01

    at a meteorological mast. The sonic measurements cover the first 100mand the wind lidar measures above 100m every 50min the vertical. Results of the analysis of observations of the horizontal wind-speed components in the range 10–1200 m and surface turbulence fluxes are illustrated in detail, combined with forcing...... for the analysis of vertical wind-speed profiles under a wide range of atmospheric stability, turbulence, and forcing conditions. One of the objectives of the campaign was to serve as a benchmark for flow over flat terrain models. The observations consist of combined wind lidar and sonic anemometer measurements...

  6. Effect of growth conditions on the Al composition and optical properties of Al x Ga 1−x N layers grown by atmospheric-pressure metal organic vapor phase epitaxy

    KAUST Repository

    Soltani, S.

    2017-02-17

    The effect of growth conditions on the Al composition and optical properties of AlxGa1-xN layers grown by atmospheric-pressure metal organic vapor phase epitaxy is investigated. The Al content of the samples is varied between 3.0% and 9.3% by changing the gas flow rate of either trimethylaluminum (TMA) or trimethylgallium (TMG) while other growth parameters are kept constant. The optical properties of the AlxGa1-xN layers are studied by photoreflectance and time-resolved photoluminescence (TR-PL) spectroscopies. A degeneration in the material quality of the samples is revealed when the Al content is increased by increasing the TMA flow rate. When the TMG flow rate is decreased with a fixed TMA flow rate, the Al content of the AlxGa1-xN layers is increased and, furthermore, an improvement in the optical properties corresponding with an increase in the PL decay time is observed. (C) 2017 Elsevier B.V. All rights reserved.

  7. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  8. On the modeling of electrical boundary layer (electrode layer) and ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 119; Issue 1. On the modeling of electrical boundary layer (electrode layer) and derivation of atmospheric electrical profiles, eddy diffusion coeffcient and scales of electrode layer. Madhuri N Kulkarni. Volume 119 Issue 1 February 2010 pp 75-86 ...

  9. Modeling turbulent flows in the atmospheric boundary layer of Mars: application to Gale crater, Mars, landing site of the Curiosity rover

    Science.gov (United States)

    Anderson, William

    2017-04-01

    Mars is a dry planet with a thin atmosphere. Aeolian processes - wind-driven mobilization of sediment and dust - are the exclusive mode of landscape variability on Mars. Craters are common topographic features on the surface of Mars, and many craters on Mars contain a prominent central mound (NASA's Curiosity rover was landed in Gale crater). Using density-normalized large-eddy simulations, we have modeled turbulent flows over crater-like topographies that feature a central mound. We have also run one simulation of flow over a digital elevation map of Gale crater. Resultant datasets suggest a deflationary mechanism wherein vortices shed from the upwind crater rim are realigned to conform to the crater profile via stretching and tilting. This was accomplished using three-dimensional datasets (momentum and vorticity) retrieved from LES. As a result, helical vortices occupy the inner region of the crater and, therefore, are primarily responsible for aeolian morphodynamics in the crater. We have also used the immersed-boundary method body force distribution to compute the aerodynamic surface stress on the crater. These results suggest that secondary flows - originating from flow separation at the crater - have played an important role in shaping landscape features observed in craters (including the dune fields observed on Mars, many of which are actively evolving).

  10. Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (Dp = 50 nm particles in the continental boundary layer: parameterization using a multivariate mixed effects model

    Directory of Open Access Journals (Sweden)

    M. C. Facchini

    2011-01-01

    Full Text Available Measurements of aerosol size distribution and different gas and meteorological parameters, made in three polluted sites in Central and Southern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany, were analysed for this study to examine which of the meteorological and trace gas variables affect the number concentration of Aitken (Dp= 50 nm particles. The aim of our study was to predict the number concentration of 50 nm particles by a combination of in-situ meteorological and gas phase parameters. The statistical model needs to describe, amongst others, the factors affecting the growth of newly formed aerosol particles (below 10 nm to 50 nm size, but also sources of direct particle emissions in that size range. As the analysis method we used multivariate nonlinear mixed effects model. Hourly averages of gas and meteorological parameters measured at the stations were used as predictor variables; the best predictive model was attained with a combination of relative humidity, new particle formation event probability, temperature, condensation sink and concentrations of SO2, NO2 and ozone. The seasonal variation was also taken into account in the mixed model structure. Model simulations with the Global Model of Aerosol Processes (GLOMAP indicate that the parameterization can be used as a part of a larger atmospheric model to predict the concentration of climatically active particles. As an additional benefit, the introduced model framework is, in theory, applicable for any kind of measured aerosol parameter.

  11. Estimation of the turbulence energy dissipation rate in the atmospheric boundary layer from measurements of the radial wind velocity by micropulse coherent Doppler lidar.

    Science.gov (United States)

    Banakh, V A; Smalikho, I N; Falits, A V

    2017-09-18

    The accuracy of the method of azimuth structure function for estimation of the dissipation rate of the kinetic energy of turbulence from an array of radial velocities measured by low-energy micropulse coherent Doppler lidars with conical scanning by a probing beam around the vertical axis has been studied numerically. The applicability of the method in dependence on the turbulence intensity and the signal-to-noise ratio has been determined. The method of azimuth structure function was applied for estimation of the turbulent energy dissipation rate from radial velocities measured by the lidar in the experiments on the coast of Lake Baikal. Two dimensional time-height patterns of the wind turbulence energy dissipation rate were obtained. Part of them were obtained in presence of the atmospheric internal waves (AIWs) and low-level jet streams. It is observed that the wind turbulence in the area occupied by jet streams is very weak. In the process of dissipation of AIWs the wind turbulence strength increases.

  12. Atmospheric HCH concentrations over the Marine Boundary Layer from Shanghai, China to the Arctic Ocean: role of human activity and climate change.

    Science.gov (United States)

    Wu, Xiaoguo; Lam, James C W; Xia, Chonghuan; Kang, Hui; Sun, Liguang; Xie, Zhouqing; Lam, Paul K S

    2010-11-15

    From July to September 2008, air samples were collected aboard the research expedition icebreaker XueLong (Snow Dragon) as part of the 2008 Chinese Arctic Research Expedition Program. Hexachlorocyclohexane (HCH) concentrations were analyzed in all of the samples. The average concentrations (± standard deviation) over the entire period were 33 ± 16, 5.4 ± 3.0, and 13 ± 7.5 pg m⁻³ for α-, β- and γ-HCH, respectively. Compared to previous studies in the same areas, total HCH (ΣHCH, the sum of α-, β-, and γ-HCH) levels declined by more than 10 × compared to those observed in the 1990s, but were approximately 4 × higher than those measured by the 2003 China Arctic Research Expedition, suggesting the increase of atmospheric ΣHCH recently. Because of the continuing use of lindane, ratios of α/γ-HCH showed an obvious decrease in North Pacific and Arctic region compared with those for 2003 Chinese Arctic Research Expedition. In Arctic, the level of α-HCH was found to be linked to sea ice distribution. Geographically, the average concentration of α-HCH in air samples from the Chukchi and Beaufort Seas, neither of which contain sea ice, was 23 ± 4.4 pg m⁻³, while samples from the area covered by seasonal ice (∼75°N to ∼83°N), the so-called "floating sea ice region", contained the highest average levels of α-HCH at 48 ± 12 pg m⁻³, likely due to emission from sea ice and strong air-sea exchange. The lowest concentrations of α-HCH were observed in the pack ice region in the high Arctic covered by multiyear sea ice (∼83°N to ∼86°N). This phenomenon implies that the re-emission of HCH trapped in ice sheets and Arctic Ocean may accelerate during the summer as ice coverage in the Arctic Ocean decreases in response to global climate change.

  13. Clean Air Slots Amid Atmospheric Pollution

    Science.gov (United States)

    Hobbs, Peter V.

    2002-01-01

    This article investigates the mechanism for those layers in the atmosphere that are free of air borne pollution even though the air above and below them carry pollutants. Atmospheric subsidence is posed as a mechanism for this phenomenon.

  14. Venus: Jet-setting atmosphere

    Science.gov (United States)

    Hauchecorne, Alain

    2017-09-01

    A fast equatorial jet in the Venusian cloud layer has been revealed by the Akatsuki orbiter by tracking cloud movement in near-infrared images. The findings suggest that the Venusian atmosphere is more variable than previously thought.

  15. Organic chemistry in Titan's atmosphere

    Science.gov (United States)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  16. Haze in Pluto's atmosphere

    Science.gov (United States)

    Cheng, A. F.; Summers, M. E.; Gladstone, G. R.; Strobel, D. F.; Young, L. A.; Lavvas, P.; Kammer, J. A.; Lisse, C. M.; Parker, A. H.; Young, E. F.; Stern, S. A.; Weaver, H. A.; Olkin, C. B.; Ennico, K.

    2017-07-01

    Haze in Pluto's atmosphere was detected in images by both the Long Range Reconnaissance Imager (LORRI) and the Multispectral Visible Imaging Camera (MVIC) on New Horizons. LORRI observed haze up to altitudes of at least 200 km above Pluto's surface at solar phase angles from ∼20° to ∼169°. The haze is structured with about ∼20 layers, and the extinction due to haze is greater in the northern hemisphere than at equatorial or southern latitudes. However, more haze layers are discerned at equatorial latitudes. A search for temporal variations found no evidence for motions of haze layers (temporal changes in layer altitudes) on time scales of 2 to 5 hours, but did find evidence of changes in haze scale height above 100 km altitude. An ultraviolet extinction attributable to the atmospheric haze was also detected by the ALICE ultraviolet spectrograph on New Horizons. The haze particles are strongly forward-scattering in the visible, and a microphysical model of haze is presented which reproduces the visible phase function just above the surface with 0.5 μm spherical particles, but also invokes fractal aggregate particles to fit the visible phase function at 45 km altitude and account for UV extinction. A model of haze layer generation by orographic excitation of gravity waves is presented. This model accounts for the observed layer thickness and distribution with altitude. Haze particles settle out of the atmosphere and onto Pluto's surface, at a rate sufficient to alter surface optical properties on seasonal time scales. Pluto's regional scale albedo contrasts may be preserved in the face of the haze deposition by atmospheric collapse.

  17. Detection of Atmospheric Composition Based on Lidar

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jinye; Tong Yala; Yang Xiaoling; Gong Jiaoli [School of science, Hubei University of Technology, Wuhan 430068 (China); Gong Wei, E-mail: yezi.zh@163.com [State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079 (China)

    2011-02-01

    A summary overview about the types of lidar and their own applications on atmosphere detection is presented. Measurement of atmospheric aerosols by Mie lidar and Raman lidar is focused. The vertical profiles of aerosols in the atmosphere are retrieved. And at the same time, through analyzing aerosol vertical content distribution, the atmosphere boundary layer and the cloud are also observed. All the results show that the lidar has good performance on detecting the atmospheric composition.

  18. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    Through the coupling of dispositif with atmosphere this paper engages in a discussion of the atmospherics as both a form of knowledge and a material practice. In doing so the objective is to provide an inventory of tools and methodologies deployed in the construction of atmosphere understood......, the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...

  19. On the modeling of electrical boundary layer (electrode layer) and ...

    Indian Academy of Sciences (India)

    The profiles of atmospheric electric field and electrical conductivity are also derived and a new term named as electrode layer constant is ... electrical conductivity and thickness of electrode layer (Willett 1978). A new simple method ... variation of the coefficient of eddy diffusivity. In all his calculations he had assumed the ...

  20. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily exper......” implications and qualities of the approach are identified through concrete examples of a design case, which also investigates the qualities and implications of addressing atmospheres both as design concern and user experience.......This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design...

  1. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  2. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  3. Urban atmospheres.

    Science.gov (United States)

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  4. Atmospheric Infancy

    DEFF Research Database (Denmark)

    Roald, Tone; Pedersen, Ida Egmose; Levin, Kasper

    2017-01-01

    In this article we establish intersubjective meaning-making in infancy as atmospheric. Through qualitative descriptions of five mother–infant dyads in a video-recorded, experimental setting when the infant is 4, 7, 10, and 13 months, we discovered atmospheric appearances with a developmental...... pattern of atmospheric variations. These appearances, we argue, are contextual and intersubjective monologues. The monologues are similar to what Daniel Stern describes with his concept of “vitality affects,” but they arise as a unified force that envelops the mother and child. As such, we present a new...

  5. Atmospheric neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, University of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)

    2004-12-01

    Neutrino oscillation was discovered through the study of atmospheric neutrinos. Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron neutrinos and muon neutrinos are produced mainly by the decay chain of charged pions to muons and electrons. Depending on the energy of the neutrinos, atmospheric neutrinos are observed as fully contained events, partially contained events and upward-going muon events. The energy range covered by these events is from a few hundred MeV to >1 TeV. Data from various experiments showed zenith angle- and energy-dependent deficit of {nu}{sub {mu}} events, while {nu}{sub e} events did not show any such effect. It was also shown that the {nu}{sub {mu}} survival probability obeys the sinusoidal function as predicted by neutrino oscillations. Two-flavour {nu}{sub {mu}} {r_reversible} {nu}{sub {tau}} oscillations, with sin{sup 2} 2{theta} > 0.90 and {delta}m{sup 2} in the region of 1.9 x 10{sup -3} to 3.0 x 10{sup -3} eV{sup 2}, explain all these data. Various detailed studies using high statistics atmospheric neutrino data excluded the alternative hypotheses that were proposed to explain the {nu}{sub {mu}} deficit.

  6. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  7. Exploring the Atmosphere Using Smartphones

    Science.gov (United States)

    Monteiro, Martin; Vogt, Patrik; Stari, Cecilia; Cabeza, Cecilia; Marti, Arturo C.

    2016-01-01

    The characteristics of the inner layer of the atmosphere, the troposphere, are determinant for Earth's life. In this experience we explore the first hundreds of meters using a smartphone mounted on a quadcopter. Both the altitude and the pressure are obtained using the smartphone's sensors. We complement these measures with data collected from the…

  8. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    Nurses working in the Neuro-Intensive Care Unit at Aarhus University Hospital lack the tools to prepare children for the alarming atmosphere they will enter when visiting a hospitalised relative. The complex soundscape dominated by alarms and sounds from equipment is mentioned as the main stressor...

  9. Atmospheric humidity

    Science.gov (United States)

    Water vapor plays a critical role in earth's atmosphere. It helps to maintain a habitable surface temperature through absorption of outgoing longwave radiation, and it transfers trmendous amounts of energy from the tropics toward the poles by absorbing latent heat during evaporation and subsequently...

  10. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  11. Pre-LBA Rondonia Boundary Layer Experiment (RBLE) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The atmospheric boundary layer (ABL) is the layer of air closest to the ground which is directly influenced on a daily basis by the heating and cooling of the...

  12. Pre-LBA Rondonia Boundary Layer Experiment (RBLE) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The atmospheric boundary layer (ABL) is the layer of air closest to the ground which is directly influenced on a daily basis by the heating and cooling of...

  13. Space Science in Action: Earth's Atmosphere [Videotape].

    Science.gov (United States)

    1999

    In this videotape recording, students learn about the layers of the atmosphere and why each is important to the survival of life on the planet. Students discover why the atmosphere is responsible for weather and see how special aircraft actually fly into hurricanes. Students build their own working barometer in a hands-on activity. Contents…

  14. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    A disjunction between the material and the immaterial has been at the heart of the architectural debate for decades. In this dialectic tension, the notion of atmosphere which increasingly claims attention in architectural discourse seems to be parallactic, leading to the re-evaluation of perceptual...... experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... and complex interferences revealed through our perception; ‘the atmospheric’ is explored as a spatial and affective quality as well as a sensory background, and materiality as a powerful and almost magical agency in shaping of atmosphere. Challenging existing dichotomies and unraveling intrinsic...

  15. Ozone Layer Research and Technical Resources

    Science.gov (United States)

    Access information on research and technical resources related to ozone layer science. This page provides links to research efforts led by organizations such as the National Oceanic and Atmospheric Administration, the United Nations Environment Program, an

  16. Circumpolar Active-Layer Permafrost System (CAPS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Circumpolar Active-Layer Permafrost System (CAPS) contains over 100 data sets pertaining to permafrost and frozen ground topics. It also contains detailed...

  17. Sorbent-Based Atmosphere Revitalization System

    Science.gov (United States)

    Knox, James C (Inventor); Miller, Lee A. (Inventor)

    2017-01-01

    The present invention is a sorbent-based atmosphere revitalization (SBAR) system using treatment beds each having a bed housing, primary and secondary moisture adsorbent layers, and a primary carbon dioxide adsorbent layer. Each bed includes a redirecting plenum between moisture adsorbent layers, inlet and outlet ports connected to inlet and outlet valves, respectively, and bypass ports connected to the redirecting plenums. The SBAR system also includes at least one bypass valve connected to the bypass ports. An inlet channel connects inlet valves to an atmosphere source. An outlet channel connects the bypass valve and outlet valves to the atmosphere source. A vacuum channel connects inlet valves, the bypass valve and outlet valves to a vacuum source. In use, one bed treats air from the atmosphere source while another bed undergoes regeneration. During regeneration, the inlet, bypass, and outlet valves sequentially open to the vacuum source, removing accumulated moisture and carbon dioxide.

  18. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  19. Identification of a surface layer structure and analysis of humidity ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    2Atmospheric Science Research Group, Physics Department, Jadavpur University, Kolkata 700 032, India. ∗e-mail: deutpal@hotmail.com. The Monsoon Trough Boundary Layer Experiment held in 1990 was a multi-institutional effort to probe the atmospheric boundary layer over the monsoon trough over northern India.

  20. Boundary-Layer & health

    Science.gov (United States)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  1. Phytoremediation of Atmospheric Methane

    Science.gov (United States)

    2013-04-15

    photosynthetically fixing it into their tissues.  To calculate the atmospheric conductance or mass transfer  coefficient in vegetated fields of  maize  we used...uptake through aerodynamic and leaf boundary layers and the stomata of  maize  at  field scale as determined by continuous stable isotope measurements... digestion  with specific homing endonucleases (Figure 4).  Completion of the triple vector construction of mmoX, Y and Z in E. coli was confirmed by PCR

  2. Estimation of urban mixed layer height in Zanjan using LIDAR ...

    Indian Academy of Sciences (India)

    pollutants on radiation budget of the atmosphere. The lowest part of the atmosphere namely the atmospheric boundary layer (ABL) has a thick- ness which is quite variable in time and space over land, ranging from hundreds of meters to a few kilometers (Stull 1988). However, over the ocean as the sea surface temperature ...

  3. Atmospheric science and power production

    Energy Technology Data Exchange (ETDEWEB)

    Randerson, D. (ed.)

    1984-07-01

    This is the third in a series of scientific publications sponsored by the US Atomic Energy Commission and the two later organizations, the US Energy Research and Development Adminstration, and the US Department of Energy. The first book, Meteorology and Atomic Energy, was published in 1955; the second, in 1968. The present volume is designed to update and to expand upon many of the important concepts presented previously. However, the present edition draws heavily on recent contributions made by atmospheric science to the analysis of air quality and on results originating from research conducted and completed in the 1970s. Special emphasis is placed on how atmospheric science can contribute to solving problems relating to the fate of combustion products released into the atmosphere. The framework of this book is built around the concept of air-quality modeling. Fundamentals are addressed first to equip the reader with basic background information and to focus on available meteorological instrumentation and to emphasize the importance of data management procedures. Atmospheric physics and field experiments are described in detail to provide an overview of atmospheric boundary layer processes, of how air flows around obstacles, and of the mechanism of plume rise. Atmospheric chemistry and removal processes are also detailed to provide fundamental knowledge on how gases and particulate matter can be transformed while in the atmosphere and how they can be removed from the atmosphere. The book closes with a review of how air-quality models are being applied to solve a wide variety of problems. Separate analytics have been prepared for each chapter.

  4. The effect of annealing atmosphere on magnetoelectric coupling of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3} layered heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingxian, E-mail: wxlltx@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455002 (China); Wang, Hongwei [School of Mathematics and Statistics, Anyang Normal University, Anyang 455002 (China); Ju, Lin; Tang, Zhenjie; Ma, Dongwei [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455002 (China); Li, Kuoshe [National Engineering Research Central for Rare earth Materials, Beijing 100088 (China)

    2015-10-15

    The epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3} (LSMO/BTO) layered heterostructure was grown on (001) oriented LaAlO{sub 3} single-crystal substrate by pulsed laser deposition. Our results showed that the in-situ annealing process in oxygen made the LSMO/BTO interface possess higher oxygen content than that of the one annealing in vacuum, which leaded to the LSMO film presented higher magnetic permeability and higher saturated magnetization. The P–E hystersis loop only could be detected in the sample annealing in oxygen. The ME voltage coefficient of the LSMO/BTO heterostructure annealing in oxygen was higher than that of the one annealing in vacuum, which suggested a more effective ME coupling. It was a combined effect of the two main ME coupling mechanisms, including strain mediation, and polarized carrier mediation.

  5. Surface Temperature and Surface-Layer Turbulence in a Convective Boundary Layer

    NARCIS (Netherlands)

    Garai, A.; Pardyjak, E.; Steeneveld, G.J.; Kleissl, J.

    2013-01-01

    Previous laboratory and atmospheric experiments have shown that turbulence influences the surface temperature in a convective boundary layer. The main objective of this study is to examine land-atmosphere coupled heat transport mechanism for different stability conditions. High frequency infrared

  6. Influences on the Height of the Stable Boundary Layer as seen in LES

    Energy Technology Data Exchange (ETDEWEB)

    Kosovic, B; Lundquist, J

    2004-06-15

    Climate models, numerical weather prediction (NWP) models, and atmospheric dispersion models often rely on parameterizations of planetary boundary layer height. In the case of a stable boundary layer, errors in boundary layer height estimation can result in gross errors in boundary-layer evolution and in prediction of turbulent mixing within the boundary layer.

  7. Turbulent dispersion in cloud-topped boundary layers

    NARCIS (Netherlands)

    Verzijlbergh, R.A.; Jonker, H.J.J.; Heus, T.; Vilà-Guerau de Arellano, J.

    2009-01-01

    Compared to dry boundary layers, dispersion in cloud-topped boundary layers has received less attention. In this LES based numerical study we investigate the dispersion of a passive tracer in the form of Lagrangian particles for four kinds of atmospheric boundary layers: 1) a dry convective boundary

  8. Atmospheric corrosion of mild steel

    Directory of Open Access Journals (Sweden)

    Morcillo, M.

    2011-10-01

    Full Text Available The atmospheric corrosion of mild steel is an extensive topic that has been studied by many authors in different regions throughout the world. This compilation paper incorporates relevant publications on the subject, in particular about the nature of atmospheric corrosion products, mechanisms of atmospheric corrosion and kinetics of the atmospheric corrosion process, paying special attention to two matters upon which relatively less information has been published: a the morphology of steel corrosion products and corrosion product layers; and b long-term atmospheric corrosion ( > 10 years.

    La corrosión atmosférica del acero suave es un tema de gran amplitud que ha sido tratado por muchos autores en numerosas regiones del mundo. Este artículo de compilación incorpora publicaciones relevantes sobre esta temática, en particular sobre la naturaleza de los productos de corrosión atmosférica, mecanismos y cinética de los procesos de corrosión atmosférica, prestando una atención especial a dos aspectos sobre los que la información publicada ha sido menos abundante: a morfología de los productos de corrosión del acero y capas de productos de corrosión, y b corrosión atmosférica a larga duración (> 10 años.

  9. Modelling the Arctic Stable boundary layer and its coupling to the surface

    NARCIS (Netherlands)

    Steeneveld, G.J.; Wiel, van de B.J.H.; Holtslag, A.A.M.

    2006-01-01

    The impact of coupling the atmosphere to the surface energy balance is examined for the stable boundary layer, as an extension of the first GABLS (GEWEX Atmospheric Boundary-Layer Study) one-dimensional model intercomparison. This coupling is of major importance for the stable boundary-layer

  10. Micrometeorological studies for the characterization of the atmospheric superficial layer in the Valley of Mexico; Estudios micrometeorologicos para la caracterizacion de la capa atmosferica superficial en el Valle de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Saldana Flores, Ricardo; Salcido Gonzalez, Victor A.; Borja Diaz, Marco Antonio R.; Morales Reyes, Maria Flor [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1995-12-31

    This work establishes the principal aspects related to two micrometeorological campaigns carried out in the Valley of Mexico, the first one from May 19 to 27, 1992 in the vicinity of the Valle de Mexico thermoelectric central and the second from September 13 to 21, 1993 in a site nearby the recreational lake of the Texcoco Plan. The first campaign of measurements encompassed the monitoring at ground level (at a height of 10 meters) of the following parameters: -wind orthogonal components; -temperature; -relative humidity; -Global radiation; - Net radiation; -Atmospheric pressure. Also, simultaneously five daily radio soundings were performed through a captive balloon and free soundings, up to an approximate height of 2500 meters. During the second campaign the same measurements as in the first campaign were carried out, except the radio soundings with the captive balloon, incorporating a turbulence ultrasonic sensor with which, among other parameters, were obtained: -Mean velocities of the wind orthogonal components; -Mean temperature; -Covariance of the wind component z and temperature; -Friction velocity; -Monin-Obukov length; -Vertical heat flow; -Wind mean velocity; -Wind mean direction. [Espanol] En el presente trabajo se anotan los principales aspectos relativos a dos campanas micrometeorologicas realizadas en el Valle de Mexico, la primera del 19 al 27 de mayo de 1992 en las inmediaciones de la central termoelectrica Valle de Mexico y la segunda del 13 al 21 de septiembre de 1993, en un sitio cercano al lago recreativo del Plan Texcoco. La primera campana de mediciones abarco el monitoreo en superficie (a 10 m de altura) de los siguientes parametros: - Componentes ortogonales del viento. - Temperatura. - Humedad relativa. - Radiacion global. - Radiacion neta. - Presion atmosferica. Asimismo, se llevaron a cabo simultaneamente cinco radiosondeos diarios a traves de un globo cautivo y de sondas libres, hasta una altura aproximada de 2500 metros. Durante la

  11. Aircraft wake vortices in the atmosphere

    Science.gov (United States)

    Gerz, Thomas; Holzäpfel, Frank; Hofbauer, Thomas; Dörnbrack, Andreas; Frech, Michael

    The studies summarized here were motivated by the need to gain information (i) about the impact of aircraft emissions upon the atmosphere and the climate and (ii) about optimized separation distances between aircraft landing at an airport for possibly increasing its capacity. To this end, large-eddy simulations have been performed to learn about the behaviour of vortex wakes shed by cruising aircraft in the free atmosphere and in the atmospheric boundary layer close to the ground. Some results are best illustrated in animated form and may be found under http://www.pa.op.dlr.de/wirbelschleppe/WakeVortex.html.

  12. Deviations from LTE in a stellar atmosphere

    Science.gov (United States)

    Kalkofen, W.; Klein, R. I.; Stein, R. F.

    1979-01-01

    Deviations for LTE are investigated in an atmosphere of hydrogen atoms with one bound level, satisfying the equations of radiative, hydrostatic, and statistical equilibrium. The departure coefficient and the kinetic temperature as functions of the frequency dependence of the radiative cross section are studied analytically and numerically. Near the outer boundary of the atmosphere, the departure coefficient is smaller than unity when the radiative cross section grows with frequency faster than with the square of frequency; it exceeds unity otherwise. Far from the boundary the departure coefficient tends to exceed unity for any frequency dependence of the radiative cross section. Overpopulation always implies that the kinetic temperature in the statistical-equilibrium atmosphere is higher than the temperature in the corresponding LTE atmosphere. Upper and lower bounds on the kinetic temperature are given for an atmosphere with deviations from LTE only in the optically shallow layers when the emergent intensity can be described by a radiation temperature.

  13. Atmospheric Prebiotic Chemistry and Organic Hazes

    Science.gov (United States)

    Trainer, Melissa G.

    2012-01-01

    Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

  14. Forecasting global atmospheric CO2

    Science.gov (United States)

    Agustí-Panareda, A.; Massart, S.; Chevallier, F.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Ciais, P.; Deutscher, N. M.; Engelen, R.; Jones, L.; Kivi, R.; Paris, J.-D.; Peuch, V.-H.; Sherlock, V.; Vermeulen, A. T.; Wennberg, P. O.; Wunch, D.

    2014-11-01

    A new global atmospheric carbon dioxide (CO2) real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate - Interim Implementation (MACC-II) service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP) system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 products retrieved from satellite measurements and

  15. Atmosphere: Power, Critique, Politics

    DEFF Research Database (Denmark)

    Albertsen, Niels

    2016-01-01

    This paper hans three interrelated parts. First, atmosphere is approached through the concept of power. Atmospheres 'grip' us directly or mediate power indirectly by manipulating moods and evoking emotions. How does atmosphere relate to different conceptions of power? Second, atmospheric powers may...

  16. From closing the atmospheric ozone hole to reducing climate change. Lessons learned

    National Research Council Canada - National Science Library

    Ewart, Gary W; Rom, William N; Braman, Sidney S; Pinkerton, Kent E

    2015-01-01

    ... the ozone layer of the earth's atmosphere. The process that led to global agreement on reducing depletion of the ozone layer holds valuable lessons, and some ironies, for scientists and policy makers seeking now to address global climate change...

  17. A global climatology of boundary layer ventilation

    Science.gov (United States)

    McNamara, David; Plant, Robert; Belcher, Stephen

    2013-04-01

    The general circulation pattern of the Earth's atmosphere is well known, however there has been relatively little effort to quantify the climatological effects of the buffer zone known as the atmospheric boundary layer. Turbulent motions in the atmospheric boundary layer act to mix the layer along with its constituent pollutants, below a temperature inversion which separates it from the free troposphere. Exchanges between the boundary layer and free troposphere can occur through the mechanisms of convection, isentropic uplift, and coastal and orographic venting. In particular the rate at which pollutants are removed from the atmosphere can be different depending on whether or not they are resident within the boundary layer or the free troposphere. Thus the limiting factor on the concentrations of, for example, certain eg NOx, pollutants in the free troposphere will be the rate at which they are vented from the boundary layer. A global climatology (spanning 10 years between 1995 and 2005) of boundary layer venting is presented here using the ERA-interim dataset which has a grid scale resolution of 0.7 degrees x 0.7 degrees. The boundary layer height is first calculated using a bulk Richardson number method and then an associated vertical velocity is found by linearly interpolating between the two model levels either side of the boundary layer height. This value along with the change in height of the boundary layer over a 3 hour period is used to give an estimate of the rate of venting. The climatology of this rate allows us to describe and quantify the areas of the globe that are responsible for boundary layer entrainment and boundary layer venting, which could be used as a basis for further comparisons with other suitable datasets. We will also present results for the climatology of the boundary layer height itself. [possibly? That could be attractive for a BL audience anyway] Furthermore we will present and discuss results from a method designed to isolate the

  18. Stochastic models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2003-01-01

    Simple stochastic differential equation models have been applied by several researchers to describe the dispersion of tracer particles in the planetary atmospheric boundary layer and to form the basis for computer simulations of particle paths. To obtain the drift coefficient, empirical vertical...... velocity distributions that depend on height above the ground both with respect to standard deviation and skewness are substituted into the stationary Fokker/Planck equation. The particle position distribution is taken to be uniform *the well/mixed condition( and also a given dispersion coefficient...

  19. Detecting recovery of the stratospheric ozone layer

    Science.gov (United States)

    Chipperfield, Martyn P.; Bekki, Slimane; Dhomse, Sandip; Harris, Neil R. P.; Hassler, Birgit; Hossaini, Ryan; Steinbrecht, Wolfgang; Thiéblemont, Rémi; Weber, Mark

    2017-09-01

    As a result of the 1987 Montreal Protocol and its amendments, the atmospheric loading of anthropogenic ozone-depleting substances is decreasing. Accordingly, the stratospheric ozone layer is expected to recover. However, short data records and atmospheric variability confound the search for early signs of recovery, and climate change is masking ozone recovery from ozone-depleting substances in some regions and will increasingly affect the extent of recovery. Here we discuss the nature and timescales of ozone recovery, and explore the extent to which it can be currently detected in different atmospheric regions.

  20. Helicity in dynamic atmospheric processes

    Science.gov (United States)

    Kurgansky, M. V.

    2017-03-01

    An overview on the helicity of the velocity field and the role played by this concept in modern research in the field of geophysical fluid dynamics and dynamic meteorology is given. Different (both previously known in the literature and first presented) formulations of the equation of helicity balance in atmospheric motions (including those with allowance for effects of air compressibility and Earth's rotation) are brought together. Equations and relationships are given which are valid in different approximations accepted in dynamic meteorology: Boussinesq approximation, quasi-static approximation, and quasi-geostrophic approximation. Emphasis is placed on the analysis of helicity budget in large-scale quasi-geostrophic systems of motion; a formula for the helicity flux across the upper boundary of the nonlinear Ekman boundary layer is given, and this flux is shown to be exactly compensated for by the helicity destruction inside the Ekman boundary layer.

  1. The Prospect of Responsive Spacecraft Using Aeroassisted, Trans-Atmospheric Maneuvers

    Science.gov (United States)

    2014-06-19

    composition – in the upper atmosphere has been demonstrated to deteriorate the ozone layer and chemically contaminate the water cycle.179 Not...at least a mono- layer ” of atomic oxygen on its surface either by mechanisms of chemisorption or physisorption. With this layer present on the TAV... layer of atomic oxygen and enters the exosphere, atmospheric species predominance shifts from oxygen to helium, and then to hydrogen. King-Hele explains

  2. Impacts of climate warming on atmospheric phase transition mechanisms

    Science.gov (United States)

    Varotsos, Costas A.; Ghosh, Satyajit

    2017-11-01

    Nowadays, climate change is a fact, and its impacts on heterogeneous chemistry mechanisms that take place in various atmospheric layers are of great interest. As an example, the uptake of atmospheric species on solid and liquid surfaces induces qualitative and quantitative changes from climatic alterations of the atmospheric thermal regime. We hereby present the experience gained on this subject by analysing real measurements of various atmospheric species and parameters conducted in Athens, Greece, exploring the atmospheric height region from the Earth's surface up to the lower stratosphere.

  3. Asymmetry of atmospheric microstructure over synoptic scales

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    Full Text Available Distortions are often seen in the angular distribution of echo-power from VHF wind-profiling radars, suggesting that thin stable layers, within the air flow, are distorted and tilted from horizontal. In vertical shear of the horizontal wind, the distribution of the layer tilt angles becomes skewed. A case study using six days of VHF radar data and synoptic charts above western Europe indicates that this asymmetry of atmospheric microstructure can exist throughout the troposphere and lower stratosphere, above and below the jet wind maximum, over horizontal scales of thousands of kilometres.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; synoptic-scale meteorology; turbulence.

  4. Tailoring graphene layer-to-layer growth

    Science.gov (United States)

    Li, Yongtao; Wu, Bin; Guo, Wei; Wang, Lifeng; Li, Jingbo; Liu, Yunqi

    2017-06-01

    A layered material grown between a substrate and the upper layer involves complex interactions and a confined reaction space, representing an unusual growth mode. Here, we show multi-layer graphene domains grown on liquid or solid Cu by the chemical vapor deposition method via this ‘double-substrate’ mode. We demonstrate the interlayer-induced coupling effect on the twist angle in bi- and multi-layer graphene. We discover dramatic growth disunity for different graphene layers, which is explained by the ideas of a chemical ‘gate’ and a material transport process within a confined space. These key results lead to a consistent framework for understanding the dynamic evolution of multi-layered graphene flakes and tailoring the layer-to-layer growth for practical applications.

  5. Modeling the summertime Arctic cloudy boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J.A.; Pinto, J.O. [Univ. of Colorado, Boulder, CO (United States); McInnes, K.L. [CSIRO Division of Atmospheric Research, Mordialloc (Australia)

    1996-04-01

    Global climate models have particular difficulty in simulating the low-level clouds during the Arctic summer. Model problems are exacerbated in the polar regions by the complicated vertical structure of the Arctic boundary layer. The presence of multiple cloud layers, a humidity inversion above cloud top, and vertical fluxes in the cloud that are decoupled from the surface fluxes, identified in Curry et al. (1988), suggest that models containing sophisticated physical parameterizations would be required to accurately model this region. Accurate modeling of the vertical structure of multiple cloud layers in climate models is important for determination of the surface radiative fluxes. This study focuses on the problem of modeling the layered structure of the Arctic summertime boundary-layer clouds and in particular, the representation of the more complex boundary layer type consisting of a stable foggy surface layer surmounted by a cloud-topped mixed layer. A hierarchical modeling/diagnosis approach is used. A case study from the summertime Arctic Stratus Experiment is examined. A high-resolution, one-dimensional model of turbulence and radiation is tested against the observations and is then used in sensitivity studies to infer the optimal conditions for maintaining two separate layers in the Arctic summertime boundary layer. A three-dimensional mesoscale atmospheric model is then used to simulate the interaction of this cloud deck with the large-scale atmospheric dynamics. An assessment of the improvements needed to the parameterizations of the boundary layer, cloud microphysics, and radiation in the 3-D model is made.

  6. Atmosphere-Ionosphere Coupling via Atmospheric Waves

    Science.gov (United States)

    Koucka Knizova, Petra; Lastovicka, Jan

    2017-04-01

    The Earth atmosphere and ionosphere is complicated and highly variable system which displays oscillations on wide range scales. The most important factor influencing the ionosphere is certainly the solar and geomagnetic activity. However, the processes even in distant regions in the neutral atmosphere cannot be simply neglected. This contribution reviews aspects of ionospheric variability originating in the lower laying atmosphere. It focuses especially on the generation and propagation of the atmospheric waves from their source region up to the heights of the ionosphere. We will show the role of infrasound, gravity waves, tides and planetary waves in the atmosphere-ionosphere coupling. Particularly gravity waves are of high importance for the ionosphere. Recent theoretical and experimental results will briefly be reviewed.

  7. Resilience Indicator Summaries and Resilience Scores CNMI Layer Package

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ArcGIS layer package of relative classifications (low to high) for six resilience indicators and two anthropogenic stressors and a map of final relative resilience...

  8. The effect of atmospheric corona treatment on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

    2010-01-01

    The effect of atmospheric corona discharge on AM 050 aluminium surface was investigated using electrochemical polarization, SEM-EDX, FIB-SEM. and XPS. The corona treatment was performed with varying time (1, 5, and 15 min) in atmospheric air. A 200 nm oxide layer was generated on AA1050 after...

  9. Atmospherics: A Look at the Earth's Airy Shell.

    Science.gov (United States)

    Byalko, A. V.

    1991-01-01

    Describes differences in the composition, pressure, and temperature at distinct altitudes of the Earth's atmosphere from the point of view of physical laws. Discusses the genesis and importance of ozone, thermal radiation and the "layer cake" arrangement of the atmosphere, and solar energy in connection with thermal equilibrium. (JJK)

  10. Study of the coastal atmospheric boundary layer during ESCOMPTE 2001. Evaluation and improvement of the efficiency of a UHF radar; Etude de la couche limite atmospherique cotiere durant ESCOMPTE 2001. Evaluation et amelioration des performances d'un radar UHF

    Energy Technology Data Exchange (ETDEWEB)

    Puygrenier, V.

    2005-12-15

    Forecasting of pollution events was the main objective of the ESCOMPTE-2001 campaign, which took place in the Marseille/Fos/Berre heterogeneous area (southeastern France) in the early summer 2001. This goal requires good understanding and taking into account, by physico-chemical numerical models, of the physical processes in the Atmospheric Boundary Layer (ABL), in which pollutants are emitted, transported and diffused. In the ESCOMPTE-2001 campaign context, this work was devoted to study the low troposphere during sea breeze events, related to meteorological conditions responsible for poor air quality of coastal areas. It presents notably an oscillation of the sea breeze intensity and competitions of locals and regional sea breeze, which change the advective time of the marine air above the continental surface and thus influence the ABL development and its pollutants concentration. This study is based principally on the network of four UHF wind profilers radars set up on the coastal area of Marseille/Fos/Berre, allowing a continuous three-dimensional description of the sea breeze flow and the ABL. For the needs of this phenomenological work, methodological developments was realized to improve the measurement of ABL turbulent properties with UHF radars (terms of turbulent kinetic energy budget) and the use of wind profilers network for the study of pollutants plumes trajectory-graphy. (author)

  11. Ozone Layer Observations

    Science.gov (United States)

    McPeters, Richard; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The US National Aeronautics and Space Administration (NASA) has been monitoring the ozone layer from space using optical remote sensing techniques since 1970. With concern over catalytic destruction of ozone (mid-1970s) and the development of the Antarctic ozone hole (mid-1980s), long term ozone monitoring has become the primary focus of NASA's series of ozone measuring instruments. A series of TOMS (Total Ozone Mapping Spectrometer) and SBUV (Solar Backscatter Ultraviolet) instruments has produced a nearly continuous record of global ozone from 1979 to the present. These instruments infer ozone by measuring sunlight backscattered from the atmosphere in the ultraviolet through differential absorption. These measurements have documented a 15 Dobson Unit drop in global average ozone since 1980, and the declines in ozone in the antarctic each October have been far more dramatic. Instruments that measure the ozone vertical distribution, the SBUV and SAGE (Stratospheric Aerosol and Gas Experiment) instruments for example, show that the largest changes are occurring in the lower stratosphere and upper troposphere. The goal of ozone measurement in the next decades will be to document the predicted recovery of the ozone layer as CFC (chlorofluorocarbon) levels decline. This will require a continuation of global measurements of total column ozone on a global basis, but using data from successor instruments to TOMS. Hyperspectral instruments capable of measuring in the UV will be needed for this purpose. Establishing the relative roles of chemistry and dynamics will require instruments to measure ozone in the troposphere and in the stratosphere with good vertical resolution. Instruments that can measure other chemicals important to ozone formation and destruction will also be needed.

  12. Atmospheric structure from Phoenix atmospheric entry data

    Science.gov (United States)

    Catling, D. C.

    2008-12-01

    The atmospheric structure at the time of landing of NASA's Phoenix probe has been derived from measurements of the aerodynamic drag of the spacecraft during atmospheric entry and descent. The result provides the first atmospheric structure in Mars' polar environment obtained from in situ measurements. Phoenix was equipped with an inertial measurement unit (IMU) that used accelerometers for linear acceleration measurement in three Cartesian axes and ring-laser gyroscopes to measure the three- dimensional orientation of the probe (Taylor et al., 2008). The temperature structure of the atmosphere along the flight path was calculated via a four-step process: (i) integrating forward the IMU data to obtain the time history of the spacecraft velocity vector relative to the atmosphere as a function of altitude; (ii) calculating atmospheric density from drag, with iteration for aerodynamic coefficient dependence on density; (iii) integrating the hydrostatic equation to derive the vertical pressure; and (iv) calculating atmospheric temperature from the equation of state. Initial profile reconstruction shows reasonable agreement with predictions in the middle atmosphere for the given season and time of day (landing occurred at 16h 33min 37sec in local solar time expressed as a 24-hour clock). However, the derived lower atmospheric structure below ~0.1 mbar is generally warmer than predicted. A possible explanation could be a shallower vertical distribution of dust that usually assumed. References: P. A. Taylor, D. C. Catling, M. Daly, C. S. Dickinson, H. O. Gunnlaugsson, A-M. Harri, C. F. Lange, Temperature, pressure and wind instrumentation on the Phoenix meteorological package, J. Geophys. Res., 113, EA0A10, doi:10.1029/2007JE003015, 2008.

  13. Atmospheric stability and complex terrain: comparing measurements and CFD

    DEFF Research Database (Denmark)

    Koblitz, Tilman; Bechmann, Andreas; Berg, Jacob

    2014-01-01

    For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface layer. So far, physical processes that are specific to the atmospheric boundary layer, for example the Coriolis force...

  14. Planetary Atmospheric Electricity

    CERN Document Server

    Leblanc, F; Yair, Y; Harrison, R. G; Lebreton, J. P; Blanc, M

    2008-01-01

    This volume presents our contemporary understanding of atmospheric electricity at Earth and in other solar system atmospheres. It is written by experts in terrestrial atmospheric electricity and planetary scientists. Many of the key issues related to planetary atmospheric electricity are discussed. The physics presented in this book includes ionisation processes in planetary atmospheres, charge generation and separation, and a discussion of electromagnetic signatures of atmospheric discharges. The measurement of thunderstorms and lightning, including its effects and hazards, is highlighted by articles on ground and space based instrumentation, and new missions.Theory and modelling of planetary atmospheric electricity complete this review of the research that is undertaken in this exciting field of space science. This book is an essential research tool for space scientists and geoscientists interested in electrical effects in atmospheres and planetary systems. Graduate students and researchers who are new to t...

  15. Mirador - Atmospheric Composition

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. Atmospheric Composition is focused on the composition of Earth's atmosphere in relation to climate prediction, solar effects,...

  16. Modeling Turbulence Generation in the Atmospheric Surface and Boundary Layers

    Science.gov (United States)

    2015-10-01

    order of kilometers—requiring on the order of 1018 computational cells—would be practically impossible given even today’s supercomputing resources . Thus...fairly easily from web resources . The mnemonics for these variables were selected as follows: LATTNE is latitude of the site of interest in degrees north...w(t)] = ∞∫ 0 e− stw (t) dt = W (s). (4.4) Standard transform and inverse-transform tables will be used to provide the results needed to express the

  17. Boundary Layer Dust Occurrence III Atmospheric Dust Over Russia

    Science.gov (United States)

    1977-05-01

    valley of the Syr - Darya , near easily-blown sands. Conditions analogous to Takhiatash and, consequently, a number of 358 dust storm days exceeding an...1 AD Reports Control Syr OSD-1366 ECOM DR 75-2 pt.3 c.l RESEARCH AND DEVELOPMENT TECHNICAL REPORT ECOM-DR-77-2 t.ND AFB, N. M...dust stream was 60 and even 100 units in the lower Don region and in the eastern and northern Azov region, 30 to 40 units in the Don and Volga delta

  18. Hydrodynamic and optical measurements in the atmosphere boundary layer

    Science.gov (United States)

    2007-01-01

    The Volpe National Transportation Systems Center (Volpe) supports the NASA Wake Vortex program in data collection, analysis and modeling of the airplane work vortex data to improve operations at a number of airports that experience capacity constrain...

  19. CFD Modeling of Non-Neutral Atmospheric Boundary Layer Conditions

    DEFF Research Database (Denmark)

    Koblitz, Tilman

    cost than e.g. using large-eddy simulations. The developed ABL model is successfully validated using a range of different test cases with increasing complexity. Data from several large scale field campaigns, wind tunnel experiments, and previous numerical simulations is presented and compared against...... model results. A method is developed how to simulate the time-dependant non-neutral ABL flow over complex terrain: a precursor simulation is used to specify unsteady inlet boundary conditions on complex terrain domains. The advantage of the developed RANS model framework is its general applicability....... All implementations in the ABL model are tuning free, and except for standard site specific input parameters, no additional model coefficients need to be specified before the simulation. In summary the results show that the implemented modifications are applicable and reproduce the main flow...

  20. A case study of atmospheric boundary layer features during winter ...

    Indian Academy of Sciences (India)

    ... reanalysis winds over Kharagpur to estimate the convergence of wind, moisture and vorticity to understand the observed variations in wind speed and relative humidity, and also the increased aerosol concentrations. The variation of ventilation coefficient (VC), a factor determining the air pollution potential over a region, ...

  1. Extreme Vertical Gusts in the Atmospheric Boundary Layer

    Science.gov (United States)

    2015-07-01

    it applies to the Southern hemisphere . Terrain, latitude, surface heating and moisture supply all have major effects on their behaviour. The cold...unrealistically severe at low altitudes. This is thought to be because, outside of specific meteorological phenomena (thunder storms, mountain waves and...paper is to promote discussion within the meteorological and aeronautical research communities as to whether this contention is correct. To facilitate

  2. Observations of the atmospheric surface layer parameters over a ...

    Indian Academy of Sciences (India)

    The spectra of the wind components and temperature indicated decrease in spectral power by one order in magnitude during the eclipse period. The rate of dissipation of turbulent kinetic energy is found to decrease by more than one order during the eclipse period. The stability parameter showed a change from unstable to ...

  3. Impact of Wind Farms on the Marine Atmospheric Boundary Layer

    DEFF Research Database (Denmark)

    Volker, Patrick J.H.; Hall, Alex; Capps, Scott B.

    The presented work is part of a study sponsored by the California Institute of Energy and Environment, in which the impact of the aimed increasing contribution of clean alternative energy sources in the next 30 years will be investigated. Due to the huge wind energy potential along the California...

  4. Atmospheric Boundary Layer Characteristics during BOBMEX-Pilot ...

    Indian Academy of Sciences (India)

    Pilot experiment are reported. Surface meteorological data were acquired continuously through an automatic weather monitoring system and manually every three hours. High resolution radiosondes were launched to obtain the vertical thermal ...

  5. Innovation in Layer-by-Layer Assembly.

    Science.gov (United States)

    Richardson, Joseph J; Cui, Jiwei; Björnmalm, Mattias; Braunger, Julia A; Ejima, Hirotaka; Caruso, Frank

    2016-12-14

    Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques. In this Review, we explore, discuss, and detail innovation in layer-by-layer assembly in terms of past and present developments, and we highlight how these might guide future advances. A particular focus is on conventional and early developments that have only recently regained interest in the layer-by-layer assembly field. We then review unconventional assemblies and approaches that have been gaining popularity, which include inorganic/organic hybrid materials, cells and tissues, and the use of stereocomplexation, patterning, and dip-pen lithography, to name a few. A relatively recent development is the use of layer-by-layer assembly materials and techniques to assemble films in a single continuous step. We name this "quasi"-layer-by-layer assembly and discuss the impacts and innovations surrounding this approach. Finally, the application of characterization methods to monitor and evaluate layer-by-layer assembly is discussed, as innovation in this area is often overlooked but is essential for development of the field. While we intend for this Review to be easily accessible and act as a guide to researchers new to layer-by-layer assembly, we also believe it will provide insight to current researchers in the field and help guide future developments and innovation.

  6. Secondary Atmospheres on HD 219134 b and c

    Science.gov (United States)

    Dorn, Caroline; Heng, Kevin

    2018-01-01

    We analyze the interiors of HD 219134 b and c, which are among the coolest super-Earths detected thus far. Without using spectroscopic measurements, we aim at constraining if the possible atmospheres are hydrogen-rich or hydrogen-poor. In the first step, we employ a full probabilistic Bayesian inference analysis to rigorously quantify the degeneracy of interior parameters given the data of mass, radius, refractory element abundances, semimajor axes, and stellar irradiation. We obtain constraints on structure and composition for core, mantle, ice layer, and atmosphere. In the second step, we aim to draw conclusions on the nature of possible atmospheres by considering atmospheric escape. Specifically, we compare the actual possible atmospheres to a threshold thickness above which a primordial (H2-dominated) atmosphere can be retained against evaporation over the planet’s lifetime. The best-constrained parameters are the individual layer thicknesses. The maximum radius fraction of possible atmospheres are 0.18 and 0.13 R (radius), for planets b and c, respectively. These values are significantly smaller than the threshold thicknesses of primordial atmospheres: 0.28 and 0.19 R, respectively. Thus, the possible atmospheres of planets b and c are unlikely to be H2-dominated. However, whether possible volatile layers are made of gas or liquid/solid water cannot be uniquely determined. Our main conclusions are (1) the possible atmospheres for planets b and c are enriched and thus possibly secondary in nature, and (2) both planets may contain a gas layer, whereas the layer of HD 219134 b must be larger. HD 219134 c can be rocky.

  7. Atmospheric refraction : a history

    NARCIS (Netherlands)

    Lehn, WH; van der Werf, S

    2005-01-01

    We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of

  8. Lidar observations of mixed layer dynamics - Tests of parameterized entrainment models of mixed layer growth rate

    Science.gov (United States)

    Boers, R.; Eloranta, E. W.; Coulter, R. L.

    1984-01-01

    Ground based lidar measurements of the atmospheric mixed layer depth, the entrainment zone depth and the wind speed and wind direction were used to test various parameterized entrainment models of mixed layer growth rate. Six case studies under clear air convective conditions over flat terrain in central Illinois are presented. It is shown that surface heating alone accounts for a major portion of the rise of the mixed layer on all days. A new set of entrainment model constants was determined which optimized height predictions for the dataset. Under convective conditions, the shape of the mixed layer height prediction curves closely resembled the observed shapes. Under conditions when significant wind shear was present, the shape of the height prediction curve departed from the data suggesting deficiencies in the parameterization of shear production. Development of small cumulus clouds on top of the layer is shown to affect mixed layer depths in the afternoon growth phase.

  9. Work on Planetary Atmospheres and Planetary Atmosphere Probes

    Science.gov (United States)

    Lester, Peter

    1999-01-01

    , greenhouse effectiveness, and the thermal structure. The researcher also reviewed problems with the Pioneer Venus Probe, that caused anomalies which occurred on the Probes at and below 12.5 km level of the Venus' atmosphere. He convened and participated in a workshop that concluded the most likely hardware cause was insulation failure in the electrical harness outside the Probes' pressure vessels. It was discovered that the shrink tubing material failed at 600K. This failure could explain the anomalies experienced by the probes. The descent data of the Pioneer probes, and the Soviet Vega Lander was analyzed to evaluate the presence of small scale gravity waves in and below the Venus cloud layer.

  10. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Yates, Jack S.; Palmer, Paul I. [School of GeoSciences, University of Edinburgh (United Kingdom); Biller, Beth; Cockell, Charles S., E-mail: j.s.yates@ed.ac.uk [Centre for Exoplanet Science, University of Edinburgh (United Kingdom)

    2017-02-20

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μ m spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 10{sup 9} cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

  11. Infrasound data inversion for atmospheric sounding

    Science.gov (United States)

    Lalande, J.-M.; Sèbe, O.; Landès, M.; Blanc-Benon, Ph.; Matoza, R. S.; Le Pichon, A.; Blanc, E.

    2012-07-01

    The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) continuously records acoustic waves in the 0.01-10 Hz frequency band, known as infrasound. These waves propagate through the layered structure of the atmosphere. Coherent infrasonic waves are produced by a variety of anthropogenic and natural sources and their propagation is controlled by spatiotemporal variations of temperature and wind velocity. Natural stratification of atmospheric properties (e.g. temperature, density and winds) forms waveguides, allowing long-range propagation of infrasound waves. However, atmospheric specifications used in infrasound propagation modelling suffer from lack and sparsity of available data above an altitude of 50 km. As infrasound can propagate in the upper atmosphere up to 120 km, we assume that infrasonic data could be used for sounding the atmosphere, analogous to the use of seismic data to infer solid Earth structure and the use of hydroacoustic data to infer oceanic structure. We therefore develop an inversion scheme for vertical atmospheric wind profiles in the framework of an iterative linear inversion. The forward problem is treated in the high-frequency approximation using a Hamiltonian formulation and complete first-order ray perturbation theory is developed to construct the Fréchet derivatives matrix. We introduce a specific parametrization for the unknown model parameters based on Principal Component Analysis. Finally, our algorithm is tested on synthetic data cases spanning different seasonal periods and network configurations. The results show that our approach is suitable for infrasound atmospheric sounding on a regional scale.

  12. Numerical simulation of the marine boundary layer characteristics ...

    Indian Academy of Sciences (India)

    A one-dimensional multi- level atmospheric boundary layer with TKE- closure scheme is employed to study the marine boundary layer characteristics. In this study two synoptic situations are chosen: one represents an active convection case and the other a suppressed convection. In the present article the marine ...

  13. Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models

    Science.gov (United States)

    Song, J.; Wang, Z.

    2013-12-01

    Studying urban land-atmospheric interactions by coupling an urban canopy model with a single column atmospheric models Jiyun Song and Zhi-Hua Wang School of Sustainable Engineering and the Built Environment, Arizona State University, PO Box 875306, Tempe, AZ 85287-5306 Landuse landcover changes in urban area will modify surface energy budgets, turbulent fluxes as well as dynamic and thermodynamic structures of the overlying atmospheric boundary layer (ABL). In order to study urban land-atmospheric interactions, we coupled a single column atmospheric model (SCM) to a cutting-edge single layer urban canopy model (SLUCM). Modification of surface parameters such as the fraction of vegetation and engineered pavements, thermal properties of building and pavement materials, and geometrical features of street canyon, etc. in SLUCM dictates the evolution of surface balance of energy, water and momentum. The land surface states then provide lower boundary conditions to the overlying atmosphere, which in turn modulates the modification of ABL structure as well as vertical profiles of temperature, humidity, wind speed and tracer gases. The coupled SLUCM-SCM model is tested against field measurements of surface layer fluxes as well as profiles of temperature and humidity in the mixed layer under convective conditions. After model test, SLUCM-SCM is used to simulate the effect of changing urban land surface conditions on the evolution of ABL structure and dynamics. Simulation results show that despite the prescribed atmospheric forcing, land surface states impose significant impact on the physics of the overlying vertical atmospheric layer. Overall, this numerical framework provides a useful standalone modeling tool to assess the impacts of urban land surface conditions on the local hydrometeorology through land-atmospheric interactions. It also has potentially far-reaching implications to urban ecohydrological services for cities under future expansion and climate challenges.

  14. Measurement of the Atmospheric $\

    CERN Document Server

    Aartsen, M G; Abdou, Y; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohaichuk, S; Bohm, C; Bose1, D; Boser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clark, K; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; De Ridder, S; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Diaz-Velez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eberhardt, B; Eisch, J; Ellsworth, R W; Engdegard, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glusenkamp, T; Goldschmidt, A; Golup, G; Goodman, J A; Gora, D; Grant, D; Gross, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Klas, J; Klein, S R; Kohne, J -H; Kohnen, G; Kolanoski, H; Kopke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lunemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meszaros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Perez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Radel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schoneberg, S; Schonherr, L; Schonwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Sheremata, C; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stoss, A; Strahler, E A; Strom, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van der Drift, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge1, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zilles, A; Zoll, M

    2012-01-01

    We report the first observation in a high energy neutrino telescope of cascades induced by atmospheric electron neutrinos and by neutral current interactions of atmospheric neutrinos of all flavors. Using data recorded during the first year of operation of IceCube's DeepCore low energy extension, a sample of 1029 events is observed in 281 days of data. The number of observed cascades is $N_{\\rm cascade} = 496 \\pm 66 (stat.) \\pm 88(syst.)$ and the rest of the sample consists of residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is determined in the energy range between approximately 80 GeV and 6 TeV and is consistent with models of atmospheric neutrinos.

  15. An instrument to measure turbulent eddy fluxes in the atmosphere of Mars

    Science.gov (United States)

    S. Rafkin; D. Banfield; R. Dissly; J. Silver; A. Stanton; E. Wilkinson; W. Massman; J. Ham

    2012-01-01

    Turbulent eddies in the planetary boundary layer of the terrestrial planet atmospheres are the primary mechanism by which energy, momentum, gasses, and aerosols are exchanged between the surface and the atmosphere [1]. The importance of eddies has long been recognized by the Earth atmospheric science community, and turbulent theory for Earth has a long history with a...

  16. Atmospheric Circulation of Exoplanets

    OpenAIRE

    Showman, Adam P.; Cho, James Y-K.; Menou, Kristen

    2009-01-01

    We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from Solar-System studies that are likely to be generalizable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-wate...

  17. Dynamics of layers in geophysical flows

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, J.C.R.; Galmiche, M. [University Coll., London (United Kingdom). Dept. of Space and Climate Physics

    2001-07-01

    The atmosphere and ocean structure consists of horizontal regions with characteristic mean flows, waves and turbulence, separated from each other by semi-permanent thin layers such as the tropopause or the thermocline. At the same time, within these regions, thin layers are continually appearing and dissipating such as clouds and fronts, which largely determine the weather. There are also sharp variations in the horizontal structure of flow and physical processes separated by thin layers with sloping or vertical boundaries (e.g. ozone hole and the intertropical convergence zone). We review here how the mechanisms of waves, wave-mean flow interactions, turbulence distortion, turbulence-wave transformation and Coriolis forces, determine the formation, location and dynamics of these layers. This review provides perspectives on current methods of calculating these critical regions in large-scale numerical models used for weather and ocean forecasting, and for climate prediction. (orig.)

  18. Designing Dynamic Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie; Højlund, Marie

    2012-01-01

    This paper addresses the notion of atmospheres from a designerly perspective, and discusses temporal challenges facing interaction designers when acknowledging the dynamic character of it. As atmospheres are created in the relation between body, space, and time, a pragmatic approach seems useful,....... The potentials and implica-­‐ tions are presented through a design case, Kidkit, highlighting temporality as design parametre within interaction design.......This paper addresses the notion of atmospheres from a designerly perspective, and discusses temporal challenges facing interaction designers when acknowledging the dynamic character of it. As atmospheres are created in the relation between body, space, and time, a pragmatic approach seems useful...

  19. Atmospheric Measurements Laboratory (AML)

    Data.gov (United States)

    Federal Laboratory Consortium — The Atmospheric Measurements Laboratory (AML) is one of the nation's leading research facilities for understanding aerosols, clouds, and their interactions. The AML...

  20. Marine atmospheric corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Morcillo, M.; Alcantara, J.; Diaz, I.; Chico, B.; Simancas, J.; Fuente, D. de la

    2015-07-01

    Basic research on marine atmospheric corrosion of carbon steels is a relatively young scientific field and there continue to be great gaps in this area of knowledge. The presence of akaganeite in the corrosion products that form on steel when it is exposed to marine atmospheres leads to a notable increase in the corrosion rate. This work addresses the following issues: (a) environmental conditions necessary for akaganeite formation; (b) characterisation of akaganeite in the corrosion products formed; (c) corrosion mechanisms of carbon steel in marine atmospheres; (d) exfoliation of rust layers formed in highly aggressive marine atmospheres; (e) long-term corrosion rate prediction; and (f) behaviour of weathering steels. Field research has been carried out at Cabo Vilano wind farm (Camarinas, Galicia) in a wide range of atmospheric salinities and laboratory work involving the use of conventional atmospheric corrosion techniques and near-surface and bulk sensitive analytical techniques: scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Mossbauer spectroscopy and SEM/μRaman spectroscopy. (Author)

  1. Atmospheric stability in CFD &NDASH; Representation of the diurnal cycle in the atmospheric boundary layer

    DEFF Research Database (Denmark)

    Koblitz, Tilman; Bechmann, Andreas; Sogachev, Andrey

    ), for example the Coriolis force, buoyancy forces and heat transport, are mostly ignored in state-of-the-art CFD models. In order to decrease the uncertainty of wind resource assessment, especially in complex terrain, the effect of thermal stratification on the ABL should be included in such models. The present...

  2. Photochemistry of planetary atmospheres. [Mars atmospheric composition

    Science.gov (United States)

    Stief, L. J.

    1973-01-01

    The atmospheric composition of Mars is presented, and the applicability of laboratory data on CO2 absorption cross sections and quantum yields of dissociation is discussed. A summary and critical evaluation are presented on the various mechanisms proposed for converting the photodissociation products CO and O2 back to CO2.

  3. Basic Ozone Layer Science

    Science.gov (United States)

    Learn about the ozone layer and how human activities deplete it. This page provides information on the chemical processes that lead to ozone layer depletion, and scientists' efforts to understand them.

  4. VSWI Wetlands Advisory Layer

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset represents the DEC Wetlands Program's Advisory layer. This layer makes the most up-to-date, non-jurisdictional, wetlands mapping avaiable to the public...

  5. Controlled Atmosphere Stunning

    NARCIS (Netherlands)

    Lambooij, E.; Gerritzen, M.A.

    2009-01-01

    Controlled atmosphere (CAS) stunning includes several variations of gaseous mixtures given to induce an anaesthetic state before slaughter poultry. One method of multi phase CAS is to unload the birds out of the crate on a conveyor belt and subject the birds to an atmosphere of 30% O2, 40% CO2 and

  6. Proterozoic atmospheric oxygen

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene

    2014-01-01

    This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the history...

  7. The Power of Atmosphere

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2014-01-01

    composed of bubbles of affects – that is, the particles that are charged with power and normativity. References Grtiffero, T. (2014 (2010)). Atmospheres: Aesthetics of Emotional Spaces. Ashgate Philippopoulos-Mihalopoulos, A. (2013). Atmospheres of law: Senses, affects, lawscapes, in Emotion, Space...

  8. Designing Dynamic Atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2012-01-01

    This paper addresses the notion of atmospheres from a designerly perspective, and discusses temporal challenges facing interaction designers when acknowledging the dynamic character of it. As atmospheres are created in the relation between body, space, and time, a pragmatic approach seems useful....... The potentials and implications are presented through a design case, Kidkit, highlighting temporality as design parametre within interaction design....

  9. Wrinkling of a two-layer polymeric coating

    Science.gov (United States)

    Basu, Soumendra K.; Bergstreser, Aaron M.; Francis, L. F.; Scriven, L. E.; McCormick, A. V.

    2005-09-01

    Wrinkling of a two-layer coating, comprised of a glassy polyvinyl alcohol top layer and a rubbery polyethyl acrylate bottom layer, was studied. The coatings were prepared on polyethylene terephthalate substrates by depositing and drying the layers in sequence. Fine, short-wavelength (180-200 μm) wrinkles formed when the two-layer coating was exposed to humid atmosphere after the second drying treatment and coarse, long-wavelength (450-500 μm) wrinkles formed when the two-layer coating was heated to a temperature above the glass transition temperature of the top layer. Both types of wrinkles must have arisen from compressive stress in the top layer. The compressive stress developed by either moisture absorption (fine wrinkles) or differential thermal expansion on heating (coarse wrinkles). When compressive stress is high enough, the top layer deforms out of plane without detaching from the bottom layer to produce wrinkles. The balance of forces in systems of three adhering layers of different thicknesses and moduli in static mechanical equilibrium was analyzed, and it was found that the layer with the highest in-plane axial stiffness, the product of elastic modulus by thickness, typically dictates the dimension of the entire composite. When the mismatch of thermal expansivities of the layers generates the compressive stress that produces wrinkling, the difference between the thermal expansivity of the top layer and the axial stiffness-weighted average thermal expansivity of the three layers governs the compressive stress in the top layer. Because polymer modulus falls abruptly at the glass transition temperature Tg, the critical compressive stress required for wrinkling falls abruptly at Tg. Therefore, the two-layer coating atop a stiff substrate is more susceptible to wrinkling when the top layer is above its Tg. When absorption of moisture in the top layer generates the compressive stress that generates wrinkling, that stress goes through a minimum because

  10. Atmosphere Impact Losses

    Science.gov (United States)

    Schlichting, Hilke E.; Mukhopadhyay, Sujoy

    2018-02-01

    Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2

  11. A New Look at Triton's Atmosphere

    Science.gov (United States)

    Person, Michael

    When it was first examined with stellar occultations in the 1990s, Triton's atmosphere was seen to undergo global expansion during the period from 1993 to 1997. This expansion was confirmed as a continuing phenomenon with a stellar occultation observation in 2001 . Unfortunately, as Triton started to pass through a fairly sparse star field, occultation observations have been much more difficult to make. There have been no published occultation data on Triton's atmosphere since the 2001 event, and reported observations in early 2007 had too low of a signal-to-noise ratio to say anything about the atmospheric profile. Thus, it has been over 15 years since the last direct measurement of Triton's expanding atmosphere was made, leaving wide open the question of Triton's current atmospheric state. Is the atmosphere still expanding or is it now collapsing? Are the haze layers seen by Voyager still present? Are the variations seen in the 1990s seasonal or cyclic on shorter time scales due to Triton surface processes? The observation of stellar occultations remains the only way to gain current data on Triton's atmosphere from Earth, and SOFIA's unique ability to be reliably placed in the central flash region of occultation events where the richest dataset is available, and its immunity to low-level weather disturbances make it the ideal platform for updating our knowledge on Triton and beginning to answer these many outstanding questions. We therefore propose to use SOFIA with HIPO, FLITECAM (FLIPO), and the FPI+ to measure temperature, pressure, and particulate haze radial profiles of Triton's atmosphere by observing a stellar occultation which will be visible over the eastern portion of North America in October of 2017. We expect to use FLITECAM/HIPO (FLIPO) Guaranteed Time Observing (GTO) hours for the included observations with the agreement of the FLITECAM and HIPO instrument teams.

  12. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  13. Photonic layered media

    Science.gov (United States)

    Fleming, James G.; Lin, Shawn-Yu

    2002-01-01

    A new class of structured dielectric media which exhibit significant photonic bandstructure has been invented. The new structures, called photonic layered media, are easy to fabricate using existing layer-by-layer growth techniques, and offer the ability to significantly extend our practical ability to tailor the properties of such optical materials.

  14. Atmospheric composition change: Ecosystems–Atmosphere interactions

    DEFF Research Database (Denmark)

    Fowler, D.; Pilegaard, Kim; Sutton, M.A.

    2009-01-01

    in the size range 1 nm–10 μm including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean–atmosphere exchange are included. The material presented is biased...... and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using...... aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement...

  15. Dynamics of Massive Atmospheres

    Science.gov (United States)

    Chemke, Rei; Kaspi, Yohai

    2017-10-01

    The many recently discovered terrestrial exoplanets are expected to hold a wide range of atmospheric masses. Here the dynamic-thermodynamic effects of atmospheric mass on atmospheric circulation are studied using an idealized global circulation model by systematically varying the atmospheric surface pressure. On an Earth analog planet, an increase in atmospheric mass weakens the Hadley circulation and decreases its latitudinal extent. These changes are found to be related to the reduction of the convective fluxes and net radiative cooling (due to the higher atmospheric heat capacity), which, respectively, cool the upper troposphere at mid-low latitudes and warm the troposphere at high latitudes. These together decrease the meridional temperature gradient, tropopause height and static stability. The reduction of these parameters, which play a key role in affecting the flow properties of the tropical circulation, weakens and contracts the Hadley circulation. The reduction of the meridional temperature gradient also decreases the extraction of mean potential energy to the eddy fields and the mean kinetic energy, which weakens the extratropical circulation. The decrease of the eddy kinetic energy decreases the Rhines wavelength, which is found to follow the meridional jet scale. The contraction of the jet scale in the extratropics results in multiple jets and meridional circulation cells as the atmospheric mass increases.

  16. Atmospheric refraction: a history

    Science.gov (United States)

    Lehn, Waldemar H.; van der Werf, Siebren

    2005-09-01

    We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of uniform density up to a sharp upper transition to the ether, at which the refraction occurred. Alhazen and Witelo transmitted his knowledge to medieval Europe. The first accurate measurements were made by Tycho Brahe in the 16th century. Finally, Kepler, who was aware of unusually strong refractions, used the Ptolemaic model to explain the first documented and recognized mirage (the Novaya Zemlya effect).

  17. New atmospheric program

    Science.gov (United States)

    The National Science Foundation's Division of Atmospheric Sciences has established an Upper Atmospheric Facilities program within its Centers and Facilities section. The program will support the operation of and the scientific research that uses the longitudinal chain of incoherent scatter radars. The program also will ensure that the chain is maintained as a state-of-the-art research tool available to all interested and qualified scientists.For additional information, contact Richard A. Behnke, Division of Atmospheric Sciences, National Science Foundation, 1800 G Street, N.W., Washington, DC 20550 (telephone: 202-357-7390).

  18. Discovery of atmospheric neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Tokyo Univ., Inst. for Cosmic Ray Research, Kashiwa, Chiba (Japan)

    2003-05-01

    Cosmic ray particles entering the atmosphere interact with the air nuclei produce neutrinos. These neutrinos are called atmospheric neutrinos. The atmospheric neutrino anomaly observed in Kamiokande is now understood as due to neutrino oscillations by high statistics measurements of the atmospheric neutrinos in Super-Kamiokande. The studies of the atmospheric neutrinos have matured into detailed studies of neutrino masses and mixings. (author)

  19. The Atmospheric Dynamics of Venus

    Science.gov (United States)

    Sánchez-Lavega, Agustín; Lebonnois, Sebastien; Imamura, Takeshi; Read, Peter; Luz, David

    2017-11-01

    We review our current knowledge of the atmospheric dynamics of Venus prior to the Akatsuki mission, in the altitude range from the surface to approximately the cloud tops located at about 100 km altitude. The three-dimensional structure of the wind field in this region has been determined with a variety of techniques over a broad range of spatial and temporal scales (from the mesoscale to planetary, from days to years, in daytime and nighttime), spanning a period of about 50 years (from the 1960s to the present). The global panorama is that the mean atmospheric motions are essentially zonal, dominated by the so-called super-rotation (an atmospheric rotation that is 60 to 80 times faster than that of the planetary body). The zonal winds blow westward (in the same direction as the planet rotation) with a nearly constant speed of ˜ 100 m s^{-1} at the cloud tops (65-70 km altitude) from latitude 50°N to 50°S, then decreasing their speeds monotonically from these latitudes toward the poles. Vertically, the zonal winds decrease with decreasing altitude towards velocities ˜ 1-3 m s^{-1} in a layer of thickness ˜ 10 km close to the surface. Meridional motions with peak speeds of ˜ 15 m s^{-1} occur within the upper cloud at 65 km altitude and are related to a Hadley cell circulation and to the solar thermal tide. Vertical motions with speeds ˜1-3 m s^{-1} occur in the statically unstable layer between altitudes of ˜ 50 - 55 km. All these motions are permanent with speed variations of the order of ˜10%. Various types of wave, from mesoscale gravity waves to Rossby-Kelvin planetary scale waves, have been detected at and above cloud heights, and are considered to be candidates as agents for carrying momentum that drives the super-rotation, although numerical models do not fully reproduce all the observed features. Momentum transport by atmospheric waves and the solar tide is thought to be an indispensable component of the general circulation of the Venus atmosphere

  20. The Atmospheric Dynamics of Venus

    Science.gov (United States)

    Sánchez-Lavega, Agustín; Lebonnois, Sebastien; Imamura, Takeshi; Read, Peter; Luz, David

    2017-08-01

    We review our current knowledge of the atmospheric dynamics of Venus prior to the Akatsuki mission, in the altitude range from the surface to approximately the cloud tops located at about 100 km altitude. The three-dimensional structure of the wind field in this region has been determined with a variety of techniques over a broad range of spatial and temporal scales (from the mesoscale to planetary, from days to years, in daytime and nighttime), spanning a period of about 50 years (from the 1960s to the present). The global panorama is that the mean atmospheric motions are essentially zonal, dominated by the so-called super-rotation (an atmospheric rotation that is 60 to 80 times faster than that of the planetary body). The zonal winds blow westward (in the same direction as the planet rotation) with a nearly constant speed of ˜ 100 m s^{-1} at the cloud tops (65-70 km altitude) from latitude 50°N to 50°S, then decreasing their speeds monotonically from these latitudes toward the poles. Vertically, the zonal winds decrease with decreasing altitude towards velocities ˜ 1-3 m s^{-1} in a layer of thickness ˜ 10 km close to the surface. Meridional motions with peak speeds of ˜ 15 m s^{-1} occur within the upper cloud at 65 km altitude and are related to a Hadley cell circulation and to the solar thermal tide. Vertical motions with speeds ˜1-3 m s^{-1} occur in the statically unstable layer between altitudes of ˜ 50 - 55 km. All these motions are permanent with speed variations of the order of ˜10%. Various types of wave, from mesoscale gravity waves to Rossby-Kelvin planetary scale waves, have been detected at and above cloud heights, and are considered to be candidates as agents for carrying momentum that drives the super-rotation, although numerical models do not fully reproduce all the observed features. Momentum transport by atmospheric waves and the solar tide is thought to be an indispensable component of the general circulation of the Venus atmosphere

  1. A global boundary-layer height climatology

    Energy Technology Data Exchange (ETDEWEB)

    Dop, H. van; Krol, M.; Holtslag, B. [Inst. for Marine and Atmospheric Research Utrecht, IMAU, Utrecht (Netherlands)

    1997-10-01

    In principle the ABL (atmospheric boundary layer) height can be retrieved from atmospheric global circulation models since they contain algorithms which determine the intensity of the turbulence as a function of height. However, these data are not routinely available, or on a (vertical) resolution which is too crude in view of the application. This justifies the development of a separate algorithm in order to define the ABL. The algorithm should include the generation of turbulence by both shear and buoyancy and should be based on readily available atmospheric parameters. There is obviously a wide application for boundary heights in off-line global and regional chemistry and transport modelling. It is also a much used parameter in air pollution meteorology. In this article we shall present a theory which is based on current insights in ABL dynamics. The theory is applicable over land and sea surfaces in all seasons. The theory is (for various reasons) not valid in mountainous areas. In areas where boundary-layer clouds or deep cumulus convection are present the theory does not apply. However, the same global atmospheric circulation models contain parameterizations for shallow and deep convection from which separate estimates can be obtained for the extent of vertical mixing. (au)

  2. Atmospheric Transport Modeling Resources

    Energy Technology Data Exchange (ETDEWEB)

    Mazzola, Carl A. [Stone and Webster Engineering Corporation, Aiken, SC (United States); Addis, Robert P. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-03-01

    The purpose of this publication is to provide DOE and other federal agency emergency managers with an in-depth compilation and description of atmospheric dispersion models available to DOE and other Federal sites.

  3. Atmospheric Heavy Metal Pollution

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 4. Atmospheric Heavy Metal Pollution - Development of Chronological Records and Geochemical Monitoring. Rohit Shrivastav. General Article Volume 6 Issue 4 April 2001 pp 62-68 ...

  4. Students 'Weigh' Atmospheric Pollution.

    Science.gov (United States)

    Caporaloni, Marina

    1998-01-01

    Describes a procedure developed by students that measures the mass concentration of particles in a polluted urban atmosphere. Uses a portable fan and filters of various materials. Compares students' data with official data. (DDR)

  5. Piezoelectric Resonator with Two Layers

    Science.gov (United States)

    Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)

    2013-01-01

    A piezoelectric resonator device includes: a top electrode layer with a patterned structure, a top piezoelectric layer adjacent to the top layer, a middle metal layer adjacent to the top piezoelectric layer opposite the top layer, a bottom piezoelectric layer adjacent to the middle layer opposite the top piezoelectric layer, and a bottom electrode layer with a patterned structure and adjacent to the bottom piezoelectric layer opposite the middle layer. The top layer includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top layer and a first one of the electrodes in the bottom layer are coupled to a first contact, and a second one of the electrodes in the top layer and a second one of the electrodes in the bottom layer are coupled to a second contact.

  6. Global atmospheric changes.

    OpenAIRE

    Piver, W T

    1991-01-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

  7. Dynamics in Atmospheric Physics

    Science.gov (United States)

    Lindzen, Richard A.

    2005-08-01

    Motion is manifest in the atmosphere in an almost infinite variety of ways. In Dynamics in Atmospheric Physics, Dr. Richard Lindzen describes the nature of motion in the atmosphere, develops fluid dynamics relevant to the atmosphere, and explores the role of motion in determining the climate and atmospheric composition. The author presents the material in a lecture note style, and the emphasis throughout is on describing phenomena that are at the frontiers of current research, but due attention is given to the methodology of research and to the historical background of these topics. The author's treatment and choice of topics is didactic. Problems at the end of each chapter will help students assimilate the material. In general the discussions emphasize physical concepts, and throughout Dr. Lindzen makes a concerted effort to avoid the notion that dynamic meteorology is simply the derivation of equations and their subsequent solution. His desire is that interested students will delve further into solution details. The book is intended as a text for first year graduate students in the atmospheric sciences. Although the material in the book is self contained, a familiarity with differential equations is assumed; some background in fluid mechanics is helpful.

  8. Modeling Transport Layer Protocols

    Science.gov (United States)

    Sasnauskas, Raimondas; Weingaertner, Elias

    In a layered communication architecture, transport layer protocols handle the data exchange between processes on different hosts over potentially lossy communication channels. Typically, transport layer protocols are either connection-oriented or are based on the transmission of individual datagrams. Well known transport protocols are the connection-oriented Transmission Control Protocol (TCP) [372] and the User Datagram Protocol (UDP) [370] as well as the Stream Control Transmission Protocol (SCTP) [340] and DCCP, the Datagram Congestion Control Protocol [259]. In this chapter, we focus on the modeling process of the transport layer. While we mostly use TCP and UDP as a base of comparison from this point, we emphasize that the methodologies discussed further on are conferrable to virtually any transport layer in any layered communication architecture.

  9. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  10. Probing the Sunspot Atmosphere with Three-Minute Oscillations

    Science.gov (United States)

    Deres, Anastasiia; Anfinogentov, Sergey

    2018-01-01

    We present a seismological method for probing the solar atmosphere above sunspot umbrae with three-minute oscillations. Our technique allows us to estimate both the vertical distance between atmospheric layers and the wave-propagation speed, without specifying any additional parameters, in particular, the phase speed of the wave or the emission formation heights. Our method uses the projected wave paths of slow magnetohydrodynamic waves that propagate through the atmospheric layers of different heights and are guided by the magnetic field. The length of the projected wave path depends upon the distance between the layers and the inclination angle of the magnetic field with respect to the line of sight, allowing us to estimate the distance between the layers from measured projected wave paths and the local magnetic-field vector. In turn, the wave-propagation delay registered at different heights allows for the calculation of the phase speed. We estimated the vertical distance between the emission layers at the temperature minimum (1600 Å) and transition region (304 Å), as well as the average phase speed above the sunspot umbrae, for three active regions. We found that the distance between the 1600 Å emission layer and the transition region above the sunspot umbrae lies in the range of 500 - 800 km. The average phase speed between these layers was found to be about 30 km s-1, giving a sound speed of 6 km s-1. The temperature between the layers has been roughly estimated as 3000 K and corresponds to the region of the temperature minimum. The results obtained are consistent with the semiempirical model of the sunspot-umbrae atmosphere by Fontenla et al. ( Astrophys. J. 707, 482, 2009).

  11. Future active layer dynamics and carbon dioxide production from thawing permafrost layers in Northeast Greenland

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    from a moist permafrost soil in High-Arctic Greenland with observed heat production and carbon dioxide (CO2) release rates from decomposition of previously frozen organic matter. Observations show that the maximum thickness of the active layer at the end of the summer has increased 1 cm yr-1 since 1996......Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures....... The model is successfully adjusted and applied for the study area and shown to be able to simulate active layer dynamics. Subsequently, the model is used to predict the active layer thickness under future warming scenarios. The model predicts an increase of maximum active layer thickness from today 70 to 80...

  12. Layering in Provenance Systems

    OpenAIRE

    Seltzer, Margo I.; Muniswamy-Reddy, Kiran-Kumar; Braun, Uri Jacob; Holland, David A.; Macko, Peter; Maclean, Diana; Margo, Daniel Wyatt; Smogor, Robin

    2009-01-01

    Digital provenance describes the ancestry or history of a digital object. Most existing provenance systems, however, operate at only one level of abstraction: the sys- tem call layer, a workflow specification, or the high-level constructs of a particular application. The provenance collectable in each of these layers is different, and all of it can be important. Single-layer systems fail to account for the different levels of abstraction at which users need to reason about their data and proc...

  13. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  14. Electroless atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, David Bruce; Cappillino, Patrick J.; Sheridan, Leah B.; Stickney, John L.; Benson, David M.

    2017-10-31

    A method of electroless atomic layer deposition is described. The method electrolessly generates a layer of sacrificial material on a surface of a first material. The method adds doses of a solution of a second material to the substrate. The method performs a galvanic exchange reaction to oxidize away the layer of the sacrificial material and deposit a layer of the second material on the surface of the first material. The method can be repeated for a plurality of iterations in order to deposit a desired thickness of the second material on the surface of the first material.

  15. Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

  16. Atmospheric Circulation of Exoplanets

    Science.gov (United States)

    Showman, A. P.; Cho, J. Y.-K.; Menou, K.

    2010-12-01

    We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from solar system studies that are likely to be generalizable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-water, and two-dimensional nondivergent models. We then survey key concepts in atmospheric dynamics, including the importance of planetary rotation, the concept of balance, and simple scaling arguments to show how turbulent interactions generally produce large-scale east-west banding on rotating planets. We next turn to issues specific to giant planets, including their expected interior and atmospheric thermal structures, the implications for their wind patterns, and mechanisms to pump their east-west jets. Hot Jupiter atmospheric dynamics are given particular attention, as these close-in planets have been the subject of most of the concrete developments in the study of exoplanetary atmospheres. We then turn to the basic elements of circulation on terrestrial planets as inferred from solar system studies, including Hadley cells, jet streams, processes that govern the large-scale horizontal temperature contrasts, and climate, and we discuss how these insights may apply to terrestrial exoplanets. Although exoplanets surely possess a greater diversity of circulation regimes than seen on the planets in our solar system, our guiding philosophy is that the multidecade study of solar system planets reviewed here provides a foundation upon which our understanding of more exotic exoplanetary meteorology must build.

  17. Atmospheric Change on Pluto

    Science.gov (United States)

    Person, Michael

    2013-10-01

    We propose to use SOFIA with HIPO and FLITECAM (FLIPO) to measure the parameters of Pluto's atmosphere (temperature, pressure, possible particulate haze) by observing a stellar occultation by Pluto on 15 November 2014. Due to its highly elliptical orbit and seasonally variable obliquity, Pluto's atmosphere is predicted to condense onto its surface within the next ~10 years and possibly within the next few years and thus frequent observations are critical. Detection of the occultation central flash will allow measurement of the structure of Pluto's lower atmosphere and atmospheric oblateness. We will use FLIPO to measure the refracted starlight contemporaneously at visible and infrared wavelengths; this approach is needed to differentiate between two competing explanations for the deficiency in the observed light refracted from Pluto's lower atmosphere (strong thermal gradients versus variable particulate extinction). Only an airborne platform such as SOFIA has the flexibility to place a large telescope in the center of the shadow path of this brief event while at the same time nearly eliminating the possibility of missing time-critical observations due to unfortunate weather systems. Occultation predictions will be updated throughout the period preceding the observations with the goal of achieving sufficient prediction accuracy at the event time to place SOFIA directly in the path of Pluto's central flash. This SOFIA observation will be combined with our ongoing ground-based observing program whose goal is to measure the temporal variability of Pluto's atmosphere in response to its changing seasonal obliquity (and resulting ice migration) and recession from the sun. For the NASA New Horizons mission to Pluto and the Kuiper Belt, this Pluto occultation event represents the last chance, prior to the spacecraft closest approach to the Pluto/Charon system (July 2015), to provide input to the mission for encounter planning, as well as context and supporting atmospheric

  18. Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems (ERASMUS)

    Energy Technology Data Exchange (ETDEWEB)

    Bland, Geoffrey [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)

    2016-06-30

    The use of small unmanned aircraft systems (sUAS) with miniature sensor systems for atmospheric research is an important capability to develop. The Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems (ERASMUS) project, lead by Dr. Gijs de Boer of the Cooperative Institute for Research in Environmental Sciences (CIRES- a partnership of NOAA and CU-Boulder), is a significant milestone in realizing this new potential. This project has clearly demonstrated that the concept of sUAS utilization is valid, and miniature instrumentation can be used to further our understanding of the atmospheric boundary layer in the arctic.

  19. Ozone in the Atlantic Ocean marine boundary layer

    OpenAIRE

    Patrick Boylan; Detlev Helmig; Samuel Oltmans

    2015-01-01

    Abstract In situ atmospheric ozone measurements aboard the R/V Ronald H. Brown during the 2008 Gas-Ex and AMMA research cruises were compared with data from four island and coastal Global Atmospheric Watch stations in the Atlantic Ocean to examine ozone transport in the marine boundary layer (MBL). Ozone measurements made at Tudor Hill, Bermuda, were subjected to continental outflow from the east coast of the United States, which resulted in elevated ozone levels above 50 ppbv. Ozone measurem...

  20. Fundamentals of Atmospheric Radiation

    Science.gov (United States)

    Bohren, Craig F.; Clothiaux, Eugene E.

    2006-02-01

    This textbook fills a gap in the literature for teaching material suitable for students of atmospheric science and courses on atmospheric radiation. It covers the fundamentals of emission, absorption, and scattering of electromagnetic radiation from ultraviolet to infrared and beyond. Much of the book applies to planetary atmosphere. The authors are physicists and teach at the largest meteorology department of the US at Penn State. Craig T. Bohren has taught the atmospheric radiation course there for the past 20 years with no book. Eugene Clothiaux has taken over and added to the course notes. Problems given in the text come from students, colleagues, and correspondents. The design of the figures especially for this book is meant to ease comprehension. Discussions have a graded approach with a thorough treatment of subjects, such as single scattering by particles, at different levels of complexity. The discussion of the multiple scattering theory begins with piles of plates. This simple theory introduces concepts in more advanced theories, i.e. optical thickness, single-scattering albedo, asymmetry parameter. The more complicated theory, the two-stream theory, then takes the reader beyond the pile-of-plates theory. Ideal for advanced undergraduate and graduate students of atmospheric science.

  1. Lidar Scanning of Momentum Flux in the Marine Boundary Layer

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Mann, Jakob; Courtney, Michael

    Momentum flux measurements are important for describing the wind profile in the atmospheric boundary layer, modeling the atmospheric flow over water, the accounting of exchange processes between air and sea, etc. It is also directly related to the friction velocity, which is a velocity scale...... required for wind engineering. Estimations of friction velocity over the sea can be performed by combining wind speed measurements, a sea roughness length formulation and the surface-layer wind profile, i.e. a bulk-derived method. This method was tested in Peña et al. (2008) by comparison with direct...

  2. Atmospheric pollution in Lisbon urban atmosphere

    Science.gov (United States)

    Oliveira, C.

    2009-04-01

    Lisbon is the capital city of Portugal with about 565,000 residents in 2008 and a population density of 6,600 inhabitants per square kilometre. Like several other major metropolis, the town is surrounded by satellite cities, forming together a region known as "Lisbon Metropolitan Area" with about 3 million inhabitants, a quarter of the overall Portuguese population. Besides their local residents, it is estimated that more than one million citizens come into the Lisbon area every day from the outskirts, leading to elevated traffic densities and intense traffic jams, with important consequences on air pollution levels and obvious negative impacts on human health. Airborne particulate matter limit values are frequently exceeded, making urgent the existence of consistent programs to monitor and help taking measures to control them. Within the Portuguese project PAHLIS (Polycyclic Aromatic Hydrocarbons Contamination in Lisbon Urban Atmosphere) financed by the Portuguese Science Foundation ("Fundação para a Ciência e a Tecnologia"), an aerosol and vapour phase sampling program is being implemented in the city of Lisbon at two selected contrasting zones, namely a typically busy area with intense road traffic and frequent exceedences of the particulate matter standard for the maximum allowable concentration, and a residential quieter area, thus with a cleaner atmosphere characterised as an urban background site. An one month-long sampling campaign was performed during the summer of 2008, where particulate matter was collected in two fractions (coarse 2.5µmcommunication, the results of both organic and inorganic analyses of aerosol samples from these two sites will be presented, compared and discussed. Results of this work are expected to cover a lack of reliable information regarding sources of atmospheric pollutants in Portugal and present, for the first time, systematic data of PAHs levels in Lisbon. Acknowledgement: This work was performed under Project PAHLIS (PTDC

  3. Mixing layer height and air pollution levels in urban area

    Science.gov (United States)

    Schäfer, Klaus; Wagner, Patrick; Emeis, Stefan; Jahn, Carsten; Muenkel, Christoph; Suppan, Peter

    2012-10-01

    Ceilometers are applied by KIT/IMK-IFU to detect layering of the lower atmosphere continuously. This is necessary because not only wind speed and direction but also atmospheric layering and especially the mixing layer height (MLH) influence exchange processes of ground level emissions. It will be discussed how the ceilometer monitoring information is used to interpret the air pollution near the ground. The information about atmospheric layering is continuously monitored by uninterrupted remote sensing measurements with the Vaisala ceilometer CL51 which is an eye-safe commercial mini-lidar system. Special software for this ceilometer provides routine retrievals of lower atmosphere layering from vertical profiles of laser backscatter data. An intensive measurement period during the winter 2011/2012 is studied. The meteorological influences upon air pollutant concentrations are investgated and the correlations of air pollutant concentrations with ceilometer MLH are determined. Benzene was detected by department of Applied Climatology and Landscape Ecology, University of Duisburg-Essen (UDE) with a gas chromatograph during the measurement period. The meteorological data are collected by UDE and the monitoring station Essen of the German national meteorological service DWD. The concentrations of the air pollutants NO, NO2 and PM10 are provided by the national air pollution network LANUV.

  4. Multiple density layered insulator

    Science.gov (United States)

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  5. Surface Morphology of Fe(III)-Porphyrin Thin Layers as Characterized by Atomic Force Microscopy

    OpenAIRE

    Utari Utari; Kusumandari Kusumandari; Budi Purnama; Mudasir Mudasir; Kamsul Abraha

    2016-01-01

    Surface morphology of Fe(III)–porphyrin thin layers was studied using atomic force microscopy. The thin layer samples used in these experiments were deposited by spin coating methods on indium–tin-oxide substrates at room temperature under atmospheric conditions. Variations of thin layer of Fe(III)-porphyrin were done by modifying the rotational speed and the concentration of the solution. The experimental results demonstrated that the Fe(III)–porphyrin layers were observed as discrete nanomo...

  6. Phenomenology of atmospheric neutrinos

    Directory of Open Access Journals (Sweden)

    Fedynitch Anatoli

    2016-01-01

    Full Text Available The detection of astrophysical neutrinos, certainly a break-through result, introduced new experimental challenges and fundamental questions about acceleration mechanisms of cosmic rays. On one hand IceCube succeeded in finding an unambiguous proof for the existence of a diffuse astrophysical neutrino flux, on the other hand the precise determination of its spectral index and normalization requires a better knowledge about the atmospheric background at hundreds of TeV and PeV energies. Atmospheric neutrinos in this energy range originate mostly from decays of heavy-flavor mesons, which production in the phase space relevant for prompt leptons is uncertain. Current accelerator-based experiments are limited by detector acceptance and not so much by the collision energy. This paper recaps phenomenological aspects of atmospheric leptons and calculation methods, linking recent progress in flux predictions with particle physics at colliders, in particular the Large Hadron Collider.

  7. Intensifying the Atmospheric

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä

    2012-01-01

    The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its under...... sufficiently intense. All things considered, the paper should be read as a sociological contribution to theoretically reconstruct the concept of urban atmospheres in the light of spatial morphology.......The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its...

  8. Atmospheric pollution; Pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Lambrozo, J.; Guillossou, G. [EDF-Gas de France, Service des Etudes Medicales, 75 - Paris (France)

    2008-10-15

    The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

  9. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  10. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution......; a method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according...

  11. Strategic Environmental Research and Development Program: Atmospheric Remote Sensing and Assessment Program -- Final Report. Part 1: The lower atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Tooman, T.P. [ed.] [Sandia National Labs., Livermore, CA (United States). Exploratory Systems Technology Dept.

    1997-01-01

    This report documents work done between FY91 and FY95 for the lower atmospheric portion of the joint Department of Defense (DoD) and Department of Energy (DOE) Atmospheric Remote Sensing and Assessment Program (ARSAP) within the Strategic Environmental Research and Development Program (SERDP). The work focused on (1) developing new measurement capabilities and (2) measuring atmospheric heating in a well-defined layer and then relating it to cloud properties an water vapor content. Seven new instruments were develop3ed for use with Unmanned Aerospace Vehicles (UAVs) as the host platform for flux, radiance, cloud, and water vapor measurements. Four major field campaigns were undertaken to use these new as well as existing instruments to make critically needed atmospheric measurements. Scientific results include the profiling of clear sky fluxes from near surface to 14 km and the strong indication of cloudy atmosphere absorption of solar radiation considerably greater than predicted by extant models.

  12. Atmospheric Infrared Radiance Variability.

    Science.gov (United States)

    1981-05-27

    ATMOSPHERIC VARIABILITY ON INFRARED RADIANCE PREDICTIONS - T. C. Degges 53 5. ATMOSPHERIC STRUCTURE - C.H. HLmphrey, C.R. Philbrick, S.M. Silverman , T.F. Tuan...variations similar to those shown in Figure 2. In arctic and subarctic regions, sudden warmings and coolings of the winter stratosphere and mesosphere... Silverman \\Jr I",rre. (;.L~~sIalmratorN Hanscom Air Force Base, Manss. T.F. Tuan Universitv of Cincinnati Cincinnati, (tio M. Anapol S.S.G.. Inc. Waltham

  13. Atmosphere and Heritage

    DEFF Research Database (Denmark)

    Ventzel Riis, Nina

    2012-01-01

    -between of the materials. This is what we identify as atmosphere, an enveloping phenomenon that surrounds and affects our sensuous system and well-being when we approach, enter, stay or move in a building. When we leave the building again we carry this atmospheric multi-sensory experience with us without adequate methods...... to describe and document it. In this paper I will introduce both new and traditional approaches to document the architectural heritage with the final conclusion to describe both tangible and intangible values, it requires an objective and geometrical approach as well as a subjective and phenomenological...

  14. Calculating the wind energy input to a system using a spatially explicit method that considers atmospheric stability

    Science.gov (United States)

    Atmospheric stability has a major effect in determining the wind energy doing work in the atmospheric boundary layer (ABL); however, it is seldom considered in determining this value in emergy analyses. One reason that atmospheric stability is not usually considered is that a sui...

  15. NOAA Climate Data Record of Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU-A) Mean Layer Temperature, Version 3.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset contains three channel-based, monthly gridded atmospheric layer temperature Climate Data Records generated by merging nine MSU NOAA polar orbiting...

  16. Laboratory simulation of Hot Jupiters atmosphere expansion

    Science.gov (United States)

    Prokopov, P. A.; Shaikhislamov, I. F.; Zakharov, Yu P.; Posukh, V. G.; Melekhov, A. V.; Boyarintsev, E. L.; Ponomarenko, A. G.

    2017-11-01

    Hot Jupiters (HJ) are exoplanets, gas giants with low orbits (≤ 0.1 a.u.). The stellar X-ray and ultraviolet (XUV) radiation energy deposition result in heating ionization and the consequent expansion of planetary atmosphere. Expansion of upper atmosphere under certain conditions could be so large that the majority of light atmospheric constituents overcome the gravitational binding and escape from the planet in a form of hydrodynamic wind. Besides interaction of two counter-streaming plasma flows (stellar wind and ionized upper layers of planet atmosphere), each of this flows interact with planetary magnetic field. In such complex situation laboratory simulation can provide data that can’t be obtained by computer simulation or observation. Experiment was carried out on KI-1 facility: high-vacuum chamber 5m long, 1.2 m in diameter with pressure ∼ 10-6 Torr. Magnetic dipole with two attached laser targets played the role of a planet, and background plasma from θ-pinch used for simulation of stellar wind. As a result, data on a behavior of plasma density and magnetic field were obtained. The novel phenomenon was registered: magnetic field is transferred by the cloud of laser plasma, which was not observed before in experiments or calculations.

  17. Global atmospheric chemistry of CFC-123.

    Science.gov (United States)

    Prinn, R G; Golombek, A

    1990-03-01

    THE compound 1,1-dichloro-2,2,2-trifluoroethane (CFC-123), which is potentially usable as a foam-blowing agent in the plastics industry, an aerosol propellant and a refrigerant, has been proposed as an industrial substitute for trichlorofluoromethane (CFC-11), the use of which is increasingly restricted because of its effects on the ozone layer and on climate(1-3). It is expected that CFC-123, although like CFC-11 an absorber of infrared radiation, will be less stable in the atmosphere because of its expected reaction with OH radicals in the troposphere. Using a three-dimensional global model of the atmosphere, we have calculated the chemical destruction rates of CFC-123 by various processes, confirming that the chief sink is destruction by OH radicals below 12 km, which accounts for 88% of its loss. The calculated destruction rate is greatest in the equatorial region below 2 km. The calculated steady-state lifetime of CFC-123 is 1.5 years, based on the best available estimate of the rate constant of the reaction with OH. This lifetime is very much shorter than that of CFC-11, the destruction of which is largely confined to the stratosphere. For equal rates (by mass) of CFC-123 and CFC-11 emission to the atmosphere, the molar content in the atmosphere and the injection rate of chlorine into the stratosphere are, respectively, 48 and 14 times greater for CFC-11 than for CFC-123 in steady-state.

  18. Coupled atmosphere-wildland fire modelling

    Directory of Open Access Journals (Sweden)

    Jacques Henri Balbi

    2009-10-01

    Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

  19. Detection of atmospheric muons with ALICE detectors

    Energy Technology Data Exchange (ETDEWEB)

    Alessandro, B. [Istituto Nazionale di Fisica Nucleare and Dep. di Fisica Universita di Torino, Torino (Italy); Cortes Maldonado, I. [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Cuautle, E. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (Mexico); Fernandez Tellez, A. [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Gomez Jimenez, R. [Dpto. de Fisica, Centro de Investigacion y Estudios Avanzados (Mexico); Gonzalez Santos, H. [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Herrera Corral, G. [Escuela de Fisica, Universidad Autonoma de Sinaloa, Culiacan, Sinaloa (Mexico); Leon, I. [Dpto. de Fisica, Centro de Investigacion y Estudios Avanzados (Mexico); Martinez, M.I.; Munoz Mata, J.L. [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Podesta, P. [Dpto. de Fisica, Centro de Investigacion y Estudios Avanzados (Mexico); Ramirez Reyes, A. [Escuela de Fisica, Universidad Autonoma de Sinaloa, Culiacan, Sinaloa (Mexico); Rodriguez Cahuantzi, M., E-mail: mrodrigu@mail.cern.c [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Sitta, M. [Universita Piemonte Orientale, Alessandria (Italy); Subieta, M. [Istituto Nazionale di Fisica Nucleare and Dep. di Fisica Universita di Torino, Torino (Italy); Tejeda Munoz, G.; Vargas, A.; Vergara, S. [Fac. Ciencias Fisico Mat. and Fac. Ciencias Electronica, Benemerita Universidad Autonoma de Puebla (Mexico)

    2010-05-21

    The calibration, alignment and commissioning of most of the ALICE (A Large Ion Collider Experiment at the CERN LHC) detectors have required a large amount of cosmic events during 2008. In particular two types of cosmic triggers have been implemented to record the atmospheric muons passing through ALICE. The first trigger, called ACORDE trigger, is performed by 60 scintillators located on the top of three sides of the large L3 magnet surrounding the central detectors, and selects atmospheric muons. The Silicon Pixel Detector (SPD) installed on the first two layers of the Inner Tracking System (ITS) gives the second trigger, called SPD trigger. This trigger selects mainly events with a single atmospheric muon crossing the SPD. Some particular events, in which the atmospheric muon interacts with the iron of the L3 magnet and creates a shower of particles crossing the SPD, are also selected. In this work the reconstruction of events with these two triggers will be presented. In particular, the performance of the ACORDE detector will be discussed by the analysis of multi-muon events. Some physical distributions are also shown.

  20. Atmospheric neutrino oscillations for earth tomography

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Walter

    2016-04-05

    Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.